[AST] Extract Decl::printNestedNameSpecifier helper from Decl::printQualifiedName

Summary:
To be used in clangd, e.g. in D66647.
Currently the alternative to this function is doing string manipulation on results of `printQualifiedName`, which is
hard-to-impossible to get right in presence of template arguments.

Reviewers: kadircet, aaron.ballman

Reviewed By: kadircet, aaron.ballman

Subscribers: aaron.ballman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67825

llvm-svn: 372863

1 files changed, 14 insertions, 8 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index b27ac907b8b..48d7c89ebba 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1558,6 +1558,19 @@ void NamedDecl::printQualifiedName(raw_ostream &OS) const {
 
 void NamedDecl::printQualifiedName(raw_ostream &OS,
                                    const PrintingPolicy &P) const {
+  printNestedNameSpecifier(OS, P);
+  if (getDeclName() || isa<DecompositionDecl>(this))
+    OS << *this;
+  else
+    OS << "(anonymous)";
+}
+
+void NamedDecl::printNestedNameSpecifier(raw_ostream &OS) const {
+  printNestedNameSpecifier(OS, getASTContext().getPrintingPolicy());
+}
+
+void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
+                                         const PrintingPolicy &P) const {
   const DeclContext *Ctx = getDeclContext();
 
   // For ObjC methods and properties, look through categories and use the
@@ -1571,10 +1584,8 @@ void NamedDecl::printQualifiedName(raw_ostream &OS,
         Ctx = ID;
   }
 
-  if (Ctx->isFunctionOrMethod()) {
-    printName(OS);
+  if (Ctx->isFunctionOrMethod())
     return;
-  }
 
   using ContextsTy = SmallVector<const DeclContext *, 8>;
   ContextsTy Contexts;
@@ -1644,11 +1655,6 @@ void NamedDecl::printQualifiedName(raw_ostream &OS,
     }
     OS << "::";
   }
-
-  if (getDeclName() || isa<DecompositionDecl>(this))
-    OS << *this;
-  else
-    OS << "(anonymous)";
 }
 
 void NamedDecl::getNameForDiagnostic(raw_ostream &OS,