fix(@angular-devkit/build-angular): do not mark standalone expression statements as pure - #34206
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… statements as pure Top-level call and new expressions that appear directly as expression statements are executed solely for their side effects, such as class property initialization, static blocks, and helper calls. When targeting browsers requiring class static block or property lowering (e.g., Chrome < 94), Babel's preset-env lowers self-referencing static properties into zero-argument IIFEs (and static blocks into _staticBlock() calls). Because pure-toplevel-functions previously only skipped IIFEs if they had arguments, zero-argument IIFE statements were marked as pure. Downstream minifiers (such as esbuild) then eliminated these standalone pure statements as dead code, dropping essential class members like Injector.ɵprov and causing NG0201 at bootstrap. This change ensures that call and new expressions that are directly expression statements are never annotated as pure, avoiding accidental elimination of side-effecting statements without requiring hardcoded whitelists of helper function names. Fixes angular#34017
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This pull request updates the pure-toplevel-functions Babel plugin to avoid annotating standalone expression statements as pure, preventing minifiers from incorrectly dropping them as dead code. It also adds corresponding unit tests to cover these scenarios. The review feedback recommends using optional chaining (path.parentPath?.isExpressionStatement()) in both newly added checks to prevent potential runtime TypeErrors if path.parentPath is null.
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Top-level call and new expressions that appear directly as expression statements are executed solely for their side effects, such as class property initialization, static blocks, and helper calls.
When targeting browsers requiring class static block or property lowering (e.g., Chrome < 94), Babel's preset-env lowers self-referencing static properties into zero-argument IIFEs (and static blocks into _staticBlock() calls). Because pure-toplevel-functions previously only skipped IIFEs if they had arguments, zero-argument IIFE statements were marked as pure. Downstream minifiers (such as esbuild) then eliminated these standalone pure statements as dead code, dropping essential class members like Injector.ɵprov and causing NG0201 at bootstrap.
This change ensures that call and new expressions that are directly expression statements are never annotated as pure, avoiding accidental elimination of side-effecting statements without requiring hardcoded whitelists of helper function names.
Fixes #34017