[commit] Improve error for hoisting violations

The previous error for hoisting violations pointed only to the variable declaration, but didn't show where the value was accessed before that declaration. We now track where each hoisted variable is first accessed and report two errors, one for the reference and one for the declaration. When we improve our diagnostic infra to support reporting errors at multiple locations we can merge these into a single conceptual error.

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

@@ -1388,6 +1388,16 @@ export enum ValueReason {
    */
   JsxCaptured = 'jsx-captured',
 
+  /**
+   * Argument to a hook
+   */
+  HookCaptured = 'hook-captured',
+
+  /**
+   * Return value of a hook
+   */
+  HookReturn = 'hook-return',
+
   /**
    * Passed to an effect
    */

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

@@ -1302,6 +1302,34 @@ export const DefaultNonmutatingHook = addHook(
     calleeEffect: Effect.Read,
     hookKind: 'Custom',
     returnValueKind: ValueKind.Frozen,
+    aliasing: {
+      receiver: makeIdentifierId(0),
+      params: [],
+      rest: makeIdentifierId(1),
+      returns: makeIdentifierId(2),
+      temporaries: [],
+      effects: [
+        // Freeze the arguments
+        {
+          kind: 'Freeze',
+          value: signatureArgument(1),
+          reason: ValueReason.HookCaptured,
+        },
+        // Returns a frozen value
+        {
+          kind: 'Create',
+          into: signatureArgument(2),
+          value: ValueKind.Frozen,
+          reason: ValueReason.HookReturn,
+        },
+        // May alias any arguments into the return
+        {
+          kind: 'Alias',
+          from: signatureArgument(1),
+          into: signatureArgument(2),
+        },
+      ],
+    },
   },
   'DefaultNonmutatingHook',
 );

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

@@ -341,6 +341,10 @@ export function getWriteErrorReason(abstractValue: AbstractValue): string {
     return "Mutating a value returned from 'useReducer()', which should not be mutated. Use the dispatch function to update instead";
   } else if (abstractValue.reason.has(ValueReason.Effect)) {
     return 'Updating a value used previously in an effect function or as an effect dependency is not allowed. Consider moving the mutation before calling useEffect()';
+  } else if (abstractValue.reason.has(ValueReason.HookCaptured)) {
+    return 'Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook';
+  } else if (abstractValue.reason.has(ValueReason.HookReturn)) {
+    return 'Updating a value returned from a hook is not allowed. Consider moving the mutation into the hook where the value is constructed';
   } else {
     return 'This mutates a variable that React considers immutable';
   }

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

@@ -38,6 +38,7 @@ import {
 import {
   eachInstructionValueLValue,
   eachInstructionValueOperand,
+  eachTerminalOperand,
   eachTerminalSuccessor,
 } from '../HIR/visitors';
 import {Ok, Result} from '../Utils/Result';
@@ -221,8 +222,19 @@ export function inferMutationAliasingEffects(
   return Ok(undefined);
 }
 
-function findHoistedContextDeclarations(fn: HIRFunction): Set<DeclarationId> {
-  const hoisted = new Set<DeclarationId>();
+function findHoistedContextDeclarations(
+  fn: HIRFunction,
+): Map<DeclarationId, Place | null> {
+  const hoisted = new Map<DeclarationId, Place | null>();
+  function visit(place: Place): void {
+    if (
+      hoisted.has(place.identifier.declarationId) &&
+      hoisted.get(place.identifier.declarationId) == null
+    ) {
+      // If this is the first load of the value, store the location
+      hoisted.set(place.identifier.declarationId, place);
+    }
+  }
   for (const block of fn.body.blocks.values()) {
     for (const instr of block.instructions) {
       if (instr.value.kind === 'DeclareContext') {
@@ -232,10 +244,17 @@ function findHoistedContextDeclarations(fn: HIRFunction): Set<DeclarationId> {
           kind == InstructionKind.HoistedFunction ||
           kind == InstructionKind.HoistedLet
         ) {
-          hoisted.add(instr.value.lvalue.place.identifier.declarationId);
+          hoisted.set(instr.value.lvalue.place.identifier.declarationId, null);
+        }
+      } else {
+        for (const operand of eachInstructionValueOperand(instr.value)) {
+          visit(operand);
         }
       }
     }
+    for (const operand of eachTerminalOperand(block.terminal)) {
+      visit(operand);
+    }
   }
   return hoisted;
 }
@@ -248,12 +267,12 @@ class Context {
   catchHandlers: Map<BlockId, Place> = new Map();
   isFuctionExpression: boolean;
   fn: HIRFunction;
-  hoistedContextDeclarations: Set<DeclarationId>;
+  hoistedContextDeclarations: Map<DeclarationId, Place | null>;
 
