From 00c472cb9e3831ea5afaaa3786f41404dc5303f4 Mon Sep 17 00:00:00 2001
From: Julie Hockett <juliehockett@google.com>
Date: Mon, 22 Jan 2018 22:45:23 +0000
Subject: [PATCH] Add hasTrailingReturn AST matcher

Adds AST matcher for a FunctionDecl that has a trailing return type.

Differential Revision: https://reviews.llvm.org/D42273

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@323158 91177308-0d34-0410-b5e6-96231b3b80d8
---
 docs/LibASTMatchersReference.html             |  9 +++++++++
 include/clang/ASTMatchers/ASTMatchers.h       | 13 +++++++++++++
 lib/ASTMatchers/Dynamic/Registry.cpp          |  1 +
 .../ASTMatchers/ASTMatchersNarrowingTest.cpp  | 19 +++++++++++++++++++
 4 files changed, 42 insertions(+)

diff --git a/docs/LibASTMatchersReference.html b/docs/LibASTMatchersReference.html
index abc2834c4c..a807672121 100644
--- a/docs/LibASTMatchersReference.html
+++ b/docs/LibASTMatchersReference.html
@@ -2749,6 +2749,15 @@ Usable as: Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1CXXOp
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html">FunctionDecl</a>&gt;</td><td class="name" onclick="toggle('hasTrailingReturn0')"><a name="hasTrailingReturn0Anchor">hasTrailingReturn</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="hasTrailingReturn0"><pre>Matches a function declared with a trailing return type.
+
+Example matches Y (matcher = functionDecl(hasTrailingReturn()))
+int X() {}
+auto Y() -&gt; int {}
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html">FunctionDecl</a>&gt;</td><td class="name" onclick="toggle('isConstexpr1')"><a name="isConstexpr1Anchor">isConstexpr</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isConstexpr1"><pre>Matches constexpr variable and function declarations.
 
diff --git a/include/clang/ASTMatchers/ASTMatchers.h b/include/clang/ASTMatchers/ASTMatchers.h
index 2f66579c87..e51ce4175e 100644
--- a/include/clang/ASTMatchers/ASTMatchers.h
+++ b/include/clang/ASTMatchers/ASTMatchers.h
@@ -5893,6 +5893,19 @@ AST_MATCHER(EnumDecl, isScoped) {
   return Node.isScoped();
 }
 
+/// \brief Matches a function declared with a trailing return type.
+///
+/// Example matches Y (matcher = functionDecl(hasTrailingReturn()))
+/// \code
+/// int X() {}
+/// auto Y() -> int {}
+/// \endcode
+AST_MATCHER(FunctionDecl, hasTrailingReturn) {
+  if (const auto *F = Node.getType()->getAs<FunctionProtoType>())
+    return F->hasTrailingReturn();
+  return false;
+}
+
 } // namespace ast_matchers
 } // namespace clang
 
diff --git a/lib/ASTMatchers/Dynamic/Registry.cpp b/lib/ASTMatchers/Dynamic/Registry.cpp
index 784581fc45..79aa4e667b 100644
--- a/lib/ASTMatchers/Dynamic/Registry.cpp
+++ b/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -296,6 +296,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(hasTemplateArgument);
   REGISTER_MATCHER(hasThen);
   REGISTER_MATCHER(hasThreadStorageDuration);
+  REGISTER_MATCHER(hasTrailingReturn);
   REGISTER_MATCHER(hasTrueExpression);
   REGISTER_MATCHER(hasTypeLoc);
   REGISTER_MATCHER(hasUnaryOperand);
diff --git a/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp b/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index eea4e6f4f2..55c53e66ec 100644
--- a/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -2112,5 +2112,24 @@ TEST(IsScopedEnum, MatchesScopedEnum) {
   EXPECT_TRUE(notMatches("enum X {};", enumDecl(isScoped())));
 }
 
+TEST(HasTrailingReturn, MatchesTrailingReturn) {
+  EXPECT_TRUE(matches("auto Y() -> int { return 0; }",
+                      functionDecl(hasTrailingReturn())));
+  EXPECT_TRUE(matches("auto X() -> int;", functionDecl(hasTrailingReturn())));
+  EXPECT_TRUE(notMatches("int X() { return 0; }", 
+                      functionDecl(hasTrailingReturn())));
+  EXPECT_TRUE(notMatches("int X();", functionDecl(hasTrailingReturn())));
+  EXPECT_TRUE(notMatchesC("void X();", functionDecl(hasTrailingReturn())));
+}
+
+TEST(HasTrailingReturn, MatchesLambdaTrailingReturn) {
+  EXPECT_TRUE(matches(
+          "auto lambda2 = [](double x, double y) -> double {return x + y;};",
+          functionDecl(hasTrailingReturn())));
+  EXPECT_TRUE(notMatches(
+          "auto lambda2 = [](double x, double y) {return x + y;};",
+          functionDecl(hasTrailingReturn())));
+}
+
 } // namespace ast_matchers
 } // namespace clang
-- 
2.40.0