https://github.com/daniel-petrovic updated https://github.com/llvm/llvm-project/pull/224393
>From 90119a8e8bec2f685d5cc044ad94b78a755d417b Mon Sep 17 00:00:00 2001 From: Daniel Petrovic <[email protected]> Date: Thu, 17 Sep 2026 21:44:57 +0200 Subject: [PATCH] [clang] Fix stack exhaustion if parsing deeply nested template arguments Issue: Stack guard is missing on the path if parsing deeply nested template args. Fix: Run template argument list parser under stack guard. --- clang/docs/ReleaseNotes.md | 5 +++++ clang/lib/Parse/ParseTemplate.cpp | 9 ++++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index a1f24a8caedae..1a8d932b8af8f 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -608,6 +608,11 @@ features cannot lower the translation-unit ABI level; - Fixed a crash when a using-declaration naming an unresolvable member of a dependent base was shadowed by an invalid using-declaration. (#GH209427) +- Fixed a stack overflow when parsing deeply nested template arguments such + as ``S<S<S<...>>>``. Parsing now goes through the existing stack guard, which + continues on a fresh stack instead of crashing when the parser's stack is + nearly exhausted. (#GH224114) + - Fixed a CTAD bug when combining with concepts. (#GH124715) - Fixed a regression where an internal-linkage function (e.g. a `static` or diff --git a/clang/lib/Parse/ParseTemplate.cpp b/clang/lib/Parse/ParseTemplate.cpp index 1e5aa55338309..fb41cace01a7b 100644 --- a/clang/lib/Parse/ParseTemplate.cpp +++ b/clang/lib/Parse/ParseTemplate.cpp @@ -1392,9 +1392,16 @@ bool Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs, Template, TemplateArgs, OpenLoc); }; + // Nested template-ids (e.g. `S<S<S<...>>>`) recurse through the parser's + // type/template disambiguation machinery, which is deeply recursive. Run the + // parse with the stack guard so that a deeply nested argument list (see + // https://github.com/llvm/llvm-project/issues/224114) continues on a fresh + // stack instead of overflowing the parser's stack. do { PreferredType.enterFunctionArgument(Tok.getLocation(), RunSignatureHelp); - ParsedTemplateArgument Arg = ParseTemplateArgument(); + ParsedTemplateArgument Arg; + StackHandler.runWithSufficientStackSpace( + OpenLoc, [&Arg, this] { Arg = ParseTemplateArgument(); }); SourceLocation EllipsisLoc; if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc); _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
