From f4dccf115cc198e552b520fda0ee623457015db7 Mon Sep 17 00:00:00 2001
From: Bruno Ricci <riccibrun@gmail.com>
Date: Tue, 11 Aug 2020 15:54:15 +0100
Subject: [PATCH] [clang] Add a matcher for template template parameters.

There are already matchers for type template parameters and non-type template
parameters, but somehow no matcher exists for template template parameters
and I need it to write unit tests.

Differential Revision: https://reviews.llvm.org/D85536

Reviewed By: aaron.ballman
---
 clang/include/clang/ASTMatchers/ASTMatchers.h       | 12 ++++++++++++
 clang/lib/ASTMatchers/ASTMatchersInternal.cpp       |  3 +++
 clang/lib/ASTMatchers/Dynamic/Registry.cpp          |  1 +
 clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp |  9 +++++++++
 4 files changed, 25 insertions(+)

diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h b/clang/include/clang/ASTMatchers/ASTMatchers.h
index e37c68a8f156..f5c4fe63182f 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -562,6 +562,18 @@ extern const internal::VariadicDynCastAllOfMatcher<Decl,
 extern const internal::VariadicDynCastAllOfMatcher<Decl, TemplateTypeParmDecl>
     templateTypeParmDecl;
 
+/// Matches template template parameter declarations.
+///
+/// Given
+/// \code
+///   template <template <typename> class Z, int N> struct C {};
+/// \endcode
+/// templateTypeParmDecl()
+///   matches 'Z', but not 'N'.
+extern const internal::VariadicDynCastAllOfMatcher<Decl,
+                                                   TemplateTemplateParmDecl>
+    templateTemplateParmDecl;
+
 /// Matches public C++ declarations and C++ base specifers that specify public
 /// inheritance.
 ///
diff --git a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
index 5b9476f3098a..6b17bd0cda0b 100644
--- a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
@@ -740,6 +740,9 @@ const internal::VariadicDynCastAllOfMatcher<Decl, NonTypeTemplateParmDecl>
     nonTypeTemplateParmDecl;
 const internal::VariadicDynCastAllOfMatcher<Decl, TemplateTypeParmDecl>
     templateTypeParmDecl;
+const internal::VariadicDynCastAllOfMatcher<Decl, TemplateTemplateParmDecl>
+    templateTemplateParmDecl;
+
 const internal::VariadicAllOfMatcher<QualType> qualType;
 const internal::VariadicAllOfMatcher<Type> type;
 const internal::VariadicAllOfMatcher<TypeLoc> typeLoc;
diff --git a/clang/lib/ASTMatchers/Dynamic/Registry.cpp b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
index ec2215804c09..058dab3333de 100644
--- a/clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -514,6 +514,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(templateArgumentCountIs);
   REGISTER_MATCHER(templateName);
   REGISTER_MATCHER(templateSpecializationType);
+  REGISTER_MATCHER(templateTemplateParmDecl);
   REGISTER_MATCHER(templateTypeParmDecl);
   REGISTER_MATCHER(templateTypeParmType);
   REGISTER_MATCHER(throughUsingDecl);
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
index 895c8ae48adc..f4e929752ea0 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
@@ -408,6 +408,15 @@ TEST_P(ASTMatchersTest, TemplateTypeParmDecl) {
   EXPECT_TRUE(notMatches("template <int N> void f();", templateTypeParmDecl()));
 }
 
+TEST_P(ASTMatchersTest, TemplateTemplateParmDecl) {
+  if (!GetParam().isCXX())
+    return;
+  EXPECT_TRUE(matches("template <template <typename> class Z> void f();",
+                      templateTemplateParmDecl(hasName("Z"))));
+  EXPECT_TRUE(notMatches("template <typename, int> void f();",
+                         templateTemplateParmDecl()));
+}
+
 TEST_P(ASTMatchersTest, UserDefinedLiteral) {
   if (!GetParam().isCXX11OrLater()) {
     return;