[clang-format] Don't detect call to ObjC class method as C++11 attribute specifier

Summary:
Previously, clang-format detected something like the following as a C++11 attribute specifier.

  @[[NSArray class]]

instead of an array with an Objective-C method call inside. In general, when the attribute specifier checking runs, if it sees 2 identifiers in a row, it decides that the square brackets represent an Objective-C method call. However, here, `class` is tokenized as a keyword instead of an identifier, so this check fails.

To fix this, the attribute specifier first checks whether the first square bracket has an "@" before it. If it does, then that square bracket is not the start of a attribute specifier because it is an Objective-C array literal. (The assumption is that @[[.*]] is not valid C/C++.)

Contributed by rkgibson2.

Reviewers: benhamilton

Reviewed By: benhamilton

Subscribers: aaron.ballman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64632

llvm-svn: 366267

clang/lib/Format/TokenAnnotator.cpp

@@ -388,6 +388,10 @@ private:
   bool isCpp11AttributeSpecifier(const FormatToken &Tok) {
     if (!Style.isCpp() || !Tok.startsSequence(tok::l_square, tok::l_square))
       return false;
+    // The first square bracket is part of an ObjC array literal
+    if (Tok.Previous && Tok.Previous->is(tok::at)) {
+      return false;
+    }
     const FormatToken *AttrTok = Tok.Next->Next;
     if (!AttrTok)
       return false;
@@ -400,7 +404,7 @@ private:
     while (AttrTok && !AttrTok->startsSequence(tok::r_square, tok::r_square)) {
       // ObjC message send. We assume nobody will use : in a C++11 attribute
       // specifier parameter, although this is technically valid:
-      // [[foo(:)]]
+      // [[foo(:)]].
       if (AttrTok->is(tok::colon) ||
           AttrTok->startsSequence(tok::identifier, tok::identifier) ||
           AttrTok->startsSequence(tok::r_paren, tok::identifier))

clang/unittests/Format/FormatTest.cpp

@@ -7027,6 +7027,12 @@ TEST_F(FormatTest, UnderstandsSquareAttributes) {
   // On the other hand, we still need to correctly find array subscripts.
   verifyFormat("int a = std::vector<int>{1, 2, 3}[0];");
 
+  // Make sure that we do not mistake Objective-C method inside array literals
+  // as attributes, even if those method names are also keywords.
+  verifyFormat("@[ [foo bar] ];");
+  verifyFormat("@[ [NSArray class] ];");
+  verifyFormat("@[ [foo enum] ];");
+
   // Make sure we do not parse attributes as lambda introducers.
   FormatStyle MultiLineFunctions = getLLVMStyle();
   MultiLineFunctions.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_None;