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fix(@ngtools/webpack): elide imports used only in type re-exports or type declarations - #34582
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alan-agius4 merged 1 commit intoOct 29, 2026
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…type declarations
When `elideImports` removes unused import specifiers (such as after
`removeIvyJitSupportCalls` removes `ɵsetClassMetadata`), it previously
walked into `interface` declarations, `type` alias declarations, and
type-only `export` declarations/specifiers (`export type { X }`,
`export { type X }`). This caused it to mark those type-only imported
symbols as used at runtime and rewrite the `ImportDeclaration` while
retaining those specifiers.
Because the `ImportDeclaration` AST node was replaced by a `before`
transformer, TypeScript skipped its own type-only import elision on the
cloned declaration, leaving the type-only specifier in the emitted JS
output. With webpack 5.112.0+, unused import specifiers are still
link-checked against the target module, causing builds with
`strictExportPresence: true` to fail.
Skip pure type declarations (`InterfaceDeclaration`,
`TypeAliasDeclaration`, `TypeParameterDeclaration`) and type-only
exports (`ExportDeclaration` and `ExportSpecifier` with `isTypeOnly`)
when collecting used identifiers in `elideImports`.
Closes angular#34580
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This pull request updates the import elision logic in both the JIT bootstrap transformer and the Webpack elide_imports transformer to correctly identify and erase pure type declarations and type-only exports at runtime. This ensures that imports are properly removed when their specifiers are only used in type-only contexts, such as interfaces, type aliases, type parameters, and type-only exports. A comprehensive unit test has been added to verify this behavior. There are no review comments to address, and I have no additional feedback to provide.
clydin
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Oct 29, 2026
alan-agius4
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clydin
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Oct 29, 2026
…y AST constructs Follow up to angular#34582 to cover remaining pure-type import elision cases and partial specifier removal in `replaceBootstrap`: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer. TypeScript skips its own import elision for declarations replaced by a transformer, so leaving other declarations untouched avoids retaining specifiers that TypeScript would have otherwise elided (such as inlined `const enum` imports). - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying `elideImports` removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
clydin
added a commit
to clydin/angular-cli
that referenced
this pull request
Oct 29, 2026
…AST constructs Follow up to angular#34582 to apply the same import elision fixes made to `@ngtools/webpack` to the `replaceBootstrap` transformer used by the application builder: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer, so TypeScript's own import elision continues to apply to all other declarations. - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying import removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
clydin
added a commit
to clydin/angular-cli
that referenced
this pull request
Oct 29, 2026
…y AST constructs Follow up to angular#34582 to cover remaining pure-type import elision cases and partial specifier removal in `replaceBootstrap`: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer. TypeScript skips its own import elision for declarations replaced by a transformer, so leaving other declarations untouched avoids retaining specifiers that TypeScript would have otherwise elided (such as inlined `const enum` imports). - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying `elideImports` removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
clydin
added a commit
to clydin/angular-cli
that referenced
this pull request
Oct 29, 2026
…AST constructs Follow up to angular#34582 to apply the same import elision fixes made to `@ngtools/webpack` to the `replaceBootstrap` transformer used by the application builder: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer, so TypeScript's own import elision continues to apply to all other declarations. - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying import removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
alan-agius4
pushed a commit
that referenced
this pull request
Oct 30, 2026
…y AST constructs Follow up to #34582 to cover remaining pure-type import elision cases and partial specifier removal in `replaceBootstrap`: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer. TypeScript skips its own import elision for declarations replaced by a transformer, so leaving other declarations untouched avoids retaining specifiers that TypeScript would have otherwise elided (such as inlined `const enum` imports). - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying `elideImports` removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
alan-agius4
pushed a commit
that referenced
this pull request
Oct 30, 2026
…AST constructs Follow up to #34582 to apply the same import elision fixes made to `@ngtools/webpack` to the `replaceBootstrap` transformer used by the application builder: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer, so TypeScript's own import elision continues to apply to all other declarations. - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying import removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports.
alan-agius4
pushed a commit
that referenced
this pull request
Oct 30, 2026
…y AST constructs Follow up to #34582 to cover remaining pure-type import elision cases and partial specifier removal in `replaceBootstrap`: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer. TypeScript skips its own import elision for declarations replaced by a transformer, so leaving other declarations untouched avoids retaining specifiers that TypeScript would have otherwise elided (such as inlined `const enum` imports). - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying `elideImports` removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports. (cherry picked from commit 9e6c1ce)
alan-agius4
pushed a commit
that referenced
this pull request
Oct 30, 2026
…AST constructs Follow up to #34582 to apply the same import elision fixes made to `@ngtools/webpack` to the `replaceBootstrap` transformer used by the application builder: - Elide imported alias symbols that do not resolve to a runtime value (or traverse a type-only alias declaration), handling non-`type` interface re-exports (`export { Foo }`) and interface parameter types under `emitDecoratorMetadata`. - Only rewrite a partially elided import declaration when a runtime value import must be removed or when the declaration was already replaced by a previous transformer, so TypeScript's own import elision continues to apply to all other declarations. - Skip all non-`ExpressionWithTypeArguments` `TypeNode`s when `emitDecoratorMetadata` is disabled, and unconditionally skip `TypeQueryNode` (`typeof X`), `ImportTypeNode`, `IndexSignatureDeclaration`, ambient `declare` statements, and external `export ... from '...'` declarations. - Recursively visit child AST nodes when applying import removals in `replaceBootstrap` so individual `ImportSpecifier`s are removed when `platformBrowserDynamic` shares an import with other used runtime exports. (cherry picked from commit 174eb34)
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When
elideImportsremoves unused import specifiers (such as afterremoveIvyJitSupportCallsremovesɵsetClassMetadata), it previously walked intointerfacedeclarations,typealias declarations, and type-onlyexportdeclarations/specifiers (export type { X },export { type X }). This caused it to mark those type-only imported symbols as used at runtime and rewrite theImportDeclarationwhile retaining those specifiers.Because the
ImportDeclarationAST node was replaced by abeforetransformer, TypeScript skipped its own type-only import elision on the cloned declaration, leaving the type-only specifier in the emitted JS output. With webpack 5.112.0+, unused import specifiers are still link-checked against the target module, causing builds withstrictExportPresence: trueto fail.Skip pure type declarations (
InterfaceDeclaration,TypeAliasDeclaration,TypeParameterDeclaration) and type-only exports (ExportDeclarationandExportSpecifierwithisTypeOnly) when collecting used identifiers inelideImports.Closes #34580