[Sema][SVE] Reject "delete" with sizeless types

Sizeless types can't be used with "new", so it doesn't make sense
to use them with "delete" either.  The SVE ACLE therefore doesn't
allow that.

This is slightly stronger than for normal incomplete types, since:

  struct S;
  void f(S *s) { delete s; }

is (by necessity) just a default-on warning rather than an error.

Differential Revision: https://reviews.llvm.org/D76219

Author: rsandifo-arm

clang/lib/Sema/SemaExprCXX.cpp

@@ -3467,7 +3467,8 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
       // this, so we treat it as a warning unless we're in a SFINAE context.
       Diag(StartLoc, diag::ext_delete_void_ptr_operand)
         << Type << Ex.get()->getSourceRange();
-    } else if (Pointee->isFunctionType() || Pointee->isVoidType()) {
+    } else if (Pointee->isFunctionType() || Pointee->isVoidType() ||
+               Pointee->isSizelessType()) {
       return ExprError(Diag(StartLoc, diag::err_delete_operand)
         << Type << Ex.get()->getSourceRange());
     } else if (!Pointee->isDependentType()) {

clang/test/SemaCXX/sizeless-1.cpp

@@ -420,6 +420,9 @@ void cxx_only(int sel) {
   new (global_int8_ptr) svint8_t();   // expected-error {{allocation of sizeless type 'svint8_t'}}
   new (global_int8_ptr) svint8_t[10]; // expected-error {{allocation of sizeless type 'svint8_t'}}
 
+  delete global_int8_ptr;   // expected-error {{cannot delete expression of type 'svint8_t *'}}
+  delete[] global_int8_ptr; // expected-error {{cannot delete expression of type 'svint8_t *'}}
+
   local_int8.~__SVInt8_t(); // expected-error {{object expression of non-scalar type 'svint8_t' (aka '__SVInt8_t') cannot be used in a pseudo-destructor expression}}
 
   (void)svint8_t();