Revert r363191 "[MS] Pretend constexpr variable template specializations are inline"

The next Visual Studio update will fix this issue, and it doesn't make
sense to implement this non-conforming behavior going forward.

llvm-svn: 364476
This commit is contained in:
Reid Kleckner 2019-06-26 21:16:51 +00:00
parent d5f7196feb
commit e6f2ff2c8d
2 changed files with 4 additions and 30 deletions

View File

@ -9809,25 +9809,10 @@ static GVALinkage basicGVALinkageForVariable(const ASTContext &Context,
return StrongLinkage;
case TSK_ExplicitSpecialization:
if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
// If this is a fully specialized constexpr variable template, pretend it
// was marked inline. MSVC 14.21.27702 headers define _Is_integral in a
// header this way, and we don't want to emit non-discardable definitions
// of these variables in every TU that includes <type_traits>. This
// behavior is non-conforming, since another TU could use an extern
// template declaration for this variable, but for constexpr variables,
// it's unlikely for a user to want to do that. This behavior can be
// removed if the headers change to explicitly mark such variable template
// specializations inline.
if (isa<VarTemplateSpecializationDecl>(VD) && VD->isConstexpr())
return GVA_DiscardableODR;
// Use ODR linkage for static data members of fully specialized templates
// to prevent duplicate definition errors with MSVC.
if (VD->isStaticDataMember())
return GVA_StrongODR;
}
return StrongLinkage;
return Context.getTargetInfo().getCXXABI().isMicrosoft() &&
VD->isStaticDataMember()
? GVA_StrongODR
: StrongLinkage;
case TSK_ExplicitInstantiationDefinition:
return GVA_StrongODR;

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@ -1,11 +0,0 @@
// RUN: %clang_cc1 -emit-llvm -triple=x86_64-windows-msvc -fms-compatibility %s -o - | FileCheck %s
template <typename> constexpr bool _Is_integer = false;
template <> constexpr bool _Is_integer<int> = true;
template <> constexpr bool _Is_integer<char> = false;
extern "C" const bool *escape = &_Is_integer<int>;
// CHECK: @"??$_Is_integer@H@@3_NB" = linkonce_odr dso_local constant i8 1, comdat, align 1
// Should not emit _Is_integer<char>, since it's not referenced.
// CHECK-NOT: @"??$_Is_integer@D@@3_NB"
// CHECK: @escape = dso_local global i8* @"??$_Is_integer@H@@3_NB", align 8