[compiler] Phase 4 (batch 2), 5, 6: Update remaining passes for fault tolerance

Update remaining validation passes to record errors on env:
- validateMemoizedEffectDependencies
- validatePreservedManualMemoization
- validateSourceLocations (added env parameter)
- validateContextVariableLValues (changed throwTodo to recordError)
- validateLocalsNotReassignedAfterRender (changed throw to recordError)
- validateNoDerivedComputationsInEffects (changed throw to recordError)

Update inference passes:
- inferMutationAliasingEffects: return void, errors on env
- inferMutationAliasingRanges: return Array<AliasingEffect> directly, errors on env

Update codegen:
- codegenFunction: return CodegenFunction directly, errors on env
- codegenReactiveFunction: same pattern

Update Pipeline.ts to call all passes directly without tryRecord/unwrap.
Also update AnalyseFunctions.ts which called inferMutationAliasingRanges.

compiler/fault-tolerance-overview.md

@@ -0,0 +1,327 @@
+## React Compiler Fault Tolerance
+
+Update React Compiler (@compiler/ directory) to always run all passes and return either the transformed code (if no error) or a list of one or more compilation errors. 
+
+## Background
+
+Currently React Compiler runs through a series of passes in Pipeline.ts. If an error occurs in a pass the compiler will generally either throw the error in the pass where it occurs, or return a Result<_, CompilerError> which is then unwrapped in Pipeline.ts, throwing there. This means that a single error that triggers early can prevent later validation from running, meaning the user has to first fix one error in order to see another.
+
+## New Approach
+
+The compiler should always run all passes in the pipeline, up to and including CodegenReactiveFunction. During this process it should accumulate errors. If at the end of compilation there were no accumulated errors, return `Ok(generatedfunction)`. Else, return `Err(CompilerError)` with *all* the accumulated errors.
+
+Note that some errors may continue to cause an eager bailout:
+* If an error is not an instanceof CompilerError, throw it as it occurs
+* If an error is a CompilerError invariant, throw it as it occurs since this represents a truly exceptional, unexpected case
+
+## Detailed Design
+
+* The Environment needs a way to record errors as compilation proceeds. This should generally store the error (and log, if a logger is configured), but should immediately throw if the error is an invariant (see above).
+* BuildHIR should always produce an HIR without error. For syntax forms that are unsupported (currently throwing a Todo error), we should instead construct record the todo error on the environment, and construct a partial HIR. The exact form of the partial HIR can be situation specific:
+  * `var` is currently unsupported, but we could pretend it was `let`
+  * `finally` blocks are unsupported, we could just prune them, or move the code after the try/catch (put the finally logic in the consequent)
+  * This may mean updating the HIR to allow representing partial code
+  * `eval()` can just be an Unsupported InstructionValue variant
+* All of the passes need to be updated to stop returning Result or CompilerError, and instead record their errors on the environment. They should always be able to proceed even in the presence of errors. For example, in InferMutationAliasingEffects if we discover that the code mutates a frozen value, we can record this as an error and then just pretend the mutation didn't happen - ie construct a scope as if the mutating code was not a mutation after all.
+* Finally, the end of the pipeline should check for errors and either turn `Ok(GeneratedFunction)` or `Err(aggregatedErrors)`. The code calling into the pipeline then needs to handle this appropriately.
+
+## Detailed Plan
+
+### Phase 1: Environment Error Accumulation Infrastructure
+
+Add error accumulation to the `Environment` class so that any pass can record errors during compilation without halting.
+
+- [x] **1.1 Add error accumulator to Environment** (`src/HIR/Environment.ts`)
+  - Add a `#errors: CompilerError` field, initialized in the constructor
+  - Add a `recordError(error: CompilerDiagnostic | CompilerErrorDetail)` method that:
+    - If an Invariant-category detail, immediately throw it
+    - Otherwise, push the diagnostic/detail onto `#errors` (and log via `this.logger` if configured)
+  - Add a `recordErrors(error: CompilerError)` method that calls `recordError()` for each of the details on the given error.
+  - Add a `hasErrors(): boolean` getter
+  - Add a `aggregateErrors(): CompilerError` method that returns the accumulated error object
+  - Consider whether `recordError` should accept the same options as `CompilerError.push()` for convenience (reason, description, severity, loc, etc.)
+
+- [x] **1.2 Add a `tryRecord` helper on Environment** (`src/HIR/Environment.ts`)
+  - Add a `tryRecord(fn: () => void): void` method that wraps a callback in try/catch:
+    - If `fn` throws a `CompilerError` that is NOT an invariant, record it via `recordError`
+    - If `fn` throws a non-CompilerError or a CompilerError invariant, re-throw
+  - This helper is the migration path for passes that currently throw: wrap their call in `env.tryRecord(() => pass(hir))` so exceptions become recorded errors
+
+### Phase 2: Update Pipeline.ts to Accumulate Errors
+
+Change `runWithEnvironment` to run all passes and check for errors at the end instead of letting exceptions propagate.
+
+- [x] **2.1 Change `runWithEnvironment` return type** (`src/Entrypoint/Pipeline.ts`)
+  - Change return type from `CodegenFunction` to `Result<CodegenFunction, CompilerError>`
+  - At the end of the pipeline, check `env.hasErrors()`:
+    - If no errors: return `Ok(ast)`
+    - If errors: return `Err(env.aggregateErrors())`
+
+- [x] **2.2 Update `compileFn` to propagate the Result** (`src/Entrypoint/Pipeline.ts`)
+  - Change `compileFn` return type from `CodegenFunction` to `Result<CodegenFunction, CompilerError>`
+  - Propagate the Result from `runWithEnvironment`
+
+- [x] **2.3 Update `run` to propagate the Result** (`src/Entrypoint/Pipeline.ts`)
+  - Same change for the internal `run` function
+
+- [x] **2.4 Update callers in Program.ts** (`src/Entrypoint/Program.ts`)
+  - In `tryCompileFunction`, change from try/catch around `compileFn` to handling the `Result`:
+    - If `Ok(codegenFn)`: return the compiled function
+    - If `Err(compilerError)`: return `{kind: 'error', error: compilerError}`
+    - Keep the try/catch only for truly unexpected (non-CompilerError) exceptions and invariants
+  - The existing `handleError`/`logError`/`panicThreshold` logic in `processFn` should continue to work unchanged since it already handles `CompilerError` instances
+
+### Phase 3: Update BuildHIR (lower) to Always Produce HIR
+
+Currently `lower()` returns `Result<HIRFunction, CompilerError>`. It already accumulates errors internally via `builder.errors`, but returns `Err` when errors exist. Change it to always return `Ok(hir)` while recording errors on the environment.
+
+- [ ] **3.1 Change `lower` to always return HIRFunction** (`src/HIR/BuildHIR.ts`)
+  - Change return type from `Result<HIRFunction, CompilerError>` to `HIRFunction`
+  - Instead of returning `Err(builder.errors)` at line 227-229, record errors on `env` via `env.recordError(builder.errors)` and return the (partial) HIR
+  - Update the pipeline to call `lower(func, env)` directly instead of `lower(func, env).unwrap()`
+
+- [ ] **3.2 Handle `var` declarations as `let`** (`src/HIR/BuildHIR.ts`, line ~855)
+  - Currently throws `Todo("Handle var kinds in VariableDeclaration")`
+  - Instead: record the Todo error on env, then treat the `var` as `let` and continue lowering
+
+- [ ] **3.3 Handle `try/finally` by pruning `finally`** (`src/HIR/BuildHIR.ts`, lines ~1281-1296)
+  - Currently throws Todo for `try` without `catch` and `try` with `finally`
+  - Instead: record the Todo error, then lower the `try/catch` portion only (put the `finally` block content in the fallthrough of the try/catch)
+
+- [ ] **3.4 Handle `eval()` via UnsupportedNode** (`src/HIR/BuildHIR.ts`, line ~3568)
+  - Currently throws `UnsupportedSyntax("The 'eval' function is not supported")`
+  - Instead: record the error, emit an `UnsupportedNode` instruction value with the original AST node
+
+- [ ] **3.5 Handle `with` statement via UnsupportedNode** (`src/HIR/BuildHIR.ts`, line ~1382)
+  - Currently throws `UnsupportedSyntax`
+  - Instead: record the error, emit the body statements as-is (or skip them), continue
+
+- [ ] **3.6 Handle inline `class` declarations** (`src/HIR/BuildHIR.ts`, line ~1402)
+  - Currently throws `UnsupportedSyntax`
+  - Already creates an `UnsupportedNode`; just record the error instead of throwing
+
+- [ ] **3.7 Handle remaining Todo errors in expression lowering** (`src/HIR/BuildHIR.ts`)
+  - For each of the ~35 Todo error sites in `lowerExpression`, `lowerAssignment`, `lowerMemberExpression`, etc.:
+    - Record the Todo error on the environment
+    - Emit an `UnsupportedNode` instruction value with the original Babel AST node as fallback
+  - Key sites include: pipe operator, tagged templates with interpolations, compound logical assignment (`&&=`, `||=`, `??=`), `for await...of`, object getters/setters, UpdateExpression on context variables, complex destructuring patterns
+  - The `UnsupportedNode` variant already exists in HIR and passes through codegen unchanged, so no new HIR types are needed for most cases
+
+- [ ] **3.8 Handle `throw` inside `try/catch`** (`src/HIR/BuildHIR.ts`, line ~284)
+  - Currently throws Todo
+  - Instead: record the error, and represent the `throw` as a terminal that ends the block (the existing `throw` terminal type may already handle this, or we can use `UnsupportedNode`)
+
+- [ ] **3.9 Handle `for` loops with missing test or expression init** (`src/HIR/BuildHIR.ts`, lines ~559, ~632)
+  - Record the error and construct a best-effort loop HIR (e.g., for `for(;;)`, use `true` as the test expression)
+
+- [ ] **3.10 Handle nested function lowering failures** (`src/HIR/BuildHIR.ts`, `lowerFunction` at line ~3504)
+  - Currently calls `lower()` recursively and merges errors if it fails (`builder.errors.merge(functionErrors)`)
+  - With the new approach, the nested `lower()` always returns an HIR, but errors are recorded on the shared environment
+  - Ensure the parent function continues lowering even if a nested function had errors
+
+### Phase 4: Update Validation Passes
+
+All validation passes need to record errors on the environment instead of returning `Result` or throwing. They should still detect the same problems, but the pipeline should continue after each one.
+
+#### Pattern A passes (currently return `Result`, called with `.unwrap()`)
+
+These passes already accumulate errors internally and return `Result<void, CompilerError>`. The change is: instead of returning the Result, record errors on `env` and return void. Remove the `.unwrap()` call in Pipeline.ts.
+
+- [x] **4.1 `validateHooksUsage`** (`src/Validation/ValidateHooksUsage.ts`)
+  - Change signature from `(fn: HIRFunction): Result<void, CompilerError>` to `(fn: HIRFunction): void`
+  - Record errors on `fn.env` instead of returning `errors.asResult()`
+  - Update Pipeline.ts call site (line 211): remove `.unwrap()`
+
+- [x] **4.2 `validateNoCapitalizedCalls`** (`src/Validation/ValidateNoCapitalizedCalls.ts`)
+  - Change signature to return void
+  - Fix the hybrid pattern: the direct `CallExpression` path currently throws via `CompilerError.throwInvalidReact()` — change to record on env
+  - The `MethodCall` path already accumulates — change to record on env
+  - Update Pipeline.ts call site (line 214): remove `.unwrap()`
+
+- [x] **4.3 `validateUseMemo`** (`src/Validation/ValidateUseMemo.ts`)
+  - Change signature to return void
+  - Record hard errors on env instead of returning `errors.asResult()`
+  - The soft `voidMemoErrors` path already uses `env.logErrors()` — keep as-is or also record
+  - Update Pipeline.ts call site (line 170): remove `.unwrap()`
+
+- [x] **4.4 `dropManualMemoization`** (`src/Inference/DropManualMemoization.ts`)
