[clang-format] Fix annotation of braces enclosing stringification (#102998)

Fixes #102937.

(cherry picked from commit ee23599)

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -507,6 +507,9 @@ void UnwrappedLineParser::calculateBraceTypes(bool ExpectClassBody) {
     if (!Line->InMacroBody && !Style.isTableGen()) {
       // Skip PPDirective lines and comments.
       while (NextTok->is(tok::hash)) {
+        NextTok = Tokens->getNextToken();
+        if (NextTok->is(tok::pp_not_keyword))
+          break;
         do {
           NextTok = Tokens->getNextToken();
         } while (NextTok->NewlinesBefore == 0 && NextTok->isNot(tok::eof));

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -3178,6 +3178,17 @@ TEST_F(TokenAnnotatorTest, BraceKind) {
   EXPECT_BRACE_KIND(Tokens[17], BK_Block);
   EXPECT_BRACE_KIND(Tokens[22], BK_Block);
   EXPECT_BRACE_KIND(Tokens[26], BK_Block);
+
+  Tokens = annotate("{\n"
+                    "#define M(x) \\\n"
+                    "  return {#x};\n"
+                    "}");
+  ASSERT_EQ(Tokens.size(), 15u) << Tokens;
+  EXPECT_TOKEN(Tokens[0], tok::l_brace, TT_BlockLBrace);
+  EXPECT_BRACE_KIND(Tokens[0], BK_Block);
+  EXPECT_BRACE_KIND(Tokens[8], BK_BracedInit);
+  EXPECT_BRACE_KIND(Tokens[11], BK_BracedInit);
+  EXPECT_BRACE_KIND(Tokens[13], BK_Block);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsElaboratedTypeSpecifier) {