llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: None (s-watanabe314) <details> <summary>Changes</summary> Fixes #<!-- -->80235 When trying to overload a function within `extern "C"`, the diagnostic `functions that differ only in their return type cannot be overloaded` is given. This diagnostic is inappropriate because overloading is basically not allowed in the C language. However, if the redeclared function has the `((overloadable))` attribute, it should be diagnosed as `functions that differ only in their return type cannot be overloaded`. This patch uses `isExternC()` to provide an appropriate diagnostic during the diagnostic process. `isExternC()` updates the linkage information cache internally, so calling it before merging functions can cause clang to crash. An example is declaring `static void foo()` and `void foo()` within an `extern "C"` block. Therefore, I decided to call `isExternC()` after the compilation error is confirmed and select the diagnostic message. The diagnostic message is `conflicting types for 'func'` similar to the diagnostic in C, and `functions that differ only in their return type cannot be overloaded` if the `((overloadable))` attribute is given. Regression tests verify that the expected diagnostics are given when trying to overload functions within `extern "C"` and when the `((overloadable))` attribute is present. --- Full diff: https://github.com/llvm/llvm-project/pull/106033.diff 2 Files Affected: - (modified) clang/lib/Sema/SemaDecl.cpp (+4) - (modified) clang/test/SemaCXX/extern-c.cpp (+19) ``````````diff diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 503e93f9257137..63bd15dad7c48a 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -3882,6 +3882,10 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, Scope *S, if (New->isCXXClassMember() && New->isOutOfLine()) Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type) << New << New->getReturnTypeSourceRange(); + else if (Old->isExternC() && New->isExternC() && + !Old->hasAttr<OverloadableAttr>() && + !New->hasAttr<OverloadableAttr>()) + Diag(New->getLocation(), diag::err_conflicting_types) << New; else Diag(New->getLocation(), diag::err_ovl_diff_return_type) << New->getReturnTypeSourceRange(); diff --git a/clang/test/SemaCXX/extern-c.cpp b/clang/test/SemaCXX/extern-c.cpp index 68d1494b94918f..86012670ddcd57 100644 --- a/clang/test/SemaCXX/extern-c.cpp +++ b/clang/test/SemaCXX/extern-c.cpp @@ -77,6 +77,19 @@ namespace foo { } } +namespace extern_ovl { + extern "C" { + __attribute__((overloadable)) + void ovl_decl(void); // expected-note {{previous}} + + __attribute__((overloadable)) + int ovl_decl(int); + + __attribute__((overloadable)) + int ovl_decl(void); // expected-error {{functions that differ only in their return type}} + } +} + namespace linkage { namespace redecl { extern "C" { @@ -88,6 +101,12 @@ namespace linkage { void linkage_redecl(double); // expected-error {{conflicting types}} } } + namespace redecl_2 { + extern "C" { + void linkage_redecl_2(); // expected-note {{previous}} + int linkage_redecl_2(int); // expected-error {{conflicting types}} + } + } namespace from_outer { void linkage_from_outer_1(); // expected-note {{previous}} void linkage_from_outer_2(); // expected-note {{previous}} `````````` </details> https://github.com/llvm/llvm-project/pull/106033 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
