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fix(@ngtools/webpack): elide non-value aliases and remaining type-only AST constructs - #34594
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alan-agius4 merged 2 commits intoOct 30, 2026
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This pull request refines import elision and bootstrap replacement logic in Angular build tools to prevent over-elision of imports, particularly handling type nodes, ambient statements, and unresolved modules more robustly. The feedback highlights two key areas for improvement: optimizing AST traversal performance during node removal by targeting only import declarations, and enhancing code robustness by explicitly parenthesizing and comparing bitwise operations to avoid operator precedence issues.
…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.
…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.
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Follow up to #34582 to cover remaining pure-type import elision cases and
partial specifier removal in
replaceBootstrap:traverse a type-only alias declaration), handling non-
typeinterfacere-exports (
export { Foo }) and interface parameter types underemitDecoratorMetadata.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 enumimports).ExpressionWithTypeArgumentsTypeNodes whenemitDecoratorMetadatais disabled, and unconditionally skipTypeQueryNode(typeof X),ImportTypeNode,IndexSignatureDeclaration, ambientdeclarestatements, and externalexport ... from '...'declarations.elideImportsremovals inreplaceBootstrapso individualImportSpecifiers are removed whenplatformBrowserDynamicshares an import with other used runtime exports.