   constructor(
     isFunctionExpression: boolean,
     fn: HIRFunction,
-    hoistedContextDeclarations: Set<DeclarationId>,
+    hoistedContextDeclarations: Map<DeclarationId, Place | null>,
   ) {
     this.isFuctionExpression = isFunctionExpression;
     this.fn = fn;
@@ -901,48 +920,69 @@ function applyEffect(
           console.log(prettyFormat(state.debugAbstractValue(value)));
         }
 
-        let reason: string;
-        let description: string | null = null;
-
         if (
           mutationKind === 'mutate-frozen' &&
           context.hoistedContextDeclarations.has(
             effect.value.identifier.declarationId,
           )
         ) {
-          reason = `This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time`;
-          if (
+          const description =
             effect.value.identifier.name !== null &&
             effect.value.identifier.name.kind === 'named'
-          ) {
-            description = `Move the declaration of \`${effect.value.identifier.name.value}\` to before it is first referenced`;
+              ? `Variable \`${effect.value.identifier.name.value}\` is accessed before it is declared`
+              : null;
+          const hoistedAccess = context.hoistedContextDeclarations.get(
+            effect.value.identifier.declarationId,
+          );
+          if (hoistedAccess != null && hoistedAccess.loc != effect.value.loc) {
+            effects.push({
+              kind: 'MutateFrozen',
+              place: effect.value,
+              error: {
+                severity: ErrorSeverity.InvalidReact,
+                reason: `This variable is accessed before it is declared, which may prevent it from updating as the assigned value changes over time`,
+                description,
+                loc: hoistedAccess.loc,
+                suggestions: null,
+              },
+            });
           }
+
+          effects.push({
+            kind: 'MutateFrozen',
+            place: effect.value,
+            error: {
+              severity: ErrorSeverity.InvalidReact,
+              reason: `This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time`,
+              description,
+              loc: effect.value.loc,
+              suggestions: null,
+            },
+          });
         } else {
-          reason = getWriteErrorReason({
+          const reason = getWriteErrorReason({
             kind: value.kind,
             reason: value.reason,
             context: new Set(),
           });
-          if (
+          const description =
             effect.value.identifier.name !== null &&
             effect.value.identifier.name.kind === 'named'
-          ) {
-            description = `Found mutation of \`${effect.value.identifier.name.value}\``;
-          }
+              ? `Found mutation of \`${effect.value.identifier.name.value}\``
+              : null;
+          effects.push({
+            kind:
+              value.kind === ValueKind.Frozen ? 'MutateFrozen' : 'MutateGlobal',
+            place: effect.value,
+            error: {
+              severity: ErrorSeverity.InvalidReact,
+              reason,
+              description,
+              loc: effect.value.loc,
+              suggestions: null,
+            },
+          });
         }
-
-        effects.push({
-          kind:
-            value.kind === ValueKind.Frozen ? 'MutateFrozen' : 'MutateGlobal',
-          place: effect.value,
-          error: {
-            severity: ErrorSeverity.InvalidReact,
-            reason,
-            description,
-            loc: effect.value.loc,
-            suggestions: null,
-          },
-        });
       }
       break;
     }
@@ -1980,28 +2020,17 @@ function computeEffectsForLegacySignature(
         break;
       }
       case Effect.ConditionallyMutateIterator: {
-        if (
-          isArrayType(place.identifier) ||
-          isSetType(place.identifier) ||
-          isMapType(place.identifier)
-        ) {
-          effects.push({
-            kind: 'Capture',
-            from: place,
-            into: lvalue,
-          });
-        } else {
-          effects.push({
-            kind: 'Capture',
-            from: place,
-            into: lvalue,
-          });
+        const mutateIterator = conditionallyMutateIterator(place);
+        if (mutateIterator != null) {
+          effects.push(mutateIterator);
+          // TODO: should we always push to captures?
           captures.push(place);
-          effects.push({
-            kind: 'MutateTransitiveConditionally',
-            value: place,
-          });
         }
+        effects.push({
+          kind: 'Capture',
+          from: place,
+          into: lvalue,
+        });
         break;
       }
       case Effect.Freeze: {
@@ -2191,6 +2220,7 @@ function computeEffectsForSignature(
     return null;
   }
   // Build substitutions
+  const mutableSpreads = new Set<IdentifierId>();
   const substitutions: Map<IdentifierId, Array<Place>> = new Map();
   substitutions.set(signature.receiver, [receiver]);
   substitutions.set(signature.returns, [lvalue]);
@@ -2208,6 +2238,13 @@ function computeEffectsForSignature(
       }
       const place = arg.kind === 'Identifier' ? arg : arg.place;
       getOrInsertWith(substitutions, signature.rest, () => []).push(place);
+
+      if (arg.kind === 'Spread') {
+        const mutateIterator = conditionallyMutateIterator(arg.place);
+        if (mutateIterator != null) {
+          mutableSpreads.add(arg.place.identifier.id);
+        }
+      }
     } else {
       const param = params[i];
       substitutions.set(param, [arg]);
@@ -2279,6 +2316,12 @@ function computeEffectsForSignature(
       case 'Freeze': {
         const values = substitutions.get(effect.value.identifier.id) ?? [];
         for (const value of values) {
+          if (mutableSpreads.has(value.identifier.id)) {
+            CompilerError.throwTodo({
+              reason: 'Support spread syntax for hook arguments',
+              loc: value.loc,
+            });
+          }
           effects.push({kind: 'Freeze', value, reason: effect.reason});
         }
         break;

