[PATCH] D97362: [clang][parser] Allow attributes in explicit template instantiations
Timm Bäder via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Tue Feb 23 23:59:18 PST 2021
tbaeder created this revision.
tbaeder added a reviewer: aaron.ballman.
Herald added a subscriber: jdoerfert.
tbaeder requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
This call to ProhibitAttributes() is almost always dead code.
For GNU attributes, it always is, even though they are being used in explicit template instantiations in, e.g. in `clang/test/CodeGenCXX/visibility.cpp`:
#define DEFAULT __attribute__((visibility("default")))
namespace PR11690 {
template<class T> struct Class {
void size() const {
}
};
template class DEFAULT Class<char>;
}
This code is accepted by current `g++` and `clang++`, even though the code claims to reject it because of the attributes.
If the attributes are changed to C++ attributes however, `clang++` _does_ reject it:
#define DEFAULT [[]]
namespace PR11690 {
template<class T> struct Class {
void size() const {
}
};
template class DEFAULT Class<char>;
}
But `g++` still accepts the above code. Simply ignoring the attributes does not work either as it breaks tests (e.g. the visibility test from above).
I am not sure why or if GNU-style and C++ attributes should be handled differently here, so I am open for a discussion but this call seems mislead to me.
Thanks,
Timm
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D97362
Files:
clang/lib/Parse/ParseDeclCXX.cpp
clang/test/Parser/cxx0x-attributes.cpp
Index: clang/test/Parser/cxx0x-attributes.cpp
===================================================================
--- clang/test/Parser/cxx0x-attributes.cpp
+++ clang/test/Parser/cxx0x-attributes.cpp
@@ -178,7 +178,7 @@
struct [[]] N::S s; // expected-error {{an attribute list cannot appear here}}
struct [[]] Template<int> t; // expected-error {{an attribute list cannot appear here}}
struct [[]] ::template Template<int> u; // expected-error {{an attribute list cannot appear here}}
-template struct [[]] Template<char>; // expected-error {{an attribute list cannot appear here}}
+template struct [[]] Template<char>;
template <> struct [[]] Template<void>;
enum [[]] E1 {};
Index: clang/lib/Parse/ParseDeclCXX.cpp
===================================================================
--- clang/lib/Parse/ParseDeclCXX.cpp
+++ clang/lib/Parse/ParseDeclCXX.cpp
@@ -1824,8 +1824,6 @@
} else if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
TUK == Sema::TUK_Declaration) {
// This is an explicit instantiation of a class template.
- ProhibitAttributes(attrs);
-
TagOrTempResult = Actions.ActOnExplicitInstantiation(
getCurScope(), TemplateInfo.ExternLoc, TemplateInfo.TemplateLoc,
TagType, StartLoc, SS, TemplateId->Template,
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