r316136 - Don't suppress instantiation of definitions for variables subject to explicit
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Wed Oct 18 15:45:01 PDT 2017
Author: rsmith
Date: Wed Oct 18 15:45:01 2017
New Revision: 316136
URL: http://llvm.org/viewvc/llvm-project?rev=316136&view=rev
Log:
Don't suppress instantiation of definitions for variables subject to explicit
instantiation declarations if they are usable from constant expressions.
We are permitted to instantiate in these cases, and required to do so in order
to have an initializer available for use within constant evaluation.
Added:
cfe/trunk/test/SemaTemplate/cxx17-inline-variables.cpp
Modified:
cfe/trunk/lib/Sema/SemaExpr.cpp
cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
cfe/trunk/test/CodeGenCXX/dllimport-members.cpp
cfe/trunk/test/SemaTemplate/extern-templates.cpp
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=316136&r1=316135&r2=316136&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Wed Oct 18 15:45:01 2017
@@ -14823,9 +14823,10 @@ static void DoMarkVarDeclReferenced(Sema
TemplateSpecializationKind TSK = Var->getTemplateSpecializationKind();
bool OdrUseContext = isOdrUseContext(SemaRef);
+ bool UsableInConstantExpr =
+ Var->isUsableInConstantExpressions(SemaRef.Context);
bool NeedDefinition =
- OdrUseContext || (isEvaluatableContext(SemaRef) &&
- Var->isUsableInConstantExpressions(SemaRef.Context));
+ OdrUseContext || (isEvaluatableContext(SemaRef) && UsableInConstantExpr);
VarTemplateSpecializationDecl *VarSpec =
dyn_cast<VarTemplateSpecializationDecl>(Var);
@@ -14844,14 +14845,19 @@ static void DoMarkVarDeclReferenced(Sema
// instantiations of variable templates, except for those that could be used
// in a constant expression.
if (NeedDefinition && isTemplateInstantiation(TSK)) {
- bool TryInstantiating = TSK == TSK_ImplicitInstantiation;
+ // Per C++17 [temp.explicit]p10, we may instantiate despite an explicit
+ // instantiation declaration if a variable is usable in a constant
+ // expression (among other cases).
+ bool TryInstantiating =
+ TSK == TSK_ImplicitInstantiation ||
+ (TSK == TSK_ExplicitInstantiationDeclaration && UsableInConstantExpr);
if (TryInstantiating && !isa<VarTemplateSpecializationDecl>(Var)) {
if (Var->getPointOfInstantiation().isInvalid()) {
// This is a modification of an existing AST node. Notify listeners.
if (ASTMutationListener *L = SemaRef.getASTMutationListener())
L->StaticDataMemberInstantiated(Var);
- } else if (!Var->isUsableInConstantExpressions(SemaRef.Context))
+ } else if (!UsableInConstantExpr)
// Don't bother trying to instantiate it again, unless we might need
// its initializer before we get to the end of the TU.
TryInstantiating = false;
@@ -14870,7 +14876,7 @@ static void DoMarkVarDeclReferenced(Sema
// Do not instantiate specializations that are still type-dependent.
if (IsNonDependent) {
- if (Var->isUsableInConstantExpressions(SemaRef.Context)) {
+ if (UsableInConstantExpr) {
// Do not defer instantiations of variables which could be used in a
// constant expression.
SemaRef.InstantiateVariableDefinition(PointOfInstantiation, Var);
Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=316136&r1=316135&r2=316136&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Wed Oct 18 15:45:01 2017
@@ -4359,10 +4359,12 @@ void Sema::InstantiateVariableDefinition
return;
// C++11 [temp.explicit]p10:
- // Except for inline functions, [...] explicit instantiation declarations
+ // Except for inline functions, const variables of literal types, variables
+ // of reference types, [...] explicit instantiation declarations
// have the effect of suppressing the implicit instantiation of the entity
// to which they refer.
- if (TSK == TSK_ExplicitInstantiationDeclaration)
+ if (TSK == TSK_ExplicitInstantiationDeclaration &&
+ !Var->isUsableInConstantExpressions(getASTContext()))
return;
// Make sure to pass the instantiated variable to the consumer at the end.
Modified: cfe/trunk/test/CodeGenCXX/dllimport-members.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllimport-members.cpp?rev=316136&r1=316135&r2=316136&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/dllimport-members.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/dllimport-members.cpp Wed Oct 18 15:45:01 2017
@@ -836,7 +836,7 @@ USEMV(MemVarTmpl, ImportedStaticVar<Impl
// Import explicit instantiation declaration of an imported member variable
// template.
-// MSC-DAG: @"\01??$ImportedStaticVar at UExplicitDecl_Imported@@@MemVarTmpl@@2HB" = external dllimport constant i32
+// MSC-DAG: @"\01??$ImportedStaticVar at UExplicitDecl_Imported@@@MemVarTmpl@@2HB" = available_externally dllimport constant i32 1
// GNU-DAG: @_ZN10MemVarTmpl17ImportedStaticVarI21ExplicitDecl_ImportedEE = external dllimport constant i32
extern template const int MemVarTmpl::ImportedStaticVar<ExplicitDecl_Imported>;
USEMV(MemVarTmpl, ImportedStaticVar<ExplicitDecl_Imported>)
@@ -861,7 +861,7 @@ USEMV(MemVarTmpl, ImportedStaticVar<Expl
// Import explicit instantiation declaration of a non-imported member variable
// template.
-// MSC-DAG: @"\01??$StaticVar at UExplicitDecl_Imported@@@MemVarTmpl@@2HB" = external dllimport constant i32
+// MSC-DAG: @"\01??$StaticVar at UExplicitDecl_Imported@@@MemVarTmpl@@2HB" = available_externally dllimport constant i32 1
// GNU-DAG: @_ZN10MemVarTmpl9StaticVarI21ExplicitDecl_ImportedEE = external dllimport constant i32
extern template __declspec(dllimport) const int MemVarTmpl::StaticVar<ExplicitDecl_Imported>;
USEMV(MemVarTmpl, StaticVar<ExplicitDecl_Imported>)
Added: cfe/trunk/test/SemaTemplate/cxx17-inline-variables.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/cxx17-inline-variables.cpp?rev=316136&view=auto
==============================================================================
--- cfe/trunk/test/SemaTemplate/cxx17-inline-variables.cpp (added)
+++ cfe/trunk/test/SemaTemplate/cxx17-inline-variables.cpp Wed Oct 18 15:45:01 2017
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -std=c++17 -verify %s
+// expected-no-diagnostics
+template<bool> struct DominatorTreeBase {
+ static constexpr bool IsPostDominator = true;
+};
+extern template class DominatorTreeBase<false>;
+constexpr bool k = DominatorTreeBase<false>::IsPostDominator;
Modified: cfe/trunk/test/SemaTemplate/extern-templates.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/extern-templates.cpp?rev=316136&r1=316135&r2=316136&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/extern-templates.cpp (original)
+++ cfe/trunk/test/SemaTemplate/extern-templates.cpp Wed Oct 18 15:45:01 2017
@@ -71,3 +71,10 @@ extern template void X1<const void*>::g(
void g_X1_2(X1<const void *> x1, const void *ptr) {
x1.g(ptr);
}
+
+namespace static_const_member {
+ template <typename T> struct A { static const int n; };
+ template <typename T> const int A<T>::n = 3;
+ extern template struct A<int>;
+ int arr[A<int>::n];
+}
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