[clang][AST] Pretty-print default template template args

Author: bolshakov-a

clang/docs/ReleaseNotes.rst

@@ -124,7 +124,7 @@ AST Dumping Potentially Breaking Changes
     ``__atomic_test_and_set(p, 0)``
 
 - Pretty-printing of templates with inherited (i.e. specified in a previous
-  redeclaration) default arguments has been fixed.
+  redeclaration) and template default arguments has been fixed.
 
 Clang Frontend Potentially Breaking Changes
 -------------------------------------------

clang/lib/AST/DeclPrinter.cpp

@@ -1190,7 +1190,11 @@ void DeclPrinter::printTemplateParameters(const TemplateParameterList *Params,
       VisitNonTypeTemplateParmDecl(NTTP);
     } else if (auto TTPD = dyn_cast<TemplateTemplateParmDecl>(Param)) {
       VisitTemplateDecl(TTPD);
-      // FIXME: print the default argument, if present.
+      if (TTPD->hasDefaultArgument() && !TTPD->defaultArgumentWasInherited()) {
+        Out << " = ";
+        TTPD->getDefaultArgument().getArgument().print(Policy, Out,
+                                                       /*IncludeType=*/false);
+      }
     }
   }
 

clang/test/AST/ast-print-record-decl.c

@@ -315,4 +315,11 @@ template <int, int = 0> KW SmearedNTTPDefArgs;
 // PRINT-CXX-NEXT: template <int = 0, int> [[KW]] SmearedNTTPDefArgs;
 template <int = 0, int> KW SmearedNTTPDefArgs;
 
+// PRINT-CXX-LABEL: Tpl
+template <int> KW Tpl;
+// PRINT-CXX-NEXT: template <template <int> class, template <int> class = Tpl> [[KW]] SmearedTplDefArgs;
+template <template <int> class, template <int> class = Tpl> KW SmearedTplDefArgs;
+// PRINT-CXX-NEXT: template <template <int> class = Tpl, template <int> class> [[KW]] SmearedTplDefArgs;
+template <template <int> class = Tpl, template <int> class> KW SmearedTplDefArgs;
+
 #endif

clang/unittests/AST/DeclPrinterTest.cpp

@@ -1090,7 +1090,7 @@ TEST(DeclPrinter, TestClassTemplateDecl9) {
     "template<typename T> struct Z { };"
     "template<template<typename U> class T = Z> struct A { };",
     classTemplateDecl(hasName("A")).bind("id"),
-    "template <template <typename U> class T> struct A {}"));
+    "template <template <typename U> class T = Z> struct A {}"));
 }
 
 TEST(DeclPrinter, TestClassTemplateDecl10) {