Author: Ashwin Banwari Date: 2025-07-02T09:52:10+08:00 New Revision: 2599a9aeb543f01cb20e3fdc2713aa8c8cb20fbf
URL: https://github.com/llvm/llvm-project/commit/2599a9aeb543f01cb20e3fdc2713aa8c8cb20fbf DIFF: https://github.com/llvm/llvm-project/commit/2599a9aeb543f01cb20e3fdc2713aa8c8cb20fbf.diff LOG: [clang] [modules] Implement P3618R0: Allow attaching main to the global module (#146461) Remove the prior warning for attaching extern "C++" to main. Added: Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaDecl.cpp clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp clang/test/SemaCXX/modules.cppm clang/www/cxx_status.html libcxx/utils/libcxx/test/features.py Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 7af5f116ee98f..3d893e0aa8e2c 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -135,6 +135,8 @@ C++2c Feature Support - Implemented `P2719R4 Type-aware allocation and deallocation functions <https://wg21.link/P2719>`_. +- Implemented `P3618R0 Allow attaching main to the global module <https://wg21.link/P3618>`_. + C++23 Feature Support ^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 5062505cf3c01..6e48f3bc88bab 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -1084,9 +1084,9 @@ def warn_main_redefined : Warning<"variable named 'main' with external linkage " "has undefined behavior">, InGroup<Main>; def ext_main_used : Extension< "referring to 'main' within an expression is a Clang extension">, InGroup<Main>; -def ext_main_invalid_linkage_specification : ExtWarn< - "'main' should not be " - "'extern \"%select{C|C++}0\"'">, InGroup<Main>; +def ext_main_invalid_linkage_specification : ExtWarn<"'main' should not be " + "'extern \"C\"'">, + InGroup<Main>; /// parser diagnostics def ext_no_declarators : ExtWarn<"declaration does not declare anything">, diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index a34e2c9cbb003..61b82b8377e22 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -12400,12 +12400,9 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD, void Sema::CheckMain(FunctionDecl *FD, const DeclSpec &DS) { // [basic.start.main]p3 - // The main function shall not be declared with a linkage-specification. - if (FD->isExternCContext() || - (FD->isExternCXXContext() && - FD->getDeclContext()->getRedeclContext()->isTranslationUnit())) - Diag(FD->getLocation(), diag::ext_main_invalid_linkage_specification) - << FD->getLanguageLinkage(); + // The main function shall not be declared with C linkage-specification. + if (FD->isExternCContext()) + Diag(FD->getLocation(), diag::ext_main_invalid_linkage_specification); // C++11 [basic.start.main]p3: // A program that [...] declares main to be inline, static or diff --git a/clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp b/clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp index 497a9328c1156..a8cd523b0837f 100644 --- a/clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp +++ b/clang/test/CXX/basic/basic.start/basic.start.main/p3.cpp @@ -102,11 +102,12 @@ namespace ns { } #elif TEST13 +// expected-no-diagnostics extern "C++" { - int main(); // expected-warning {{'main' should not be 'extern "C++"'}} + int main(); } -extern "C++" int main(); // expected-warning {{'main' should not be 'extern "C++"'}} +extern "C++" int main(); namespace ns1 { extern "C++" int main(); // ok diff --git a/clang/test/SemaCXX/modules.cppm b/clang/test/SemaCXX/modules.cppm index 5d0d6da44a2ed..ddbbc7cd86360 100644 --- a/clang/test/SemaCXX/modules.cppm +++ b/clang/test/SemaCXX/modules.cppm @@ -68,6 +68,8 @@ int n; //--- test3.cpp export module bar; +extern "C++" int main() {} + static int m; int n; diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html index a70e65e35d5ee..e5f51bfb2e36e 100755 --- a/clang/www/cxx_status.html +++ b/clang/www/cxx_status.html @@ -317,7 +317,7 @@ <h2 id="cxx26">C++2c implementation status</h2> <tr> <td>Attaching main to the global module</td> <td><a href="https://wg21.link/P3618";>P3618R0</a> (<a href="#dr">DR</a>)</td> - <td class="none" align="center">No</td> + <td class="unreleased" align="center">Clang 21</td> </tr> <tr> <td>Expansion Statements</td> diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py index 74746e37d3bc4..c478d99fbed00 100644 --- a/libcxx/utils/libcxx/test/features.py +++ b/libcxx/utils/libcxx/test/features.py @@ -336,12 +336,22 @@ def _mingwSupportsModules(cfg): or platform.system().lower().startswith("aix") # Avoid building on platforms that don't support modules properly. or not hasCompileFlag(cfg, "-Wno-reserved-module-identifier") - or not sourceBuilds( - cfg, - """ + # older versions don't support extern "C++", newer versions don't support main in named module. + or not ( + sourceBuilds( + cfg, + """ + export module test; + extern "C++" int main(int, char**) { return 0; } + """, + ) + or sourceBuilds( + cfg, + """ export module test; int main(int, char**) { return 0; } """, + ) ), ), # The time zone validation tests compare the output of zdump against the _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
