Fully qualify template template parameters when printing

I discovered this quirk when working on some DWARF - AST printing prints
type template parameters fully qualified, but printed template template
parameters the way they were written syntactically, or wholely
unqualified - instead, we should print them consistently with the way we
print type template parameters: fully qualified.

The one place this got weird was for partial specializations like in
ast-print-temp-class.cpp - hence the need for checking for
TemplateNameDependenceScope::DependentInstantiation template template
parameters. (not 100% sure that's the right solution to that, though -
open to ideas)

Differential Revision: https://reviews.llvm.org/D108794

clang-tools-extra/clangd/DumpAST.cpp

@@ -295,7 +295,7 @@ class DumpVisitor : public RecursiveASTVisitor<DumpVisitor> {
   }
   std::string getDetail(const TemplateName &TN) {
     return toString([&](raw_ostream &OS) {
-      TN.print(OS, Ctx.getPrintingPolicy(), /*SuppressNNS=*/true);
+      TN.print(OS, Ctx.getPrintingPolicy(), TemplateName::Qualified::None);
     });
   }
   std::string getDetail(const Attr *A) {

clang/include/clang/AST/TemplateName.h

@@ -309,16 +309,17 @@ public:
   /// unexpanded parameter pack (for C++0x variadic templates).
   bool containsUnexpandedParameterPack() const;
 
+  enum class Qualified { None, AsWritten, Fully };
   /// Print the template name.
   ///
   /// \param OS the output stream to which the template name will be
   /// printed.
   ///
-  /// \param SuppressNNS if true, don't print the
-  /// nested-name-specifier that precedes the template name (if it has
-  /// one).
+  /// \param Qual print the (Qualified::None) simple name,
+  /// (Qualified::AsWritten) any written (possibly partial) qualifier, or
+  /// (Qualified::Fully) the fully qualified name.
   void print(raw_ostream &OS, const PrintingPolicy &Policy,
-             bool SuppressNNS = false) const;
+             Qualified Qual = Qualified::AsWritten) const;
 
   /// Debugging aid that dumps the template name.
   void dump(raw_ostream &OS) const;

clang/lib/AST/NestedNameSpecifier.cpp

@@ -311,7 +311,8 @@ void NestedNameSpecifier::print(raw_ostream &OS, const PrintingPolicy &Policy,
           = dyn_cast<TemplateSpecializationType>(T)) {
       // Print the template name without its corresponding
       // nested-name-specifier.
-      SpecType->getTemplateName().print(OS, InnerPolicy, true);
+      SpecType->getTemplateName().print(OS, InnerPolicy,
+                                        TemplateName::Qualified::None);
 
       // Print the template argument list.
       printTemplateArgumentList(OS, SpecType->template_arguments(),

clang/lib/AST/TemplateBase.cpp

@@ -452,7 +452,7 @@ void TemplateArgument::print(const PrintingPolicy &Policy, raw_ostream &Out,
     break;
 
   case Template:
-    getAsTemplate().print(Out, Policy);
+    getAsTemplate().print(Out, Policy, TemplateName::Qualified::Fully);
     break;
 
   case TemplateExpansion:

clang/lib/AST/TemplateName.cpp

@@ -220,19 +220,28 @@ bool TemplateName::containsUnexpandedParameterPack() const {
   return getDependence() & TemplateNameDependence::UnexpandedPack;
 }
 
-void
-TemplateName::print(raw_ostream &OS, const PrintingPolicy &Policy,
-                    bool SuppressNNS) const {
+void TemplateName::print(raw_ostream &OS, const PrintingPolicy &Policy,
+                         Qualified Qual) const {
   if (TemplateDecl *Template = Storage.dyn_cast<TemplateDecl *>())
-    OS << *Template;
+    if (Qual == Qualified::Fully &&
+        getDependence() != TemplateNameDependenceScope::DependentInstantiation)
+      Template->printQualifiedName(OS, Policy);
+    else
+      OS << *Template;
   else if (QualifiedTemplateName *QTN = getAsQualifiedTemplateName()) {
-    if (!SuppressNNS)
+    if (Qual == Qualified::Fully &&
+        getDependence() !=
+            TemplateNameDependenceScope::DependentInstantiation) {
+      QTN->getTemplateDecl()->printQualifiedName(OS, Policy);
+      return;
+    }
+    if (Qual == Qualified::AsWritten)
       QTN->getQualifier()->print(OS, Policy);
     if (QTN->hasTemplateKeyword())
       OS << "template ";
     OS << *QTN->getDecl();
   } else if (DependentTemplateName *DTN = getAsDependentTemplateName()) {
-    if (!SuppressNNS && DTN->getQualifier())
+    if (Qual == Qualified::AsWritten && DTN->getQualifier())
       DTN->getQualifier()->print(OS, Policy);
     OS << "template ";
 
@@ -242,7 +251,7 @@ TemplateName::print(raw_ostream &OS, const PrintingPolicy &Policy,
       OS << "operator " << getOperatorSpelling(DTN->getOperator());
   } else if (SubstTemplateTemplateParmStorage *subst
                = getAsSubstTemplateTemplateParm()) {
-    subst->getReplacement().print(OS, Policy, SuppressNNS);
+    subst->getReplacement().print(OS, Policy, Qual);
   } else if (SubstTemplateTemplateParmPackStorage *SubstPack
                                         = getAsSubstTemplateTemplateParmPack())
     OS << *SubstPack->getParameterPack();

