From 412f7d58ce2a949b9b70dd942dbdcc646e7b3fee Mon Sep 17 00:00:00 2001
From: tanhongmin <tanhongmin1@huawei.com>
Date: Fri, 27 Jun 2025 06:42:09 +0000
Subject: [PATCH] [Parser] Fix the recognition issue of the `impl` keyword and
 optimize the parsing of `impl` trait declarations.

Previously, in the definition of the marker, the `impl` keyword was not correctly recognized as a BSC keyword, but was instead treated as an identifier for lexical analysis.

This patch adds `impl` as the correct BSC keyword to `TokenKinds.def` and refactors the parsing of `impl` trait declarations in the following ways:
- Moves the recognition of the `impl` keyword directly into the main parsing switch statement
- Removes the separate `ShouldParseImplTraitDecl` static function
- Simplifies the condition checks for `impl` trait declarations

This enhances the reliability and consistency of BSC interface parsing.
---
 clang/include/clang/Basic/TokenKinds.def      |  1 +
 clang/lib/Parse/Parser.cpp                    | 22 +++++--------------
 .../impl_keyword/impl_keyword.cbs             | 19 ++++++++++++++++
 3 files changed, 26 insertions(+), 16 deletions(-)
 create mode 100644 clang/test/BSC/Negative/Trait/GenericTrait/impl_keyword/impl_keyword.cbs

diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
index 0def6903efe1..4a428d77ef14 100644
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -478,6 +478,7 @@ KEYWORD(await                       , KEYBSC)
 KEYWORD(owned                       , KEYBSC)
 KEYWORD(borrow                      , KEYBSC)
 KEYWORD(trait                       , KEYBSC)
+KEYWORD(impl                        , KEYBSC)
 KEYWORD(safe                        , KEYBSC)
 KEYWORD(unsafe                      , KEYBSC)
 KEYWORD(__conditional               , KEYBSC)
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 178d939e3056..2bd24ffe8ae2 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -785,19 +785,6 @@ bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result,
   return false;
 }
 
-#if ENABLE_BSC
-static bool ShouldParseImplTraitDecl(Sema &S, const Token &Tok,
-                                     const Token &TokNext) {
-  if (!S.getLangOpts().BSC)
-    return false;
-  if (Tok.is(tok::identifier) &&
-      Tok.getIdentifierInfo()->getName().equals("impl"))
-    if (TokNext.isOneOf(tok::kw_trait, tok::identifier))
-      return true;
-  return false;
-}
-#endif
-
 /// ParseExternalDeclaration:
 ///
 /// The `Attrs` that are passed in are C++11 attributes and appertain to the
@@ -1059,13 +1046,16 @@ Parser::DeclGroupPtrTy Parser::ParseExternalDeclaration(ParsedAttributes &Attrs,
     SkipUntil(tok::semi);
     return nullptr;
 
-  default:
-  dont_know:
 #if ENABLE_BSC
+  case tok::kw_impl:
     if (getLangOpts().BSC &&
-        ShouldParseImplTraitDecl(Actions, Tok, NextToken()))
+        NextToken().isOneOf(tok::kw_trait, tok::identifier))
       return ParseImplTraitDeclaration();
+#endif
 
+  default:
+  dont_know:
+#if ENABLE_BSC
     // parse BSC template declaration
     // TODO: change if entrance condition, abandon isBSCTemplateDecl()
     if (isBSCTemplateDecl(Tok)) {
diff --git a/clang/test/BSC/Negative/Trait/GenericTrait/impl_keyword/impl_keyword.cbs b/clang/test/BSC/Negative/Trait/GenericTrait/impl_keyword/impl_keyword.cbs
new file mode 100644
index 000000000000..b414722c0fc8
--- /dev/null
+++ b/clang/test/BSC/Negative/Trait/GenericTrait/impl_keyword/impl_keyword.cbs
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -verify %s
+
+trait T {
+    void f(This* this);
+};
+
+void int::f(int* this) {};
+
+impl trait T for int;
+
+struct S { // expected-error{{expected ';' at end of declaration list}}
+    impl x; // expected-error{{type name requires a specifier or qualifier}} expected-error{{expected member name or ';' after declaration specifiers}}
+};
+
+struct S2<impl> {}; // expected-error{{expected expression}} expected-error{{explicit specialization of undeclared template struct 'S2'}}
+
+int main() {
+    int impl = 1; // expected-error{{expected identifier or '('}}
+}
\ No newline at end of file
-- 
Gitee