update C2x diagnostic handling logic

Author: a-tarasyuk

clang/lib/Sema/SemaType.cpp

@@ -1621,9 +1621,11 @@ QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
       Diag(Loc, DiagID) << EltTy;
       Qs.removeRestrict();
     } else {
-      if (!getLangOpts().C23 && T->isArrayType()) {
-        Diag(Loc, diag::ext_restrict_on_array_of_pointers_c23);
-        Diag(Loc, diag::warn_c23_compat_restrict_on_array_of_pointers);
+      if (T->isArrayType()) {
+        if (getLangOpts().C23)
+          Diag(Loc, diag::warn_c23_compat_restrict_on_array_of_pointers);
+        else
+          Diag(Loc, diag::ext_restrict_on_array_of_pointers_c23);
       }
     }
   }

clang/test/Sema/pre-c2x-restrict-qualifier.c

@@ -1,25 +1,25 @@
 // RUN: %clang_cc1 -std=c23 -fsyntax-only -verify %s
 // RUN: %clang_cc1 -std=c17 -fsyntax-only -pedantic -verify=pedantic %s
-// RUN: %clang_cc1 -std=c17 -fsyntax-only -Wpre-c2x-compat -verify=pre-c2x-compat %s
+// RUN: %clang_cc1 -std=c2x -fsyntax-only -Wpre-c2x-compat -verify=c2x-compat %s
 
 typedef int (*T1)[2];
 restrict T1 t1;
 
 typedef int *T2[2];
 restrict T2 t2;         // pedantic-warning {{'restrict' qualifier on an array of pointers is a C23 extension}} \
-                        // pre-c2x-compat-warning {{'restrict' qualifier on an array of pointers is incompatible with C standards before C23}}
+                        // c2x-compat-warning {{'restrict' qualifier on an array of pointers is incompatible with C standards before C23}}
 
 typedef int *T3[2][2];
 restrict T3 t3;         // pedantic-warning {{'restrict' qualifier on an array of pointers is a C23 extension}} \
-                        // pre-c2x-compat-warning {{'restrict' qualifier on an array of pointers is incompatible with C standards before C23}}
+                        // c2x-compat-warning {{'restrict' qualifier on an array of pointers is incompatible with C standards before C23}}
 
 typedef int (*t4)();    // pedantic-warning {{a function declaration without a prototype is deprecated in all versions of C}}
 typedef t4 t5[2];
 typedef t5 restrict t6; // expected-error {{pointer to function type 'int (void)' may not be 'restrict' qualified}} \
                         // pedantic-error {{pointer to function type 'int ()' may not be 'restrict' qualified}} \
-                        // pre-c2x-compat-error {{pointer to function type 'int ()' may not be 'restrict' qualified}}
+                        // c2x-compat-error {{pointer to function type 'int (void)' may not be 'restrict' qualified}}
 
 typedef int t7[2];
 typedef t7 restrict t8; // expected-error {{restrict requires a pointer or reference ('t7' (aka 'int[2]') is invalid)}} \
                         // pedantic-error {{restrict requires a pointer or reference ('t7' (aka 'int[2]') is invalid)}} \
-                        // pre-c2x-compat-error {{restrict requires a pointer or reference ('t7' (aka 'int[2]') is invalid}}
+                        // c2x-compat-error {{restrict requires a pointer or reference ('t7' (aka 'int[2]') is invalid}}