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -1226,7 +1226,8 @@ llvm::DIType *CGDebugInfo::CreateType(const TemplateSpecializationType *Ty,
 
   SmallString<128> NS;
   llvm::raw_svector_ostream OS(NS);
-  Ty->getTemplateName().print(OS, getPrintingPolicy(), /*qualified*/ false);
+  Ty->getTemplateName().print(OS, getPrintingPolicy(),
+                              TemplateName::Qualified::None);
   printTemplateArgumentList(OS, Ty->template_arguments(), getPrintingPolicy());
 
   SourceLocation Loc = AliasDecl->getLocation();

clang/test/CXX/drs/dr10xx.cpp

@@ -17,8 +17,8 @@ namespace dr1004 { // dr1004: 5
   template<typename> struct B1 {};
   template<template<typename> class> struct B2 {};
   template<typename X> void f(); // expected-note {{[with X = dr1004::A<int>]}}
-  template<template<typename> class X> void f(); // expected-note {{[with X = A]}}
-  template<template<typename> class X> void g(); // expected-note {{[with X = A]}}
+  template<template<typename> class X> void f(); // expected-note {{[with X = dr1004::A]}}
+  template<template<typename> class X> void g(); // expected-note {{[with X = dr1004::A]}}
   template<typename X> void g(); // expected-note {{[with X = dr1004::A<int>]}}
   struct C : A<int> {
     B1<A> b1a;

clang/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.type/p9-0x.cpp

@@ -93,7 +93,7 @@ namespace DeduceNonTypeTemplateArgsInArray {
 }
 
 namespace DeduceWithDefaultArgs {
-  template<template<typename...> class Container> void f(Container<int>); // expected-note {{deduced type 'X<[...], (default) int>' of 1st parameter does not match adjusted type 'X<[...], double>' of argument [with Container = X]}}
+  template<template<typename...> class Container> void f(Container<int>); // expected-note {{deduced type 'X<[...], (default) int>' of 1st parameter does not match adjusted type 'X<[...], double>' of argument [with Container = DeduceWithDefaultArgs::X]}}
   template<typename, typename = int> struct X {};
   void g() {
     // OK, use default argument for the second template parameter.

clang/test/Index/print-type.cpp

@@ -132,7 +132,7 @@ inline namespace InlineNS {}
 // CHECK: TypedefDecl=OtherType:26:18 (Definition) [type=outer::inner::Bar::OtherType] [typekind=Typedef] [canonicaltype=double] [canonicaltypekind=Double] [isPOD=1]
 // CHECK: TypedefDecl=ArrayType:27:15 (Definition) [type=outer::inner::Bar::ArrayType] [typekind=Typedef] [canonicaltype=int [5]] [canonicaltypekind=ConstantArray] [isPOD=1]
 // CHECK: IntegerLiteral= [type=int] [typekind=Int] [isPOD=1]
-// CHECK: FieldDecl=baz:28:20 (Definition) [type=Baz<int, 1, Foo>] [typekind=Unexposed] [templateargs/3= [type=int] [typekind=Int]] [canonicaltype=outer::Baz<int, 1, Foo>] [canonicaltypekind=Record] [canonicaltemplateargs/3= [type=int] [typekind=Int]] [isPOD=1]
+// CHECK: FieldDecl=baz:28:20 (Definition) [type=Baz<int, 1, outer::Foo>] [typekind=Unexposed] [templateargs/3= [type=int] [typekind=Int]] [canonicaltype=outer::Baz<int, 1, outer::Foo>] [canonicaltypekind=Record] [canonicaltemplateargs/3= [type=int] [typekind=Int]] [isPOD=1]
 // CHECK: TemplateRef=Baz:9:8 [type=] [typekind=Invalid] [isPOD=0]
 // CHECK: IntegerLiteral= [type=int] [typekind=Int] [isPOD=1]
 // CHECK: TemplateRef=Foo:4:8 [type=] [typekind=Invalid] [isPOD=0]

clang/test/Misc/diag-template.cpp

@@ -34,8 +34,8 @@ namespace default_args {
     f(Q<>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<>'}}
     f(Q<allocator>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<>'}}
     f(Q<allocator, allocator>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<>'}}
-    f(Q<char_traits>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<char_traits>'}}
-    f(Q<char_traits, char_traits>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<char_traits>'}}
-    f(Q<char_traits, allocator>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<char_traits, allocator>'}}
+    f(Q<char_traits>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<default_args::char_traits>'}}
+    f(Q<char_traits, char_traits>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<default_args::char_traits>'}}
+    f(Q<char_traits, allocator>()).g(); // expected-error {{no member named 'g' in 'default_args::Q<default_args::char_traits, default_args::allocator>'}}
   }
 }

clang/test/SemaTemplate/temp_arg_template.cpp

@@ -59,7 +59,7 @@ namespace N {
     0 << a.const_ref(); // expected-error{{invalid operands to binary expression ('int' and 'X<int>')}}
   }
 
-  void f0( Y<int,1> y){ 1 << y; } // expected-note{{in instantiation of function template specialization 'N::operator<<<Y, int, 1>' requested here}}
+  void f0( Y<int,1> y){ 1 << y; } // expected-note{{in instantiation of function template specialization 'N::operator<<<N::Y, int, 1>' requested here}}
 }
 
 // PR12179