+  - Change signature to return void
+  - Record errors on env instead of returning `errors.asResult()`
+  - Update Pipeline.ts call site (line 178): remove `.unwrap()`
+
+- [x] **4.5 `validateNoRefAccessInRender`** (`src/Validation/ValidateNoRefAccessInRender.ts`)
+  - Change signature to return void
+  - Record errors on env instead of returning Result
+  - Update Pipeline.ts call site (line 275): remove `.unwrap()`
+
+- [x] **4.6 `validateNoSetStateInRender`** (`src/Validation/ValidateNoSetStateInRender.ts`)
+  - Change signature to return void
+  - Record errors on env
+  - Update Pipeline.ts call site (line 279): remove `.unwrap()`
+
+- [x] **4.7 `validateNoImpureFunctionsInRender`** (`src/Validation/ValidateNoImpureFunctionsInRender.ts`)
+  - Change signature to return void
+  - Record errors on env
+  - Update Pipeline.ts call site (line 300): remove `.unwrap()`
+
+- [x] **4.8 `validateNoFreezingKnownMutableFunctions`** (`src/Validation/ValidateNoFreezingKnownMutableFunctions.ts`)
+  - Change signature to return void
+  - Record errors on env
+  - Update Pipeline.ts call site (line 303): remove `.unwrap()`
+
+- [x] **4.9 `validateExhaustiveDependencies`** (`src/Validation/ValidateExhaustiveDependencies.ts`)
+  - Change signature to return void
+  - Record errors on env
+  - Update Pipeline.ts call site (line 315): remove `.unwrap()`
+
+- [x] **4.10 `validateMemoizedEffectDependencies`** (`src/Validation/ValidateMemoizedEffectDependencies.ts`)
+  - Change signature to return void (note: operates on `ReactiveFunction`)
+  - Record errors on the function's env
+  - Update Pipeline.ts call site (line 565): remove `.unwrap()`
+
+- [x] **4.11 `validatePreservedManualMemoization`** (`src/Validation/ValidatePreservedManualMemoization.ts`)
+  - Change signature to return void (note: operates on `ReactiveFunction`)
+  - Record errors on the function's env
+  - Update Pipeline.ts call site (line 572): remove `.unwrap()`
+
+- [x] **4.12 `validateSourceLocations`** (`src/Validation/ValidateSourceLocations.ts`)
+  - Change signature to return void
+  - Record errors on env
+  - Update Pipeline.ts call site (line 585): remove `.unwrap()`
+
+#### Pattern B passes (currently use `env.logErrors()`)
+
+These already use a soft-logging pattern and don't block compilation. They can be migrated to `env.recordError()` so all errors are aggregated in one place.
+
+- [ ] **4.13 `validateNoDerivedComputationsInEffects_exp`** — change to record on env directly
+- [ ] **4.14 `validateNoSetStateInEffects`** — change to record on env directly
+- [ ] **4.15 `validateNoJSXInTryStatement`** — change to record on env directly
+- [ ] **4.16 `validateStaticComponents`** — change to record on env directly
+
+#### Pattern D passes (currently throw directly, no Result)
+
+These throw `CompilerError` directly (not via Result). They need the most work.
+
+- [x] **4.17 `validateContextVariableLValues`** (`src/Validation/ValidateContextVariableLValues.ts`)
+  - Currently throws via `CompilerError.throwTodo()` and `CompilerError.invariant()`
+  - Change to record Todo errors on env and continue
+  - Keep invariant throws (those indicate internal bugs)
+
+- [x] **4.18 `validateLocalsNotReassignedAfterRender`** (`src/Validation/ValidateLocalsNotReassignedAfterRender.ts`)
+  - Currently constructs a `CompilerError` and `throw`s it directly
+  - Change to record errors on env
+
+- [x] **4.19 `validateNoDerivedComputationsInEffects`** (`src/Validation/ValidateNoDerivedComputationsInEffects.ts`)
+  - Currently throws directly
+  - Change to record errors on env
+
+### Phase 5: Update Inference Passes
+
+The inference passes are the most critical to handle correctly because they produce side effects (populating effects on instructions, computing mutable ranges) that downstream passes depend on. They must continue producing valid (even if imprecise) output when errors are encountered.
+
+- [x] **5.1 `inferMutationAliasingEffects`** (`src/Inference/InferMutationAliasingEffects.ts`)
+  - Currently returns `Result<void, CompilerError>` — errors are about mutation of frozen/global values
+  - Change to record errors on `fn.env` instead of accumulating internally
+  - **Key recovery strategy**: When a mutation of a frozen value is detected, record the error but treat the operation as a non-mutating read. This way downstream passes see a consistent (if conservative) view
+  - When a mutation of a global is detected, record the error but continue with the global unchanged
+  - Update Pipeline.ts (lines 233-239): remove the conditional `.isErr()` / throw pattern
+
+- [x] **5.2 `inferMutationAliasingRanges`** (`src/Inference/InferMutationAliasingRanges.ts`)
+  - Currently returns `Result<Array<AliasingEffect>, CompilerError>`
+  - This pass has a meaningful success value (the function's external aliasing effects)
+  - Change to: always produce a best-effort effects array, record errors on env
+  - When errors are encountered, produce conservative effects (e.g., assume no external mutation)
+  - Update Pipeline.ts (lines 258-267): remove the conditional throw pattern, call directly
+
+### Phase 6: Update Codegen
+
+- [x] **6.1 `codegenFunction`** (`src/ReactiveScopes/CodegenReactiveFunction.ts`)
+  - Currently returns `Result<CodegenFunction, CompilerError>`
+  - Change to: always produce a `CodegenFunction`, record errors on env
+  - If codegen encounters an error (e.g., an instruction it can't generate code for), it should:
+    - Record the error
+    - For `UnsupportedNode` values: pass through the original AST node (already works this way)
+    - For other error cases: emit a placeholder or the original AST where possible
+  - Update Pipeline.ts (line 575-578): remove `.unwrap()`
+
+### Phase 7: Pipeline.ts Pass-by-Pass Migration
+
+Walk through `runWithEnvironment` and wrap each pass call site. This is the integration work tying Phases 3-6 together.
+
+- [x] **7.1 Wrap `lower()` call** (line 163)
+  - Change from `lower(func, env).unwrap()` to `lower(func, env)` (direct return after Phase 3.1)
+
+- [x] **7.2 Wrap validation calls that use `.unwrap()`** (lines 169-303)
+  - Remove `.unwrap()` from all validation calls after they're updated in Phase 4
+  - For validations guarded by `env.enableValidations`, keep the guard but remove the `.unwrap()`
+
+- [x] **7.3 Wrap inference calls** (lines 233-267)
+  - After Phase 5, `inferMutationAliasingEffects` and `inferMutationAliasingRanges` record errors directly
+  - Remove the `mutabilityAliasingErrors` / `mutabilityAliasingRangeErrors` variables and their conditional throw logic
+
+- [x] **7.4 Wrap `env.logErrors()` calls** (lines 286-331)
+  - After Phase 4.13-4.16, these passes record on env directly
+  - Remove the `env.logErrors()` wrapper calls
+
+- [x] **7.5 Wrap codegen** (lines 575-578)
+  - After Phase 6.1, `codegenFunction` returns directly
+  - Remove the `.unwrap()`
+
+- [x] **7.6 Add final error check** (end of `runWithEnvironment`)
+  - After all passes complete, check `env.hasErrors()`
+  - If no errors: return `Ok(ast)`
+  - If errors: return `Err(env.aggregateErrors())`
+
+- [x] **7.7 Consider wrapping each pass in `env.tryRecord()`** as a safety net
+  - Even after individual passes are updated, wrapping each pass call in `env.tryRecord()` provides defense-in-depth
+  - If a pass unexpectedly throws a CompilerError (e.g., from a code path we missed), it gets caught and recorded rather than aborting the pipeline
+  - Non-CompilerError exceptions and invariants still propagate immediately
+
+### Phase 8: Testing
+
+- [ ] **8.1 Update existing `error.todo-*` fixture expectations**
+  - Currently, fixtures with `error.todo-` prefix expect a single error and bailout
+  - After fault tolerance, some of these may now produce multiple errors
+  - Update the `.expect.md` files to reflect the new aggregated error output
+
+- [ ] **8.2 Add multi-error test fixtures**
+  - Create test fixtures that contain multiple independent errors (e.g., both a `var` declaration and a mutation of a frozen value)
+  - Verify that all errors are reported, not just the first one
+
+- [ ] **8.3 Add test for invariant-still-throws behavior**
+  - Verify that `CompilerError.invariant()` failures still cause immediate abort
+  - Verify that non-CompilerError exceptions still cause immediate abort
+
+- [ ] **8.4 Add test for partial HIR codegen**
+  - Verify that when BuildHIR produces partial HIR (with `UnsupportedNode` values), later passes handle it gracefully and codegen produces the original AST for unsupported portions
+
+- [ ] **8.5 Verify error severity in aggregated output**
+  - Test that the aggregated `CompilerError` correctly reports `hasErrors()` vs `hasWarning()` vs `hasHints()` based on the mix of accumulated diagnostics
+  - Verify that `panicThreshold` behavior in Program.ts is correct for aggregated errors
+
+- [ ] **8.6 Run full test suite**
+  - Run `yarn snap` and `yarn snap -u` to update all fixture expectations
+  - Ensure no regressions in passing tests
+
+### Implementation Notes
+
+**Ordering**: Phases 1 → 2 → 3 → 4/5/6 (parallel) → 7 → 8. Phase 1 (Environment infrastructure) is the foundation. Phase 2 (Pipeline return type) sets up the contract. Phases 3-6 can be done incrementally — each pass can be migrated independently using `env.tryRecord()` as a transitional wrapper. Phase 7 is the integration. Phase 8 validates everything.
+
+**Incremental migration path**: Rather than updating all passes at once, each pass can be individually migrated. During the transition:
+1. First add `env.tryRecord()` in Phase 7.7 around all pass calls in the pipeline — this immediately provides fault tolerance by catching any thrown CompilerError
+2. Then individually update passes (Phases 3-6) to record errors directly on env, which is cleaner but not required for the basic behavior
+3. This means the feature can be landed incrementally: Phase 1 + 2 + 7.7 gives basic fault tolerance, then individual passes can be refined over time
+
+**What NOT to change**:
+- `CompilerError.invariant()` must continue to throw immediately — these represent internal bugs
+- Non-CompilerError exceptions must continue to throw — these are unexpected JS errors
+- The `assertConsistentIdentifiers`, `assertTerminalSuccessorsExist`, `assertTerminalPredsExist`, `assertValidBlockNesting`, `assertValidMutableRanges`, `assertWellFormedBreakTargets`, `assertScopeInstructionsWithinScopes` assertion functions should continue to throw — they are invariant checks on internal data structure consistency
+- The `panicThreshold` mechanism in Program.ts should continue to work — it now operates on the aggregated error from the Result rather than a caught exception, but the behavior is the same
+
+## Key Learnings
+
+* **Phase 2+7 (Pipeline tryRecord wrapping) was sufficient for basic fault tolerance.** Wrapping all passes in `env.tryRecord()` immediately enabled the compiler to continue past errors that previously threw. This caused 52 test fixtures to produce additional errors that were previously masked by the first error bailing out. For example, `error.todo-reassign-const` previously reported only "Support destructuring of context variables" but now also reports the immutability violation.
+* **Lint-only passes (Pattern B: `env.logErrors()`) should not use `tryRecord()`/`recordError()`** because those errors are intentionally non-blocking. They are reported via the logger only and should not cause the pipeline to return `Err`. The `logErrors` pattern was kept for `validateNoDerivedComputationsInEffects_exp`, `validateNoSetStateInEffects`, `validateNoJSXInTryStatement`, and `validateStaticComponents`.
+* **Inference passes that return `Result` with validation errors** (`inferMutationAliasingEffects`, `inferMutationAliasingRanges`) were changed to record errors via `env.recordErrors()` instead of throwing, allowing subsequent passes to proceed.
+* **Value-producing passes** (`memoizeFbtAndMacroOperandsInSameScope`, `renameVariables`, `buildReactiveFunction`) need safe default values when wrapped in `tryRecord()` since the callback can't return values. We initialize with empty defaults (e.g., `new Set()`) before the `tryRecord()` call.
+

