Improve error message and detail ordering for shadowing case

This PR adds infra to disambiguate between two types of derived state in effects:
  1. State derived from props
  2. State derived from other state

TODO:
- [ ] Props tracking through destructuring and property access does not seem to be propagated correctly inside of Functions' instructions (or i might be misunderstanding how we track aliasing effects)
- [ ] compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/invalid-derived-state-from-props-computed.js should be failing
- [ ] Handle "mixed" case where deps flow from at least one prop AND state. Should probably have a different error reason, to aid with categorization

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

@@ -5,20 +5,52 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity, SourceLocation} from '..';
+import {
+  CompilerDiagnostic,
+  CompilerError,
+  Effect,
+  ErrorSeverity,
+  SourceLocation,
+} from '..';
 import {
   ArrayExpression,
+  BasicBlock,
   BlockId,
   FunctionExpression,
   HIRFunction,
   IdentifierId,
+  Instruction,
+  Place,
   isSetStateType,
   isUseEffectHookType,
+  isUseStateType,
+  GeneratedSource,
 } from '../HIR';
-import {
-  eachInstructionValueOperand,
-  eachTerminalOperand,
-} from '../HIR/visitors';
+import {eachInstructionOperand, eachInstructionLValue} from '../HIR/visitors';
+import {isMutable} from '../ReactiveScopes/InferReactiveScopeVariables';
+import {assertExhaustive} from '../Utils/utils';
+
+type SetStateCall = {
+  loc: SourceLocation;
+  derivedDep: DerivationMetadata;
+  setStateId: IdentifierId;
+};
+
+type TypeOfValue = 'ignored' | 'fromProps' | 'fromState' | 'fromPropsOrState';
+
+type DerivationMetadata = {
+  typeOfValue: TypeOfValue;
+  place: Place;
+  sources: Array<Place>;
+};
+
+type ErrorMetadata = {
+  type: TypeOfValue;
+  description: string | undefined;
+  loc: SourceLocation;
+  setStateName: string | undefined | null;
+  derivedDepsNames: Array<string>;
+};
 
 /**
  * Validates that useEffect is not used for derived computations which could/should
@@ -47,12 +79,46 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
   const candidateDependencies: Map<IdentifierId, ArrayExpression> = new Map();
   const functions: Map<IdentifierId, FunctionExpression> = new Map();
   const locals: Map<IdentifierId, IdentifierId> = new Map();
+  const derivationCache: Map<IdentifierId, DerivationMetadata> = new Map();
+  const shadowingUseState: Map<string, Array<SourceLocation>> = new Map();
 
-  const errors = new CompilerError();
+  const effectSetStates: Map<
+    string | undefined | null,
+    Array<Place>
+  > = new Map();
+  const setStateCalls: Map<string | undefined | null, Array<Place>> = new Map();
+
+  const errors: Array<ErrorMetadata> = [];
+
+  if (fn.fnType === 'Hook') {
+    for (const param of fn.params) {
+      if (param.kind === 'Identifier') {
+        derivationCache.set(param.identifier.id, {
+          place: param,
+          sources: [param],
+          typeOfValue: 'fromProps',
+        });
+      }
+    }
+  } else if (fn.fnType === 'Component') {
+    const props = fn.params[0];
+    if (props != null && props.kind === 'Identifier') {
+      derivationCache.set(props.identifier.id, {
+        place: props,
+        sources: [props],
+        typeOfValue: 'fromProps',
+      });
+    }
+  }
 
