[clang] [C++][Modules] A module directive may only appear as the first preprocessing tokens in a file (PR #144233)

[via cfe-commits]

================
@@ -3725,13 +3727,21 @@ bool Lexer::Lex(Token &Result) {
     HasLeadingEmptyMacro = false;
   }
 
+  if (IsFirstPPToken) {
+    Result.setFlag(Token::FirstPPToken);
+    IsFirstPPToken = false;
+  }
+
   bool atPhysicalStartOfLine = IsAtPhysicalStartOfLine;
   IsAtPhysicalStartOfLine = false;
   bool isRawLex = isLexingRawMode();
   (void) isRawLex;
   bool returnedToken = LexTokenInternal(Result, atPhysicalStartOfLine);
   // (After the LexTokenInternal call, the lexer might be destroyed.)
   assert((returnedToken || !isRawLex) && "Raw lex must succeed");
+
+  if (returnedToken && Result.isFirstPPToken() && PP)
+    PP->setFirstPPToken(Result);
----------------
yronglin wrote:

Fixed

https://github.com/llvm/llvm-project/pull/144233