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Pipeline.ts

@@ -9,8 +9,11 @@ import {NodePath} from '@babel/traverse';
 import * as t from '@babel/types';
 import prettyFormat from 'pretty-format';
 import {CompilerOutputMode, Logger, ProgramContext} from '.';
+import {CompilerError} from '../CompilerError';
+import {Err, Ok, Result} from '../Utils/Result';
 import {
   HIRFunction,
+  IdentifierId,
   ReactiveFunction,
   assertConsistentIdentifiers,
   assertTerminalPredsExist,
@@ -118,7 +121,7 @@ function run(
   logger: Logger | null,
   filename: string | null,
   code: string | null,
-): CodegenFunction {
+): Result<CodegenFunction, CompilerError> {
   const contextIdentifiers = findContextIdentifiers(func);
   const env = new Environment(
     func.scope,
@@ -149,93 +152,109 @@ function runWithEnvironment(
     t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
   >,
   env: Environment,
-): CodegenFunction {
+): Result<CodegenFunction, CompilerError> {
   const log = (value: CompilerPipelineValue): void => {
     env.logger?.debugLogIRs?.(value);
   };
   const hir = lower(func, env).unwrap();
   log({kind: 'hir', name: 'HIR', value: hir});
 
-  pruneMaybeThrows(hir);
+  env.tryRecord(() => {
+    pruneMaybeThrows(hir);
+  });
   log({kind: 'hir', name: 'PruneMaybeThrows', value: hir});
 
   validateContextVariableLValues(hir);
-  validateUseMemo(hir).unwrap();
+  validateUseMemo(hir);
 
   if (env.enableDropManualMemoization) {
-    dropManualMemoization(hir).unwrap();
+    dropManualMemoization(hir);
     log({kind: 'hir', name: 'DropManualMemoization', value: hir});
   }
 
-  inlineImmediatelyInvokedFunctionExpressions(hir);
+  env.tryRecord(() => {
+    inlineImmediatelyInvokedFunctionExpressions(hir);
+  });
   log({
     kind: 'hir',
     name: 'InlineImmediatelyInvokedFunctionExpressions',
     value: hir,
   });
 
-  mergeConsecutiveBlocks(hir);
+  env.tryRecord(() => {
+    mergeConsecutiveBlocks(hir);
+  });
   log({kind: 'hir', name: 'MergeConsecutiveBlocks', value: hir});
 
   assertConsistentIdentifiers(hir);
   assertTerminalSuccessorsExist(hir);
 
-  enterSSA(hir);
+  env.tryRecord(() => {
+    enterSSA(hir);
+  });
   log({kind: 'hir', name: 'SSA', value: hir});
 
-  eliminateRedundantPhi(hir);
+  env.tryRecord(() => {
+    eliminateRedundantPhi(hir);
+  });
   log({kind: 'hir', name: 'EliminateRedundantPhi', value: hir});
 
   assertConsistentIdentifiers(hir);
 
-  constantPropagation(hir);
+  env.tryRecord(() => {
+    constantPropagation(hir);
+  });
   log({kind: 'hir', name: 'ConstantPropagation', value: hir});
 
-  inferTypes(hir);
+  env.tryRecord(() => {
+    inferTypes(hir);
+  });
   log({kind: 'hir', name: 'InferTypes', value: hir});
 
   if (env.enableValidations) {
     if (env.config.validateHooksUsage) {
-      validateHooksUsage(hir).unwrap();
+      validateHooksUsage(hir);
     }
     if (env.config.validateNoCapitalizedCalls) {
-      validateNoCapitalizedCalls(hir).unwrap();
+      validateNoCapitalizedCalls(hir);
     }
   }
 
-  optimizePropsMethodCalls(hir);
+  env.tryRecord(() => {
+    optimizePropsMethodCalls(hir);
+  });
   log({kind: 'hir', name: 'OptimizePropsMethodCalls', value: hir});
 
-  analyseFunctions(hir);
+  env.tryRecord(() => {
+    analyseFunctions(hir);
+  });
   log({kind: 'hir', name: 'AnalyseFunctions', value: hir});
 
-  const mutabilityAliasingErrors = inferMutationAliasingEffects(hir);
+  inferMutationAliasingEffects(hir);
   log({kind: 'hir', name: 'InferMutationAliasingEffects', value: hir});
-  if (env.enableValidations) {
-    if (mutabilityAliasingErrors.isErr()) {
-      throw mutabilityAliasingErrors.unwrapErr();
-    }
-  }
 
   if (env.outputMode === 'ssr') {
-    optimizeForSSR(hir);
+    env.tryRecord(() => {
+      optimizeForSSR(hir);
+    });
     log({kind: 'hir', name: 'OptimizeForSSR', value: hir});
   }
 
   // Note: Has to come after infer reference effects because "dead" code may still affect inference
-  deadCodeElimination(hir);
+  env.tryRecord(() => {
+    deadCodeElimination(hir);
+  });
   log({kind: 'hir', name: 'DeadCodeElimination', value: hir});
-  pruneMaybeThrows(hir);
+  env.tryRecord(() => {
+    pruneMaybeThrows(hir);
+  });
   log({kind: 'hir', name: 'PruneMaybeThrows', value: hir});
 
-  const mutabilityAliasingRangeErrors = inferMutationAliasingRanges(hir, {
+  inferMutationAliasingRanges(hir, {
     isFunctionExpression: false,
   });
   log({kind: 'hir', name: 'InferMutationAliasingRanges', value: hir});
   if (env.enableValidations) {
-    if (mutabilityAliasingRangeErrors.isErr()) {
-      throw mutabilityAliasingRangeErrors.unwrapErr();
-    }
     validateLocalsNotReassignedAfterRender(hir);
   }
 
@@ -245,11 +264,11 @@ function runWithEnvironment(
     }
 
     if (env.config.validateRefAccessDuringRender) {
-      validateNoRefAccessInRender(hir).unwrap();
+      validateNoRefAccessInRender(hir);
     }
 
     if (env.config.validateNoSetStateInRender) {
-      validateNoSetStateInRender(hir).unwrap();
+      validateNoSetStateInRender(hir);
     }
 
     if (
@@ -270,13 +289,15 @@ function runWithEnvironment(
     }
 
     if (env.config.validateNoImpureFunctionsInRender) {
-      validateNoImpureFunctionsInRender(hir).unwrap();
+      validateNoImpureFunctionsInRender(hir);
     }
 
-    validateNoFreezingKnownMutableFunctions(hir).unwrap();
+    validateNoFreezingKnownMutableFunctions(hir);
   }
 
-  inferReactivePlaces(hir);
+  env.tryRecord(() => {
+    inferReactivePlaces(hir);
+  });
   log({kind: 'hir', name: 'InferReactivePlaces', value: hir});
 
   if (env.enableValidations) {
@@ -285,11 +306,13 @@ function runWithEnvironment(
       env.config.validateExhaustiveEffectDependencies
     ) {
       // NOTE: this relies on reactivity inference running first
-      validateExhaustiveDependencies(hir).unwrap();
+      validateExhaustiveDependencies(hir);
     }
   }
 
-  rewriteInstructionKindsBasedOnReassignment(hir);
+  env.tryRecord(() => {
+    rewriteInstructionKindsBasedOnReassignment(hir);
+  });
   log({
     kind: 'hir',
     name: 'RewriteInstructionKindsBasedOnReassignment',
@@ -310,11 +333,16 @@ function runWithEnvironment(
      * if inferred memoization is enabled. This makes all later passes which
      * transform reactive-scope labeled instructions no-ops.
      */
-    inferReactiveScopeVariables(hir);
+    env.tryRecord(() => {
+      inferReactiveScopeVariables(hir);
+    });
     log({kind: 'hir', name: 'InferReactiveScopeVariables', value: hir});
   }
 
-  const fbtOperands = memoizeFbtAndMacroOperandsInSameScope(hir);
+  let fbtOperands: Set<IdentifierId> = new Set();
+  env.tryRecord(() => {
+    fbtOperands = memoizeFbtAndMacroOperandsInSameScope(hir);
+  });
   log({
     kind: 'hir',
     name: 'MemoizeFbtAndMacroOperandsInSameScope',
@@ -322,11 +350,15 @@ function runWithEnvironment(
   });
 
   if (env.config.enableJsxOutlining) {
-    outlineJSX(hir);
+    env.tryRecord(() => {
+      outlineJSX(hir);
+    });
   }
 
   if (env.config.enableNameAnonymousFunctions) {
-    nameAnonymousFunctions(hir);
+    env.tryRecord(() => {
+      nameAnonymousFunctions(hir);
+    });
     log({
       kind: 'hir',
       name: 'NameAnonymousFunctions',
@@ -335,39 +367,51 @@ function runWithEnvironment(
   }
 
   if (env.config.enableFunctionOutlining) {
-    outlineFunctions(hir, fbtOperands);
+    env.tryRecord(() => {
+      outlineFunctions(hir, fbtOperands);
+    });
     log({kind: 'hir', name: 'OutlineFunctions', value: hir});
   }
 
-  alignMethodCallScopes(hir);
+  env.tryRecord(() => {
+    alignMethodCallScopes(hir);
+  });
   log({
     kind: 'hir',
     name: 'AlignMethodCallScopes',
     value: hir,
   });
 
-  alignObjectMethodScopes(hir);
+  env.tryRecord(() => {
+    alignObjectMethodScopes(hir);
+  });
   log({
     kind: 'hir',
     name: 'AlignObjectMethodScopes',
     value: hir,
   });
 
-  pruneUnusedLabelsHIR(hir);
+  env.tryRecord(() => {
+    pruneUnusedLabelsHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'PruneUnusedLabelsHIR',
     value: hir,
   });
 
-  alignReactiveScopesToBlockScopesHIR(hir);
+  env.tryRecord(() => {
+    alignReactiveScopesToBlockScopesHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'AlignReactiveScopesToBlockScopesHIR',
     value: hir,
   });
 
-  mergeOverlappingReactiveScopesHIR(hir);
+  env.tryRecord(() => {
+    mergeOverlappingReactiveScopesHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'MergeOverlappingReactiveScopesHIR',
@@ -375,7 +419,9 @@ function runWithEnvironment(
   });
   assertValidBlockNesting(hir);
 
-  buildReactiveScopeTerminalsHIR(hir);
+  env.tryRecord(() => {
+    buildReactiveScopeTerminalsHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'BuildReactiveScopeTerminalsHIR',
@@ -384,14 +430,18 @@ function runWithEnvironment(
 
   assertValidBlockNesting(hir);
 
-  flattenReactiveLoopsHIR(hir);
+  env.tryRecord(() => {
+    flattenReactiveLoopsHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'FlattenReactiveLoopsHIR',
     value: hir,
   });
 
-  flattenScopesWithHooksOrUseHIR(hir);
+  env.tryRecord(() => {
+    flattenScopesWithHooksOrUseHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'FlattenScopesWithHooksOrUseHIR',
@@ -399,14 +449,19 @@ function runWithEnvironment(
   });
   assertTerminalSuccessorsExist(hir);
   assertTerminalPredsExist(hir);
-  propagateScopeDependenciesHIR(hir);
+  env.tryRecord(() => {
+    propagateScopeDependenciesHIR(hir);
+  });
   log({
     kind: 'hir',
     name: 'PropagateScopeDependenciesHIR',
     value: hir,
   });
 
-  const reactiveFunction = buildReactiveFunction(hir);
+  let reactiveFunction!: ReactiveFunction;
+  env.tryRecord(() => {
+    reactiveFunction = buildReactiveFunction(hir);
+  });
   log({
     kind: 'reactive',
     name: 'BuildReactiveFunction',
@@ -415,7 +470,9 @@ function runWithEnvironment(
 
   assertWellFormedBreakTargets(reactiveFunction);
 
-  pruneUnusedLabels(reactiveFunction);
+  env.tryRecord(() => {
+    pruneUnusedLabels(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneUnusedLabels',
@@ -423,108 +480,134 @@ function runWithEnvironment(
   });
   assertScopeInstructionsWithinScopes(reactiveFunction);
 
-  pruneNonEscapingScopes(reactiveFunction);
+  env.tryRecord(() => {
+    pruneNonEscapingScopes(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneNonEscapingScopes',
     value: reactiveFunction,
   });
 
-  pruneNonReactiveDependencies(reactiveFunction);
+  env.tryRecord(() => {
+    pruneNonReactiveDependencies(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneNonReactiveDependencies',
     value: reactiveFunction,
   });
 
-  pruneUnusedScopes(reactiveFunction);
+  env.tryRecord(() => {
+    pruneUnusedScopes(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneUnusedScopes',
     value: reactiveFunction,
   });
 
-  mergeReactiveScopesThatInvalidateTogether(reactiveFunction);
+  env.tryRecord(() => {
+    mergeReactiveScopesThatInvalidateTogether(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'MergeReactiveScopesThatInvalidateTogether',
     value: reactiveFunction,
   });
 
-  pruneAlwaysInvalidatingScopes(reactiveFunction);
+  env.tryRecord(() => {
+    pruneAlwaysInvalidatingScopes(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneAlwaysInvalidatingScopes',
     value: reactiveFunction,
   });
 
-  propagateEarlyReturns(reactiveFunction);
+  env.tryRecord(() => {
+    propagateEarlyReturns(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PropagateEarlyReturns',
     value: reactiveFunction,
   });
 
-  pruneUnusedLValues(reactiveFunction);
+  env.tryRecord(() => {
+    pruneUnusedLValues(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneUnusedLValues',
     value: reactiveFunction,
   });
 
