[clang-format] Add TT_AfterPPDirective for better annotation (#121622)

For now, we only need to annotate the token after #error or #warning.

Fixes #117706.

Author: owenca

clang/lib/Format/FormatToken.h

@@ -25,6 +25,7 @@ namespace clang {
 namespace format {
 
 #define LIST_TOKEN_TYPES                                                       \
+  TYPE(AfterPPDirective)                                                       \
   TYPE(ArrayInitializerLSquare)                                                \
   TYPE(ArraySubscriptLSquare)                                                  \
   TYPE(AttributeColon)                                                         \

clang/lib/Format/TokenAnnotator.cpp

@@ -4941,6 +4941,10 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
         Right.is(TT_ModulePartitionColon)) {
       return true;
     }
+
+    if (Right.is(TT_AfterPPDirective))
+      return true;
+
     // No space between import foo:bar but keep a space between import :bar;
     if (Left.is(tok::identifier) && Right.is(TT_ModulePartitionColon))
       return false;

clang/lib/Format/UnwrappedLineParser.cpp

@@ -1030,6 +1030,12 @@ void UnwrappedLineParser::parsePPDirective() {
   case tok::pp_pragma:
     parsePPPragma();
     break;
+  case tok::pp_error:
+  case tok::pp_warning:
+    nextToken();
+    if (!eof() && Style.isCpp())
+      FormatTok->setFinalizedType(TT_AfterPPDirective);
+    [[fallthrough]];
   default:
     parsePPUnknown();
     break;
@@ -1209,9 +1215,8 @@ void UnwrappedLineParser::parsePPPragma() {
 }
 
 void UnwrappedLineParser::parsePPUnknown() {
-  do {
+  while (!eof())
     nextToken();
-  } while (!eof());
   if (Style.IndentPPDirectives != FormatStyle::PPDIS_None)
     Line->Level += PPBranchLevel + 1;
   addUnwrappedLine();

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -3635,6 +3635,13 @@ TEST_F(TokenAnnotatorTest, SwitchInMacroArgument) {
   EXPECT_TOKEN(Tokens[9], tok::l_brace, TT_FunctionLBrace);
 }
 
+TEST_F(TokenAnnotatorTest, AfterPPDirective) {
+  auto Tokens = annotate("#error -- My error message");
+
+  ASSERT_EQ(Tokens.size(), 7u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::minusminus, TT_AfterPPDirective);
+}
+
 } // namespace
 } // namespace format
 } // namespace clang