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

@@ -32,7 +32,7 @@ export const FIXTURE_ENTRYPOINT = {
   11 |   });
   12 |
 > 13 |   x.value += count;
-     |   ^ InvalidReact: This mutates a variable that React considers immutable (13:13)
+     |   ^ InvalidReact: Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook (13:13)
   14 |   return <Stringify x={x} cb={cb} />;
   15 | }
   16 |

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

@@ -32,7 +32,7 @@ export const FIXTURE_ENTRYPOINT = {
   11 |   });
   12 |
 > 13 |   x.value += count;
-     |   ^ InvalidReact: This mutates a variable that React considers immutable (13:13)
+     |   ^ InvalidReact: Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook (13:13)
   14 |   return <Stringify x={x} cb={cb} />;
   15 | }
   16 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-hoisting-setstate.expect.md

@@ -38,13 +38,15 @@ export const FIXTURE_ENTRYPOINT = {
 ## Error
 
 ```
-  19 |   useEffect(() => setState(2), []);
+  17 |    * $2 = Function context=setState
+  18 |    */
+> 19 |   useEffect(() => setState(2), []);
+     |                   ^^^^^^^^ InvalidReact: This variable is accessed before it is declared, which may prevent it from updating as the assigned value changes over time. Variable `setState` is accessed before it is declared (19:19)
+
+InvalidReact: This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time. Variable `setState` is accessed before it is declared (21:21)
   20 |
-> 21 |   const [state, setState] = useState(0);
-     |                 ^^^^^^^^ InvalidReact: This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time. Move the declaration of `setState` to before it is first referenced (21:21)
+  21 |   const [state, setState] = useState(0);
   22 |   return <Stringify state={state} />;
-  23 | }
-  24 |
 ```
           
       

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-non-imported-reanimated-shared-value-writes.expect.md

@@ -27,7 +27,7 @@ function SomeComponent() {
    9 |   return (
   10 |     <Button
 > 11 |       onPress={() => (sharedVal.value = Math.random())}
-     |                       ^^^^^^^^^ InvalidReact: This mutates a variable that React considers immutable. Found mutation of `sharedVal` (11:11)
+     |                       ^^^^^^^^^ InvalidReact: Updating a value returned from a hook is not allowed. Consider moving the mutation into the hook where the value is constructed. Found mutation of `sharedVal` (11:11)
   12 |       title="Randomize"
   13 |     />
   14 |   );

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/no-emit/retry-no-emit.expect.md

