[clang] [clang] fix comment lexing of special command names (PR #152943)

[via cfe-commits]

https://github.com/mdenson updated https://github.com/llvm/llvm-project/pull/152943

>From 475d513b79339da73f322f9b7d14122f103998a5 Mon Sep 17 00:00:00 2001
From: Brock Denson <brock.denson at virscient.com>
Date: Wed, 6 Aug 2025 21:50:02 -0500
Subject: [PATCH] [clang] fix comment parsing of special commands with
 non-alphanumeric names. fixes #33296

---
 clang/lib/AST/CommentLexer.cpp      | 2 +-
 clang/test/AST/ast-dump-comment.cpp | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/clang/lib/AST/CommentLexer.cpp b/clang/lib/AST/CommentLexer.cpp
index e19c2327aebdc..a0903d0903dd8 100644
--- a/clang/lib/AST/CommentLexer.cpp
+++ b/clang/lib/AST/CommentLexer.cpp
@@ -214,7 +214,7 @@ bool isCommandNameStartCharacter(char C) {
 }
 
 bool isCommandNameCharacter(char C) {
-  return isAlphanumeric(C);
+  return isAsciiIdentifierContinue(C, false);
 }
 
 const char *skipCommandName(const char *BufferPtr, const char *BufferEnd) {
diff --git a/clang/test/AST/ast-dump-comment.cpp b/clang/test/AST/ast-dump-comment.cpp
index 40c3edb62821b..2b4ec63765f41 100644
--- a/clang/test/AST/ast-dump-comment.cpp
+++ b/clang/test/AST/ast-dump-comment.cpp
@@ -131,3 +131,9 @@ void Test_TemplatedFunctionVariadic(int arg, ...);
 // CHECK:        ParamCommandComment{{.*}} [in] implicitly Param="..."
 // CHECK-NEXT:     ParagraphComment
 // CHECK-NEXT:       TextComment{{.*}} Text=" More arguments"
+
+/// \thread_safe test for underscore in special command
+int Test_UnderscoreInSpecialCommand;
+// CHECK:      VarDecl{{.*}}Test_UnderscoreInSpecialCommand 'int'
+// CHECK:        InlineCommandComment{{.*}} Name="thread_safe" RenderNormal
+// CHECK-NEXT:     TextComment{{.*}} Text=" test for underscore in special command"
\ No newline at end of file