fixup: also reject names that collide only by case

Author: thekhegay

packages/angular/build/src/builders/library/options.ts

@@ -296,6 +296,8 @@ function normalizeEntryPoints(
 
   const entryPoints = new Map<string, NormalizedEntryPoint>();
   // Bundle names flatten '/' to '-', so two distinct subpaths can produce one.
+  // Keyed case-insensitively: names differing only in case are distinct keys in
+  // the bundler input map but one file on a case-insensitive filesystem.
   const bundleNameOrigins = new Map<string, string>();
   let hasPrimary = false;
 
@@ -348,15 +350,17 @@ function normalizeEntryPoints(
       );
     }
 
-    const collidingKey = bundleNameOrigins.get(entryPoint.bundleName);
+    const bundleNameKey = entryPoint.bundleName.toLowerCase();
+    const collidingKey = bundleNameOrigins.get(bundleNameKey);
     if (collidingKey !== undefined) {
       throw new Error(
         `Entry points '${collidingKey}' and '${key}' both produce the bundle name ` +
-          `'${entryPoint.bundleName}'. Entry point subpaths must not differ only by '/' versus '-'.`,
+          `'${entryPoint.bundleName}'. Entry point subpaths must not differ only by ` +
+          `'/' versus '-', or by case.`,
       );
     }
 
-    bundleNameOrigins.set(entryPoint.bundleName, key);
+    bundleNameOrigins.set(bundleNameKey, key);
     entryPoints.set(entryPoint.name, entryPoint);
 
     if (entryPoint.isPrimary) {

packages/angular/build/src/builders/library/tests/options/entry-points_spec.ts

@@ -98,6 +98,33 @@ describeLibraryBuilder(executeLibraryBuilder, LIBRARY_BUILDER_INFO, (harness) =>
       );
     });
 
+    it('should fail when two entry points differ only by case', async () => {
+      // Distinct keys in the bundler input map, but one file on a case-insensitive
+      // filesystem, so the emitted bundle depends on which OS ran the build.
+      await harness.writeFiles({
+        'projects/lib/Zz/public-api.ts': 'export const UPPER = 42;\n',
+        'projects/lib/zz/public-api.ts': 'export const LOWER = 7;\n',
+      });
+      await harness.modifyFile('projects/lib/package.json', (content) => {
+        const pkg = JSON.parse(content);
+        pkg.exports = {
+          '.': './src/public-api.ts',
+          './Zz': './Zz/public-api.ts',
+          './zz': './zz/public-api.ts',
+        };
+
+        return JSON.stringify(pkg, null, 2);
+      });
+
+      const { result, error } = await harness.executeOnce({
+        outputLogsOnException: false,
+        outputLogsOnFailure: false,
+      });
+      expect(result).toBeUndefined();
+      expect(error).toBeDefined();
+      expect((error as Error).message).toMatch(/both produce the bundle name/);
+    });
+
     it('should fail when entry point is not a .ts or .mts file', async () => {
       await harness.modifyFile('projects/lib/package.json', (content) => {
         const pkg = JSON.parse(content);