[clang-format] Improve detection of Objective-C block types

Summary:
Previously, clang-format would detect the following as an
Objective-C block type:

  FOO(^);

when it actually must be a C or C++ macro dealing with an XOR
statement or an XOR operator overload.

According to the Clang Block Language Spec:

https://clang.llvm.org/docs/BlockLanguageSpec.html

block types are of the form:

  int (^)(char, float)

and block variables of block type are of the form:

  void (^blockReturningVoidWithVoidArgument)(void);
  int (^blockReturningIntWithIntAndCharArguments)(int, char);
  void (^arrayOfTenBlocksReturningVoidWithIntArgument[10])(int);

This tightens up the detection so we don't unnecessarily detect
C macros which pass in the XOR operator.

Depends On D43904

Test Plan: New tests added. Ran tests with:
  make -j12 FormatTests &&
  ./tools/clang/unittests/Format/FormatTests

Reviewers: krasimir, jolesiak, djasper

Reviewed By: djasper

Subscribers: djasper, cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D43906

llvm-svn: 327285

clang/lib/Format/TokenAnnotator.cpp

@@ -141,10 +141,7 @@ private:
         Contexts.size() == 2 && Contexts[0].ColonIsForRangeExpr;
 
     bool StartsObjCMethodExpr = false;
-    if (CurrentToken->is(tok::caret)) {
-      // (^ can start a block type.
-      Left->Type = TT_ObjCBlockLParen;
-    } else if (FormatToken *MaybeSel = Left->Previous) {
+    if (FormatToken *MaybeSel = Left->Previous) {
       // @selector( starts a selector.
       if (MaybeSel->isObjCAtKeyword(tok::objc_selector) && MaybeSel->Previous &&
           MaybeSel->Previous->is(tok::at)) {
@@ -210,8 +207,16 @@ private:
       Left->Type = TT_ObjCMethodExpr;
     }
 
+    // MightBeFunctionType and ProbablyFunctionType are used for
+    // function pointer and reference types as well as Objective-C
+    // block types:
+    //
+    // void (*FunctionPointer)(void);
+    // void (&FunctionReference)(void);
+    // void (^ObjCBlock)(void);
     bool MightBeFunctionType = !Contexts[Contexts.size() - 2].IsExpression;
-    bool ProbablyFunctionType = CurrentToken->isOneOf(tok::star, tok::amp);
+    bool ProbablyFunctionType =
+        CurrentToken->isOneOf(tok::star, tok::amp, tok::caret);
     bool HasMultipleLines = false;
     bool HasMultipleParametersOnALine = false;
     bool MightBeObjCForRangeLoop =
@@ -248,7 +253,8 @@ private:
         if (MightBeFunctionType && ProbablyFunctionType && CurrentToken->Next &&
             (CurrentToken->Next->is(tok::l_paren) ||
              (CurrentToken->Next->is(tok::l_square) && Line.MustBeDeclaration)))
-          Left->Type = TT_FunctionTypeLParen;
+          Left->Type = Left->Next->is(tok::caret) ? TT_ObjCBlockLParen
+                                                  : TT_FunctionTypeLParen;
         Left->MatchingParen = CurrentToken;
         CurrentToken->MatchingParen = Left;
 

clang/unittests/Format/FormatTest.cpp

@@ -12128,6 +12128,22 @@ TEST_F(FormatTest, GuessLanguageWithCpp11AttributeSpecifiers) {
   EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "[[foo::bar, ...]]"));
 }
 
+TEST_F(FormatTest, GuessLanguageWithCaret) {
+  EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "FOO(^);"));
+  EXPECT_EQ(FormatStyle::LK_Cpp, guessLanguage("foo.h", "FOO(^, Bar);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^)(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo)(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo[10])(char, float);"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "int(^foo[kNumEntries])(char, float);"));
+  EXPECT_EQ(
+      FormatStyle::LK_ObjC,
+      guessLanguage("foo.h", "int(^foo[(kNumEntries + 10)])(char, float);"));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang

clang/unittests/Format/FormatTestObjC.cpp

@@ -845,6 +845,15 @@ TEST_F(FormatTestObjC, ObjCAt) {
   verifyFormat("@ /*foo*/ interface");
 }
 
+TEST_F(FormatTestObjC, ObjCBlockTypesAndVariables) {
+  verifyFormat("void DoStuffWithBlockType(int (^)(char));");
+  verifyFormat("int (^foo)(char, float);");
+  verifyFormat("int (^foo[10])(char, float);");
+  verifyFormat("int (^foo[kNumEntries])(char, float);");
+  verifyFormat("int (^foo[kNumEntries + 10])(char, float);");
+  verifyFormat("int (^foo[(kNumEntries + 10)])(char, float);");
+}
+
 TEST_F(FormatTestObjC, ObjCSnippets) {
   verifyFormat("@autoreleasepool {\n"
                "  foo();\n"