From 500e126155299db89682b74b7ad434c06d6ee5db Mon Sep 17 00:00:00 2001
From: Eric Liu <ioeric@google.com>
Date: Wed, 21 Feb 2018 13:51:27 +0000
Subject: [PATCH] [ASTMatchers] isTemplateInstantiation: also match explicit
 instantiation declaration.

Summary:
Example:
template <typename T> class X {}; class A {};
// Explicit instantiation declaration.
extern template class X<A>;

Reviewers: bkramer

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D43567

llvm-svn: 325678
---
 clang/include/clang/ASTMatchers/ASTMatchers.h            | 8 +++++++-
 clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/clang/include/clang/ASTMatchers/ASTMatchers.h b/clang/include/clang/ASTMatchers/ASTMatchers.h
index e51ce4175e75..b9ce28629422 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchers.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -4649,6 +4649,10 @@ AST_MATCHER_P(UsingShadowDecl, hasTargetDecl,
 /// \code
 ///   template <typename T> class X {}; class A {}; template class X<A>;
 /// \endcode
+/// or
+/// \code
+///   template <typename T> class X {}; class A {}; extern template class X<A>;
+/// \endcode
 /// cxxRecordDecl(hasName("::X"), isTemplateInstantiation())
 ///   matches the template instantiation of X<A>.
 ///
@@ -4666,7 +4670,9 @@ AST_POLYMORPHIC_MATCHER(isTemplateInstantiation,
                                                         CXXRecordDecl)) {
   return (Node.getTemplateSpecializationKind() == TSK_ImplicitInstantiation ||
           Node.getTemplateSpecializationKind() ==
-          TSK_ExplicitInstantiationDefinition);
+              TSK_ExplicitInstantiationDefinition ||
+          Node.getTemplateSpecializationKind() ==
+              TSK_ExplicitInstantiationDeclaration);
 }
 
 /// \brief Matches declarations that are template instantiations or are inside
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index 55c53e66ecd6..3e27948db787 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -1623,6 +1623,14 @@ TEST(IsTemplateInstantiation, MatchesExplicitClassTemplateInstantiation) {
       "template class X<A>;",
     cxxRecordDecl(isTemplateInstantiation(), hasDescendant(
       fieldDecl(hasType(recordDecl(hasName("A"))))))));
+
+  // Make sure that we match the instantiation instead of the template
+  // definition by checking whether the member function is present.
+  EXPECT_TRUE(
+      matches("template <typename T> class X { void f() { T t; } };"
+              "extern template class X<int>;",
+              cxxRecordDecl(isTemplateInstantiation(),
+                            unless(hasDescendant(varDecl(hasName("t")))))));
 }
 
 TEST(IsTemplateInstantiation,