[clang-format] Correctly annotate braces in ObjC square brackets (#106654)

See
#88238 (comment).

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -2682,6 +2682,7 @@ void UnwrappedLineParser::parseSquare(bool LambdaIntroducer) {
       break;
     }
     case tok::at:
+    case tok::colon:
       nextToken();
       if (FormatTok->is(tok::l_brace)) {
         nextToken();

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -3286,6 +3286,15 @@ TEST_F(TokenAnnotatorTest, BlockLBrace) {
   EXPECT_BRACE_KIND(Tokens[4], BK_Block);
   EXPECT_TOKEN(Tokens[5], tok::l_brace, TT_BlockLBrace);
   EXPECT_BRACE_KIND(Tokens[5], BK_Block);
+
+  Tokens = annotate("[foo bar:{{0, 1}} baz:baz];",
+                    getLLVMStyle(FormatStyle::LK_ObjC));
+  ASSERT_EQ(Tokens.size(), 17u) << Tokens;
+  EXPECT_TOKEN(Tokens[4], tok::l_brace, TT_Unknown); // Not TT_BlockLBrace.
+  EXPECT_BRACE_KIND(Tokens[4], BK_Unknown);          // Not BK_Block.
+  EXPECT_BRACE_KIND(Tokens[5], BK_BracedInit);
+  EXPECT_BRACE_KIND(Tokens[9], BK_Unknown);  // Not BK_Block.
+  EXPECT_BRACE_KIND(Tokens[10], BK_Unknown); // Not BK_Block.
 }
 
 TEST_F(TokenAnnotatorTest, SwitchExpression) {