[PATCH] Fix -Wunused-var-35.C (was Re: [PATCH][C++] Improve compile-time by ordering expensive checks last)

[Jakub Jelinek <jakub@redhat.com>]

On Thu, Apr 25, 2019 at 01:09:00PM +0200, Rainer Orth wrote:
> > 	cp/
> > 	* call.c (null_ptr_cst_p): Order checks according to expensiveness.
> > 	(conversion_null_warnings): Likewise.
> > 	* typeck.c (same_type_ignoring_top_level_qualifiers_p): Return
> > 	early if type1 == type2.
> 
> this patch caused
> 
> +XPASS: g++.dg/warn/Wunused-var-35.C  -std=gnu++98 bug (test for warnings, line 14)
> 
> First seen on i386-pc-solaris2.11 and sparc-sun-solaris2.11, according
> to gcc-testresults everywhere.  Confirmed by reverting the patch locally
> and re-testing the affected testcase.

I can reproduce that too, seems to be the
@@ -6896,8 +6897,8 @@
     }
   /* Handle zero as null pointer warnings for cases other
      than EQ_EXPR and NE_EXPR */
-  else if (null_ptr_cst_p (expr) &&
-	   (TYPE_PTR_OR_PTRMEM_P (totype) || NULLPTR_TYPE_P (totype)))
+  else if ((TYPE_PTR_OR_PTRMEM_P (totype) || NULLPTR_TYPE_P (totype))
+	   && null_ptr_cst_p (expr))
     {
       location_t loc = get_location_for_expr_unwinding_for_system_header (expr);
       maybe_warn_zero_as_null_pointer_constant (expr, loc);
hunk.  The Wunused-var-35.C patch hasn't been posted to gcc-patches, but
judging from the corresponding PR, I'd say the right thing is below.

Regtested on x86_64-linux and i686-linux, ok for trunk?

2019-04-25  Jakub Jelinek  <jakub@redhat.com>

	PR c++/44648
	* g++.dg/warn/Wunused-var-35.C: Remove xfail.

--- gcc/testsuite/g++.dg/warn/Wunused-var-35.C.jj	2019-02-04 09:44:31.365413407 +0100
+++ gcc/testsuite/g++.dg/warn/Wunused-var-35.C	2019-04-25 13:24:49.717065815 +0200
@@ -11,9 +11,8 @@ int main()
   else
     return 1;
 
-  if (const bool b2 = 1) // { dg-warning "\\\[-Wunused-variable\\\]" "bug" { xfail c++98_only } }
+  if (const bool b2 = 1) // { dg-warning "\\\[-Wunused-variable\\\]" }
     return 0;
   else
     return 1;
 }
-


	Jakub