-  promoteUsedTemporaries(reactiveFunction);
+  env.tryRecord(() => {
+    promoteUsedTemporaries(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PromoteUsedTemporaries',
     value: reactiveFunction,
   });
 
-  extractScopeDeclarationsFromDestructuring(reactiveFunction);
+  env.tryRecord(() => {
+    extractScopeDeclarationsFromDestructuring(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'ExtractScopeDeclarationsFromDestructuring',
     value: reactiveFunction,
   });
 
-  stabilizeBlockIds(reactiveFunction);
+  env.tryRecord(() => {
+    stabilizeBlockIds(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'StabilizeBlockIds',
     value: reactiveFunction,
   });
 
-  const uniqueIdentifiers = renameVariables(reactiveFunction);
+  let uniqueIdentifiers: Set<string> = new Set();
+  env.tryRecord(() => {
+    uniqueIdentifiers = renameVariables(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'RenameVariables',
     value: reactiveFunction,
   });
 
-  pruneHoistedContexts(reactiveFunction);
+  env.tryRecord(() => {
+    pruneHoistedContexts(reactiveFunction);
+  });
   log({
     kind: 'reactive',
     name: 'PruneHoistedContexts',
     value: reactiveFunction,
   });
 
+
   if (
     env.config.enablePreserveExistingMemoizationGuarantees ||
     env.config.validatePreserveExistingMemoizationGuarantees
   ) {
-    validatePreservedManualMemoization(reactiveFunction).unwrap();
+    validatePreservedManualMemoization(reactiveFunction);
   }
 
   const ast = codegenFunction(reactiveFunction, {
     uniqueIdentifiers,
     fbtOperands,
-  }).unwrap();
+  });
   log({kind: 'ast', name: 'Codegen', value: ast});
   for (const outlined of ast.outlined) {
     log({kind: 'ast', name: 'Codegen (outlined)', value: outlined.fn});
   }
 
   if (env.config.validateSourceLocations) {
-    validateSourceLocations(func, ast).unwrap();
+    validateSourceLocations(func, ast, env);
   }
 
   /**
@@ -536,7 +619,10 @@ function runWithEnvironment(
     throw new Error('unexpected error');
   }
 
-  return ast;
+  if (env.hasErrors()) {
+    return Err(env.aggregateErrors());
+  }
+  return Ok(ast);
 }
 
 export function compileFn(
@@ -550,7 +636,7 @@ export function compileFn(
   logger: Logger | null,
   filename: string | null,
   code: string | null,
-): CodegenFunction {
+): Result<CodegenFunction, CompilerError> {
   return run(
     func,
     config,

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts

@@ -704,24 +704,27 @@ function tryCompileFunction(
   }
 
   try {
-    return {
-      kind: 'compile',
-      compiledFn: compileFn(
-        fn,
-        programContext.opts.environment,
-        fnType,
-        outputMode,
-        programContext,
-        programContext.opts.logger,
-        programContext.filename,
-        programContext.code,
-      ),
-    };
+    const result = compileFn(
+      fn,
+      programContext.opts.environment,
+      fnType,
+      outputMode,
+      programContext,
+      programContext.opts.logger,
+      programContext.filename,
+      programContext.code,
+    );
+    if (result.isOk()) {
+      return {kind: 'compile', compiledFn: result.unwrap()};
+    } else {
+      return {kind: 'error', error: result.unwrapErr()};
+    }
   } catch (err) {
     return {kind: 'error', error: err};
   }
 }
 
+
 /**
  * Applies React Compiler generated functions to the babel AST by replacing
  * existing functions in place or inserting new declarations.

compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts

@@ -8,7 +8,12 @@
 import * as t from '@babel/types';
 import {ZodError, z} from 'zod/v4';
 import {fromZodError} from 'zod-validation-error/v4';
-import {CompilerError} from '../CompilerError';
+import {
+  CompilerDiagnostic,
+  CompilerError,
+  CompilerErrorDetail,
+  ErrorCategory,
+} from '../CompilerError';
 import {CompilerOutputMode, Logger, ProgramContext} from '../Entrypoint';
 import {Err, Ok, Result} from '../Utils/Result';
 import {
@@ -545,6 +550,12 @@ export class Environment {
 
   #flowTypeEnvironment: FlowTypeEnv | null;
 
+  /**
+   * Accumulated compilation errors. Passes record errors here instead of
+   * throwing, so the pipeline can continue and report all errors at once.
+   */
+  #errors: CompilerError = new CompilerError();
+
   constructor(
     scope: BabelScope,
     fnType: ReactFunctionType,
@@ -709,6 +720,82 @@ export class Environment {
     }
   }
 
+  /**
+   * Record a single diagnostic or error detail on this environment.
+   * If the error is an Invariant, it is immediately thrown since invariants
+   * represent internal bugs that cannot be recovered from.
+   * Otherwise, the error is accumulated and optionally logged.
+   */
+  recordError(error: CompilerDiagnostic | CompilerErrorDetail): void {
+    if (error.category === ErrorCategory.Invariant) {
+      const compilerError = new CompilerError();
+      if (error instanceof CompilerDiagnostic) {
+        compilerError.pushDiagnostic(error);
+      } else {
+        compilerError.pushErrorDetail(error);
+      }
+      throw compilerError;
+    }
+    if (error instanceof CompilerDiagnostic) {
+      this.#errors.pushDiagnostic(error);
+    } else {
+      this.#errors.pushErrorDetail(error);
+    }
+    if (this.logger != null) {
+      this.logger.logEvent(this.filename, {
+        kind: 'CompileError',
+        detail: error,
+        fnLoc: null,
+      });
+    }
+  }
+
+  /**
+   * Record all diagnostics from a CompilerError onto this environment.
+   */
+  recordErrors(error: CompilerError): void {
+    for (const detail of error.details) {
+      this.recordError(detail);
+    }
+  }
+
+  /**
+   * Returns true if any errors have been recorded during compilation.
+   */
+  hasErrors(): boolean {
+    return this.#errors.hasAnyErrors();
+  }
+
+  /**
+   * Returns the accumulated CompilerError containing all recorded diagnostics.
+   */
+  aggregateErrors(): CompilerError {
+    return this.#errors;
+  }
+
+  /**
+   * Wraps a callback in try/catch: if the callback throws a CompilerError
+   * that is NOT an invariant, the error is recorded and execution continues.
+   * Non-CompilerError exceptions and invariants are re-thrown.
+   */
+  tryRecord(fn: () => void): void {
+    try {
+      fn();
+    } catch (err) {
+      if (err instanceof CompilerError) {
+        // Check if any detail is an invariant — if so, re-throw
+        for (const detail of err.details) {
+          if (detail.category === ErrorCategory.Invariant) {
+            throw err;
+          }
+        }
+        this.recordErrors(err);
+      } else {
+        throw err;
+      }
+    }
+  }
+
   isContextIdentifier(node: t.Identifier): boolean {
     return this.#contextIdentifiers.has(node);
   }

compiler/packages/babel-plugin-react-compiler/src/Inference/AnalyseFunctions.ts

@@ -54,7 +54,7 @@ function lowerWithMutationAliasing(fn: HIRFunction): void {
   deadCodeElimination(fn);
   const functionEffects = inferMutationAliasingRanges(fn, {
     isFunctionExpression: true,
-  }).unwrap();
+  });
   rewriteInstructionKindsBasedOnReassignment(fn);
   inferReactiveScopeVariables(fn);
   fn.aliasingEffects = functionEffects;

compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts

@@ -31,7 +31,6 @@ import {
   makeInstructionId,
 } from '../HIR';
 import {createTemporaryPlace, markInstructionIds} from '../HIR/HIRBuilder';
-import {Result} from '../Utils/Result';
 
 type ManualMemoCallee = {
   kind: 'useMemo' | 'useCallback';
@@ -389,9 +388,7 @@ function extractManualMemoizationArgs(
  * This pass also validates that useMemo callbacks return a value (not void), ensuring that useMemo
  * is only used for memoizing values and not for running arbitrary side effects.
  */
-export function dropManualMemoization(
-  func: HIRFunction,
-): Result<void, CompilerError> {
+export function dropManualMemoization(func: HIRFunction): void {
   const errors = new CompilerError();
   const isValidationEnabled =
     func.env.config.validatePreserveExistingMemoizationGuarantees ||
@@ -553,7 +550,9 @@ export function dropManualMemoization(
     }
   }
 
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    func.env.recordErrors(errors);
+  }
 }
 
 function findOptionalPlaces(fn: HIRFunction): Set<IdentifierId> {

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutationAliasingEffects.ts

@@ -45,7 +45,7 @@ import {
   eachTerminalOperand,
   eachTerminalSuccessor,
 } from '../HIR/visitors';
-import {Ok, Result} from '../Utils/Result';
+
 import {
   assertExhaustive,
   getOrInsertDefault,
@@ -100,7 +100,7 @@ export function inferMutationAliasingEffects(
   {isFunctionExpression}: {isFunctionExpression: boolean} = {
     isFunctionExpression: false,
   },
-): Result<void, CompilerError> {
+): void {
   const initialState = InferenceState.empty(fn.env, isFunctionExpression);
 
   // Map of blocks to the last (merged) incoming state that was processed
@@ -220,7 +220,7 @@ export function inferMutationAliasingEffects(
       }
     }
   }
-  return Ok(undefined);
+  return;
 }
 
 function findHoistedContextDeclarations(

compiler/packages/babel-plugin-react-compiler/src/Inference/InferMutationAliasingRanges.ts

@@ -26,7 +26,7 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {assertExhaustive, getOrInsertWith} from '../Utils/utils';
-import {Err, Ok, Result} from '../Utils/Result';
+
 import {AliasingEffect, MutationReason} from './AliasingEffects';
 
 /**
@@ -74,7 +74,7 @@ import {AliasingEffect, MutationReason} from './AliasingEffects';
 export function inferMutationAliasingRanges(
   fn: HIRFunction,
   {isFunctionExpression}: {isFunctionExpression: boolean},
-): Result<Array<AliasingEffect>, CompilerError> {
+): Array<AliasingEffect> {
   // The set of externally-visible effects
   const functionEffects: Array<AliasingEffect> = [];
 
@@ -547,10 +547,14 @@ export function inferMutationAliasingRanges(
     }
   }
 
-  if (errors.hasAnyErrors() && !isFunctionExpression) {
-    return Err(errors);
+  if (
+    errors.hasAnyErrors() &&
+    !isFunctionExpression &&
+    fn.env.enableValidations
+  ) {
+    fn.env.recordErrors(errors);
   }
-  return Ok(functionEffects);
+  return functionEffects;
 }
 
 function appendFunctionErrors(errors: CompilerError, fn: HIRFunction): void {

compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/CodegenReactiveFunction.ts

@@ -46,7 +46,7 @@ import {
 } from '../HIR/HIR';
 import {printIdentifier, printInstruction, printPlace} from '../HIR/PrintHIR';
 import {eachPatternOperand} from '../HIR/visitors';
-import {Err, Ok, Result} from '../Utils/Result';
+
 import {GuardKind} from '../Utils/RuntimeDiagnosticConstants';
 import {assertExhaustive} from '../Utils/utils';
 import {buildReactiveFunction} from './BuildReactiveFunction';
@@ -111,7 +111,7 @@ export function codegenFunction(
     uniqueIdentifiers: Set<string>;
     fbtOperands: Set<IdentifierId>;
   },
-): Result<CodegenFunction, CompilerError> {
+): CodegenFunction {
   const cx = new Context(
     fn.env,
     fn.id ?? '[[ anonymous ]]',
@@ -141,11 +141,7 @@ export function codegenFunction(
     };
   }
 
-  const compileResult = codegenReactiveFunction(cx, fn);
-  if (compileResult.isErr()) {
-    return compileResult;
-  }
-  const compiled = compileResult.unwrap();
+  const compiled = codegenReactiveFunction(cx, fn);
 
   const hookGuard = fn.env.config.enableEmitHookGuards;
   if (hookGuard != null && fn.env.outputMode === 'client') {
@@ -273,7 +269,7 @@ export function codegenFunction(
         emitInstrumentForget.globalGating,
       );
       if (assertResult.isErr()) {
-        return assertResult;
+        fn.env.recordErrors(assertResult.unwrapErr());
       }
     }
 
@@ -323,20 +319,17 @@ export function codegenFunction(
       ),
       reactiveFunction,
     );
-    if (codegen.isErr()) {
-      return codegen;
-    }
-    outlined.push({fn: codegen.unwrap(), type});
+    outlined.push({fn: codegen, type});
   }
   compiled.outlined = outlined;
 
