[clang-format] Fix a bug in formating #define A x: (#73220)

Fixed #70789.

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -1171,6 +1171,12 @@ void UnwrappedLineParser::parsePPDefine() {
   assert((int)Line->PPLevel >= 0);
   Line->InMacroBody = true;
 
+  if (FormatTok->is(tok::identifier) &&
+      Tokens->peekNextToken()->is(tok::colon)) {
+    nextToken();
+    nextToken();
+  }
+
   // Errors during a preprocessor directive can only affect the layout of the
   // preprocessor directive, and thus we ignore them. An alternative approach
   // would be to use the same approach we use on the file level (no

clang/unittests/Format/FormatTest.cpp

@@ -1863,6 +1863,8 @@ TEST_F(FormatTest, UnderstandsMacros) {
   verifyFormat("MACRO(something##something)");
   verifyFormat("MACRO(return##something)");
   verifyFormat("MACRO(co_return##something)");
+
+  verifyFormat("#define A x:");
 }
 
 TEST_F(FormatTest, ShortBlocksInMacrosDontMergeWithCodeAfterMacro) {