   for (const block of fn.body.blocks.values()) {
+    parseBlockPhi(block, derivationCache);
+
     for (const instr of block.instructions) {
       const {lvalue, value} = instr;
+
+      parseInstr(instr, derivationCache, setStateCalls, shadowingUseState);
+
       if (value.kind === 'LoadLocal') {
         locals.set(lvalue.identifier.id, value.place.identifier.id);
       } else if (value.kind === 'ArrayExpression') {
@@ -65,6 +131,7 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
       ) {
         const callee =
           value.kind === 'CallExpression' ? value.callee : value.property;
+
         if (
           isUseEffectHookType(callee.identifier) &&
           value.args.length === 2 &&
@@ -89,6 +156,8 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
             validateEffect(
               effectFunction.loweredFunc.func,
               dependencies,
+              derivationCache,
+              effectSetStates,
               errors,
             );
           }
@@ -96,43 +165,325 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
       }
     }
   }
-  if (errors.hasErrors()) {
-    throw errors;
+
+  const compilerError = generateCompilerError(
+    setStateCalls,
+    effectSetStates,
+    shadowingUseState,
+    errors,
+  );
+
+  if (compilerError.hasErrors()) {
+    throw compilerError;
+  }
+}
+
+function generateCompilerError(
+  setStateCalls: Map<string | undefined | null, Array<Place>>,
+  effectSetStates: Map<string | undefined | null, Array<Place>>,
+  shadowingUseState: Map<string, Array<SourceLocation>>,
+  errors: Array<ErrorMetadata>,
+): CompilerError {
+  const throwableErrors = new CompilerError();
+  for (const error of errors) {
+    let compilerDiagnostic: CompilerDiagnostic | undefined = undefined;
+
+    /*
+     * If we use a setState from an invalid useEffect elsewhere then we probably have to
+     * hoist state up, else we should calculate in render
+     */
+    if (
+      setStateCalls.get(error.setStateName)?.length !=
+        effectSetStates.get(error.setStateName)?.length &&
+      error.type !== 'fromState'
+    ) {
+      compilerDiagnostic = CompilerDiagnostic.create({
+        description: `The setState within a useEffect is deriving from ${error.description} Instead of shadowing the prop with local state, hoist the state to the parent component and update it there. If you are purposefully initializing state with a prop, and want to update it when a prop changes, do so conditionally in render`,
+        category: `You might not need an effect. Local state shadows parent state.`,
+        severity: ErrorSeverity.InvalidReact,
+      }).withDetail({
+        kind: 'error',
+        loc: error.loc,
+        message: `this derives values from props ${error.type === 'fromPropsOrState' ? 'and local state ' : ''}to synchronize state`,
+      });
+
+      for (const derivedDep of error.derivedDepsNames) {
+        if (shadowingUseState.has(derivedDep)) {
+          for (const loc of shadowingUseState.get(derivedDep)!) {
+            compilerDiagnostic.withDetail({
+              kind: 'error',
+              loc: loc,
+              message: `this useState shadows ${derivedDep}`,
+            });
+          }
+        }
+      }
+
+      for (const [key, setStateCallArray] of effectSetStates) {
+        if (setStateCallArray.length === 0) {
+          continue;
+        }
+
+        const nonUseEffectSetStateCalls = setStateCalls.get(key);
+        if (nonUseEffectSetStateCalls) {
+          for (const place of nonUseEffectSetStateCalls) {
+            if (!setStateCallArray.includes(place)) {
+              compilerDiagnostic.withDetail({
+                kind: 'error',
+                loc: place.loc,
+                message:
+                  'this setState updates the shadowed state, but should call an onChange event from the parent',
+              });
+            }
+          }
+        }
+      }
+    } else {
+      compilerDiagnostic = CompilerDiagnostic.create({
+        description: `${error.description} Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.`,
+        category: `You might not need an effect. Derive values in render, not effects.`,
+        severity: ErrorSeverity.InvalidReact,
+      }).withDetail({
+        kind: 'error',
+        loc: error.loc,
+        message: 'This should be computed during render, not in an effect',
+      });
+    }
+
+    if (compilerDiagnostic) {
+      throwableErrors.pushDiagnostic(compilerDiagnostic);
+    }
+  }
+
+  return throwableErrors;
+}
+
+function joinValue(
+  lvalueType: TypeOfValue,
+  valueType: TypeOfValue,
+): TypeOfValue {
+  if (lvalueType === 'ignored') return valueType;
+  if (valueType === 'ignored') return lvalueType;
+  if (lvalueType === valueType) return lvalueType;
+  return 'fromPropsOrState';
+}
+
+function updateDerivationMetadata(
+  target: Place,
+  sources: Array<DerivationMetadata> | undefined,
+  typeOfValue: TypeOfValue | undefined,
+  derivationCache: Map<IdentifierId, DerivationMetadata>,
+): void {
+  let newValue: DerivationMetadata = {
+    place: target,
+    sources: [],
+    typeOfValue: typeOfValue ?? 'ignored',
