fix(compiler-cli): show proper error for custom decorators in local c…

…ompilation mode

At the moment local compilation mode does not support custom decorators, and it leads to unhandled errors. In this change a compile time diagnostic is produced in local mode for custom decorators. This is a temporary solution since there are few custom decorators are in use in g3. Custom decorators will be eventually supported in local mode.

packages/compiler-cli/src/ngtsc/transform/src/compilation.ts

@@ -259,12 +259,21 @@ export class TraitCompiler implements ProgramTypeCheckAdapter {
     let record: ClassRecord|null = this.recordFor(clazz);
     let foundTraits: PendingTrait<unknown, unknown, SemanticSymbol|null, unknown>[] = [];
 
+    // A set to track the non-Angular decorators in local compilation mode. An error will be issued
+    // if non-Angular decorators is found in local compilation mode.
+    const nonNgDecoratorsInLocalMode =
+        this.compilationMode === CompilationMode.LOCAL ? new Set(decorators) : null;
+
     for (const handler of this.handlers) {
       const result = handler.detect(clazz, decorators);
       if (result === undefined) {
         continue;
       }
 
+      if (nonNgDecoratorsInLocalMode !== null && result.decorator !== null) {
+        nonNgDecoratorsInLocalMode.delete(result.decorator);
+      }
+
       const isPrimaryHandler = handler.precedence === HandlerPrecedence.PRIMARY;
       const isWeakHandler = handler.precedence === HandlerPrecedence.WEAK;
       const trait = Trait.pending(handler, result);
@@ -332,6 +341,23 @@ export class TraitCompiler implements ProgramTypeCheckAdapter {
       }
     }
 
+    if (nonNgDecoratorsInLocalMode !== null && nonNgDecoratorsInLocalMode.size > 0 &&
+        record !== null && record.metaDiagnostics === null) {
+      // Custom decorators found in local compilation mode! In this mode we don't support custom
+      // decorators yet. But will eventually do (b/320536434). For now a temporary error is thrown.
+      record.metaDiagnostics = [...nonNgDecoratorsInLocalMode].map(
+          decorator => ({
+            category: ts.DiagnosticCategory.Error,
+            code: Number('-99' + ErrorCode.DECORATOR_UNEXPECTED),
+            file: getSourceFile(clazz),
+            start: decorator.node.getStart(),
+            length: decorator.node.getWidth(),
+            messageText:
+                'In local compilation mode, Angular does not support custom decorators. Ensure all class decorators are from Angular.',
+          }));
+      record.traits = foundTraits = [];
+    }
+
     return foundTraits.length > 0 ? foundTraits : null;
   }
 

packages/compiler-cli/test/ngtsc/local_compilation_spec.ts

@@ -1734,5 +1734,36 @@ runInEachFileSystem(
                    }
                  });
             });
+
+            describe('custom decorator', () => {
+              it('should produce diagnostic for each custom decorator', () => {
+                env.write('test.ts', `
+          import {Component} from '@angular/core';
+          import {customDecorator1, customDecorator2} from './some-where';
+
+          @customDecorator1('hello')
+          @Component({
+            template: ExternalString,
+          })
+          @customDecorator2
+          export class Main {
+          }
+          `);
+
+                const errors = env.driveDiagnostics();
+
+                expect(errors.length).toBe(2);
+
+                const text1 = ts.flattenDiagnosticMessageText(errors[0].messageText, '\n');
+                const text2 = ts.flattenDiagnosticMessageText(errors[1].messageText, '\n');
+
+                expect(errors[0].code).toBe(ngErrorCode(ErrorCode.DECORATOR_UNEXPECTED));
+                expect(errors[1].code).toBe(ngErrorCode(ErrorCode.DECORATOR_UNEXPECTED));
+                expect(text1).toContain(
+                    'In local compilation mode, Angular does not support custom decorators');
+                expect(text2).toContain(
+                    'In local compilation mode, Angular does not support custom decorators');
+              });
+            });
           });
     });