[pull] main from facebook:main

compiler/CLAUDE.md

@@ -229,20 +229,19 @@ Would enable the `enableJsxOutlining` feature and disable the `enableNameAnonymo
 3. Look for `Impure`, `Render`, `Capture` effects on instructions
 4. Check the pass ordering in Pipeline.ts to understand when effects are populated vs validated
 
-## Error Handling for Unsupported Features
+## Error Handling and Fault Tolerance
 
-When the compiler encounters an unsupported but known pattern, use `CompilerError.throwTodo()` instead of `CompilerError.invariant()`. Todo errors cause graceful bailouts in production; Invariant errors are hard failures indicating unexpected/invalid states.
+The compiler is fault-tolerant: it runs all passes and accumulates errors on the `Environment` rather than throwing on the first error. This lets users see all compilation errors at once.
 
-```typescript
-// Unsupported but expected pattern - graceful bailout
-CompilerError.throwTodo({
-  reason: `Support [description of unsupported feature]`,
-  loc: terminal.loc,
-});
-
-// Invariant is for truly unexpected/invalid states - hard failure
-CompilerError.invariant(false, {
-  reason: `Unexpected [thing]`,
-  loc: terminal.loc,
-});
-```
+**Recording errors** — Passes record errors via `env.recordError(diagnostic)`. Errors are accumulated on `Environment.#errors` and checked at the end of the pipeline via `env.hasErrors()` / `env.aggregateErrors()`.
+
+**`tryRecord()` wrapper** — In Pipeline.ts, validation passes are wrapped in `env.tryRecord(() => pass(hir))` which catches thrown `CompilerError`s (non-invariant) and records them. Infrastructure/transformation passes are NOT wrapped in `tryRecord()` because later passes depend on their output being structurally valid.
+
+**Error categories:**
+- `CompilerError.throwTodo()` — Unsupported but known pattern. Graceful bailout. Can be caught by `tryRecord()`.
+- `CompilerError.invariant()` — Truly unexpected/invalid state. Always throws immediately, never caught by `tryRecord()`.
+- Non-`CompilerError` exceptions — Always re-thrown.
+
+**Key files:** `Environment.ts` (`recordError`, `tryRecord`, `hasErrors`, `aggregateErrors`), `Pipeline.ts` (pass orchestration), `Program.ts` (`tryCompileFunction` handles the `Result`).
+
+**Test fixtures:** `__tests__/fixtures/compiler/fault-tolerance/` contains multi-error fixtures verifying all errors are reported.

