https://github.com/ChuanqiXu9 created https://github.com/llvm/llvm-project/pull/174704
Close https://github.com/llvm/llvm-project/issues/174543 The root cause of the problem is that the recursion in the code pattern triggers infinite loop in the checking process for TU local exposure. >From 0d7e00f184e0b38cd62a92d80d18270ebad16397 Mon Sep 17 00:00:00 2001 From: Chuanqi Xu <[email protected]> Date: Wed, 7 Jan 2026 14:56:05 +0800 Subject: [PATCH] [C++20] [Modules] Avoid infinite loop when checking TU local exposures Close https://github.com/llvm/llvm-project/issues/174543 The root cause of the problem is that the recursion in the code pattern triggers infinite loop in the checking process for TU local exposure. --- clang/lib/Sema/SemaModule.cpp | 8 ++++++++ clang/test/Modules/pr174543.cppm | 8 ++++++++ 2 files changed, 16 insertions(+) create mode 100644 clang/test/Modules/pr174543.cppm diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp index cbe37cd47793b..24275b97b7462 100644 --- a/clang/lib/Sema/SemaModule.cpp +++ b/clang/lib/Sema/SemaModule.cpp @@ -18,6 +18,7 @@ #include "clang/Lex/Preprocessor.h" #include "clang/Sema/ParsedAttr.h" #include "clang/Sema/SemaInternal.h" +#include "llvm/ADT/ScopeExit.h" #include "llvm/ADT/StringExtras.h" using namespace clang; @@ -1140,6 +1141,7 @@ class ExposureChecker { private: llvm::DenseSet<const NamedDecl *> ExposureSet; llvm::DenseSet<const NamedDecl *> KnownNonExposureSet; + llvm::DenseSet<const NamedDecl *> CheckingDecls; }; bool ExposureChecker::isTULocal(QualType Ty) { @@ -1226,6 +1228,12 @@ bool ExposureChecker::isTULocal(const NamedDecl *D) { } } + // Avoid recursions. + if (CheckingDecls.count(D)) + return false; + CheckingDecls.insert(D); + llvm::scope_exit RemoveCheckingDecls([&] { CheckingDecls.erase(D); }); + // [basic.link]p15.5 // - a specialization of a template whose (possibly instantiated) declaration // is an exposure. diff --git a/clang/test/Modules/pr174543.cppm b/clang/test/Modules/pr174543.cppm new file mode 100644 index 0000000000000..39dc57f791ff6 --- /dev/null +++ b/clang/test/Modules/pr174543.cppm @@ -0,0 +1,8 @@ +// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s +// expected-no-diagnostics +export module m; +template < typename T > +void fun(T) +{ + fun(9); +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
