[index/AST] Determine if a typedef shares a name and spelling location with its underlying tag type

In such a case, as when using the NS_ENUM macro, for indexing purposes treat the typedef as 'transparent',
meaning we treat its references as symbols of the underlying tag symbol.
Also provide a libclang API to check for such typedefs.

llvm-svn: 298392

1 files changed, 24 insertions, 0 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 5b0404e38dd..2b22e5bb50a 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4242,6 +4242,30 @@ TagDecl *TypedefNameDecl::getAnonDeclWithTypedefName(bool AnyRedecl) const {
   return nullptr;
 }
 
+bool TypedefNameDecl::isTransparentTagSlow() const {
+  auto determineIsTransparent = [&]() {
+    if (auto *TT = getUnderlyingType()->getAs<TagType>()) {
+      if (auto *TD = TT->getDecl()) {
+        if (TD->getName() != getName())
+          return false;
+        SourceLocation TTLoc = getLocation();
+        SourceLocation TDLoc = TD->getLocation();
+        if (!TTLoc.isMacroID() || !TDLoc.isMacroID())
+          return false;
+        SourceManager &SM = getASTContext().getSourceManager();
+        return SM.getSpellingLoc(TTLoc) == SM.getSpellingLoc(TDLoc);
+      }
+    }
+    return false;
+  };
+
+  bool isTransparent = determineIsTransparent();
+  CacheIsTransparentTag = 1;
+  if (isTransparent)
+    CacheIsTransparentTag |= 0x2;
+  return isTransparent;
+}
+
 TypedefDecl *TypedefDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   return new (C, ID) TypedefDecl(C, nullptr, SourceLocation(), SourceLocation(),
                                  nullptr, nullptr);