-  return compileResult;
+  return compiled;
 }
 
 function codegenReactiveFunction(
   cx: Context,
   fn: ReactiveFunction,
-): Result<CodegenFunction, CompilerError> {
+): CodegenFunction {
   for (const param of fn.params) {
     const place = param.kind === 'Identifier' ? param : param.place;
     cx.temp.set(place.identifier.declarationId, null);
@@ -355,13 +348,13 @@ function codegenReactiveFunction(
   }
 
   if (cx.errors.hasAnyErrors()) {
-    return Err(cx.errors);
+    fn.env.recordErrors(cx.errors);
   }
 
   const countMemoBlockVisitor = new CountMemoBlockVisitor(fn.env);
   visitReactiveFunction(fn, countMemoBlockVisitor, undefined);
 
-  return Ok({
+  return {
     type: 'CodegenFunction',
     loc: fn.loc,
     id: fn.id !== null ? t.identifier(fn.id) : null,
@@ -376,7 +369,7 @@ function codegenReactiveFunction(
     prunedMemoBlocks: countMemoBlockVisitor.prunedMemoBlocks,
     prunedMemoValues: countMemoBlockVisitor.prunedMemoValues,
     outlined: [],
-  });
+  };
 }
 
 class CountMemoBlockVisitor extends ReactiveFunctionVisitor<void> {
@@ -1665,7 +1658,7 @@ function codegenInstructionValue(
                   cx.temp,
                 ),
                 reactiveFunction,
-              ).unwrap();
+              );
 
               /*
                * ObjectMethod builder must be backwards compatible with older versions of babel.
@@ -1864,7 +1857,7 @@ function codegenInstructionValue(
           cx.temp,
         ),
         reactiveFunction,
-      ).unwrap();
+      );
 
       if (instrValue.type === 'ArrowFunctionExpression') {
         let body: t.BlockStatement | t.Expression = fn.body;

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateContextVariableLValues.ts

@@ -5,7 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError} from '..';
+import {CompilerDiagnostic, CompilerError} from '..';
+import {ErrorCategory} from '../CompilerError';
+import {Environment} from '../HIR/Environment';
 import {HIRFunction, IdentifierId, Place} from '../HIR';
 import {printPlace} from '../HIR/PrintHIR';
 import {eachInstructionValueLValue, eachPatternOperand} from '../HIR/visitors';
@@ -17,12 +19,13 @@ import {eachInstructionValueLValue, eachPatternOperand} from '../HIR/visitors';
  */
 export function validateContextVariableLValues(fn: HIRFunction): void {
   const identifierKinds: IdentifierKinds = new Map();
-  validateContextVariableLValuesImpl(fn, identifierKinds);
+  validateContextVariableLValuesImpl(fn, identifierKinds, fn.env);
 }
 
 function validateContextVariableLValuesImpl(
   fn: HIRFunction,
   identifierKinds: IdentifierKinds,
+  env: Environment,
 ): void {
   for (const [, block] of fn.body.blocks) {
     for (const instr of block.instructions) {
@@ -30,30 +33,30 @@ function validateContextVariableLValuesImpl(
       switch (value.kind) {
         case 'DeclareContext':
         case 'StoreContext': {
-          visit(identifierKinds, value.lvalue.place, 'context');
+          visit(identifierKinds, value.lvalue.place, 'context', env);
           break;
         }
         case 'LoadContext': {
-          visit(identifierKinds, value.place, 'context');
+          visit(identifierKinds, value.place, 'context', env);
           break;
         }
         case 'StoreLocal':
         case 'DeclareLocal': {
-          visit(identifierKinds, value.lvalue.place, 'local');
+          visit(identifierKinds, value.lvalue.place, 'local', env);
           break;
         }
         case 'LoadLocal': {
-          visit(identifierKinds, value.place, 'local');
+          visit(identifierKinds, value.place, 'local', env);
           break;
         }
         case 'PostfixUpdate':
         case 'PrefixUpdate': {
-          visit(identifierKinds, value.lvalue, 'local');
+          visit(identifierKinds, value.lvalue, 'local', env);
           break;
         }
         case 'Destructure': {
           for (const lvalue of eachPatternOperand(value.lvalue.pattern)) {
-            visit(identifierKinds, lvalue, 'destructure');
+            visit(identifierKinds, lvalue, 'destructure', env);
           }
           break;
         }
@@ -62,18 +65,24 @@ function validateContextVariableLValuesImpl(
           validateContextVariableLValuesImpl(
             value.loweredFunc.func,
             identifierKinds,
+            env,
           );
           break;
         }
         default: {
           for (const _ of eachInstructionValueLValue(value)) {
-            CompilerError.throwTodo({
-              reason:
-                'ValidateContextVariableLValues: unhandled instruction variant',
-              loc: value.loc,
-              description: `Handle '${value.kind} lvalues`,
-              suggestions: null,
-            });
+            fn.env.recordError(
+              CompilerDiagnostic.create({
+                category: ErrorCategory.Todo,
+                reason:
+                  'ValidateContextVariableLValues: unhandled instruction variant',
+                description: `Handle '${value.kind} lvalues`,
+              }).withDetails({
+                kind: 'error',
+                loc: value.loc,
+                message: null,
+              }),
+            );
           }
         }
       }
@@ -90,6 +99,7 @@ function visit(
   identifiers: IdentifierKinds,
   place: Place,
   kind: 'local' | 'context' | 'destructure',
+  env: Environment,
 ): void {
   const prev = identifiers.get(place.identifier.id);
   if (prev !== undefined) {
@@ -97,12 +107,18 @@ function visit(
     const isContext = kind === 'context';
     if (wasContext !== isContext) {
       if (prev.kind === 'destructure' || kind === 'destructure') {
-        CompilerError.throwTodo({
-          reason: `Support destructuring of context variables`,
-          loc: kind === 'destructure' ? place.loc : prev.place.loc,
-          description: null,
-          suggestions: null,
-        });
+        env.recordError(
+          CompilerDiagnostic.create({
+            category: ErrorCategory.Todo,
+            reason: `Support destructuring of context variables`,
+            description: null,
+          }).withDetails({
+            kind: 'error',
+            loc: kind === 'destructure' ? place.loc : prev.place.loc,
+            message: null,
+          }),
+        );
+        return;
       }
 
       CompilerError.invariant(false, {

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateExhaustiveDependencies.ts

@@ -44,7 +44,6 @@ import {
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
-import {Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
 const DEBUG = false;
@@ -88,9 +87,7 @@ const DEBUG = false;
  * When we go to compute the dependencies, we then think that the user's manual dep
  * logic is part of what the memo computation logic.
  */
-export function validateExhaustiveDependencies(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateExhaustiveDependencies(fn: HIRFunction): void {
   const env = fn.env;
   const reactive = collectReactiveIdentifiersHIR(fn);
 
@@ -217,7 +214,9 @@ export function validateExhaustiveDependencies(
     },
     false, // isFunctionExpression
   );
-  return error.asResult();
+  if (error.hasAnyErrors()) {
+    fn.env.recordErrors(error);
+  }
 }
 
 function validateDependencies(

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateHooksUsage.ts

@@ -26,7 +26,6 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {assertExhaustive} from '../Utils/utils';
-import {Result} from '../Utils/Result';
 
 /**
  * Represents the possible kinds of value which may be stored at a given Place during
@@ -88,9 +87,7 @@ function joinKinds(a: Kind, b: Kind): Kind {
  *   may not appear as the callee of a conditional call.
  *   See the note for Kind.PotentialHook for sources of potential hooks
  */
-export function validateHooksUsage(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateHooksUsage(fn: HIRFunction): void {
   const unconditionalBlocks = computeUnconditionalBlocks(fn);
 
   const errors = new CompilerError();
@@ -426,7 +423,9 @@ export function validateHooksUsage(
   for (const [, error] of errorsByPlace) {
     errors.pushErrorDetail(error);
   }
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }
 
 function visitFunctionExpression(errors: CompilerError, fn: HIRFunction): void {

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateLocalsNotReassignedAfterRender.ts

@@ -7,6 +7,7 @@
 
 import {CompilerDiagnostic, CompilerError, Effect} from '..';
 import {ErrorCategory} from '../CompilerError';
+import {Environment} from '../HIR/Environment';
 import {HIRFunction, IdentifierId, Place} from '../HIR';
 import {
   eachInstructionLValue,
@@ -27,15 +28,15 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
     contextVariables,
     false,
     false,
+    fn.env,
   );
   if (reassignment !== null) {
-    const errors = new CompilerError();
     const variable =
       reassignment.identifier.name != null &&
       reassignment.identifier.name.kind === 'named'
         ? `\`${reassignment.identifier.name.value}\``
         : 'variable';
-    errors.pushDiagnostic(
+    fn.env.recordError(
       CompilerDiagnostic.create({
         category: ErrorCategory.Immutability,
         reason: 'Cannot reassign variable after render completes',
@@ -46,7 +47,6 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
         message: `Cannot reassign ${variable} after render completes`,
       }),
     );
-    throw errors;
   }
 }
 
@@ -55,6 +55,7 @@ function getContextReassignment(
   contextVariables: Set<IdentifierId>,
   isFunctionExpression: boolean,
   isAsync: boolean,
+  env: Environment,
 ): Place | null {
   const reassigningFunctions = new Map<IdentifierId, Place>();
   for (const [, block] of fn.body.blocks) {
@@ -68,6 +69,7 @@ function getContextReassignment(
             contextVariables,
             true,
             isAsync || value.loweredFunc.func.async,
+            env,
           );
           if (reassignment === null) {
             // If the function itself doesn't reassign, does one of its dependencies?
@@ -84,13 +86,12 @@ function getContextReassignment(
           // if the function or its depends reassign, propagate that fact on the lvalue
           if (reassignment !== null) {
             if (isAsync || value.loweredFunc.func.async) {
-              const errors = new CompilerError();
               const variable =
                 reassignment.identifier.name !== null &&
                 reassignment.identifier.name.kind === 'named'
                   ? `\`${reassignment.identifier.name.value}\``
                   : 'variable';
-              errors.pushDiagnostic(
+              env.recordError(
                 CompilerDiagnostic.create({
                   category: ErrorCategory.Immutability,
                   reason: 'Cannot reassign variable in async function',
@@ -102,7 +103,7 @@ function getContextReassignment(
                   message: `Cannot reassign ${variable}`,
                 }),
               );
-              throw errors;
+              return null;
             }
             reassigningFunctions.set(lvalue.identifier.id, reassignment);
           }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoCapitalizedCalls.ts

@@ -5,15 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, EnvironmentConfig} from '..';
+import {CompilerError, CompilerErrorDetail, EnvironmentConfig} from '..';
 import {ErrorCategory} from '../CompilerError';
 import {HIRFunction, IdentifierId} from '../HIR';
 import {DEFAULT_GLOBALS} from '../HIR/Globals';
-import {Result} from '../Utils/Result';
 
-export function validateNoCapitalizedCalls(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateNoCapitalizedCalls(fn: HIRFunction): void {
   const envConfig: EnvironmentConfig = fn.env.config;
   const ALLOW_LIST = new Set([
     ...DEFAULT_GLOBALS.keys(),
@@ -48,13 +45,16 @@ export function validateNoCapitalizedCalls(
           const calleeIdentifier = value.callee.identifier.id;
           const calleeName = capitalLoadGlobals.get(calleeIdentifier);
           if (calleeName != null) {
-            CompilerError.throwInvalidReact({
-              category: ErrorCategory.CapitalizedCalls,
-              reason,
-              description: `${calleeName} may be a component`,
-              loc: value.loc,
-              suggestions: null,
-            });
+            fn.env.recordError(
+              new CompilerErrorDetail({
+                category: ErrorCategory.CapitalizedCalls,
+                reason,
+                description: `${calleeName} may be a component`,
+                loc: value.loc,
+                suggestions: null,
+              }),
+            );
+            continue;
           }
           break;
         }
@@ -85,5 +85,7 @@ export function validateNoCapitalizedCalls(
       }
     }
   }
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoDerivedComputationsInEffects.ts

@@ -97,8 +97,8 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
       }
     }
   }
-  if (errors.hasAnyErrors()) {
-    throw errors;
+  for (const detail of errors.details) {
+    fn.env.recordError(detail);
   }
 }
 

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoFreezingKnownMutableFunctions.ts

@@ -18,7 +18,6 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {AliasingEffect} from '../Inference/AliasingEffects';
-import {Result} from '../Utils/Result';
 
