Fix stack overflow in error generation for recursive mapped types#63215
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hamzax180 wants to merge 1 commit intomicrosoft:mainfrom
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Fix stack overflow in error generation for recursive mapped types#63215hamzax180 wants to merge 1 commit intomicrosoft:mainfrom
hamzax180 wants to merge 1 commit intomicrosoft:mainfrom
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With 6.0 out as the final release vehicle for this codebase, we're closing all PRs that don't fit the merge criteria for post-6.0 patches. If you think this was a mistake and this PR fits the post-6.0 patch criteria, please post to the 6.0 iteration issue with details (specifically, which PR and which patch criteria it satisfies). Next steps for PRs:
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Fixes #63090
Bug Description
When a mapped type contains a deeply recursive or circular reference, TypeScript correctly identifies it as an error. However, when generating the diagnostic message (
Type_of_property_0_circularly_references_itself_in_mapped_type_1), the compiler calls typeToString(mappedType) to format the error text.Evaluating typeToString(mappedType) triggers property resolution, which evaluates the symbol's type by calling getTypeOfMappedSymbol again. Since
symbol.links.typehasn't been cached with theerrorTypeyet, this hits the same circularity, which attempts to throw another error, triggering typeToString again, leading to an infinite cycle and an eventualRangeError: Maximum call stack size exceeded.Fix Explanation
This PR breaks the infinite recursion by eagerly caching
symbol.links.type = errorType;immediately before calling error(...) and typeToString(mappedType).When typeToString evaluates the mapped type, it now sees the cached
errorTypefor the symbol and safely halts recursion, generating the correct error message without blowing up the call stack.Testing
Added the provided reproduction from the issue as a compiler test case:
tests/cases/compiler/issue63090.tshereby baseline-acceptso the baseline error generation accurately outputs the circularity error instead of crashing.