@@ -52,7 +52,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":5,"column":0,"index":163},"end":{"line":13,"column":1,"index":357},"filename":"retry-no-emit.ts"},"detail":{"reason":"This mutates a variable that React considers immutable","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":11,"column":2,"index":320},"end":{"line":11,"column":6,"index":324},"filename":"retry-no-emit.ts","identifierName":"arr2"}}}
+{"kind":"CompileError","fnLoc":{"start":{"line":5,"column":0,"index":163},"end":{"line":13,"column":1,"index":357},"filename":"retry-no-emit.ts"},"detail":{"reason":"Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":11,"column":2,"index":320},"end":{"line":11,"column":6,"index":324},"filename":"retry-no-emit.ts","identifierName":"arr2"}}}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":7,"column":2,"index":216},"end":{"line":7,"column":36,"index":250},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":7,"column":31,"index":245},"end":{"line":7,"column":34,"index":248},"filename":"retry-no-emit.ts","identifierName":"arr"}]}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":10,"column":2,"index":274},"end":{"line":10,"column":44,"index":316},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":10,"column":25,"index":297},"end":{"line":10,"column":29,"index":301},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":10,"column":25,"index":297},"end":{"line":10,"column":29,"index":301},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":10,"column":35,"index":307},"end":{"line":10,"column":42,"index":314},"filename":"retry-no-emit.ts","identifierName":"propVal"}]}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":5,"column":0,"index":163},"end":{"line":13,"column":1,"index":357},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}

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

@@ -31,13 +31,15 @@ function Component({content, refetch}) {
 ## Error
 
 ```
-  17 |   // This has to error: onRefetch needs to memoize with `content` as a
-  18 |   // dependency, but the dependency comes later
-> 19 |   const {data = null} = content;
-     |          ^^^^^^^^^^^ InvalidReact: This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time. Move the declaration of `data` to before it is first referenced (19:19)
-  20 |
-  21 |   return <Foo data={data} onSubmit={onSubmit} />;
-  22 | }
+   9 |   // TDZ violation!
+  10 |   const onRefetch = useCallback(() => {
+> 11 |     refetch(data);
+     |             ^^^^ InvalidReact: This variable is accessed before it is declared, which may prevent it from updating as the assigned value changes over time. Variable `data` is accessed before it is declared (11:11)
+
+InvalidReact: This variable is accessed before it is declared, which prevents the earlier access from updating when this value changes over time. Variable `data` is accessed before it is declared (19:19)
+  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/new-mutability/error.mutate-frozen-value.expect.md

@@ -19,7 +19,7 @@ function Component({a, b}) {
   3 |   const x = {a};
   4 |   useFreeze(x);
 > 5 |   x.y = true;
-    |   ^ InvalidReact: This mutates a variable that React considers immutable (5:5)
+    |   ^ InvalidReact: Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook (5:5)
   6 |   return <div>error</div>;
   7 | }
   8 |

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/retry-no-emit.expect.md

@@ -52,7 +52,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":5,"column":0,"index":195},"end":{"line":13,"column":1,"index":389},"filename":"retry-no-emit.ts"},"detail":{"reason":"This mutates a variable that React considers immutable","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":11,"column":2,"index":352},"end":{"line":11,"column":6,"index":356},"filename":"retry-no-emit.ts","identifierName":"arr2"}}}
+{"kind":"CompileError","fnLoc":{"start":{"line":5,"column":0,"index":195},"end":{"line":13,"column":1,"index":389},"filename":"retry-no-emit.ts"},"detail":{"reason":"Updating a value previously passed as an argument to a hook is not allowed. Consider moving the mutation before calling the hook","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":11,"column":2,"index":352},"end":{"line":11,"column":6,"index":356},"filename":"retry-no-emit.ts","identifierName":"arr2"}}}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":7,"column":2,"index":248},"end":{"line":7,"column":36,"index":282},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":7,"column":31,"index":277},"end":{"line":7,"column":34,"index":280},"filename":"retry-no-emit.ts","identifierName":"arr"}]}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":10,"column":2,"index":306},"end":{"line":10,"column":44,"index":348},"filename":"retry-no-emit.ts"},"decorations":[{"start":{"line":10,"column":25,"index":329},"end":{"line":10,"column":29,"index":333},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":10,"column":25,"index":329},"end":{"line":10,"column":29,"index":333},"filename":"retry-no-emit.ts","identifierName":"arr2"},{"start":{"line":10,"column":35,"index":339},"end":{"line":10,"column":42,"index":346},"filename":"retry-no-emit.ts","identifierName":"propVal"}]}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":5,"column":0,"index":195},"end":{"line":13,"column":1,"index":389},"filename":"retry-no-emit.ts"},"fnName":"Foo","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}