PR c++/80473 allow suppressing notes about over-aligned new

Message ID 20170420150920.GO3412@redhat.com
State New
Headers show

Commit Message

Jonathan Wakely April 20, 2017, 3:09 p.m.
This suppresses the notes about over-aligned new when the
corresponding warning is suppressed, either by -w or because it's in a
system header (as in PR 80390, which I originally tried to fix in the
library).

OK for trunk? And gcc-7-branch after 7.1 is released?

Is this the right place for the new test?


gcc/cp:

	PR c++/80473
	* init.c (build_new_1): Suppress notes about over-aligned new when
	the warning is suppressed.

gcc/testsuite:

	PR c++/80473
	* init.c (build_new_1): Suppress notes in system headers.
	PR c++/80473
	* g++.dg/diagnostic/pr80473.C: New test.

Comments

Jakub Jelinek April 20, 2017, 3:22 p.m. | #1
On Thu, Apr 20, 2017 at 04:09:20PM +0100, Jonathan Wakely wrote:
> --- a/gcc/cp/init.c
> +++ b/gcc/cp/init.c
> @@ -3128,11 +3128,14 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
>      {
>        warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
>  	       "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type));
> -      inform (input_location, "uses %qD, which does not have an alignment "
> -	      "parameter", alloc_fn);
> -      if (!aligned_new_threshold)
> -	inform (input_location, "use %<-faligned-new%> to enable C++17 "
> -				"over-aligned new support");
> +      if (diagnostic_report_warnings_p (global_dc, input_location))
> +	{
> +	  inform (input_location, "uses %qD, which does not have an alignment "
> +		  "parameter", alloc_fn);
> +	  if (!aligned_new_threshold)
> +	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
> +				    "over-aligned new support");
> +	}

This looks weird.  I'd expect instead:
      if (warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
		   "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type)))
	{
	  inform (input_location, "uses %qD, which does not have an alignment "
		  "parameter", alloc_fn);
	  if (!aligned_new_threshold)
	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
				    "over-aligned new support");
	}
That is a standard idiom used if some inform or later warning/error depends
on whether earlier warning/error has been diagnosed.

If that works, this is ok for trunk and 7.1 (we don't have a rc1 yet, it is
ok now).

	Jakub
Jonathan Wakely April 20, 2017, 3:32 p.m. | #2
On 20/04/17 17:22 +0200, Jakub Jelinek wrote:
>On Thu, Apr 20, 2017 at 04:09:20PM +0100, Jonathan Wakely wrote:
>> --- a/gcc/cp/init.c
>> +++ b/gcc/cp/init.c
>> @@ -3128,11 +3128,14 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
>>      {
>>        warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
>>  	       "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type));
>> -      inform (input_location, "uses %qD, which does not have an alignment "
>> -	      "parameter", alloc_fn);
>> -      if (!aligned_new_threshold)
>> -	inform (input_location, "use %<-faligned-new%> to enable C++17 "
>> -				"over-aligned new support");
>> +      if (diagnostic_report_warnings_p (global_dc, input_location))
>> +	{
>> +	  inform (input_location, "uses %qD, which does not have an alignment "
>> +		  "parameter", alloc_fn);
>> +	  if (!aligned_new_threshold)
>> +	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
>> +				    "over-aligned new support");
>> +	}
>
>This looks weird.  I'd expect instead:
>      if (warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
>		   "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type)))
>	{
>	  inform (input_location, "uses %qD, which does not have an alignment "
>		  "parameter", alloc_fn);
>	  if (!aligned_new_threshold)
>	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
>				    "over-aligned new support");
>	}
>That is a standard idiom used if some inform or later warning/error depends
>on whether earlier warning/error has been diagnosed.

Aha, thanks.

>If that works, this is ok for trunk and 7.1 (we don't have a rc1 yet, it is
>ok now).

OK, I'll test it now.
Marek Polacek April 20, 2017, 3:33 p.m. | #3
On Thu, Apr 20, 2017 at 05:22:00PM +0200, Jakub Jelinek wrote:
> On Thu, Apr 20, 2017 at 04:09:20PM +0100, Jonathan Wakely wrote:
> > --- a/gcc/cp/init.c
> > +++ b/gcc/cp/init.c
> > @@ -3128,11 +3128,14 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
> >      {
> >        warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
> >  	       "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type));
> > -      inform (input_location, "uses %qD, which does not have an alignment "
> > -	      "parameter", alloc_fn);
> > -      if (!aligned_new_threshold)
> > -	inform (input_location, "use %<-faligned-new%> to enable C++17 "
> > -				"over-aligned new support");
> > +      if (diagnostic_report_warnings_p (global_dc, input_location))
> > +	{
> > +	  inform (input_location, "uses %qD, which does not have an alignment "
> > +		  "parameter", alloc_fn);
> > +	  if (!aligned_new_threshold)
> > +	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
> > +				    "over-aligned new support");
> > +	}
> 
> This looks weird.  I'd expect instead:
>       if (warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
> 		   "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type)))
> 	{
> 	  inform (input_location, "uses %qD, which does not have an alignment "
> 		  "parameter", alloc_fn);
> 	  if (!aligned_new_threshold)
> 	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
> 				    "over-aligned new support");
> 	}
> That is a standard idiom used if some inform or later warning/error depends
> on whether earlier warning/error has been diagnosed.
 
