https://github.com/jcsxky created https://github.com/llvm/llvm-project/pull/89862
attempt to fix https://github.com/llvm/llvm-project/issues/68885#issuecomment-1764201896 Deduction of NTTP whose type is `decltype(auto)` would create an implicit cast expression to dependent type and makes the type of primary template definition (`InjectedClassNameSpecialization`) and its partial specialization different. Prevent emitting cast expression to make clang knows their types are identical by removing `CTAK == CTAK_Deduced` when the type is `decltype(auto)`. >From 9b3e69844033a99be0eef90e816b9dff3e64c901 Mon Sep 17 00:00:00 2001 From: huqizhi <huqi...@feysh.com> Date: Wed, 24 Apr 2024 09:37:53 +0800 Subject: [PATCH] [Clang][Sema] fix a bug on template partial specialization --- clang/docs/ReleaseNotes.rst | 1 + clang/lib/Sema/SemaTemplate.cpp | 2 +- ...dentical-type-primary-partial-specialization.cpp | 13 +++++++++++++ 3 files changed, 15 insertions(+), 1 deletion(-) create mode 100644 clang/test/SemaCXX/identical-type-primary-partial-specialization.cpp diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 3db558a1c11a3f..27341fb0e3a772 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -561,6 +561,7 @@ Bug Fixes to C++ Support - Fixed a crash when trying to evaluate a user-defined ``static_assert`` message whose ``size()`` function returns a large or negative value. Fixes (#GH89407). - Fixed a use-after-free bug in parsing of type constraints with default arguments that involve lambdas. (#GH67235) +- Fix a bug on template partial specialization whose template parameter is `decltype(auto)`. Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp index 4bda31ba67c02d..345d77849b49d0 100644 --- a/clang/lib/Sema/SemaTemplate.cpp +++ b/clang/lib/Sema/SemaTemplate.cpp @@ -7706,7 +7706,7 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param, // FIXME: The language rules don't say what happens in this case. // FIXME: We get an opaque dependent type out of decltype(auto) if the // expression is merely instantiation-dependent; is this enough? - if (CTAK == CTAK_Deduced && Arg->isTypeDependent()) { + if (Arg->isTypeDependent()) { auto *AT = dyn_cast<AutoType>(DeducedT); if (AT && AT->isDecltypeAuto()) { SugaredConverted = TemplateArgument(Arg); diff --git a/clang/test/SemaCXX/identical-type-primary-partial-specialization.cpp b/clang/test/SemaCXX/identical-type-primary-partial-specialization.cpp new file mode 100644 index 00000000000000..ad51ca8252ef50 --- /dev/null +++ b/clang/test/SemaCXX/identical-type-primary-partial-specialization.cpp @@ -0,0 +1,13 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s + +template <decltype(auto) a> +struct S { // expected-note {{previous definition is here}} + static constexpr int i = 42; +}; + +template <decltype(auto) a> +struct S<a> { // expected-error {{class template partial specialization does not specialize any template argument; to define the primary template, remove the template argument list}} \ + // expected-error {{redefinition of 'S'}} + static constexpr int i = 0; +}; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
