[clang-format] Fix support for ObjC blocks with pointer return types

[jaredgrubb]

Summary

The ObjC-block detection code only supports a single token as the return type. Add support to detect pointers, too (ObjC has lots of object-pointers).

For example, using BasedOnStyle: WebKit, the following is stable output:

int* p = ^int*(void)
{ //
    return nullptr;
}
();

After the patch:

int* p = ^int*(void) { //
    return nullptr;
}();

[MyDeveloperDay]

clang/unittests/Format/FormatTest.cpp

22178

I don’t like us changing tests

[jaredgrubb]

clang/unittests/Format/FormatTest.cpp

22178

Normally I would agree, but in this case, this is a bug-fix for the test as well.

If you look at the verifyFormat just below this one, its braces are broken across separate lines. The inconsistency between these two tests was due to the difference in the block's return type (pointer vs non-pointer).

My patch corrects exactly that inconsistency.

[MyDeveloperDay]

LGTM

[owenpan]

clang/lib/Format/UnwrappedLineParser.cpp

1779–1782

clang/unittests/Format/FormatTestObjC.cpp

1007–1010

[jaredgrubb]

clang/lib/Format/UnwrappedLineParser.cpp

1779–1782

I think this obscures the logic a bit. The first one is to consume one token (the return type) and the next is to consume a different kind of token (trailing stars). Putting them in a while loop makes it harder to reason about why it's looping in that way.

clang/unittests/Format/FormatTestObjC.cpp

1007–1010

Fixed!

[jaredgrubb]

Address review comment and rebase to re-run tests. Intend to merge if everything is green! (If there are further comments, I will commit to address them!)

[egorzhdan]

Merged as 63d6659a.

clang/lib/Format/UnwrappedLineParser.cpp

do {
     }
     case tok::kw_operator:
       nextToken();
       if (FormatTok->isBinaryOperator())
         nextToken();
       break;
     case tok::caret:
       nextToken();
+      // Block return type.
       if (FormatTok->Tok.isAnyIdentifier() ||
           FormatTok->isSimpleTypeSpecifier()) {
         nextToken();
+        // Return types: pointers are ok too.
+        while (FormatTok->is(tok::star))
+          nextToken();
       }
+      // Block argument list.
       if (FormatTok->is(tok::l_paren))
         parseParens();
+      // Block body.
       if (FormatTok->is(tok::l_brace))
         parseChildBlock();
       break;
     case tok::l_brace:
       if (NextLBracesType != TT_Unknown)
         FormatTok->setFinalizedType(NextLBracesType);
       if (!tryToParsePropertyAccessor() && !tryToParseBracedList()) {
         // A block outside of parentheses must be the last part of a

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, FormatsBlocks) {
 
   verifyFormat("f(^{\n"
                "  @autoreleasepool {\n"
                "    if (a) {\n"
                "      g();\n"
                "    }\n"
                "  }\n"
                "});");
-  verifyFormat("Block b = ^int *(A *a, B *b) {}");
+  verifyFormat("Block b = ^int *(A *a, B *b) {\n"
+               "};");
   verifyFormat("BOOL (^aaa)(void) = ^BOOL {\n"
                "};");
 
   FormatStyle FourIndent = getLLVMStyle();
   FourIndent.ObjCBlockIndentWidth = 4;
   verifyFormat("[operation setCompletionBlock:^{\n"
                "    [self onOperationDone];\n"
                "}];",

clang/unittests/Format/FormatTestObjC.cpp

 
 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);");
+
+  verifyFormat("int *p = ^int *() { //\n"
+               "  return nullptr;\n"
+               "}();");
+
+  verifyFormat("int * (^p)(void) = ^int *(void) { //\n"
+               "  return nullptr;\n"
+               "};");
+
+  // WebKit forces function braces onto a newline, but blocks should not.
+  Style = getWebKitStyle();
+  verifyFormat("int* p = ^int*() { //\n"
+               "    return nullptr;\n"
+               "}();");
 }
 
 TEST_F(FormatTestObjC, ObjCSnippets) {
   verifyFormat("@autoreleasepool {\n"
                "  foo();\n"
                "}");
   verifyFormat("@class Foo, Bar;");
   verifyFormat("@compatibility_alias AliasName ExistingClass;");