[clangd] Print template arguments helper

Summary:
Prepares ground for printing template arguments as written in the
source code, part of re-landing rC356541 with D59599 applied.

Reviewers: ioeric, ilya-biryukov

Subscribers: mgorny, MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59639

llvm-svn: 358272

1 files changed, 15 insertions, 1 deletions

diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index ebcc01aa46d..82a2fa09c76 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -1632,6 +1632,19 @@ static const TemplateArgument &getArgument(const TemplateArgumentLoc &A) {
   return A.getArgument();
 }
 
+static void printArgument(const TemplateArgument &A, const PrintingPolicy &PP,
+                          llvm::raw_ostream &OS) {
+  A.print(PP, OS);
+}
+
+static void printArgument(const TemplateArgumentLoc &A,
+                          const PrintingPolicy &PP, llvm::raw_ostream &OS) {
+  const TemplateArgument::ArgKind &Kind = A.getArgument().getKind();
+  if (Kind == TemplateArgument::ArgKind::Type)
+    return A.getTypeSourceInfo()->getType().print(OS, PP);
+  return A.getArgument().print(PP, OS);
+}
+
 template<typename TA>
 static void printTo(raw_ostream &OS, ArrayRef<TA> Args,
                     const PrintingPolicy &Policy, bool SkipBrackets) {
@@ -1653,7 +1666,8 @@ static void printTo(raw_ostream &OS, ArrayRef<TA> Args,
     } else {
       if (!FirstArg)
         OS << Comma;
-      Argument.print(Policy, ArgOS);
+      // Tries to print the argument with location info if exists.
+      printArgument(Arg, Policy, ArgOS);
     }
     StringRef ArgString = ArgOS.str();