[compiler] Add Intl formatter types and fix moduleTypeProvider fallback

Add type definitions for all Intl formatter objects (DateTimeFormat,
NumberFormat, Collator, PluralRules, ListFormat, RelativeTimeFormat,
Segmenter, DisplayNames) so the compiler understands that formatter
instances are immutable and their methods only read arguments.

Without these types, `new Intl.DateTimeFormat().format(date)` would
conservatively assume the format call captures `date` into the
formatter, creating an unnecessary dependency.

Also fix `#resolveModuleType` to always fall back to
`defaultModuleTypeProvider` when a custom `moduleTypeProvider` returns
null, so that tools like the snap runner that set their own provider
still get the default module types (react-hook-form, tanstack, etc.).

Author: josephsavona

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

@@ -792,18 +792,20 @@ export class Environment {
        * NOTE: Zod doesn't work when specifying a function as a default, so we have to
        * fallback to the default value here
        */
-      const moduleTypeProvider =
-        this.config.moduleTypeProvider ?? defaultModuleTypeProvider;
-      if (moduleTypeProvider == null) {
-        return null;
-      }
-      if (typeof moduleTypeProvider !== 'function') {
+      const moduleTypeProvider = this.config.moduleTypeProvider;
+      if (
+        moduleTypeProvider != null &&
+        typeof moduleTypeProvider !== 'function'
+      ) {
         CompilerError.throwInvalidConfig({
           reason: `Expected a function for \`moduleTypeProvider\``,
           loc,
         });
       }
-      const unparsedModuleConfig = moduleTypeProvider(moduleName);
+      const unparsedModuleConfig =
+        (typeof moduleTypeProvider === 'function'
+          ? moduleTypeProvider(moduleName)
+          : null) ?? defaultModuleTypeProvider(moduleName);
       if (unparsedModuleConfig != null) {
         const parsedModuleConfig = TypeSchema.safeParse(unparsedModuleConfig);
         if (!parsedModuleConfig.success) {

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

@@ -28,6 +28,14 @@ import {
   BuiltInWeakMapId,
   BuiltInWeakSetId,
   BuiltInEffectEventId,
+  BuiltInIntlDateTimeFormatId,
+  BuiltInIntlNumberFormatId,
+  BuiltInIntlCollatorId,
+  BuiltInIntlPluralRulesId,
+  BuiltInIntlListFormatId,
+  BuiltInIntlRelativeTimeFormatId,
+  BuiltInIntlSegmenterId,
+  BuiltInIntlDisplayNamesId,
   ReanimatedSharedValueId,
   ShapeRegistry,
   addFunction,
@@ -620,6 +628,145 @@ const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
       true,
     ),
   ],
+  [
+    'Intl',
+    addObject(DEFAULT_SHAPES, 'Intl', [
+      [
+        'DateTimeFormat',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {
+              kind: 'Object',
+              shapeId: BuiltInIntlDateTimeFormatId,
+            },
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'NumberFormat',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlNumberFormatId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'Collator',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlCollatorId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'PluralRules',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlPluralRulesId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'ListFormat',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlListFormatId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'RelativeTimeFormat',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {
+              kind: 'Object',
+              shapeId: BuiltInIntlRelativeTimeFormatId,
+            },
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'Segmenter',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlSegmenterId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+      [
+        'DisplayNames',
+        addFunction(
+          DEFAULT_SHAPES,
+          [],
+          {
+            positionalParams: [Effect.Read, Effect.Read],
+            restParam: null,
+            returnType: {kind: 'Object', shapeId: BuiltInIntlDisplayNamesId},
+            calleeEffect: Effect.Read,
+            returnValueKind: ValueKind.Frozen,
+          },
+          null,
+          true,
+        ),
+      ],
+    ]),
+  ],
   // TODO: rest of Global objects
 ];