 /**
  * Validates that functions with known mutations (ie due to types) cannot be passed
@@ -43,9 +42,7 @@ import {Result} from '../Utils/Result';
  * This pass detects functions with *known* mutations (Store or Mutate, not ConditionallyMutate)
  * that are passed where a frozen value is expected and rejects them.
  */
-export function validateNoFreezingKnownMutableFunctions(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateNoFreezingKnownMutableFunctions(fn: HIRFunction): void {
   const errors = new CompilerError();
   const contextMutationEffects: Map<
     IdentifierId,
@@ -162,5 +159,7 @@ export function validateNoFreezingKnownMutableFunctions(
       visitOperand(operand);
     }
   }
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoImpureFunctionsInRender.ts

@@ -9,7 +9,6 @@ import {CompilerDiagnostic, CompilerError} from '..';
 import {ErrorCategory} from '../CompilerError';
 import {HIRFunction} from '../HIR';
 import {getFunctionCallSignature} from '../Inference/InferMutationAliasingEffects';
-import {Result} from '../Utils/Result';
 
 /**
  * Checks that known-impure functions are not called during render. Examples of invalid functions to
@@ -20,9 +19,7 @@ import {Result} from '../Utils/Result';
  * this in several of our validation passes and should unify those analyses into a reusable helper
  * and use it here.
  */
-export function validateNoImpureFunctionsInRender(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateNoImpureFunctionsInRender(fn: HIRFunction): void {
   const errors = new CompilerError();
   for (const [, block] of fn.body.blocks) {
     for (const instr of block.instructions) {
@@ -55,5 +52,7 @@ export function validateNoImpureFunctionsInRender(
       }
     }
   }
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoRefAccessInRender.ts

@@ -27,7 +27,6 @@ import {
   eachPatternOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
-import {Err, Ok, Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
 
 /**
@@ -120,12 +119,14 @@ class Env {
   }
 }
 
-export function validateNoRefAccessInRender(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateNoRefAccessInRender(fn: HIRFunction): void {
   const env = new Env();
   collectTemporariesSidemap(fn, env);
-  return validateNoRefAccessInRenderImpl(fn, env).map(_ => undefined);
+  const errors = new CompilerError();
+  validateNoRefAccessInRenderImpl(fn, env, errors);
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }
 
 function collectTemporariesSidemap(fn: HIRFunction, env: Env): void {
@@ -305,7 +306,8 @@ function joinRefAccessTypes(...types: Array<RefAccessType>): RefAccessType {
 function validateNoRefAccessInRenderImpl(
   fn: HIRFunction,
   env: Env,
-): Result<RefAccessType, CompilerError> {
+  errors: CompilerError,
+): RefAccessType {
   let returnValues: Array<undefined | RefAccessType> = [];
   let place;
   for (const param of fn.params) {
@@ -336,7 +338,6 @@ function validateNoRefAccessInRenderImpl(
     env.resetChanged();
     returnValues = [];
     const safeBlocks: Array<{block: BlockId; ref: RefId}> = [];
-    const errors = new CompilerError();
     for (const [, block] of fn.body.blocks) {
       retainWhere(safeBlocks, entry => entry.block !== block.id);
       for (const phi of block.phis) {
@@ -432,13 +433,15 @@ function validateNoRefAccessInRenderImpl(
           case 'FunctionExpression': {
             let returnType: RefAccessType = {kind: 'None'};
             let readRefEffect = false;
+            const innerErrors = new CompilerError();
             const result = validateNoRefAccessInRenderImpl(
               instr.value.loweredFunc.func,
               env,
+              innerErrors,
             );
-            if (result.isOk()) {
-              returnType = result.unwrap();
-            } else if (result.isErr()) {
+            if (!innerErrors.hasAnyErrors()) {
+              returnType = result;
+            } else {
               readRefEffect = true;
             }
             env.set(instr.lvalue.identifier.id, {
@@ -729,7 +732,7 @@ function validateNoRefAccessInRenderImpl(
     }
 
     if (errors.hasAnyErrors()) {
-      return Err(errors);
+      return {kind: 'None'};
     }
   }
 
@@ -738,10 +741,8 @@ function validateNoRefAccessInRenderImpl(
     loc: GeneratedSource,
   });
 
-  return Ok(
-    joinRefAccessTypes(
-      ...returnValues.filter((env): env is RefAccessType => env !== undefined),
-    ),
+  return joinRefAccessTypes(
+    ...returnValues.filter((env): env is RefAccessType => env !== undefined),
   );
 }
 

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInRender.ts

@@ -13,7 +13,6 @@ import {
 import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {eachInstructionValueOperand} from '../HIR/visitors';
-import {Result} from '../Utils/Result';
 
 /**
  * Validates that the given function does not have an infinite update loop
@@ -43,17 +42,21 @@ import {Result} from '../Utils/Result';
  * y();
  * ```
  */
-export function validateNoSetStateInRender(
-  fn: HIRFunction,
-): Result<void, CompilerError> {
+export function validateNoSetStateInRender(fn: HIRFunction): void {
   const unconditionalSetStateFunctions: Set<IdentifierId> = new Set();
-  return validateNoSetStateInRenderImpl(fn, unconditionalSetStateFunctions);
+  const errors = validateNoSetStateInRenderImpl(
+    fn,
+    unconditionalSetStateFunctions,
+  );
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }
 
 function validateNoSetStateInRenderImpl(
   fn: HIRFunction,
   unconditionalSetStateFunctions: Set<IdentifierId>,
-): Result<void, CompilerError> {
+): CompilerError {
   const unconditionalBlocks = computeUnconditionalBlocks(fn);
   let activeManualMemoId: number | null = null;
   const errors = new CompilerError();
@@ -92,7 +95,7 @@ function validateNoSetStateInRenderImpl(
             validateNoSetStateInRenderImpl(
               instr.value.loweredFunc.func,
               unconditionalSetStateFunctions,
-            ).isErr()
+            ).hasAnyErrors()
           ) {
             // This function expression unconditionally calls a setState
             unconditionalSetStateFunctions.add(instr.lvalue.identifier.id);
@@ -183,5 +186,5 @@ function validateNoSetStateInRenderImpl(
     }
   }
 
-  return errors.asResult();
+  return errors;
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts

@@ -37,7 +37,6 @@ import {
   ReactiveFunctionVisitor,
   visitReactiveFunction,
 } from '../ReactiveScopes/visitors';
-import {Result} from '../Utils/Result';
 import {getOrInsertDefault} from '../Utils/utils';
 
 /**
@@ -47,15 +46,15 @@ import {getOrInsertDefault} from '../Utils/utils';
  * This can occur if a value's mutable range somehow extended to include a hook and
  * was pruned.
  */
-export function validatePreservedManualMemoization(
-  fn: ReactiveFunction,
-): Result<void, CompilerError> {
+export function validatePreservedManualMemoization(fn: ReactiveFunction): void {
   const state = {
     errors: new CompilerError(),
     manualMemoState: null,
   };
   visitReactiveFunction(fn, new Visitor(), state);
-  return state.errors.asResult();
+  for (const detail of state.errors.details) {
+    fn.env.recordError(detail);
+  }
 }
 
 const DEBUG = false;

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateSourceLocations.ts

@@ -9,7 +9,7 @@ import {NodePath} from '@babel/traverse';
 import * as t from '@babel/types';
 import {CompilerDiagnostic, CompilerError, ErrorCategory} from '..';
 import {CodegenFunction} from '../ReactiveScopes';
-import {Result} from '../Utils/Result';
+import {Environment} from '../HIR/Environment';
 
 /**
  * IMPORTANT: This validation is only intended for use in unit tests.
@@ -123,7 +123,8 @@ export function validateSourceLocations(
     t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
   >,
   generatedAst: CodegenFunction,
-): Result<void, CompilerError> {
+  env: Environment,
+): void {
   const errors = new CompilerError();
 
   /*
@@ -309,5 +310,7 @@ export function validateSourceLocations(
     }
   }
 
-  return errors.asResult();
+  for (const detail of errors.details) {
+    env.recordError(detail);
+  }
 }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateUseMemo.ts

@@ -20,9 +20,8 @@ import {
   eachInstructionValueOperand,
   eachTerminalOperand,
 } from '../HIR/visitors';
-import {Result} from '../Utils/Result';
 
-export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
+export function validateUseMemo(fn: HIRFunction): void {
   const errors = new CompilerError();
   const voidMemoErrors = new CompilerError();
   const useMemos = new Set<IdentifierId>();
@@ -177,7 +176,9 @@ export function validateUseMemo(fn: HIRFunction): Result<void, CompilerError> {
     }
   }
   fn.env.logErrors(voidMemoErrors.asResult());
-  return errors.asResult();
+  if (errors.hasAnyErrors()) {
+    fn.env.recordErrors(errors);
+  }
 }
 
 function validateNoContextVariableAssignment(

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.dont-hoist-inline-reference.expect.md

@@ -21,15 +21,15 @@ export const FIXTURE_ENTRYPOINT = {
 ```
 Found 1 error:
 
-Todo: [hoisting] EnterSSA: Expected identifier to be defined before being used
+Invariant: [InferMutationAliasingEffects] Expected value kind to be initialized
 
-Identifier x$1 is undefined.
+<unknown> x$1.
 
-error.dont-hoist-inline-reference.ts:3:2
+error.dont-hoist-inline-reference.ts:3:21
   1 | import {identity} from 'shared-runtime';
   2 | function useInvalid() {
 > 3 |   const x = identity(x);
-    |   ^^^^^^^^^^^^^^^^^^^^^^ [hoisting] EnterSSA: Expected identifier to be defined before being used
+    |                      ^ this is uninitialized
   4 |   return x;
   5 | }
   6 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.hook-call-freezes-captured-memberexpr.expect.md

@@ -29,7 +29,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: This value cannot be modified
 
@@ -43,6 +43,32 @@ error.hook-call-freezes-captured-memberexpr.ts:13:2
   14 |   return <Stringify x={x} cb={cb} />;
   15 | }
   16 |
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `x` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.hook-call-freezes-captured-memberexpr.ts:9:25
+   7 |    * After this custom hook call, it's no longer valid to mutate x.
+   8 |    */
+>  9 |   const cb = useIdentity(() => {
+     |                          ^^^^^^^
+> 10 |     x.value++;
+     | ^^^^^^^^^^^^^^
+> 11 |   });
+     | ^^^^ This function may (indirectly) reassign or modify `x` after render
+  12 |
+  13 |   x.value += count;
+  14 |   return <Stringify x={x} cb={cb} />;
+
+error.hook-call-freezes-captured-memberexpr.ts:10:4
+   8 |    */
+   9 |   const cb = useIdentity(() => {
+> 10 |     x.value++;
+     |     ^ This modifies `x`
+  11 |   });
+  12 |
+  13 |   x.value += count;
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-ReactUseMemo-async-callback.expect.md

@@ -15,7 +15,7 @@ function component(a, b) {
 ## Error
 
 ```
-Found 1 error:
+Found 3 errors:
 
 Error: useMemo() callbacks may not be async or generator functions
 
@@ -32,6 +32,37 @@ error.invalid-ReactUseMemo-async-callback.ts:2:24
   5 |   return x;
   6 | }
   7 |
+
+Error: Found missing memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI.
+
+error.invalid-ReactUseMemo-async-callback.ts:3:10
+  1 | function component(a, b) {
+  2 |   let x = React.useMemo(async () => {
+> 3 |     await a;
+    |           ^ Missing dependency `a`
+  4 |   }, []);
+  5 |   return x;
+  6 | }
+
+Inferred dependencies: `[a]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `a`, but the source dependencies were []. Inferred dependency not present in source.
+
+error.invalid-ReactUseMemo-async-callback.ts:2:24
+  1 | function component(a, b) {
+> 2 |   let x = React.useMemo(async () => {
+    |                         ^^^^^^^^^^^^^
+> 3 |     await a;
+    | ^^^^^^^^^^^^
+> 4 |   }, []);
+    | ^^^^ Could not preserve existing manual memoization
+  5 |   return x;
+  6 | }
+  7 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-conditional-setState-in-useMemo.expect.md

@@ -22,7 +22,7 @@ function Component({item, cond}) {
 ## Error
 
 ```
-Found 2 errors:
+Found 3 errors:
 
