From 38df4e8d58547a691318935bb7d1d4be41e9803c Mon Sep 17 00:00:00 2001 From: Alex Lorenz Date: Wed, 12 Oct 2016 09:36:35 +0000 Subject: [PATCH] [Sema] Handle transparent_union attributes in C mode only This commit marks the transparent_union attributes as C only because clang doesn't support them in C++ mode. Prior to this commit, clang still tried to verify these attributes in C++, leading to crashes when analyzing templated transparent_union unions that have dependent field types. This commit ensures that such crashes won't happen again. As a result of this commit clang now displays a warning every time it encounters a transparent_union attribute in C++ mode. Differential Revision: https://reviews.llvm.org/D25308 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@283995 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/clang/Basic/Attr.td | 1 + test/SemaCXX/attr-gnu.cpp | 16 ++++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td index b4af0e5af8..1fea69ff0e 100644 --- a/include/clang/Basic/Attr.td +++ b/include/clang/Basic/Attr.td @@ -1543,6 +1543,7 @@ def TransparentUnion : InheritableAttr { let Spellings = [GCC<"transparent_union">]; // let Subjects = SubjectList<[Record, TypedefName]>; let Documentation = [Undocumented]; + let LangOpts = [COnly]; } def Unavailable : InheritableAttr { diff --git a/test/SemaCXX/attr-gnu.cpp b/test/SemaCXX/attr-gnu.cpp index b4e9f4609f..a553f0d210 100644 --- a/test/SemaCXX/attr-gnu.cpp +++ b/test/SemaCXX/attr-gnu.cpp @@ -27,3 +27,19 @@ public: void test3() __attribute__((cf_unknown_transfer)) override {} // Ok, not known to GCC. }; } + +template +union Tu { T b; } __attribute__((transparent_union)); // expected-warning {{'transparent_union' attribute ignored}} + +template +union Tu2 { int x; T b; } __attribute__((transparent_union)); // expected-warning {{'transparent_union' attribute ignored}} + +union Tu3 { int x; } __attribute((transparent_union)); // expected-warning {{'transparent_union' attribute ignored}} + +void tuTest1(Tu u); // expected-note {{candidate function not viable: no known conversion from 'int' to 'Tu' for 1st argument}} +void tuTest2(Tu3 u); // expected-note {{candidate function not viable: no known conversion from 'int' to 'Tu3' for 1st argument}} +void tu() { + int x = 2; + tuTest1(x); // expected-error {{no matching function for call to 'tuTest1'}} + tuTest2(x); // expected-error {{no matching function for call to 'tuTest2'}} +} -- 2.40.0