Author: Vlad Serebrennikov Date: 2024-01-20T12:23:08+04:00 New Revision: 9eb0f86c279f40a792ec27bf0e9b491b8c90a640
URL: https://github.com/llvm/llvm-project/commit/9eb0f86c279f40a792ec27bf0e9b491b8c90a640 DIFF: https://github.com/llvm/llvm-project/commit/9eb0f86c279f40a792ec27bf0e9b491b8c90a640.diff LOG: [clang] Implement CWG1878 "`operator auto` template" (#78103) C++14 introduced deduced return type for regular functions, but shortly after [CWG1878](https://wg21.link/cwg1878) was filed and resolved to disallow deduced return types in conversion function templates. So this patch diagnoses such usage of deduced return type in C++14 mode onwards. Fixes #51776 Added: Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaDeclCXX.cpp clang/test/CXX/drs/dr18xx.cpp clang/test/SemaCXX/deduced-return-type-cxx14.cpp clang/www/cxx_dr_status.html Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 4d152d220289b0c..4c69bdf131aaa53 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -575,6 +575,8 @@ Improvements to Clang's diagnostics - Clang now diagnoses unexpanded packs within the template argument lists of function template specializations. - Clang now diagnoses attempts to bind a bitfield to an NTTP of a reference type as erroneous converted constant expression and not as a reference to subobject. +- Clang now diagnoses ``auto`` and ``decltype(auto)`` in declarations of conversion function template + (`CWG1878: <https://cplusplus.github.io/CWG/issues/1878.html>`_) - Clang now diagnoses the requirement that non-template friend declarations with requires clauses and template friend declarations with a constraint that depends on a template parameter from an enclosing template must be a definition. diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 03b0122d1c08f75..23692758e9b8a57 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -2411,7 +2411,8 @@ def err_auto_not_allowed : Error< "|in type allocated by 'new'|in K&R-style function parameter" "|in template parameter|in friend declaration|in function prototype that is " "not a function declaration|in requires expression parameter" - "|in array declaration}1">; + "|in array declaration" + "|in declaration of conversion function template}1">; def err_dependent_deduced_tst : Error< "typename specifier refers to " "%select{class template|function template|variable template|alias template|" diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp index 828a0ec3dd042b9..df5bd55e7c28368 100644 --- a/clang/lib/Sema/SemaDeclCXX.cpp +++ b/clang/lib/Sema/SemaDeclCXX.cpp @@ -11321,9 +11321,20 @@ Decl *Sema::ActOnConversionDeclarator(CXXConversionDecl *Conversion) { << ClassType << ConvType; } - if (FunctionTemplateDecl *ConversionTemplate - = Conversion->getDescribedFunctionTemplate()) + if (FunctionTemplateDecl *ConversionTemplate = + Conversion->getDescribedFunctionTemplate()) { + if (const auto *ConvTypePtr = ConvType->getAs<PointerType>()) { + ConvType = ConvTypePtr->getPointeeType(); + } + if (ConvType->isUndeducedAutoType()) { + Diag(Conversion->getTypeSpecStartLoc(), diag::err_auto_not_allowed) + << getReturnTypeLoc(Conversion).getSourceRange() + << llvm::to_underlying(ConvType->getAs<AutoType>()->getKeyword()) + << /* in declaration of conversion function template= */ 24; + } + return ConversionTemplate; + } return Conversion; } diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp index 0245f03986dd73c..f2c056e13ecad78 100644 --- a/clang/test/CXX/drs/dr18xx.cpp +++ b/clang/test/CXX/drs/dr18xx.cpp @@ -1,10 +1,10 @@ // RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx98 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors // RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx11-17,since-cxx11 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors -// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors -// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors -// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors -// RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors -// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors +// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx14,cxx98-14,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors +// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx14,since-cxx17,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors +// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx14,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors +// RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx14,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors +// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify=expected,since-cxx14,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors #if __cplusplus == 199711L #define static_assert(...) __extension__ _Static_assert(__VA_ARGS__) @@ -319,6 +319,41 @@ namespace dr1872 { // dr1872: 9 #endif } +namespace dr1878 { // dr1878: 18 +#if __cplusplus >= 201402L +#if __cplusplus >= 202002L +template <typename T> +concept C = true; +#endif + +struct S { + template <typename T> + operator auto() const { return short(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator const auto() const { return int(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator const auto&() const { return char(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator const auto*() const { return long(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator decltype(auto)() const { return unsigned(); } + // since-cxx14-error@-1 {{'decltype(auto)' not allowed in declaration of conversion function template}} +#if __cplusplus >= 202002L + template <typename T> + operator C auto() const { return float(); } + // since-cxx20-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator C decltype(auto)() const { return double(); } + // since-cxx20-error@-1 {{'decltype(auto)' not allowed in declaration of conversion function template}} +#endif +}; +#endif +} + namespace dr1881 { // dr1881: 7 struct A { int a : 4; }; struct B : A { int b : 3; }; diff --git a/clang/test/SemaCXX/deduced-return-type-cxx14.cpp b/clang/test/SemaCXX/deduced-return-type-cxx14.cpp index eac9c587869f552..c0d43911b8c7174 100644 --- a/clang/test/SemaCXX/deduced-return-type-cxx14.cpp +++ b/clang/test/SemaCXX/deduced-return-type-cxx14.cpp @@ -1,11 +1,11 @@ -// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify=expected,cxx20_23,cxx23 %s -// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify=expected,cxx20_23,cxx23 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING +// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify=expected,since-cxx20,since-cxx14,cxx20_23,cxx23 %s +// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify=expected,since-cxx20,since-cxx14,cxx20_23,cxx23 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING -// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_23 %s -// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_23 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING +// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,since-cxx20,since-cxx14,cxx14_20,cxx20_23 %s +// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,since-cxx20,since-cxx14,cxx14_20,cxx20_23 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING -// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20,cxx14 %s -// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20,cxx14 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING +// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,since-cxx14,cxx14_20,cxx14 %s +// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,since-cxx14,cxx14_20,cxx14 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING auto f(); // expected-note {{previous}} int f(); // expected-error {{ diff er only in their return type}} @@ -686,3 +686,41 @@ auto f(auto x) { // cxx14-error {{'auto' not allowed in function prototype}} } } + +#if __cplusplus >= 202002L +template <typename T> +concept C = true; +#endif + +struct DeducedTargetTypeOfConversionFunction { + operator auto() const { return char(); } + operator const auto() const { return float(); } + operator const auto&() const { return int(); } + // expected-warning@-1 {{returning reference to local temporary object}} + operator decltype(auto)() const { return double(); } +#if __cplusplus >= 202002L + operator C auto() const { return unsigned(); } + operator C decltype(auto)() const { return long(); } +#endif + + template <typename T> + operator auto() const { return short(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator const auto() const { return int(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator const auto&() const { return char(); } + // since-cxx14-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator decltype(auto)() const { return unsigned(); } + // since-cxx14-error@-1 {{'decltype(auto)' not allowed in declaration of conversion function template}} +#if __cplusplus >= 202002L + template <typename T> + operator C auto() const { return float(); } + // since-cxx20-error@-1 {{'auto' not allowed in declaration of conversion function template}} + template <typename T> + operator C decltype(auto)() const { return double(); } + // since-cxx20-error@-1 {{'decltype(auto)' not allowed in declaration of conversion function template}} +#endif +}; diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index b29a746bcf6e8a4..f0d835fc091ceae 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -11076,7 +11076,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td><a href="https://cplusplus.github.io/CWG/issues/1878.html">1878</a></td> <td>CD4</td> <td><TT>operator auto</TT> template</td> - <td class="unknown" align="center">Unknown</td> + <td class="unreleased" align="center">Clang 18</td> </tr> <tr id="1879"> <td><a href="https://cplusplus.github.io/CWG/issues/1879.html">1879</a></td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits