[PATCH RFA] build: add -Wconditionally-supported to strict_warn [PR64867]

[PATCH RFA] build: add -Wconditionally-supported to strict_warn [PR64867]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, OK for trunk?

-- 8< --

The PR (which isn't resolved by this commit) pointed out to me that GCC
should build with -Wconditionally-supported to support bootstrapping with a
C++11 compiler that makes different choices.

	PR c++/64867

gcc/ChangeLog:

	* configure.ac (strict_warn): Add -Wconditionally-supported.
	* configure: Regenerate.
---
 gcc/configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/configure.ac b/gcc/configure.ac
index 7ca08726efa..12771fc292c 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -580,7 +580,7 @@ ACX_PROG_CC_WARNING_OPTS(
 	m4_quote(m4_do([-Wstrict-prototypes -Wmissing-prototypes ],
 		       [])), [c_loose_warn])
 ACX_PROG_CXX_WARNING_OPTS(
-	m4_quote(m4_do([-Wmissing-format-attribute ],
+	m4_quote(m4_do([-Wmissing-format-attribute ], [-Wconditionally-supported ],
 		       [-Woverloaded-virtual])), [strict_warn])
 ACX_PROG_CC_WARNING_OPTS(
 	m4_quote(m4_do([-Wold-style-definition -Wc++-compat])), [c_strict_warn])

base-commit: d19aa6af6634b1e97f38431ad091f3b3f12baf2f
-- 
2.31.1

Re: [PATCH PING] build: add -Wconditionally-supported to strict_warn [PR64867]

[Jason Merrill]

On 12/6/22 08:26, Jason Merrill wrote:
> Tested x86_64-pc-linux-gnu, OK for trunk?

Ping.

> -- 8< --
> 
> The PR (which isn't resolved by this commit) pointed out to me that GCC
> should build with -Wconditionally-supported to support bootstrapping with a
> C++11 compiler that makes different choices.
> 
> 	PR c++/64867
> 
> gcc/ChangeLog:
> 
> 	* configure.ac (strict_warn): Add -Wconditionally-supported.
> 	* configure: Regenerate.
> ---
>   gcc/configure.ac | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gcc/configure.ac b/gcc/configure.ac
> index 7ca08726efa..12771fc292c 100644
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -580,7 +580,7 @@ ACX_PROG_CC_WARNING_OPTS(
>   	m4_quote(m4_do([-Wstrict-prototypes -Wmissing-prototypes ],
>   		       [])), [c_loose_warn])
>   ACX_PROG_CXX_WARNING_OPTS(
> -	m4_quote(m4_do([-Wmissing-format-attribute ],
> +	m4_quote(m4_do([-Wmissing-format-attribute ], [-Wconditionally-supported ],
>   		       [-Woverloaded-virtual])), [strict_warn])
>   ACX_PROG_CC_WARNING_OPTS(
>   	m4_quote(m4_do([-Wold-style-definition -Wc++-compat])), [c_strict_warn])
> 
> base-commit: d19aa6af6634b1e97f38431ad091f3b3f12baf2f

Re: [PATCH RFA] build: add -Wconditionally-supported to strict_warn [PR64867]

[Jeff Law]

On 12/6/22 06:26, Jason Merrill via Gcc-patches wrote:
> Tested x86_64-pc-linux-gnu, OK for trunk?
> 
> -- 8< --
> 
> The PR (which isn't resolved by this commit) pointed out to me that GCC
> should build with -Wconditionally-supported to support bootstrapping with a
> C++11 compiler that makes different choices.
> 
> 	PR c++/64867
> 
> gcc/ChangeLog:
> 
> 	* configure.ac (strict_warn): Add -Wconditionally-supported.
> 	* configure: Regenerate.
OK.  I wonder if it'll trip anything, particularly in the target files.

Jeff

Re: [PATCH RFA] build: add -Wconditionally-supported to strict_warn [PR64867]

[Jason Merrill]

[-- Attachment #1: Type: text/plain, Size: 657 bytes --]

On 12/16/22 19:52, Jeff Law wrote:
> 
> 
> On 12/6/22 06:26, Jason Merrill via Gcc-patches wrote:
>> Tested x86_64-pc-linux-gnu, OK for trunk?
>>
>> -- 8< --
>>
>> The PR (which isn't resolved by this commit) pointed out to me that GCC
>> should build with -Wconditionally-supported to support bootstrapping 
>> with a
>> C++11 compiler that makes different choices.
>>
>>     PR c++/64867
>>
>> gcc/ChangeLog:
>>
>>     * configure.ac (strict_warn): Add -Wconditionally-supported.
>>     * configure: Regenerate.
> OK.  I wonder if it'll trip anything, particularly in the target files.

Also applying this to fix a breakage reported on IRC:


[-- Attachment #2: 0001-build-avoid-Wconditionally-supported-on-qsort-check.patch --]
[-- Type: text/x-patch, Size: 1212 bytes --]

From eef0873b6906d5404a04b817377c33f585cf3f21 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Mon, 19 Dec 2022 15:41:36 -0500
Subject: [PATCH] build: avoid -Wconditionally-supported on qsort check
To: gcc-patches@gcc.gnu.org

It's OK to rely on conditionally-supported features in #if CHECKING_P, since
that isn't defined in stage 1.

gcc/ChangeLog:

	* sort.cc: Disable -Wconditionally-supported in
	CHECKING_P code.
---
 gcc/sort.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gcc/sort.cc b/gcc/sort.cc
index 87f826818bb..eeddfcf1fef 100644
--- a/gcc/sort.cc
+++ b/gcc/sort.cc
@@ -237,6 +237,10 @@ do {                                            \
 }
 
 #if CHECKING_P
+  /* Don't complain about cast from void* to function pointer.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconditionally-supported"
+
 /* Adapter for using two-argument comparators in functions expecting the
    three-argument sort_r_cmp_fn type.  */
 static int
@@ -266,6 +270,7 @@ gcc_qsort (void *vbase, size_t n, size_t size, cmp_fn *cmp)
     free (buf);
 #if CHECKING_P
   qsort_chk (vbase, n, size, cmp2to3, (void*)cmp);
+#pragma GCC diagnostic pop
 #endif
 }
 
-- 
2.31.1