 Error: Calling setState from useMemo may trigger an infinite loop
 
@@ -49,6 +49,39 @@ error.invalid-conditional-setState-in-useMemo.ts:8:6
    9 |     }
   10 |   }, [cond, key, init]);
   11 |
+
+Error: Found missing/extra memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI. Extra dependencies can cause a value to update more often than it should, resulting in performance problems such as excessive renders or effects firing too often.
+
+error.invalid-conditional-setState-in-useMemo.ts:7:18
+   5 |   useMemo(() => {
+   6 |     if (cond) {
+>  7 |       setPrevItem(item);
+     |                   ^^^^ Missing dependency `item`
+   8 |       setState(0);
+   9 |     }
+  10 |   }, [cond, key, init]);
+
+error.invalid-conditional-setState-in-useMemo.ts:10:12
+   8 |       setState(0);
+   9 |     }
+> 10 |   }, [cond, key, init]);
+     |             ^^^ Unnecessary dependency `key`. Values declared outside of a component/hook should not be listed as dependencies as the component will not re-render if they change
+  11 |
+  12 |   return state;
+  13 | }
+
+error.invalid-conditional-setState-in-useMemo.ts:10:17
+   8 |       setState(0);
+   9 |     }
+> 10 |   }, [cond, key, init]);
+     |                  ^^^^ Unnecessary dependency `init`. Values declared outside of a component/hook should not be listed as dependencies as the component will not re-render if they change
+  11 |
+  12 |   return state;
+  13 | }
+
+Inferred dependencies: `[cond, item]`
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-impure-functions-in-render.expect.md

@@ -17,7 +17,7 @@ function Component() {
 ## Error
 
 ```
-Found 3 errors:
+Found 6 errors:
 
 Error: Cannot call impure function during render
 
@@ -57,6 +57,45 @@ error.invalid-impure-functions-in-render.ts:6:15
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
   9 |
+
+Error: Cannot call impure function during render
+
+`Date.now` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:4:15
+  2 |
+  3 | function Component() {
+> 4 |   const date = Date.now();
+    |                ^^^^^^^^ Cannot call impure function
+  5 |   const now = performance.now();
+  6 |   const rand = Math.random();
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+
+Error: Cannot call impure function during render
+
+`performance.now` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:5:14
+  3 | function Component() {
+  4 |   const date = Date.now();
+> 5 |   const now = performance.now();
+    |               ^^^^^^^^^^^^^^^ Cannot call impure function
+  6 |   const rand = Math.random();
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+  8 | }
+
+Error: Cannot call impure function during render
+
+`Math.random` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:6:15
+  4 |   const date = Date.now();
+  5 |   const now = performance.now();
+> 6 |   const rand = Math.random();
+    |                ^^^^^^^^^^^ Cannot call impure function
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+  8 | }
+  9 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-mutation-in-closure.expect.md

@@ -16,7 +16,7 @@ function useInvalidMutation(options) {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: This value cannot be modified
 
@@ -30,6 +30,27 @@ error.invalid-mutation-in-closure.ts:4:4
   5 |   }
   6 |   return test;
   7 | }
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `options` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-mutation-in-closure.ts:6:9
+  4 |     options.foo = 'bar';
+  5 |   }
+> 6 |   return test;
+    |          ^^^^ This function may (indirectly) reassign or modify `options` after render
+  7 | }
+  8 |
+
+error.invalid-mutation-in-closure.ts:4:4
+  2 |   function test() {
+  3 |     foo(options.foo); // error should not point on this line
+> 4 |     options.foo = 'bar';
+    |     ^^^^^^^ This modifies `options`
+  5 |   }
+  6 |   return test;
+  7 | }
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-in-hook-return-value.expect.md

@@ -15,7 +15,7 @@ function useFoo() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -29,6 +29,31 @@ error.invalid-reassign-local-in-hook-return-value.ts:4:4
   5 |   };
   6 | }
   7 |
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `x` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-in-hook-return-value.ts:3:9
+  1 | function useFoo() {
+  2 |   let x = 0;
+> 3 |   return value => {
+    |          ^^^^^^^^^^
+> 4 |     x = value;
+    | ^^^^^^^^^^^^^^
+> 5 |   };
+    | ^^^^ This function may (indirectly) reassign or modify `x` after render
+  6 | }
+  7 |
+
+error.invalid-reassign-local-in-hook-return-value.ts:4:4
+  2 |   let x = 0;
+  3 |   return value => {
+> 4 |     x = value;
+    |     ^ This modifies `x`
+  5 |   };
+  6 | }
+  7 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-effect.expect.md

@@ -47,7 +47,7 @@ function Component() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -61,6 +61,32 @@ error.invalid-reassign-local-variable-in-effect.ts:7:4
    8 |   };
    9 |
   10 |   const onMount = newValue => {
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `local` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-variable-in-effect.ts:33:12
+  31 |   };
+  32 |
+> 33 |   useEffect(() => {
+     |             ^^^^^^^
+> 34 |     onMount();
+     | ^^^^^^^^^^^^^^
+> 35 |   }, [onMount]);
+     | ^^^^ This function may (indirectly) reassign or modify `local` after render
+  36 |
+  37 |   return 'ok';
+  38 | }
+
+error.invalid-reassign-local-variable-in-effect.ts:7:4
+   5 |
+   6 |   const reassignLocal = newValue => {
+>  7 |     local = newValue;
+     |     ^^^^^ This modifies `local`
+   8 |   };
+   9 |
+  10 |   const onMount = newValue => {
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-hook-argument.expect.md

@@ -48,7 +48,7 @@ function Component() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -62,6 +62,32 @@ error.invalid-reassign-local-variable-in-hook-argument.ts:8:4
    9 |   };
   10 |
   11 |   const callback = newValue => {
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `local` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-variable-in-hook-argument.ts:34:14
+  32 |   };
+  33 |
+> 34 |   useIdentity(() => {
+     |               ^^^^^^^
+> 35 |     callback();
+     | ^^^^^^^^^^^^^^^
+> 36 |   });
+     | ^^^^ This function may (indirectly) reassign or modify `local` after render
+  37 |
+  38 |   return 'ok';
+  39 | }
+
+error.invalid-reassign-local-variable-in-hook-argument.ts:8:4
+   6 |
+   7 |   const reassignLocal = newValue => {
+>  8 |     local = newValue;
+     |     ^^^^^ This modifies `local`
+   9 |   };
+  10 |
+  11 |   const callback = newValue => {
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-reassign-local-variable-in-jsx-callback.expect.md

@@ -41,7 +41,7 @@ function Component() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -55,6 +55,27 @@ error.invalid-reassign-local-variable-in-jsx-callback.ts:5:4
   6 |   };
   7 |
   8 |   const onClick = newValue => {
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `local` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-variable-in-jsx-callback.ts:31:26
+  29 |   };
+  30 |
+> 31 |   return <button onClick={onClick}>Submit</button>;
+     |                           ^^^^^^^ This function may (indirectly) reassign or modify `local` after render
+  32 | }
+  33 |
+
+error.invalid-reassign-local-variable-in-jsx-callback.ts:5:4
+  3 |
+  4 |   const reassignLocal = newValue => {
+> 5 |     local = newValue;
+    |     ^^^^^ This modifies `local`
+  6 |   };
+  7 |
+  8 |   const onClick = newValue => {
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-setState-in-useMemo-indirect-useCallback.expect.md

@@ -26,7 +26,7 @@ function useKeyedState({key, init}) {
 ## Error
 
 ```
-Found 1 error:
+Found 3 errors:
 
 Error: Calling setState from useMemo may trigger an infinite loop
 
@@ -40,6 +40,61 @@ error.invalid-setState-in-useMemo-indirect-useCallback.ts:13:4
   14 |   }, [key, init]);
   15 |
   16 |   return state;
+
+Error: Found missing memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI.
+
+error.invalid-setState-in-useMemo-indirect-useCallback.ts:9:13
+   7 |   const fn = useCallback(() => {
+   8 |     setPrevKey(key);
+>  9 |     setState(init);
+     |              ^^^^ Missing dependency `init`
+  10 |   });
+  11 |
+  12 |   useMemo(() => {
+
+error.invalid-setState-in-useMemo-indirect-useCallback.ts:8:15
+   6 |
+   7 |   const fn = useCallback(() => {
+>  8 |     setPrevKey(key);
+     |                ^^^ Missing dependency `key`
+   9 |     setState(init);
+  10 |   });
+  11 |
+
+Error: Found missing/extra memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI. Extra dependencies can cause a value to update more often than it should, resulting in performance problems such as excessive renders or effects firing too often.
+
+error.invalid-setState-in-useMemo-indirect-useCallback.ts:13:4
+  11 |
+  12 |   useMemo(() => {
+> 13 |     fn();
+     |     ^^ Missing dependency `fn`
+  14 |   }, [key, init]);
+  15 |
+  16 |   return state;
+
+error.invalid-setState-in-useMemo-indirect-useCallback.ts:14:6
+  12 |   useMemo(() => {
+  13 |     fn();
+> 14 |   }, [key, init]);
+     |       ^^^ Unnecessary dependency `key`
+  15 |
+  16 |   return state;
+  17 | }
+
+error.invalid-setState-in-useMemo-indirect-useCallback.ts:14:11
+  12 |   useMemo(() => {
+  13 |     fn();
+> 14 |   }, [key, init]);
+     |            ^^^^ Unnecessary dependency `init`
+  15 |
+  16 |   return state;
+  17 | }
+
+Inferred dependencies: `[fn]`
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-useMemo-async-callback.expect.md

@@ -15,7 +15,7 @@ function component(a, b) {
 ## Error
 
 ```
-Found 1 error:
+Found 3 errors:
 
 Error: useMemo() callbacks may not be async or generator functions
 
@@ -32,6 +32,37 @@ error.invalid-useMemo-async-callback.ts:2:18
   5 |   return x;
   6 | }
   7 |
+
+Error: Found missing memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI.
+
+error.invalid-useMemo-async-callback.ts:3:10
+  1 | function component(a, b) {
+  2 |   let x = useMemo(async () => {
+> 3 |     await a;
+    |           ^ Missing dependency `a`
+  4 |   }, []);
+  5 |   return x;
+  6 | }
+
+Inferred dependencies: `[a]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `a`, but the source dependencies were []. Inferred dependency not present in source.
+
+error.invalid-useMemo-async-callback.ts:2:18
+  1 | function component(a, b) {
+> 2 |   let x = useMemo(async () => {
+    |                   ^^^^^^^^^^^^^
+> 3 |     await a;
+    | ^^^^^^^^^^^^
+> 4 |   }, []);
+    | ^^^^ Could not preserve existing manual memoization
+  5 |   return x;
+  6 | }
+  7 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-useMemo-callback-args.expect.md

@@ -13,7 +13,7 @@ function component(a, b) {
 ## Error
 
 ```
-Found 1 error:
+Found 3 errors:
 
 Error: useMemo() callbacks may not accept parameters
 
@@ -26,6 +26,32 @@ error.invalid-useMemo-callback-args.ts:2:18
   3 |   return x;
   4 | }
   5 |
+
+Error: Found missing memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI.
+
+error.invalid-useMemo-callback-args.ts:2:23
+  1 | function component(a, b) {
+> 2 |   let x = useMemo(c => a, []);
+    |                        ^ Missing dependency `a`
+  3 |   return x;
+  4 | }
+  5 |
+
+Inferred dependencies: `[a]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `a`, but the source dependencies were []. Inferred dependency not present in source.
+
+error.invalid-useMemo-callback-args.ts:2:18
+  1 | function component(a, b) {
+> 2 |   let x = useMemo(c => a, []);
+    |                   ^^^^^^ Could not preserve existing manual memoization
+  3 |   return x;
+  4 | }
+  5 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.mutable-range-shared-inner-outer-function.expect.md

@@ -32,7 +32,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -46,6 +46,28 @@ error.mutable-range-shared-inner-outer-function.ts:8:6
    9 |       b = [];
   10 |     } else {
   11 |       a = {};
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `a` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.mutable-range-shared-inner-outer-function.ts:17:23
+  15 |     b.push(false);
+  16 |   };
+> 17 |   return <div onClick={f} />;
+     |                        ^ This function may (indirectly) reassign or modify `a` after render
+  18 | }
+  19 |
+  20 | export const FIXTURE_ENTRYPOINT = {
+
+error.mutable-range-shared-inner-outer-function.ts:8:6
+   6 |   const f = () => {
+   7 |     if (cond) {
+>  8 |       a = {};
+     |       ^ This modifies `a`
+   9 |       b = [];
+  10 |     } else {
+  11 |       a = {};
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-allow-assigning-to-inferred-ref-prop-in-callback.expect.md

@@ -29,7 +29,7 @@ function useHook(parentRef) {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: This value cannot be modified
 
