[FOLD] address review feedback, reword diagnostic

Author: sdkrystian

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -373,8 +373,6 @@ def err_requires_clause_must_appear_after_trailing_return : Error<
   "trailing return type must appear before trailing requires clause">;
 def err_requires_clause_on_declarator_not_declaring_a_function : Error<
   "trailing requires clause can only be used when declaring a function">;
-def err_requires_clause_explicit_object_parameter: Error<
-  "a requires clause cannot have an explicit object parameter">;
 def err_requires_clause_inside_parens : Error<
   "trailing requires clause should be placed outside parentheses">;
 def ext_auto_storage_class : ExtWarn<
@@ -865,6 +863,8 @@ def err_empty_requires_expr : Error<
   "a requires expression must contain at least one requirement">;
 def err_requires_expr_parameter_list_ellipsis : Error<
   "varargs not allowed in requires expression">;
+def err_requires_expr_explicit_object_parameter: Error<
+  "a requires expression cannot have an explicit object parameter">;
 def err_expected_semi_requirement : Error<
   "expected ';' at end of requirement">;
 def err_requires_expr_missing_arrow : Error<

clang/lib/Parse/ParseDecl.cpp

@@ -7673,7 +7673,7 @@ void Parser::ParseParameterDeclarationClause(
       // The parameter-declaration-list of a requires-expression is not such
       // a context.
       if (DeclaratorCtx == DeclaratorContext::RequiresExpr)
-        Diag(ThisLoc, diag::err_requires_clause_explicit_object_parameter);
+        Diag(ThisLoc, diag::err_requires_expr_explicit_object_parameter);
     }
 
     ParseDeclarationSpecifiers(DS, /*TemplateInfo=*/ParsedTemplateInfo(),

clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p6-cxx23.cpp

@@ -1,4 +1,8 @@
 // RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify %s
 
-auto x0 = requires (this int) { true; }; // expected-error {{a requires clause cannot have an explicit object parameter}}
-auto x1 = requires (int, this int) { true; }; // expected-error {{a requires clause cannot have an explicit object parameter}}
+auto x0 = requires (this int) { true; }; // expected-error {{a requires expression cannot have an explicit object parameter}}
+auto x1 = requires (int, this int) { true; }; // expected-error {{a requires expression cannot have an explicit object parameter}}
+
+template<this auto>
+void f(); // expected-error {{expected template parameter}}
+          // expected-error@-1 {{no function template matches function template specialization 'f'}}