facebook · josephsavona · Jul 24, 2025 · Jul 24, 2025
diff --git a/compiler/packages/babel-plugin-react-compiler/src/CompilerError.ts b/compiler/packages/babel-plugin-react-compiler/src/CompilerError.ts
@@ -59,7 +59,7 @@ export type CompilerDiagnosticDetail =
    */
   {
     kind: 'error';
-    loc: SourceLocation;
+    loc: SourceLocation | null;
     message: string;
   };
 
@@ -100,6 +100,12 @@ export class CompilerDiagnostic {
     this.options = options;
   }
 
+  static create(
+    options: Omit<CompilerDiagnosticOptions, 'details'>,
+  ): CompilerDiagnostic {
+    return new CompilerDiagnostic({...options, details: []});
+  }
+
   get category(): CompilerDiagnosticOptions['category'] {
     return this.options.category;
   }
@@ -113,6 +119,11 @@ export class CompilerDiagnostic {
     return this.options.suggestions;
   }
 
+  withDetail(detail: CompilerDiagnosticDetail): CompilerDiagnostic {
+    this.options.details.push(detail);
+    return this;
+  }
+
   primaryLocation(): SourceLocation | null {
     return this.options.details.filter(d => d.kind === 'error')[0]?.loc ?? null;
   }
@@ -127,7 +138,7 @@ export class CompilerDiagnostic {
       switch (detail.kind) {
         case 'error': {
           const loc = detail.loc;
-          if (typeof loc === 'symbol') {
+          if (loc == null || typeof loc === 'symbol') {
             continue;
           }
           let codeFrame: string;

diff --git a/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts b/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts
@@ -9,6 +9,7 @@ import {NodePath, Scope} from '@babel/traverse';
 import * as t from '@babel/types';
 import invariant from 'invariant';
 import {
+  CompilerDiagnostic,
   CompilerError,
   CompilerSuggestionOperation,
   ErrorSeverity,
@@ -104,12 +105,18 @@ export function lower(
     if (param.isIdentifier()) {
       const binding = builder.resolveIdentifier(param);
       if (binding.kind !== 'Identifier') {
-        builder.errors.push({
-          reason: `(BuildHIR::lower) Could not find binding for param \`${param.node.name}\``,
-          severity: ErrorSeverity.Invariant,
-          loc: param.node.loc ?? null,
-          suggestions: null,
-        });
+        builder.errors.pushDiagnostic(
+          CompilerDiagnostic.create({
+            category: 'Could not find binding',
+            description: `[BuildHIR] Could not find binding for param \`${param.node.name}\``,
+            severity: ErrorSeverity.Invariant,
+            suggestions: null,
+          }).withDetail({
+            kind: 'error',
+            loc: param.node.loc ?? null,
+            message: 'Could not find binding',
+          }),
+        );
         return;
       }
       const place: Place = {
@@ -163,12 +170,18 @@ export function lower(
         'Assignment',
       );
     } else {
-      builder.errors.push({
-        reason: `(BuildHIR::lower) Handle ${param.node.type} params`,
-        severity: ErrorSeverity.Todo,
-        loc: param.node.loc ?? null,
-        suggestions: null,
-      });
+      builder.errors.pushDiagnostic(
+        CompilerDiagnostic.create({
+          category: `Handle ${param.node.type} parameters`,
+          description: `[BuildHIR] Add support for ${param.node.type} parameters`,
+          severity: ErrorSeverity.Todo,
+          suggestions: null,
+        }).withDetail({
+          kind: 'error',
+          loc: param.node.loc ?? null,
+          message: 'Unsupported parameter type',
+        }),
+      );
     }
   });
 
@@ -188,13 +201,18 @@ export function lower(
     lowerStatement(builder, body);
     directives = body.get('directives').map(d => d.node.value.value);
   } else {
-    builder.errors.push({
-      severity: ErrorSeverity.InvalidJS,
-      reason: `Unexpected function body kind`,
-      description: `Expected function body to be an expression or a block statement, got \`${body.type}\``,
-      loc: body.node.loc ?? null,
-      suggestions: null,
-    });
+    builder.errors.pushDiagnostic(
+      CompilerDiagnostic.create({
+        severity: ErrorSeverity.InvalidJS,
+        category: `Unexpected function body kind`,
+        description: `Expected function body to be an expression or a block statement, got \`${body.type}\``,
+        suggestions: null,
+      }).withDetail({
+        kind: 'error',
+        loc: body.node.loc ?? null,
+        message: 'Expected a block statement or expression',
+      }),
+    );
   }
 