+  };
+
+  if (sources !== undefined) {
+    for (const source of sources) {
+      /*
+       * If the identifier of the source is a promoted identifier, then
+       *  we should set the target as the source.
+       */
+      for (const place of source.sources) {
+        if (
+          place.identifier.name === null ||
+          place.identifier.name?.kind === 'promoted'
+        ) {
+          newValue.sources.push(target);
+        } else {
+          newValue.sources.push(place);
+        }
+      }
+    }
+  }
+
+  derivationCache.set(target.identifier.id, newValue);
+}
+
+function parseInstr(
+  instr: Instruction,
+  derivationCache: Map<IdentifierId, DerivationMetadata>,
+  setStateCalls: Map<string | undefined | null, Array<Place>>,
+  shadowingUseState: Map<string, Array<SourceLocation>>,
+): void {
+  // Recursively parse function expressions
+  if (instr.value.kind === 'FunctionExpression') {
+    for (const [, block] of instr.value.loweredFunc.func.body.blocks) {
+      for (const instr of block.instructions) {
+        parseInstr(instr, derivationCache, setStateCalls, shadowingUseState);
+      }
+    }
+  }
+
+  let typeOfValue: TypeOfValue = 'ignored';
+
+  let sources: Array<DerivationMetadata> = [];
+  // Catch setState calls
+  if (
+    instr.value.kind === 'CallExpression' &&
+    isSetStateType(instr.value.callee.identifier) &&
+    instr.value.args.length === 1 &&
+    instr.value.args[0].kind === 'Identifier' &&
+    instr.value.callee.loc !== GeneratedSource
+  ) {
+    if (setStateCalls.has(instr.value.callee.loc.identifierName)) {
+      setStateCalls
+        .get(instr.value.callee.loc.identifierName)!
+        .push(instr.value.callee);
+    } else {
+      setStateCalls.set(instr.value.callee.loc.identifierName, [
+        instr.value.callee,
+      ]);
+    }
+  }
+
+  for (const operand of eachInstructionOperand(instr)) {
+    const opSource = derivationCache.get(operand.identifier.id);
+    if (opSource === undefined) {
+      continue;
+    }
+
+    typeOfValue = joinValue(typeOfValue, opSource.typeOfValue);
+    sources.push(opSource);
+
+    if (
+      instr.value.kind === 'Destructure' &&
+      instr.value.lvalue.pattern.kind === 'ArrayPattern' &&
+      isUseStateType(instr.value.value.identifier) &&
+      opSource.typeOfValue === 'fromProps'
+    ) {
+      opSource.sources.forEach(source => {
+        if (instr.value.kind !== 'Destructure') {
+          return;
+        }
+
+        if (source.identifier.name !== null) {
+          if (shadowingUseState.has(source.identifier.name.value)) {
+            shadowingUseState
+              .get(source.identifier.name.value)
+              ?.push(instr.value.value.loc);
+          } else {
+            shadowingUseState.set(source.identifier.name.value, [
+              instr.value.value.loc,
+            ]);
+          }
+        }
+      });
+    }
+  }
+
+  // Catch useState hook calls
+  if (
+    instr.value.kind === 'Destructure' &&
+    instr.value.lvalue.pattern.kind === 'ArrayPattern' &&
+    isUseStateType(instr.value.value.identifier)
+  ) {
+    const stateValueSource = instr.value.lvalue.pattern.items[0];
+    if (stateValueSource.kind === 'Identifier') {
+      sources.push({
+        place: stateValueSource,
+        typeOfValue: typeOfValue,
+        sources: [stateValueSource],
+      });
+    }
+
+    typeOfValue = joinValue(typeOfValue, 'fromState');
+  }
+
+  if (typeOfValue !== 'ignored') {
+    for (const lvalue of eachInstructionLValue(instr)) {
+      updateDerivationMetadata(lvalue, sources, typeOfValue, derivationCache);
+    }
+
+    for (const operand of eachInstructionOperand(instr)) {
+      switch (operand.effect) {
+        case Effect.Capture:
+        case Effect.Store:
+        case Effect.ConditionallyMutate:
+        case Effect.ConditionallyMutateIterator:
+        case Effect.Mutate: {
+          if (isMutable(instr, operand)) {
+            updateDerivationMetadata(
+              operand,
+              sources,
+              typeOfValue,
+              derivationCache,
+            );
+          }
+          break;
+        }
+        case Effect.Freeze:
+        case Effect.Read: {
+          // no-op
+          break;
+        }
+        case Effect.Unknown: {
+          CompilerError.invariant(false, {
+            reason: 'Unexpected unknown effect',
+            description: null,
+            loc: operand.loc,
+            suggestions: null,
+          });
+        }
+        default: {
+          assertExhaustive(
+            operand.effect,
+            `Unexpected effect kind \`${operand.effect}\``,
+          );
+        }
+      }
+    }
+  }
+}
+
+function parseBlockPhi(
+  block: BasicBlock,
+  derivationCache: Map<IdentifierId, DerivationMetadata>,
+): void {
+  for (const phi of block.phis) {
+    for (const operand of phi.operands.values()) {
+      const phiSource = derivationCache.get(operand.identifier.id);
+      if (phiSource !== undefined) {
+        updateDerivationMetadata(
+          phi.place,
+          [phiSource],
+          phiSource?.typeOfValue,
+          derivationCache,
+        );
+      }
+    }
   }
 }
 
