https://github.com/AhmedKamel10 created https://github.com/llvm/llvm-project/pull/221249
A friend function defined inline in a class body has no implicit 'this', so a parameter with the same name as a field cannot actually shadow it. CheckShadow only exempted static members and members with an explicit object parameter (via a valid CXXMethodDecl cast); it never handled the case where the enclosing function isn't a member function at all, which silently fell through to the generic diagnostic. Extend the exemption to cover that case. Fixes #221190 >From fc5404b2673ec59e5a8d657752f52bf99e085405 Mon Sep 17 00:00:00 2001 From: ahmedkamel10 <[email protected]> Date: Fri, 4 Sep 2026 18:11:08 +0300 Subject: [PATCH] [clang][Sema] Fix false-positive -Wshadow for friend functions A friend function defined inline in a class body has no implicit 'this', so a parameter with the same name as a field cannot actually shadow it. CheckShadow only exempted static members and members with an explicit object parameter (via a valid CXXMethodDecl cast); it never handled the case where the enclosing function isn't a member function at all, which silently fell through to the generic diagnostic. Extend the exemption to cover that case. Fixes #221190 --- clang/docs/ReleaseNotes.md | 2 ++ clang/lib/Sema/SemaDecl.cpp | 12 +++++------- clang/test/SemaCXX/warn-shadow.cpp | 11 +++++++++++ 3 files changed, 18 insertions(+), 7 deletions(-) diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index ca5c63fbaa17d..398b1eec0aee0 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -469,6 +469,8 @@ features cannot lower the translation-unit ABI level; dimension that is a zero integer constant, as in `struct Empty vla[n]` or `int vla[n][0]`. (#GH28328) +- Fixed a false-positive `-Wshadow` warning when a function parameter in an inline-defined friend function shares the name of a non-static class member variable. (#GH221190) + ### Improvements to Clang's time-trace ### Improvements to Coverage Mapping diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index ccdc33d6fa39b..3339acb3bead4 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -8623,13 +8623,11 @@ void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl, DeclContext *NewDC = D->getDeclContext(); if (FieldDecl *FD = dyn_cast<FieldDecl>(ShadowedDecl)) { - if (const auto *MD = - dyn_cast<CXXMethodDecl>(getFunctionLevelDeclContext())) { - // Fields aren't shadowed in C++ static members or in member functions - // with an explicit object parameter. - if (MD->isStatic() || MD->isExplicitObjectMemberFunction()) - return; - } + const auto *MD = dyn_cast<CXXMethodDecl>(getFunctionLevelDeclContext()); + // Fields aren't shadowed in C++ static members or in member functions + // with an explicit object parameter. + if (!MD || MD->isStatic() || MD->isExplicitObjectMemberFunction()) + return; // Fields shadowed by constructor parameters are a special case. Usually // the constructor initializes the field with the parameter. if (isa<CXXConstructorDecl>(NewDC)) diff --git a/clang/test/SemaCXX/warn-shadow.cpp b/clang/test/SemaCXX/warn-shadow.cpp index 98a235a73c7e5..766766e465bdf 100644 --- a/clang/test/SemaCXX/warn-shadow.cpp +++ b/clang/test/SemaCXX/warn-shadow.cpp @@ -90,6 +90,17 @@ class A { } }; +class FriendFunction { + int x; // expected-note {{previous declaration is here}} + + friend bool operator==(const FriendFunction &f, int x) { + return f.x == x; + } + + void test(int x) { // expected-warning {{declaration shadows a field of 'FriendFunction'}} + } +}; + struct path { using value_type = char; typedef char value_type2; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
