On 8/24/22 17:30, Marek Polacek wrote:
On Tue, Aug 23, 2022 at 05:27:00PM -0400, Jason Merrill wrote:
On 8/23/22 09:39, Marek Polacek wrote:
+  tree arg = CALL_EXPR_ARG (fn, 0);
+  extract_op (arg);
+  if (TREE_CODE (arg) == ADDR_EXPR)
+    arg = TREE_OPERAND (arg, 0);
+  tree type = TREE_TYPE (lhs);
+  lhs = maybe_undo_parenthesized_ref (lhs);
+  STRIP_ANY_LOCATION_WRAPPER (lhs);
+  const bool print_var_p = (DECL_P (lhs)
+                           || REFERENCE_REF_P (lhs)
+                           || TREE_CODE (lhs) == COMPONENT_REF);

Why include REFERENCE_REF_P and COMPONENT_REF?  Reference refs should be
stripped before this test, member refs aren't variables.

I'm checking REFERENCE_REF_P and COMPONENT_REF to say "moving a variable"
in #1 and #3.  The REFERENCE_REF_P check means that we also say "variable"
for #2.  Sure, "A variable is introduced by the declaration of a reference
other than a non-static data member", but I'm not sure if users care about
that here?

If I strip REFERENCE_REFs before the check then the result will be the
same.

That's what I was suggesting, yes: Strip the REFERENCE_REF so DECL_P can see the decl.

I don't see where COMPONENT_REF comes in?

Or I could keep only the DECL_P check, but then we'll say "moving
an expression" for #1 and #2, which seems strange.

struct S {
   int x;
   int &r;
   void foo () {
     x = std::move (x); // #1
     r = std::move (r); // #2
   };
};

void
foo (int &r)
{
   r = std::move (r); // #3
}

Marek


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