Author: Krystian Stasiowski Date: 2024-05-16T14:10:46-04:00 New Revision: da928c6d6e0e2f619fdaef71cea8747d9aef188d
URL: https://github.com/llvm/llvm-project/commit/da928c6d6e0e2f619fdaef71cea8747d9aef188d DIFF: https://github.com/llvm/llvm-project/commit/da928c6d6e0e2f619fdaef71cea8747d9aef188d.diff LOG: [Clang][Sema] ASTContext::getUnconstrainedType propagates dependence (#92425) When the argument passed to `ASTContext::getUnconstrainedType` is an unconstrained `AutoType`, will return the argument unchanged. However, when called with a constrained `AutoType`, an unconstrained, non-dependent `AutoType` will be returned even if the argument was dependent. Consider the following: ``` template<typename T> concept C = sizeof(T) == sizeof(int); template<auto N> struct A; template<C auto N> struct A<N>; // error: class template partial specialization is not more specialized than the primary template ``` When comparing the template parameters for equivalence, `ASTContext::getUnconstrainedType` is used to remove the constraints per [temp.over.link] p6 sentence 2. For the template parameter `N` of the class template, it returns a dependent `AutoType`. For the template parameter `N` of the class template partial specialization, it returns a non-dependent `AutoType`. We subsequently compare the adjusted types and find they are not equivalent, thus we consider the partial specialization to not be more specialized than the primary template per [temp.func.order] p6.2.2. This patch changes `ASTContext::getUnconstrainedType` such that the dependence of a constrained `AutoType` will propagate to the returned unconstrained `AutoType`. This causes the above example to be correctly accepted, fixing #77377. Added: clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p2.cpp Modified: clang/docs/ReleaseNotes.rst clang/lib/AST/ASTContext.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index be4cded276321..2d2928e418623 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -723,6 +723,7 @@ Bug Fixes to C++ Support - Clang now ignores template parameters only used within the exception specification of candidate function templates during partial ordering when deducing template arguments from a function declaration or when taking the address of a function template. +- Fix a bug with checking constrained non-type template parameters for equivalence. Fixes (#GH77377). Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp index 4475f399a120b..8fc2bb8c401c2 100644 --- a/clang/lib/AST/ASTContext.cpp +++ b/clang/lib/AST/ASTContext.cpp @@ -5910,7 +5910,8 @@ QualType ASTContext::getUnconstrainedType(QualType T) const { if (auto *AT = CanonT->getAs<AutoType>()) { if (!AT->isConstrained()) return T; - return getQualifiedType(getAutoType(QualType(), AT->getKeyword(), false, + return getQualifiedType(getAutoType(QualType(), AT->getKeyword(), + AT->isDependentType(), AT->containsUnexpandedParameterPack()), T.getQualifiers()); } diff --git a/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p2.cpp b/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p2.cpp new file mode 100644 index 0000000000000..df1bbd5fe8128 --- /dev/null +++ b/clang/test/CXX/temp/temp.decls/temp.fct/temp.func.order/p2.cpp @@ -0,0 +1,13 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s +// expected-no-diagnostics + +namespace GH77377 { + template<typename T> + concept C = sizeof(T) == sizeof(int); + + template<auto N> + struct A; + + template<C auto N> + struct A<N>; +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