 function validateEffect(
   effectFunction: HIRFunction,
   effectDeps: Array<IdentifierId>,
-  errors: CompilerError,
+  derivationCache: Map<IdentifierId, DerivationMetadata>,
+  effectSetStates: Map<string | undefined | null, Array<Place>>,
+  errors: Array<ErrorMetadata>,
 ): void {
-  for (const operand of effectFunction.context) {
-    if (isSetStateType(operand.identifier)) {
-      continue;
-    } else if (effectDeps.find(dep => dep === operand.identifier.id) != null) {
-      continue;
-    } else {
-      // Captured something other than the effect dep or setState
-      return;
+  let isUsingDerivedDeps = false;
+  for (const dep of effectDeps) {
+    const depMetadata = derivationCache.get(dep);
+    if (
+      effectFunction.context.find(operand => operand.identifier.id === dep) !=
+        null ||
+      (depMetadata !== undefined && depMetadata.typeOfValue !== 'ignored')
+    ) {
+      isUsingDerivedDeps = true;
     }
   }
-  for (const dep of effectDeps) {
-    if (
-      effectFunction.context.find(operand => operand.identifier.id === dep) ==
-      null
-    ) {
-      // effect dep wasn't actually used in the function
-      return;
-    }
+
+  if (!isUsingDerivedDeps) {
+    // no prop/state derived deps were used in the body of the effect
+    return;
   }
 