   if (builder.errors.hasErrors()) {

diff --git a/...ages/babel-plugin-react-compiler/src/Validation/ValidateLocalsNotReassignedAfterRender.ts b/...ages/babel-plugin-react-compiler/src/Validation/ValidateLocalsNotReassignedAfterRender.ts
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, Effect} from '..';
+import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
 import {HIRFunction, IdentifierId, Place} from '../HIR';
 import {
   eachInstructionLValue,
@@ -28,16 +28,19 @@ export function validateLocalsNotReassignedAfterRender(fn: HIRFunction): void {
     false,
   );
   if (reassignment !== null) {
-    CompilerError.throwInvalidReact({
-      reason:
-        'Reassigning a variable after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead',
-      description:
-        reassignment.identifier.name !== null &&
-        reassignment.identifier.name.kind === 'named'
-          ? `Variable \`${reassignment.identifier.name.value}\` cannot be reassigned after render`
-          : '',
-      loc: reassignment.loc,
-    });
+    const errors = new CompilerError();
+    errors.pushDiagnostic(
+      CompilerDiagnostic.create({
+        severity: ErrorSeverity.InvalidReact,
+        category: 'Cannot reassign a variable after render completes',
+        description: `Reassigning ${reassignment.identifier.name != null && reassignment.identifier.name.kind === 'named' ? `variable \`${reassignment.identifier.name.value}\`` : 'a variable'} after render has completed can cause inconsistent behavior on subsequent renders. Consider using state instead`,
+      }).withDetail({
+        kind: 'error',
+        loc: reassignment.loc,
+        message: 'Cannot reassign variable after render completes',
+      }),
+    );
+    throw errors;
   }
 }
 

diff --git a/...ges/babel-plugin-react-compiler/src/Validation/ValidateNoFreezingKnownMutableFunctions.ts b/...ges/babel-plugin-react-compiler/src/Validation/ValidateNoFreezingKnownMutableFunctions.ts
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, Effect, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError, Effect, ErrorSeverity} from '..';
 import {
   FunctionEffect,
   HIRFunction,
@@ -57,16 +57,24 @@ export function validateNoFreezingKnownMutableFunctions(
     if (operand.effect === Effect.Freeze) {
       const effect = contextMutationEffects.get(operand.identifier.id);
       if (effect != null) {
-        errors.push({
-          reason: `This argument is a function which may reassign or mutate local variables after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead`,
-          loc: operand.loc,
-          severity: ErrorSeverity.InvalidReact,
-        });
-        errors.push({
-          reason: `The function modifies a local variable here`,
-          loc: effect.loc,
-          severity: ErrorSeverity.InvalidReact,
-        });
+        errors.pushDiagnostic(
+          CompilerDiagnostic.create({
+            severity: ErrorSeverity.InvalidReact,
+            category: 'Cannot modify local variables after render completes',
+            description: `This argument is a function which may reassign or mutate local variables after render, which can cause inconsistent behavior on subsequent renders. Consider using state instead`,
+          })
+            .withDetail({
+              kind: 'error',
+              loc: operand.loc,
+              message:
+                'This function may (indirectly) reassign or modify local variables after render',
+            })
+            .withDetail({
+              kind: 'error',
+              loc: effect.loc,
+              message: 'This modifies a local variable',
+            }),
+        );
       }
     }
   }

diff --git a/.../packages/babel-plugin-react-compiler/src/Validation/ValidateNoImpureFunctionsInRender.ts b/.../packages/babel-plugin-react-compiler/src/Validation/ValidateNoImpureFunctionsInRender.ts
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
 import {HIRFunction} from '../HIR';
 import {getFunctionCallSignature} from '../Inference/InferReferenceEffects';
 import {Result} from '../Utils/Result';
@@ -34,17 +34,22 @@ export function validateNoImpureFunctionsInRender(
           callee.identifier.type,
         );
         if (signature != null && signature.impure === true) {
-          errors.push({
-            reason:
-              'Calling an impure function can produce unstable results. (https://react.dev/reference/rules/components-and-hooks-must-be-pure#components-and-hooks-must-be-idempotent)',
-            description:
-              signature.canonicalName != null
-                ? `\`${signature.canonicalName}\` is an impure function whose results may change on every call`
-                : null,
-            severity: ErrorSeverity.InvalidReact,
-            loc: callee.loc,
-            suggestions: null,
-          });
+          errors.pushDiagnostic(
+            CompilerDiagnostic.create({
+              category: 'Cannot call impure function during render',
+              description:
+                (signature.canonicalName != null
+                  ? `\`${signature.canonicalName}\` 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)',
+              severity: ErrorSeverity.InvalidReact,
+              suggestions: null,
+            }).withDetail({
+              kind: 'error',
+              loc: callee.loc,
+              message: 'Cannot call impure function',
+            }),
+          );
         }
       }
     }

diff --git a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoJSXInTryStatement.ts b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoJSXInTryStatement.ts
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '..';
+import {CompilerDiagnostic, CompilerError, ErrorSeverity} from '..';
 import {BlockId, HIRFunction} from '../HIR';
 import {Result} from '../Utils/Result';
 import {retainWhere} from '../Utils/utils';
@@ -34,11 +34,17 @@ export function validateNoJSXInTryStatement(
         switch (value.kind) {
           case 'JsxExpression':
           case 'JsxFragment': {
-            errors.push({
-              severity: ErrorSeverity.InvalidReact,
-              reason: `Unexpected JSX element within a try statement. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
-              loc: value.loc,
-            });
+            errors.pushDiagnostic(
+              CompilerDiagnostic.create({
+                severity: ErrorSeverity.InvalidReact,
+                category: 'Avoid constructing JSX within try/catch',
+                description: `React does not immediately render components when JSX is rendered, so any errors from this component will not be caught by the try/catch. To catch errors in rendering a given component, wrap that component in an error boundary. (https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary)`,
+              }).withDetail({
+                kind: 'error',
+                loc: value.loc,
+                message: 'Avoid constructing JSX within try/catch',
+              }),
+            );
             break;
           }
         }

diff --git a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInEffects.ts
@@ -5,7 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '../CompilerError';
+import {
+  CompilerDiagnostic,
+  CompilerError,
+  ErrorSeverity,
+} from '../CompilerError';
 import {
   HIRFunction,
   IdentifierId,
@@ -90,14 +94,21 @@ export function validateNoSetStateInEffects(
             if (arg !== undefined && arg.kind === 'Identifier') {
               const setState = setStateFunctions.get(arg.identifier.id);
               if (setState !== undefined) {
-                errors.push({
-                  reason:
-                    'Calling setState directly within a useEffect causes cascading renders and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect)',
-                  description: null,
-                  severity: ErrorSeverity.InvalidReact,
-                  loc: setState.loc,
-                  suggestions: null,
-                });
+                errors.pushDiagnostic(
+                  CompilerDiagnostic.create({
+                    category:
+                      'Calling setState within an effect can trigger cascading renders',
+                    description:
+                      'Calling setState directly within a useEffect causes cascading renders that can hurt performance, and is not recommended. Consider alternatives to useEffect. (https://react.dev/learn/you-might-not-need-an-effect)',
+                    severity: ErrorSeverity.InvalidReact,
+                    suggestions: null,
+                  }).withDetail({
+                    kind: 'error',
+                    loc: setState.loc,
+                    message:
+                      'Avoid calling setState() in the top-level of an effect',
+                  }),
+                );
               }
             }
           }

diff --git a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInRender.ts b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoSetStateInRender.ts
@@ -5,7 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {CompilerError, ErrorSeverity} from '../CompilerError';
+import {
+  CompilerDiagnostic,
+  CompilerError,
+  ErrorSeverity,
+} from '../CompilerError';
 import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
 import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
 import {eachInstructionValueOperand} from '../HIR/visitors';
@@ -122,23 +126,35 @@ function validateNoSetStateInRenderImpl(
             unconditionalSetStateFunctions.has(callee.identifier.id)
           ) {
             if (activeManualMemoId !== null) {
-              errors.push({
-                reason:
-                  'Calling setState from useMemo may trigger an infinite loop. (https://react.dev/reference/react/useState)',
-                description: null,
-                severity: ErrorSeverity.InvalidReact,
-                loc: callee.loc,
-                suggestions: null,
-              });
+              errors.pushDiagnostic(
+                CompilerDiagnostic.create({
+                  category:
+                    'Calling setState from useMemo may trigger an infinite loop',
+                  description:
+                    'Each time the memo callback is evaluated it will change state. This can cause a memoization dependency to change, running the memo function again and causing an infinite loop. Instead of setting state in useMemo(), prefer deriving the value during render. (https://react.dev/reference/react/useState)',
+                  severity: ErrorSeverity.InvalidReact,
+                  suggestions: null,
+                }).withDetail({
+                  kind: 'error',
+                  loc: callee.loc,
+                  message: 'Found setState() within useMemo()',
+                }),
+              );
             } else if (unconditionalBlocks.has(block.id)) {
-              errors.push({
-                reason:
-                  'This is an unconditional set state during render, which will trigger an infinite loop. (https://react.dev/reference/react/useState)',
-                description: null,
-                severity: ErrorSeverity.InvalidReact,
-                loc: callee.loc,
-                suggestions: null,
-              });
+              errors.pushDiagnostic(
+                CompilerDiagnostic.create({
+                  category:
+                    'Calling setState during render may trigger an infinite loop',
+                  description:
+                    'Calling setState during render will trigger another render, and can lead to infinite loops. (https://react.dev/reference/react/useState)',
+                  severity: ErrorSeverity.InvalidReact,
+                  suggestions: null,
+                }).withDetail({
+                  kind: 'error',
+                  loc: callee.loc,
+                  message: 'Found setState() within useMemo()',
+                }),
+              );
             }
           }
           break;