Yes.

> If that works, this is ok for trunk and 7.1 (we don't have a rc1 yet, it is
> ok now).

One more thing, the test passes even without the patch.  Did you mean to add
// { dg-options "-Wall -w" }
?

	Marek
Jonathan Wakely April 20, 2017, 4:43 p.m. | #4
On 20/04/17 17:33 +0200, Marek Polacek wrote:
>On Thu, Apr 20, 2017 at 05:22:00PM +0200, Jakub Jelinek wrote:
>> On Thu, Apr 20, 2017 at 04:09:20PM +0100, Jonathan Wakely wrote:
>> > --- a/gcc/cp/init.c
>> > +++ b/gcc/cp/init.c
>> > @@ -3128,11 +3128,14 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
>> >      {
>> >        warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
>> >  	       "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type));
>> > -      inform (input_location, "uses %qD, which does not have an alignment "
>> > -	      "parameter", alloc_fn);
>> > -      if (!aligned_new_threshold)
>> > -	inform (input_location, "use %<-faligned-new%> to enable C++17 "
>> > -				"over-aligned new support");
>> > +      if (diagnostic_report_warnings_p (global_dc, input_location))
>> > +	{
>> > +	  inform (input_location, "uses %qD, which does not have an alignment "
>> > +		  "parameter", alloc_fn);
>> > +	  if (!aligned_new_threshold)
>> > +	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
>> > +				    "over-aligned new support");
>> > +	}
>>
>> This looks weird.  I'd expect instead:
>>       if (warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
>> 		   "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type)))
>> 	{
>> 	  inform (input_location, "uses %qD, which does not have an alignment "
>> 		  "parameter", alloc_fn);
>> 	  if (!aligned_new_threshold)
>> 	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
>> 				    "over-aligned new support");
>> 	}
>> That is a standard idiom used if some inform or later warning/error depends
>> on whether earlier warning/error has been diagnosed.
>
>Yes.
>
>> If that works, this is ok for trunk and 7.1 (we don't have a rc1 yet, it is
>> ok now).
>
>One more thing, the test passes even without the patch.  Did you mean to add
>// { dg-options "-Wall -w" }
>?

Good catch. My original testcase used <type_traits> but I changed it
to not depend on the library, and didn't fix the dg-options.

Patch

commit 66697a6551dd13715c2156ac6b2d5969010c12db
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Apr 20 15:24:09 2017 +0100

    PR c++/80473 allow suppressing notes about over-aligned new
    
    gcc/cp:
    
    	PR c++/80473
    	* init.c (build_new_1): Suppress notes about over-aligned new when
    	the warning is suppressed.
    
    gcc/testsuite:
    
    	PR c++/80473
    	* g++.dg/diagnostic/pr80473.C: New test.

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index bfa9020..2e72451 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -3128,11 +3128,14 @@  build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
     {
       warning (OPT_Waligned_new_, "%<new%> of type %qT with extended "
 	       "alignment %d", elt_type, TYPE_ALIGN_UNIT (elt_type));
-      inform (input_location, "uses %qD, which does not have an alignment "
-	      "parameter", alloc_fn);
-      if (!aligned_new_threshold)
-	inform (input_location, "use %<-faligned-new%> to enable C++17 "
-				"over-aligned new support");
+      if (diagnostic_report_warnings_p (global_dc, input_location))
+	{
+	  inform (input_location, "uses %qD, which does not have an alignment "
+		  "parameter", alloc_fn);
+	  if (!aligned_new_threshold)
+	    inform (input_location, "use %<-faligned-new%> to enable C++17 "
+				    "over-aligned new support");
+	}
     }
 
   /* If we found a simple case of PLACEMENT_EXPR above, then copy it
diff --git a/gcc/testsuite/g++.dg/diagnostic/pr80473.C b/gcc/testsuite/g++.dg/diagnostic/pr80473.C
new file mode 100644
index 0000000..6a739f5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/pr80473.C
@@ -0,0 +1,14 @@ 
+// { dg-do compile { target c++11 } }
+// { dg-bogus "over-aligned new" "PR c++/80473" { target *-*-* } 0 }
+template<typename T> T&& declval();
+
+template<typename T, typename U, typename = void>
+struct is_constructible { enum { value = 0 }; };
+
+template<typename T, typename U>
+struct is_constructible<T, U, decltype(::new T(declval<U>()), void())>
+{ enum { value = 1 }; };
+
+struct alignas(64) A { int i; };
+
+constexpr bool b = is_constructible<A, A>::value;