ASTMangler: Add mangleTypeAsUSR()

For now this just duplicates mangleTypeForDebugger(), but the latter's
behavior is going to change.

Author: slavapestov

include/swift/AST/ASTMangler.h

@@ -169,6 +169,8 @@ class ASTMangler : public Mangler {
     return finalize();
   }
 
+  std::string mangleTypeAsUSR(Type decl);
+
   std::string mangleTypeAsContextUSR(const NominalTypeDecl *type);
 
   std::string mangleDeclAsUSR(const ValueDecl *Decl, StringRef USRPrefix);

lib/AST/ASTMangler.cpp

@@ -468,6 +468,20 @@ std::string ASTMangler::mangleTypeAsContextUSR(const NominalTypeDecl *type) {
   return finalize();
 }
 
+std::string ASTMangler::mangleTypeAsUSR(Type Ty) {
+  DWARFMangling = true;
+  beginMangling();
+  
+  if (auto *fnType = Ty->getAs<AnyFunctionType>()) {
+    appendFunction(fnType, false);
+  } else {
+    appendType(Ty);
+  }
+
+  appendOperator("D");
+  return finalize();
+}
+
 std::string ASTMangler::mangleDeclAsUSR(const ValueDecl *Decl,
                                         StringRef USRPrefix) {
   beginManglingWithoutPrefix();

lib/AST/USRGeneration.cpp

@@ -35,7 +35,7 @@ static inline StringRef getUSRSpacePrefix() {
 bool ide::printTypeUSR(Type Ty, raw_ostream &OS) {
   assert(!Ty->hasArchetype() && "cannot have contextless archetypes mangled.");
   Mangle::ASTMangler Mangler;
-  OS << Mangler.mangleTypeForDebugger(Ty->getRValueType(), nullptr);
+  OS << Mangler.mangleTypeAsUSR(Ty->getRValueType());
   return false;
 }