[clang] Add AST matcher for block expressions 🔍

Summary:
This change adds a new AST matcher for block expressions.

Test Notes:
Ran the clang unit tests.

Reviewers: aaron.ballman

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D55546

llvm-svn: 349004

clang/docs/LibASTMatchersReference.html

@@ -707,6 +707,14 @@ Example matches a || b
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('blockExpr0')"><a name="blockExpr0Anchor">blockExpr</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BlockExpr.html">BlockExpr</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="blockExpr0"><pre>MAtches a reference to a block.
+
+Example: matches "^{}":
+  void f() { ^{}(); }
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('breakStmt0')"><a name="breakStmt0Anchor">breakStmt</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BreakStmt.html">BreakStmt</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="breakStmt0"><pre>Matches break statements.
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -1798,6 +1798,14 @@ extern const internal::VariadicDynCastAllOfMatcher<Stmt, DeclRefExpr>
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCIvarRefExpr>
     objcIvarRefExpr;
 
+/// Matches a reference to a block.
+///
+/// Example: matches "^{}":
+/// \code
+///   void f() { ^{}(); }
+/// \endcode
+extern const internal::VariadicDynCastAllOfMatcher<Stmt, BlockExpr> blockExpr;
+
 /// Matches if statements.
 ///
 /// Example matches 'if (x) {}'

clang/lib/ASTMatchers/ASTMatchersInternal.cpp

@@ -688,6 +688,7 @@ const internal::VariadicDynCastAllOfMatcher<Stmt, CXXOperatorCallExpr>
 const internal::VariadicDynCastAllOfMatcher<Stmt, Expr> expr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, DeclRefExpr> declRefExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCIvarRefExpr> objcIvarRefExpr;
+const internal::VariadicDynCastAllOfMatcher<Stmt, BlockExpr> blockExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, IfStmt> ifStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, ForStmt> forStmt;
 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXForRangeStmt>

clang/lib/ASTMatchers/Dynamic/Registry.cpp

@@ -139,6 +139,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(binaryConditionalOperator);
   REGISTER_MATCHER(binaryOperator);
   REGISTER_MATCHER(blockDecl);
+  REGISTER_MATCHER(blockExpr);
   REGISTER_MATCHER(blockPointerType);
   REGISTER_MATCHER(booleanType);
   REGISTER_MATCHER(breakStmt);

clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

@@ -1386,6 +1386,10 @@ TEST(ObjCIvarRefExprMatcher, IvarExpr) {
         hasDeclaration(namedDecl(hasName("y"))))));
 }
 
+TEST(BlockExprMatcher, BlockExpr) {
+  EXPECT_TRUE(matchesObjC("void f() { ^{}(); }", blockExpr()));
+}
+
 TEST(StatementCountIs, FindsNoStatementsInAnEmptyCompoundStatement) {
   EXPECT_TRUE(matches("void f() { }",
                       compoundStmt(statementCountIs(0))));