[clang] [C++][Modules][Preprocessor] Clang should not convert a import preprocessing token to contextual keyword if a digraph character following import (PR #191004)

[Corentin Jabot via cfe-commits]

================
@@ -1380,13 +1380,34 @@ bool Preprocessor::HandleModuleContextualKeyword(Token &Result) {
   llvm::SaveAndRestore<bool> SavedParsingPreprocessorDirective(
       CurPPLexer->ParsingPreprocessorDirective, true);
 
-  // The next token may be an angled string literal after import keyword.
-  llvm::SaveAndRestore<bool> SavedParsingFilemame(
-      CurPPLexer->ParsingFilename,
-      Result.getIdentifierInfo()->isImportKeyword());
+  bool ParsingFilename = false;
+  if (Result.getIdentifierInfo()->isImportKeyword()) {
+    if (getLangOpts().Digraphs && CurLexer &&
+        CurLexer->getCurrentBufferOffset() + 2 < CurLexer->getBuffer().size()) {
+      // If the import preprocessing token folled by a digraph character '<:',
+      // the import preprocessing should not traited as a import contextual
+      // keyword. Eg.
+      //    int
+      //    import <:10
+      //    :>;
+      //
+      // This is a array definition, and equivalent to:
+      //
+      //    int import[10];
+      const char *CurPtr = CurLexer->getBufferLocation();
----------------
cor3ntin wrote:

```suggestion
      // If the import preprocessing token is followed by a digraph such as '<:',
      // the import preprocessing should not be treated as an import contextual
      // keyword. Eg.
      //    int
      //    import <:10
      //    :>;
      //
      // This is an array definition and equivalent to `int import[10];`
      const char *CurPtr = CurLexer->getBufferLocation();
```

https://github.com/llvm/llvm-project/pull/191004