   const seenBlocks: Set<BlockId> = new Set();
-  const values: Map<IdentifierId, Array<IdentifierId>> = new Map();
-  for (const dep of effectDeps) {
-    values.set(dep, [dep]);
-  }
 
-  const setStateLocations: Array<SourceLocation> = [];
+  const derivedSetStateCall: Array<SetStateCall> = [];
   for (const block of effectFunction.body.blocks.values()) {
     for (const pred of block.preds) {
       if (!seenBlocks.has(pred)) {
@@ -140,21 +491,29 @@ function validateEffect(
         return;
       }
     }
-    for (const phi of block.phis) {
-      const aggregateDeps: Set<IdentifierId> = new Set();
-      for (const operand of phi.operands.values()) {
-        const deps = values.get(operand.identifier.id);
-        if (deps != null) {
-          for (const dep of deps) {
-            aggregateDeps.add(dep);
-          }
+
+    parseBlockPhi(block, derivationCache);
+
+    for (const instr of block.instructions) {
+      if (
+        instr.value.kind === 'CallExpression' &&
+        isSetStateType(instr.value.callee.identifier) &&
+        instr.value.args.length === 1 &&
+        instr.value.args[0].kind === 'Identifier' &&
+        instr.value.callee.loc !== GeneratedSource &&
+        instr.value.callee.loc.identifierName !== undefined &&
+        instr.value.callee.loc.identifierName !== null
+      ) {
+        if (effectSetStates.has(instr.value.callee.loc.identifierName)) {
+          effectSetStates
+            .get(instr.value.callee.loc.identifierName)!
+            .push(instr.value.callee);
+        } else {
+          effectSetStates.set(instr.value.callee.loc.identifierName, [
+            instr.value.callee,
+          ]);
         }
       }
-      if (aggregateDeps.size !== 0) {
-        values.set(phi.place.identifier.id, Array.from(aggregateDeps));
-      }
-    }
-    for (const instr of block.instructions) {
       switch (instr.value.kind) {
         case 'Primitive':
         case 'JSXText':
@@ -162,10 +521,6 @@ function validateEffect(
           break;
         }
         case 'LoadLocal': {
-          const deps = values.get(instr.value.place.identifier.id);
-          if (deps != null) {
-            values.set(instr.lvalue.identifier.id, deps);
-          }
           break;
         }
         case 'ComputedLoad':
@@ -174,57 +529,61 @@ function validateEffect(
         case 'TemplateLiteral':
         case 'CallExpression':
         case 'MethodCall': {
-          const aggregateDeps: Set<IdentifierId> = new Set();
-          for (const operand of eachInstructionValueOperand(instr.value)) {
-            const deps = values.get(operand.identifier.id);
-            if (deps != null) {
-              for (const dep of deps) {
-                aggregateDeps.add(dep);
-              }
-            }
-          }
-          if (aggregateDeps.size !== 0) {
-            values.set(instr.lvalue.identifier.id, Array.from(aggregateDeps));
-          }
-
           if (
             instr.value.kind === 'CallExpression' &&
             isSetStateType(instr.value.callee.identifier) &&
             instr.value.args.length === 1 &&
             instr.value.args[0].kind === 'Identifier'
           ) {
-            const deps = values.get(instr.value.args[0].identifier.id);
-            if (deps != null && new Set(deps).size === effectDeps.length) {
-              setStateLocations.push(instr.value.callee.loc);
-            } else {
-              // doesn't depend on any deps
-              return;
+            const derivedDep = derivationCache.get(
+              instr.value.args[0].identifier.id,
+            );
+
+            if (derivedDep !== undefined) {
+              derivedSetStateCall.push({
+                loc: instr.value.callee.loc,
+                setStateId: instr.value.callee.identifier.id,
+                derivedDep: derivedDep,
+              });
             }
           }
           break;
         }
-        default: {
-          return;
-        }
-      }
-    }
-    for (const operand of eachTerminalOperand(block.terminal)) {
-      if (values.has(operand.identifier.id)) {
-        //
-        return;
       }
     }
+
     seenBlocks.add(block.id);
   }
 
-  for (const loc of setStateLocations) {
+  for (const call of derivedSetStateCall) {
+    const derivedDepsStr = Array.from(call.derivedDep.sources)
+      .map(place => {
+        return place.identifier.name?.value;
+      })
+      .filter(Boolean)
+      .join(', ');
+
+    let errorDescription = '';
+
+    if (call.derivedDep.typeOfValue === 'fromProps') {
+      errorDescription = `props [${derivedDepsStr}].`;
+    } else if (call.derivedDep.typeOfValue === 'fromState') {
+      errorDescription = `local state [${derivedDepsStr}].`;
+    } else {
+      errorDescription = `both props and local state [${derivedDepsStr}].`;
+    }
+
     errors.push({
-      reason:
-        'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
-      description: null,
-      severity: ErrorSeverity.InvalidReact,
-      loc,
-      suggestions: null,
+      type: call.derivedDep.typeOfValue,
+      description: `${errorDescription}`,
+      loc: call.loc,
+      setStateName:
+        call.loc !== GeneratedSource ? call.loc.identifierName : undefined,
+      derivedDepsNames: Array.from(call.derivedDep.sources)
+        .map(place => {
+          return place.identifier.name?.value ?? '';
+        })
+        .filter(Boolean),
     });
   }
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/derived-state-one-time-init-no-error.expect.md

@@ -0,0 +1,87 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({initialName}) {
+  const [name, setName] = useState('');
+
+  useEffect(() => {
+    setName(initialName);
+  }, []);
+
+  return (
+    <div>
+      <input value={name} onChange={e => setName(e.target.value)} />
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{initialName: 'John'}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validateNoDerivedComputationsInEffects
+import { useEffect, useState } from "react";
+
+function Component(t0) {
+  const $ = _c(6);
+  const { initialName } = t0;
+  const [name, setName] = useState("");
+  let t1;
+  if ($[0] !== initialName) {
+    t1 = () => {
+      setName(initialName);
+    };
+    $[0] = initialName;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  let t2;
+  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
+    t2 = [];
+    $[2] = t2;
+  } else {
+    t2 = $[2];
+  }
+  useEffect(t1, t2);
+  let t3;
+  if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
+    t3 = (e) => setName(e.target.value);
+    $[3] = t3;
+  } else {
+    t3 = $[3];
+  }
+  let t4;
+  if ($[4] !== name) {
+    t4 = (
+      <div>
+        <input value={name} onChange={t3} />
+      </div>
+    );
+    $[4] = name;
+    $[5] = t4;
+  } else {
+    t4 = $[5];
+  }
+  return t4;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ initialName: "John" }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div><input value="John"></div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/derived-state-one-time-init-no-error.js

@@ -0,0 +1,21 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({initialName}) {
+  const [name, setName] = useState('');
+
+  useEffect(() => {
+    setName(initialName);
+  }, []);
+
+  return (
+    <div>
+      <input value={name} onChange={e => setName(e.target.value)} />
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{initialName: 'John'}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.bug-derived-state-from-mixed-deps.expect.md

@@ -0,0 +1,51 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({prefix}) {
+  const [name, setName] = useState('');
+  const [displayName, setDisplayName] = useState('');
+
+  useEffect(() => {
+    setDisplayName(prefix + name);
+  }, [prefix, name]);
+
+  return (
+    <div>
+      <input value={name} onChange={e => setName(e.target.value)} />
+      <div>{displayName}</div>
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{prefix: 'Hello, '}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from both props and local state [prefix, name]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.bug-derived-state-from-mixed-deps.ts:9:4
+   7 |
+   8 |   useEffect(() => {
+>  9 |     setDisplayName(prefix + name);
+     |     ^^^^^^^^^^^^^^ This should be computed during render, not in an effect
+  10 |   }, [prefix, name]);
+  11 |
+  12 |   return (
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.bug-derived-state-from-mixed-deps.js

@@ -0,0 +1,23 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({prefix}) {
+  const [name, setName] = useState('');
+  const [displayName, setDisplayName] = useState('');
+
+  useEffect(() => {
+    setDisplayName(prefix + name);
+  }, [prefix, name]);
+
+  return (
+    <div>
+      <input value={name} onChange={e => setName(e.target.value)} />
+      <div>{displayName}</div>
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{prefix: 'Hello, '}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-from-shadowed-props.expect.md

