[clang-format] Fix ObjC style guesser to also iterate over child lines

[benhamilton]

Summary

When I wrote ObjCHeaderStyleGuesser, I incorrectly assumed the
correct way to iterate over all tokens in AnnotatedLine was to
iterate over the linked list tokens starting with
AnnotatedLine::First.

However, AnnotatedLine also contains a vector
AnnotedLine::Children with child AnnotedLines which have their own
tokens which we need to iterate over.

Because I didn't iterate over the tokens in the children lines, the
ObjC style guesser would fail on syntax like:

#define FOO ({ NSString *s = ... })

as the statement(s) inside { ... } are child lines.

This fixes the bug and adds a test. I confirmed the test
failed before the fix, and passed after the fix.

Test Plan: New tests added. Ran tests with:

% make -j12 FormatTests && ./tools/clang/unittests/Format/FormatTests

[djasper]

Looks good, thank you!

lib/Format/Format.cpp

1517–1518

Maybe choose a name that indicates what the bool result value means, e.g. LinesContainObjCCode or something.

[benhamilton]

CheckLineTokens -> LineContainsObjCCode

[benhamilton]

lib/Format/Format.cpp

1517–1518

Done, thanks!

[djasper]

cfe/trunk/lib/Format/Format.cpp

1544 ↗

(On Diff #139473)

Sorry that I missed this in the original review. But doesn't this still fail for Children of Child lines, etc.? I think this probably needs to be fully recursive.

[benhamilton]

cfe/trunk/lib/Format/Format.cpp

1544 ↗

(On Diff #139473)

Oh, of course. I'll send a follow-up.

[benhamilton]

cfe/trunk/lib/Format/Format.cpp

1544 ↗

(On Diff #139473)

Follow-up in D44831.

lib/Format/Format.cpp

static constexpr llvm::StringLiteral FoundationIdentifiers[] = {
         "NSURLComponents",
         "NSURLQueryItem",
         "NSUUID",
         "NSValue",
         "UIImage",
         "UIView",
     };
 
-    for (auto &Line : AnnotatedLines) {
-      for (FormatToken *FormatTok = Line->First; FormatTok;
+    auto LineContainsObjCCode = [&Keywords](const AnnotatedLine &Line) {
+      for (const FormatToken *FormatTok = Line.First; FormatTok;
            FormatTok = FormatTok->Next) {
         if ((FormatTok->Previous && FormatTok->Previous->is(tok::at) &&
              (FormatTok->isObjCAtKeyword(tok::objc_interface) ||
               FormatTok->isObjCAtKeyword(tok::objc_implementation) ||
               FormatTok->isObjCAtKeyword(tok::objc_protocol) ||
               FormatTok->isObjCAtKeyword(tok::objc_end) ||
               FormatTok->isOneOf(tok::numeric_constant, tok::l_square,
                                  tok::l_brace))) ||
             (FormatTok->Tok.isAnyIdentifier() &&
              std::binary_search(std::begin(FoundationIdentifiers),
                                 std::end(FoundationIdentifiers),
                                 FormatTok->TokenText)) ||
             FormatTok->is(TT_ObjCStringLiteral) ||
             FormatTok->isOneOf(Keywords.kw_NS_ENUM, Keywords.kw_NS_OPTIONS,
                                TT_ObjCBlockLBrace, TT_ObjCBlockLParen,
                                TT_ObjCDecl, TT_ObjCForIn, TT_ObjCMethodExpr,
                                TT_ObjCMethodSpecifier, TT_ObjCProperty)) {
           return true;
         }
       }
+      return false;
+    };
+    for (auto Line : AnnotatedLines) {
+      if (LineContainsObjCCode(*Line))
+        return true;
+      for (auto ChildLine : Line->Children) {
+        if (LineContainsObjCCode(*ChildLine))
+          return true;
+      }
     }
     return false;
   }
 
   bool IsObjC;
 };
 
 struct IncludeDirective {

unittests/Format/FormatTest.cpp

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);"));
 }
 
+TEST_F(FormatTest, GuessLanguageWithChildLines) {
+  EXPECT_EQ(FormatStyle::LK_Cpp,
+            guessLanguage("foo.h", "#define FOO ({ std::string s; })"));
+  EXPECT_EQ(FormatStyle::LK_ObjC,
+            guessLanguage("foo.h", "#define FOO ({ NSString *s; })"));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang