[clang] Add the exclude_from_explicit_instantiation attribute
Summary:
This attribute allows excluding a member of a class template from being part
of an explicit template instantiation of that class template. This also makes
sure that code using such a member will not take for granted that an external
instantiation exists in another translation unit. The attribute was discussed
on cfe-dev at [1] and is primarily motivated by the removal of always_inline
in libc++ to control what's part of the ABI (see links in [1]).
[1]: http://lists.llvm.org/pipermail/cfe-dev/2018-August/059024.html
rdar://problem/43428125
Reviewers: rsmith
Subscribers: dexonsmith, cfe-commits
Differential Revision: https://reviews.llvm.org/D51789
llvm-svn: 343790
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 5666cf0..cfedf0a 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2574,10 +2574,14 @@
for (auto *D : Instantiation->decls()) {
bool SuppressNew = false;
if (auto *Function = dyn_cast<FunctionDecl>(D)) {
- if (FunctionDecl *Pattern
- = Function->getInstantiatedFromMemberFunction()) {
- MemberSpecializationInfo *MSInfo
- = Function->getMemberSpecializationInfo();
+ if (FunctionDecl *Pattern =
+ Function->getInstantiatedFromMemberFunction()) {
+
+ if (Function->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+ continue;
+
+ MemberSpecializationInfo *MSInfo =
+ Function->getMemberSpecializationInfo();
assert(MSInfo && "No member specialization information?");
if (MSInfo->getTemplateSpecializationKind()
== TSK_ExplicitSpecialization)
@@ -2618,6 +2622,9 @@
continue;
if (Var->isStaticDataMember()) {
+ if (Var->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+ continue;
+
MemberSpecializationInfo *MSInfo = Var->getMemberSpecializationInfo();
assert(MSInfo && "No member specialization information?");
if (MSInfo->getTemplateSpecializationKind()
@@ -2649,6 +2656,9 @@
}
}
} else if (auto *Record = dyn_cast<CXXRecordDecl>(D)) {
+ if (Record->hasAttr<ExcludeFromExplicitInstantiationAttr>())
+ continue;
+
// Always skip the injected-class-name, along with any
// redeclarations of nested classes, since both would cause us
// to try to instantiate the members of a class twice.