compiler/packages/babel-plugin-react-compiler/docs/passes/README.md

@@ -302,6 +302,15 @@ yarn snap minimize <path>
 yarn snap -u
 ```
 
+## Fault Tolerance
+
+The pipeline is fault-tolerant: all passes run to completion, accumulating errors on `Environment` rather than aborting on the first error.
+
+- **Validation passes** are wrapped in `env.tryRecord()` in Pipeline.ts, which catches non-invariant `CompilerError`s and records them. If a validation pass throws, compilation continues.
+- **Infrastructure/transformation passes** (enterSSA, eliminateRedundantPhi, inferMutationAliasingEffects, codegen, etc.) are NOT wrapped in `tryRecord()` because subsequent passes depend on their output being structurally valid. If they fail, compilation aborts.
+- **`lower()` (BuildHIR)** always produces an `HIRFunction`, recording errors on `env` instead of returning `Err`. Unsupported constructs (e.g., `var`) are lowered best-effort.
+- At the end of the pipeline, `env.hasErrors()` determines whether to return `Ok(codegen)` or `Err(aggregatedErrors)`.
+
 ## Further Reading
 
 - [MUTABILITY_ALIASING_MODEL.md](../../src/Inference/MUTABILITY_ALIASING_MODEL.md): Detailed aliasing model docs

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

@@ -252,6 +252,7 @@ export type LoggerEvent =
   | CompileErrorEvent
   | CompileDiagnosticEvent
   | CompileSkipEvent
+  | CompileUnexpectedThrowEvent
   | PipelineErrorEvent
   | TimingEvent;
 
@@ -286,6 +287,11 @@ export type PipelineErrorEvent = {
   fnLoc: t.SourceLocation | null;
   data: string;
 };
+export type CompileUnexpectedThrowEvent = {
+  kind: 'CompileUnexpectedThrow';
+  fnLoc: t.SourceLocation | null;
+  data: string;
+};
 export type TimingEvent = {
   kind: 'Timing';
   measurement: PerformanceMeasure;

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

@@ -9,6 +9,8 @@ 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,
   ReactiveFunction,
@@ -89,7 +91,6 @@ import {validateNoJSXInTryStatement} from '../Validation/ValidateNoJSXInTryState
 import {propagateScopeDependenciesHIR} from '../HIR/PropagateScopeDependenciesHIR';
 import {outlineJSX} from '../Optimization/OutlineJsx';
 import {optimizePropsMethodCalls} from '../Optimization/OptimizePropsMethodCalls';
-import {validateNoImpureFunctionsInRender} from '../Validation/ValidateNoImpureFunctionsInRender';
 import {validateStaticComponents} from '../Validation/ValidateStaticComponents';
 import {validateNoFreezingKnownMutableFunctions} from '../Validation/ValidateNoFreezingKnownMutableFunctions';
 import {inferMutationAliasingEffects} from '../Inference/InferMutationAliasingEffects';
@@ -118,7 +119,7 @@ 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,
@@ -149,21 +150,21 @@ 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();
+  const hir = lower(func, env);
   log({kind: 'hir', name: 'HIR', value: hir});
 
   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});
   }
 
@@ -196,10 +197,10 @@ function runWithEnvironment(
 
   if (env.enableValidations) {
     if (env.config.validateHooksUsage) {
-      validateHooksUsage(hir).unwrap();
+      validateHooksUsage(hir);
     }
     if (env.config.validateNoCapitalizedCalls) {
-      validateNoCapitalizedCalls(hir).unwrap();
+      validateNoCapitalizedCalls(hir);
     }
   }
 
@@ -209,13 +210,8 @@ function runWithEnvironment(
   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);
@@ -228,28 +224,23 @@ function runWithEnvironment(
   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);
-  }
 
-  if (env.enableValidations) {
     if (env.config.assertValidMutableRanges) {
       assertValidMutableRanges(hir);
     }
 
     if (env.config.validateRefAccessDuringRender) {
-      validateNoRefAccessInRender(hir).unwrap();
+      validateNoRefAccessInRender(hir);
     }
 
     if (env.config.validateNoSetStateInRender) {
-      validateNoSetStateInRender(hir).unwrap();
+      validateNoSetStateInRender(hir);
     }
 
     if (
@@ -269,11 +260,7 @@ function runWithEnvironment(
       env.logErrors(validateNoJSXInTryStatement(hir));
     }
 
-    if (env.config.validateNoImpureFunctionsInRender) {
-      validateNoImpureFunctionsInRender(hir).unwrap();
-    }
-
-    validateNoFreezingKnownMutableFunctions(hir).unwrap();
+    validateNoFreezingKnownMutableFunctions(hir);
   }
 
   inferReactivePlaces(hir);
@@ -285,7 +272,7 @@ function runWithEnvironment(
       env.config.validateExhaustiveEffectDependencies
     ) {
       // NOTE: this relies on reactivity inference running first
-      validateExhaustiveDependencies(hir).unwrap();
+      validateExhaustiveDependencies(hir);
     }
   }
 
@@ -399,6 +386,7 @@ function runWithEnvironment(
   });
   assertTerminalSuccessorsExist(hir);
   assertTerminalPredsExist(hir);
+
   propagateScopeDependenciesHIR(hir);
   log({
     kind: 'hir',
@@ -511,20 +499,20 @@ function runWithEnvironment(
     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 +524,10 @@ function runWithEnvironment(
     throw new Error('unexpected error');
   }
 
-  return ast;
+  if (env.hasErrors()) {
+    return Err(env.aggregateErrors());
+  }
+  return Ok(ast);
 }
 
 export function compileFn(
@@ -550,7 +541,7 @@ 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

@@ -697,20 +697,36 @@ 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) {
+    /**
+     * A pass incorrectly threw instead of recording the error.
+     * Log for detection in development.
+     */
+    if (
+      err instanceof CompilerError &&
+      err.details.every(detail => detail.category !== ErrorCategory.Invariant)
+    ) {
+      programContext.logEvent({
+        kind: 'CompileUnexpectedThrow',
+        fnLoc: fn.node.loc ?? null,
+        data: err.toString(),
+      });
+    }
     return {kind: 'error', error: err};
   }
 }