Implement __attribute__((internal_linkage)).

The attrubite is applicable to functions and variables and changes
the linkage of the subject to internal.

This is the same functionality as C-style "static", but applicable to
class methods; and the same as anonymouns namespaces, but can apply
to individual methods of a class.

Following the proposal in
http://lists.llvm.org/pipermail/cfe-dev/2015-October/045580.html

llvm-svn: 252648

1 files changed, 24 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 009fe16f948..92bbadd627d 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2216,6 +2216,15 @@ static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
     NewAttr = S.mergeMinSizeAttr(D, MA->getRange(), AttrSpellingListIndex);
   else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
     NewAttr = S.mergeOptimizeNoneAttr(D, OA->getRange(), AttrSpellingListIndex);
+  else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
+    NewAttr = S.mergeInternalLinkageAttr(
+        D, InternalLinkageA->getRange(),
+        &S.Context.Idents.get(InternalLinkageA->getSpelling()),
+        AttrSpellingListIndex);
+  else if (const auto *CommonA = dyn_cast<CommonAttr>(Attr))
+    NewAttr = S.mergeCommonAttr(D, CommonA->getRange(),
+                                &S.Context.Idents.get(CommonA->getSpelling()),
+                                AttrSpellingListIndex);
   else if (isa<AlignedAttr>(Attr))
     // AlignedAttrs are handled separately, because we need to handle all
     // such attributes on a declaration at the same time.
@@ -2664,6 +2673,13 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD,
     }
   }
 
+  if (New->hasAttr<InternalLinkageAttr>() &&
+      !Old->hasAttr<InternalLinkageAttr>()) {
+    Diag(New->getLocation(), diag::err_internal_linkage_redeclaration)
+        << New->getDeclName();
+    Diag(Old->getLocation(), diag::note_previous_definition);
+    New->dropAttr<InternalLinkageAttr>();
+  }
 
   // If a function is first declared with a calling convention, but is later
   // declared or defined without one, all following decls assume the calling
@@ -3377,6 +3393,14 @@ void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
     New->dropAttr<WeakImportAttr>();
   }
 
+  if (New->hasAttr<InternalLinkageAttr>() &&
+      !Old->hasAttr<InternalLinkageAttr>()) {
+    Diag(New->getLocation(), diag::err_internal_linkage_redeclaration)
+        << New->getDeclName();
+    Diag(Old->getLocation(), diag::note_previous_definition);
+    New->dropAttr<InternalLinkageAttr>();
+  }
+
   // Merge the types.
   VarDecl *MostRecent = Old->getMostRecentDecl();
   if (MostRecent != Old) {