@@ -0,0 +1,76 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useState, useEffect} from 'react';
+
+function Component({props, number}) {
+  const nothing = 0;
+  const missDirection = number;
+  const [displayValue, setDisplayValue] = useState(props.prefix + missDirection + nothing);
+
+  useEffect(() => {
+    setDisplayValue(props.prefix + missDirection + nothing);
+  }, [props.prefix, missDirection, nothing]);
+
+  return (
+    <div
+      onClick={() => {
+        setDisplayValue('clicked');
+      }}>
+      {displayValue}
+    </div>
+  );
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Local state shadows parent state.
+
+This setState() appears to derive a value from props [props, number]. This state value shadows a value passed as a prop. Instead of shadowing the prop with local state, hoist the state to the parent component and update it there.
+
+error.derived-state-from-shadowed-props.ts:7:42
+   5 |   const nothing = 0;
+   6 |   const missDirection = number;
+>  7 |   const [displayValue, setDisplayValue] = useState(props.prefix + missDirection + nothing);
+     |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this useState shadows props
+   8 |
+   9 |   useEffect(() => {
+  10 |     setDisplayValue(props.prefix + missDirection + nothing);
+
+error.derived-state-from-shadowed-props.ts:7:42
+   5 |   const nothing = 0;
+   6 |   const missDirection = number;
+>  7 |   const [displayValue, setDisplayValue] = useState(props.prefix + missDirection + nothing);
+     |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this useState shadows number
+   8 |
+   9 |   useEffect(() => {
+  10 |     setDisplayValue(props.prefix + missDirection + nothing);
+
+error.derived-state-from-shadowed-props.ts:10:4
+   8 |
+   9 |   useEffect(() => {
+> 10 |     setDisplayValue(props.prefix + missDirection + nothing);
+     |     ^^^^^^^^^^^^^^^ this setState synchronizes the state
+  11 |   }, [props.prefix, missDirection, nothing]);
+  12 |
+  13 |   return (
+
+error.derived-state-from-shadowed-props.ts:16:8
+  14 |     <div
+  15 |       onClick={() => {
+> 16 |         setDisplayValue('clicked');
+     |         ^^^^^^^^^^^^^^^ this setState updates the shadowed state, but should call an onChange event from the parent
+  17 |       }}>
+  18 |       {displayValue}
+  19 |     </div>
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-from-shadowed-props.js

@@ -0,0 +1,21 @@
+// @validateNoDerivedComputationsInEffects
+import {useState, useEffect} from 'react';
+
+function Component({props, number}) {
+  const nothing = 0;
+  const missDirection = number;
+  const [displayValue, setDisplayValue] = useState(props.prefix + missDirection + nothing);
+
+  useEffect(() => {
+    setDisplayValue(props.prefix + missDirection + nothing);
+  }, [props.prefix, missDirection, nothing]);
+
+  return (
+    <div
+      onClick={() => {
+        setDisplayValue('clicked');
+      }}>
+      {displayValue}
+    </div>
+  );
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-with-conditional.expect.md

@@ -0,0 +1,49 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({value, enabled}) {
+  const [localValue, setLocalValue] = useState('');
+
+  useEffect(() => {
+    if (enabled) {
+      setLocalValue(value);
+    } else {
+      setLocalValue('disabled');
+    }
+  }, [value, enabled]);
+
+  return <div>{localValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 'test', enabled: true}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [value]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.derived-state-with-conditional.ts:9:6
+   7 |   useEffect(() => {
+   8 |     if (enabled) {
+>  9 |       setLocalValue(value);
+     |       ^^^^^^^^^^^^^ This should be computed during render, not in an effect
+  10 |     } else {
+  11 |       setLocalValue('disabled');
+  12 |     }
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-with-conditional.js

@@ -0,0 +1,21 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({value, enabled}) {
+  const [localValue, setLocalValue] = useState('');
+
+  useEffect(() => {
+    if (enabled) {
+      setLocalValue(value);
+    } else {
+      setLocalValue('disabled');
+    }
+  }, [value, enabled]);
+
+  return <div>{localValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 'test', enabled: true}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-with-side-effects.expect.md

@@ -0,0 +1,47 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({value}) {
+  const [localValue, setLocalValue] = useState('');
+
+  useEffect(() => {
+    console.log('Value changed:', value);
+    setLocalValue(value);
+    document.title = `Value: ${value}`;
+  }, [value]);
+
+  return <div>{localValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 'test'}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [value]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.derived-state-with-side-effects.ts:9:4
+   7 |   useEffect(() => {
+   8 |     console.log('Value changed:', value);
+>  9 |     setLocalValue(value);
+     |     ^^^^^^^^^^^^^ This should be computed during render, not in an effect
+  10 |     document.title = `Value: ${value}`;
+  11 |   }, [value]);
+  12 |
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.derived-state-with-side-effects.js

@@ -0,0 +1,19 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({value}) {
+  const [localValue, setLocalValue] = useState('');
+
+  useEffect(() => {
+    console.log('Value changed:', value);
+    setLocalValue(value);
+    document.title = `Value: ${value}`;
+  }, [value]);
+
+  return <div>{localValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 'test'}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-computation-in-effect.expect.md

