fix(compiler-cli): improve error message when non-exported class is used in component imports#67223
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…sed in component imports When a class that is not exported is used in a standalone component's `imports` array, the compiler now produces a more helpful error message explaining that the class needs to be exported, instead of the generic "Component imports must be standalone components, directives, pipes, or must be NgModules" message. This is especially important for the Angular Language Service which sets `compileNonExportedClasses: false`, causing non-exported classes to not be analyzed and resulting in confusing diagnostics. The new error message includes related information pointing to the class declaration and suggesting to add the `export` keyword. Fixes angular#49874
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Closing this PR. Apologies for the low-quality submissions — the changes were not properly tested in the actual application before submitting. I will ensure thorough manual testing before any future contributions. |
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What kind of change does this PR introduce?
Bug fix (improved error message / developer experience)
What is the current behavior?
When a non-exported class is used in a standalone component's
importsarray, the compiler produces the generic error message:This is particularly confusing because the class may have all the correct Angular decorators (e.g.,
@Directive,@Component,@Pipe) -- the real issue is simply that the class is not exported.This is especially impactful in the Angular Language Service, which always sets
compileNonExportedClasses: false, causing non-exported classes to not be analyzed and leading to misleading diagnostics.Closes #49874
What is the new behavior?
When a non-exported class is used in
imports(ordeferredImports), the compiler now produces a more helpful error message:The diagnostic also includes related information pointing to the class declaration with the suggestion:
If the class IS exported but still unrecognized, the original generic error message is preserved.
Additional context
The fix is in
packages/compiler-cli/src/ngtsc/scope/src/util.ts, modifyingmakeUnknownComponentImportDiagnosticandmakeUnknownComponentDeferredImportDiagnosticto check whether the referenced class declaration has theexportkeyword modifier. A helper functionisNonExportedClasswas extracted to avoid code duplication.A test case was added to
standalone_spec.tsthat usescompileNonExportedClasses: falseto simulate the language service behavior.