@@ -43,6 +43,27 @@ error.todo-allow-assigning-to-inferred-ref-prop-in-callback.ts:15:8
   16 |       }
   17 |     }
   18 |   };
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `parentRef` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.todo-allow-assigning-to-inferred-ref-prop-in-callback.ts:19:9
+  17 |     }
+  18 |   };
+> 19 |   return handler;
+     |          ^^^^^^^ This function may (indirectly) reassign or modify `parentRef` after render
+  20 | }
+  21 |
+
+error.todo-allow-assigning-to-inferred-ref-prop-in-callback.ts:15:8
+  13 |       } else {
+  14 |         // So this assignment fails since we don't know its a ref
+> 15 |         parentRef.current = instance;
+     |         ^^^^^^^^^ This modifies `parentRef`
+  16 |       }
+  17 |     }
+  18 |   };
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-function-expression-references-later-variable-declaration.expect.md

@@ -17,7 +17,7 @@ function Component() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -31,6 +31,27 @@ error.todo-function-expression-references-later-variable-declaration.ts:3:4
   4 |   };
   5 |   let onClick;
   6 |
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `onClick` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.todo-function-expression-references-later-variable-declaration.ts:7:23
+  5 |   let onClick;
+  6 |
+> 7 |   return <div onClick={callback} />;
+    |                        ^^^^^^^^ This function may (indirectly) reassign or modify `onClick` after render
+  8 | }
+  9 |
+
+error.todo-function-expression-references-later-variable-declaration.ts:3:4
+  1 | function Component() {
+  2 |   let callback = () => {
+> 3 |     onClick = () => {};
+    |     ^^^^^^^ This modifies `onClick`
+  4 |   };
+  5 |   let onClick;
+  6 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-reassign-const.expect.md

@@ -21,7 +21,7 @@ function Component({foo}) {
 ## Error
 
 ```
-Found 1 error:
+Found 3 errors:
 
 Todo: Support destructuring of context variables
 
@@ -29,10 +29,34 @@ error.todo-reassign-const.ts:3:20
   1 | import {Stringify} from 'shared-runtime';
   2 |
 > 3 | function Component({foo}) {
-    |                     ^^^ Support destructuring of context variables
+    |                     ^^^
   4 |   let bar = foo.bar;
   5 |   return (
   6 |     <Stringify
+
+Todo: Support destructuring of context variables
+
+error.todo-reassign-const.ts:3:20
+  1 | import {Stringify} from 'shared-runtime';
+  2 |
+> 3 | function Component({foo}) {
+    |                     ^^^
+  4 |   let bar = foo.bar;
+  5 |   return (
+  6 |     <Stringify
+
+Error: This value cannot be modified
+
+Modifying component props or hook arguments is not allowed. Consider using a local variable instead.
+
+error.todo-reassign-const.ts:8:8
+   6 |     <Stringify
+   7 |       handler={() => {
+>  8 |         foo = true;
+     |         ^^^ `foo` cannot be modified
+   9 |       }}
+  10 |     />
+  11 |   );
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/exhaustive-deps/error.invalid-exhaustive-deps.expect.md

@@ -51,7 +51,7 @@ function Component({x, y, z}) {
 ## Error
 
 ```
-Found 4 errors:
+Found 6 errors:
 
 Error: Found missing/extra memoization dependencies
 
@@ -157,6 +157,48 @@ error.invalid-exhaustive-deps.ts:37:13
   40 |   }, []);
 
 Inferred dependencies: `[ref]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `x.y.z.a.b`, but the source dependencies were [x?.y.z.a?.b.z]. Inferred different dependency than source.
+
+error.invalid-exhaustive-deps.ts:14:20
+  12 |     // ok, not our job to type check nullability
+  13 |   }, [x.y.z.a]);
+> 14 |   const c = useMemo(() => {
+     |                     ^^^^^^^
+> 15 |     return x?.y.z.a?.b;
+     | ^^^^^^^^^^^^^^^^^^^^^^^
+> 16 |     // error: too precise
+     | ^^^^^^^^^^^^^^^^^^^^^^^
+> 17 |   }, [x?.y.z.a?.b.z]);
+     | ^^^^ Could not preserve existing manual memoization
+  18 |   const d = useMemo(() => {
+  19 |     return x?.y?.[(console.log(y), z?.b)];
+  20 |     // ok
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `ref`, but the source dependencies were []. Inferred dependency not present in source.
+
+error.invalid-exhaustive-deps.ts:35:21
+  33 |   const ref2 = useRef(null);
+  34 |   const ref = z ? ref1 : ref2;
+> 35 |   const cb = useMemo(() => {
+     |                      ^^^^^^^
+> 36 |     return () => {
+     | ^^^^^^^^^^^^^^^^^^
+> 37 |       return ref.current;
+     | ^^^^^^^^^^^^^^^^^^
+> 38 |     };
+     | ^^^^^^^^^^^^^^^^^^
+> 39 |     // error: ref is a stable type but reactive
+     | ^^^^^^^^^^^^^^^^^^
+> 40 |   }, []);
+     | ^^^^ Could not preserve existing manual memoization
+  41 |   return <Stringify results={[a, b, c, d, e, f, cb]} />;
+  42 | }
+  43 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/exhaustive-deps/error.invalid-missing-nonreactive-dep-unmemoized.expect.md

@@ -22,7 +22,7 @@ function useHook() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Found missing memoization dependencies
 
@@ -38,6 +38,19 @@ error.invalid-missing-nonreactive-dep-unmemoized.ts:11:31
   14 |
 
 Inferred dependencies: `[object]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `object`, but the source dependencies were []. Inferred dependency not present in source.
+
+error.invalid-missing-nonreactive-dep-unmemoized.ts:11:24
+   9 |   useIdentity();
+  10 |   object.x = 0;
+> 11 |   const array = useMemo(() => [object], []);
+     |                         ^^^^^^^^^^^^^^ Could not preserve existing manual memoization
+  12 |   return array;
+  13 | }
+  14 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/gating/dynamic-gating-bailout-nopanic.expect.md

@@ -58,6 +58,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
+{"kind":"CompileError","detail":{"options":{"category":"PreserveManualMemo","reason":"Existing memoization could not be preserved","description":"React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `value`, but the source dependencies were []. Inferred dependency not present in source","suggestions":null,"details":[{"kind":"error","loc":{"start":{"line":9,"column":31,"index":337},"end":{"line":9,"column":52,"index":358},"filename":"dynamic-gating-bailout-nopanic.ts"},"message":"Could not preserve existing manual memoization"}]}},"fnLoc":null}
 {"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":255},"end":{"line":16,"column":1,"index":482},"filename":"dynamic-gating-bailout-nopanic.ts"},"detail":{"options":{"category":"PreserveManualMemo","reason":"Existing memoization could not be preserved","description":"React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `value`, but the source dependencies were []. Inferred dependency not present in source","suggestions":null,"details":[{"kind":"error","loc":{"start":{"line":9,"column":31,"index":337},"end":{"line":9,"column":52,"index":358},"filename":"dynamic-gating-bailout-nopanic.ts"},"message":"Could not preserve existing manual memoization"}]}}}
 ```
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-impure-functions-in-render.expect.md

@@ -17,7 +17,7 @@ function Component() {
 ## Error
 
 ```
-Found 3 errors:
+Found 6 errors:
 
 Error: Cannot call impure function during render
 
@@ -57,6 +57,45 @@ error.invalid-impure-functions-in-render.ts:6:15
   7 |   return <Foo date={date} now={now} rand={rand} />;
   8 | }
   9 |
+
+Error: Cannot call impure function during render
+
+`Date.now` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:4:15
+  2 |
+  3 | function Component() {
+> 4 |   const date = Date.now();
+    |                ^^^^^^^^ Cannot call impure function
+  5 |   const now = performance.now();
+  6 |   const rand = Math.random();
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+
+Error: Cannot call impure function during render
+
+`performance.now` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:5:14
+  3 | function Component() {
+  4 |   const date = Date.now();
+> 5 |   const now = performance.now();
+    |               ^^^^^^^^^^^^^^^ Cannot call impure function
+  6 |   const rand = Math.random();
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+  8 | }
+
+Error: Cannot call impure function during render
+
+`Math.random` is an impure function. Calling an impure function can produce unstable results that update unpredictably when the component happens to re-render. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent).
+
+error.invalid-impure-functions-in-render.ts:6:15
+  4 |   const date = Date.now();
+  5 |   const now = performance.now();
+> 6 |   const rand = Math.random();
+    |                ^^^^^^^^^^^ Cannot call impure function
+  7 |   return <Foo date={date} now={now} rand={rand} />;
+  8 | }
+  9 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-reassign-local-variable-in-jsx-callback.expect.md

@@ -42,7 +42,7 @@ function Component() {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot reassign variable after render completes
 
@@ -56,6 +56,27 @@ error.invalid-reassign-local-variable-in-jsx-callback.ts:6:4
   7 |   };
   8 |
   9 |   const onClick = newValue => {
+
+Error: Cannot modify local variables after render completes
+
+This argument is a function which may reassign or mutate `local` after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead.
+
+error.invalid-reassign-local-variable-in-jsx-callback.ts:32:26
+  30 |   };
+  31 |
+> 32 |   return <button onClick={onClick}>Submit</button>;
+     |                           ^^^^^^^ This function may (indirectly) reassign or modify `local` after render
+  33 | }
+  34 |
+
+error.invalid-reassign-local-variable-in-jsx-callback.ts:6:4
+  4 |
+  5 |   const reassignLocal = newValue => {
+> 6 |     local = newValue;
+    |     ^^^^^ This modifies `local`
+  7 |   };
+  8 |
+  9 |   const onClick = newValue => {
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/error.invalid-referencing-frozen-hoisted-storecontext-const.expect.md

@@ -31,7 +31,7 @@ function Component({content, refetch}) {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Cannot access variable before it is declared
 
@@ -52,6 +52,18 @@ Error: Cannot access variable before it is declared
   20 |
   21 |   return <Foo data={data} onSubmit={onSubmit} />;
   22 | }
+
+Error: Found missing memoization dependencies
+
+Missing dependencies can cause a value to update less often than it should, resulting in stale UI.
+
+   9 |   // TDZ violation!
+  10 |   const onRefetch = useCallback(() => {
+> 11 |     refetch(data);
+     |             ^^^^ Missing dependency `data`
+  12 |   }, [refetch]);
+  13 |
+  14 |   // The context variable gets frozen here since it's passed to a hook
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.useMemo-unrelated-mutation-in-depslist.expect.md

@@ -30,7 +30,7 @@ function useFoo(input1) {
 ## Error
 
 ```
-Found 1 error:
+Found 2 errors:
 
 Error: Found missing memoization dependencies
 
@@ -46,6 +46,23 @@ error.useMemo-unrelated-mutation-in-depslist.ts:18:14
   21 | }
 
 Inferred dependencies: `[x, y]`
+
+Compilation Skipped: Existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `input1`, but the source dependencies were [y]. Inferred different dependency than source.
+
+error.useMemo-unrelated-mutation-in-depslist.ts:16:27
+  14 |   const x = {};
+  15 |   const y = [input1];
+> 16 |   const memoized = useMemo(() => {
+     |                            ^^^^^^^
+> 17 |     return [y];
+     | ^^^^^^^^^^^^^^^
+> 18 |   }, [(mutate(x), y)]);
+     | ^^^^ Could not preserve existing manual memoization
+  19 |
+  20 |   return [x, memoized];
+  21 | }
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/rules-of-hooks/error.invalid-hook-for.expect.md

@@ -16,29 +16,24 @@ function Component(props) {
 ## Error
 
 ```
-Found 2 errors:
+Found 1 error:
 
-Error: Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)
+Invariant: Unexpected empty block with `goto` terminal
 
-error.invalid-hook-for.ts:4:9
-  2 |   let i = 0;
-  3 |   for (let x = 0; useHook(x) < 10; useHook(i), x++) {
-> 4 |     i += useHook(x);
-    |          ^^^^^^^ Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)
-  5 |   }
-  6 |   return i;
-  7 | }
+Block bb5 is empty.
 
-Error: Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)
-
-error.invalid-hook-for.ts:3:35
+error.invalid-hook-for.ts:3:2
   1 | function Component(props) {
   2 |   let i = 0;
 > 3 |   for (let x = 0; useHook(x) < 10; useHook(i), x++) {
-    |                                    ^^^^^^^ Hooks must always be called in a consistent order, and may not be called conditionally. See the Rules of Hooks (https://react.dev/warnings/invalid-hook-call-warning)
-  4 |     i += useHook(x);
-  5 |   }
+    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+> 4 |     i += useHook(x);
+    | ^^^^^^^^^^^^^^^^^^^^
+> 5 |   }
+    | ^^^^ Unexpected empty block with `goto` terminal
   6 |   return i;
+  7 | }
+  8 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/use-no-forget-multiple-with-eslint-suppression.expect.md

@@ -25,6 +25,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
+import { c as _c } from "react/compiler-runtime";
 import { useRef } from "react";
 
 const useControllableState = (options) => {};