fix(minifier): preserve annotation comments when inlining single-use variables during DCE#21567
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Dunqing
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April 20, 2026 07:57
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This is actually similar to what the workaround at vitejs/vite#21950 (comment) does. |
sapphi-red
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…variables during DCE (#21567) When `substitute_single_use_symbol_in_expression` inlines a single-use `const` variable, it replaced the identifier with the init expression using `replacement.take_in()`, which kept the replacement's original span from the variable declaration site. Since comments are associated with AST nodes via the `attached_to` field (keyed by span start), `@vite-ignore` and `webpackIgnore` comments attached to the original identifier were lost because the replacement expression had a different span start. This only manifested in DCE mode (used by rolldown) because in full optimization mode, `inline_identifier_reference` runs first and correctly preserves the span via `ctx.value_to_expr(expr.span(), ...)`. The fix preserves the target identifier's span on the replacement expression after substitution. Fixes rolldown/rolldown#8248 Closes vitejs/vite#21950
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When
substitute_single_use_symbol_in_expressioninlines a single-useconstvariable, it replaced the identifier with the init expression usingreplacement.take_in(), which kept the replacement's original span from the variable declaration site. Since comments are associated with AST nodes via theattached_tofield (keyed by span start),@vite-ignoreandwebpackIgnorecomments attached to the original identifier were lost because the replacement expression had a different span start.This only manifested in DCE mode (used by rolldown) because in full optimization mode,
inline_identifier_referenceruns first and correctly preserves the span viactx.value_to_expr(expr.span(), ...).The fix preserves the target identifier's span on the replacement expression after substitution.
Fixes rolldown/rolldown#8248
Closes vitejs/vite#21950