@@ -24,13 +24,15 @@ function BadExample() {
 ```
 Found 1 error:
 
-Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from local state [firstName, lastName]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
 
 error.invalid-derived-computation-in-effect.ts:9:4
    7 |   const [fullName, setFullName] = useState('');
    8 |   useEffect(() => {
 >  9 |     setFullName(capitalize(firstName + ' ' + lastName));
-     |     ^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
+     |     ^^^^^^^^^^^ This should be computed during render, not in an effect
   10 |   }, [firstName, lastName]);
   11 |
   12 |   return <div>{fullName}</div>;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-computed.expect.md

@@ -0,0 +1,46 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component(props) {
+  const [displayValue, setDisplayValue] = useState('');
+
+  useEffect(() => {
+    const computed = props.prefix + props.value + props.suffix;
+    setDisplayValue(computed);
+  }, [props.prefix, props.value, props.suffix]);
+
+  return <div>{displayValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{prefix: '[', value: 'test', suffix: ']'}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [props, props, props]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.invalid-derived-state-from-props-computed.ts:9:4
+   7 |   useEffect(() => {
+   8 |     const computed = props.prefix + props.value + props.suffix;
+>  9 |     setDisplayValue(computed);
+     |     ^^^^^^^^^^^^^^^ This should be computed during render, not in an effect
+  10 |   }, [props.prefix, props.value, props.suffix]);
+  11 |
+  12 |   return <div>{displayValue}</div>;
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-computed.js

@@ -0,0 +1,18 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component(props) {
+  const [displayValue, setDisplayValue] = useState('');
+
+  useEffect(() => {
+    const computed = props.prefix + props.value + props.suffix;
+    setDisplayValue(computed);
+  }, [props.prefix, props.value, props.suffix]);
+
+  return <div>{displayValue}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{prefix: '[', value: 'test', suffix: ']'}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-destructured.expect.md

@@ -0,0 +1,45 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({props}) {
+  const [fullName, setFullName] = useState(props.firstName + ' ' + props.lastName);
+
+  useEffect(() => {
+    setFullName(props.firstName + ' ' + props.lastName);
+  }, [props.firstName, props.lastName]);
+
+  return <div>{fullName}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{firstName: 'John', lastName: 'Doe'}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [props, props]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.invalid-derived-state-from-props-destructured.ts:8:4
+   6 |
+   7 |   useEffect(() => {
+>  8 |     setFullName(props.firstName + ' ' + props.lastName);
+     |     ^^^^^^^^^^^ This should be computed during render, not in an effect
+   9 |   }, [props.firstName, props.lastName]);
+  10 |
+  11 |   return <div>{fullName}</div>;
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-destructured.js

@@ -0,0 +1,17 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({props}) {
+  const [fullName, setFullName] = useState(props.firstName + ' ' + props.lastName);
+
+  useEffect(() => {
+    setFullName(props.firstName + ' ' + props.lastName);
+  }, [props.firstName, props.lastName]);
+
+  return <div>{fullName}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{firstName: 'John', lastName: 'Doe'}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-in-effect.expect.md

@@ -0,0 +1,45 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({firstName, lastName}) {
+  const [fullName, setFullName] = useState('');
+
+  useEffect(() => {
+    setFullName(firstName + ' ' + lastName);
+  }, [firstName, lastName]);
+
+  return <div>{fullName}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{firstName: 'John', lastName: 'Doe'}],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [firstName, lastName]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.invalid-derived-state-from-props-in-effect.ts:8:4
+   6 |
+   7 |   useEffect(() => {
+>  8 |     setFullName(firstName + ' ' + lastName);
+     |     ^^^^^^^^^^^ This should be computed during render, not in an effect
+   9 |   }, [firstName, lastName]);
+  10 |
+  11 |   return <div>{fullName}</div>;
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-in-effect.js

@@ -0,0 +1,17 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component({firstName, lastName}) {
+  const [fullName, setFullName] = useState('');
+
+  useEffect(() => {
+    setFullName(firstName + ' ' + lastName);
+  }, [firstName, lastName]);
+
+  return <div>{fullName}</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{firstName: 'John', lastName: 'Doe'}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-with-default-value.expect.md

@@ -0,0 +1,43 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+
+export default function InProductLobbyGeminiCard(
+  input = 'empty',
+) {
+  const [currInput, setCurrInput] = useState(input);
+
+  useEffect(() => {
+    setCurrInput(input)
+  }, [input]);
+
+  return (
+    <div>{currInput}</div>
+  )
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from props [input]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.invalid-derived-state-from-props-with-default-value.ts:9:4
+   7 |
+   8 |   useEffect(() => {
+>  9 |     setCurrInput(input)
+     |     ^^^^^^^^^^^^ This should be computed during render, not in an effect
+  10 |   }, [input]);
+  11 |
+  12 |   return (
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-props-with-default-value.js

@@ -0,0 +1,15 @@
+// @validateNoDerivedComputationsInEffects
+
+export default function InProductLobbyGeminiCard(
+  input = 'empty',
+) {
+  const [currInput, setCurrInput] = useState(input);
+
+  useEffect(() => {
+    setCurrInput(input)
+  }, [input]);
+
+  return (
+    <div>{currInput}</div>
+  )
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-state-in-effect.expect.md

@@ -0,0 +1,53 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component() {
+  const [firstName, setFirstName] = useState('John');
+  const [lastName, setLastName] = useState('Doe');
+  const [fullName, setFullName] = useState('');
+
+  useEffect(() => {
+    setFullName(firstName + ' ' + lastName);
+  }, [firstName, lastName]);
+
+  return (
+    <div>
+      <input value={firstName} onChange={e => setFirstName(e.target.value)} />
+      <input value={lastName} onChange={e => setLastName(e.target.value)} />
+      <div>{fullName}</div>
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+};
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Derive values in render, not effects.
+
+This setState() appears to derive a value from local state [firstName, lastName]. Derived values should be computed during render, rather than in effects. Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user.
+
+error.invalid-derived-state-from-state-in-effect.ts:10:4
+   8 |
+   9 |   useEffect(() => {
+> 10 |     setFullName(firstName + ' ' + lastName);
+     |     ^^^^^^^^^^^ This should be computed during render, not in an effect
+  11 |   }, [firstName, lastName]);
+  12 |
+  13 |   return (
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.invalid-derived-state-from-state-in-effect.js

@@ -0,0 +1,25 @@
+// @validateNoDerivedComputationsInEffects
+import {useEffect, useState} from 'react';
+
+function Component() {
+  const [firstName, setFirstName] = useState('John');
+  const [lastName, setLastName] = useState('Doe');
+  const [fullName, setFullName] = useState('');
+
+  useEffect(() => {
+    setFullName(firstName + ' ' + lastName);
+  }, [firstName, lastName]);
+
+  return (
+    <div>
+      <input value={firstName} onChange={e => setFirstName(e.target.value)} />
+      <input value={lastName} onChange={e => setLastName(e.target.value)} />
+      <div>{fullName}</div>
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.shadowed-props-with-onchange.expect.md

@@ -0,0 +1,61 @@
+
+## Input
+
+```javascript
+// @validateNoDerivedComputationsInEffects
+
+function EndDate({startDate, endDate, onStartDateChange}) {
+   const [localStartDate, setLocalStartDate] = useState(startDate);
+
+    useEffect(() => {
+        setLocalStartDate(startDate);
+    }, [startDate]);
+
+    const onChange = (date) => {
+        setLocalStartDate(date);
+        onStartDateChange(date);
+    }
+    return <DateInput value={localStartDate} second={endDate} onChange={onChange} />
+}
+
+```
+
+
+## Error
+
+```
+Found 1 error:
+
+Error: Local state shadows parent state.
+
+This setState() appears to derive a value from props [startDate]. This state value shadows a value passed as a prop. Instead of shadowing the prop with local state, hoist the state to the parent component and update it there.
+
+error.shadowed-props-with-onchange.ts:4:47
+  2 |
+  3 | function EndDate({startDate, endDate, onStartDateChange}) {
+> 4 |    const [localStartDate, setLocalStartDate] = useState(startDate);
+    |                                                ^^^^^^^^^^^^^^^^^^^ this useState shadows startDate
+  5 |
+  6 |     useEffect(() => {
+  7 |         setLocalStartDate(startDate);
+
+error.shadowed-props-with-onchange.ts:7:8
+   5 |
+   6 |     useEffect(() => {
+>  7 |         setLocalStartDate(startDate);
+     |         ^^^^^^^^^^^^^^^^^ this setState synchronizes the state
+   8 |     }, [startDate]);
+   9 |
+  10 |     const onChange = (date) => {
+
+error.shadowed-props-with-onchange.ts:11:8
+   9 |
+  10 |     const onChange = (date) => {
+> 11 |         setLocalStartDate(date);
+     |         ^^^^^^^^^^^^^^^^^ this setState updates the shadowed state, but should call an onChange event from the parent
+  12 |         onStartDateChange(date);
+  13 |     }
+  14 |     return <DateInput value={localStartDate} second={endDate} onChange={onChange} />
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/error.shadowed-props-with-onchange.js

@@ -0,0 +1,15 @@
+// @validateNoDerivedComputationsInEffects
+
+function EndDate({startDate, endDate, onStartDateChange}) {
+   const [localStartDate, setLocalStartDate] = useState(startDate);
+
+    useEffect(() => {
+        setLocalStartDate(startDate);
+    }, [startDate]);
+
+    const onChange = (date) => {
+        setLocalStartDate(date);
+        onStartDateChange(date);
+    }
+    return <DateInput value={localStartDate} second={endDate} onChange={onChange} />
+}

compiler/packages/babel-plugin-react-compiler/test.txt

@@ -0,0 +1,4 @@
+yarn run v1.22.22
+$ ./scripts/link-react-compiler-runtime.sh && yarn snap:ci
+success Using linked package for "react-compiler-runtime".
+$ yarn snap:build && yarn snap