[FFmpeg-devel] [PATCH] configure: force erroring out in check_disable_warning() if an option doesn't exists

[James Almer]

On 10/13/2017 11:30 AM, Hendrik Leppkes wrote:
> On Fri, Oct 13, 2017 at 4:14 PM, James Almer <jamrial at gmail.com> wrote:
>> On 10/12/2017 6:30 PM, James Almer wrote:
>>> Should prevent some options from being added to cflags when they
>>> don't exist and the compiler only warns about it.
>>>
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>> I figure this is safer than adding
>>> -Werror=unused-command-line-argument -Werror=unknown-warning-option
>>> as Ronald suggested.
>>>
>>>  configure | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/configure b/configure
>>> index ade67a31bb..c7962665f1 100755
>>> --- a/configure
>>> +++ b/configure
>>> @@ -6370,7 +6370,7 @@ fi
>>>
>>>  check_disable_warning(){
>>>      warning_flag=-W${1#-Wno-}
>>> -    test_cflags $warning_flag && add_cflags $1
>>> +    test_cflags -Werror $warning_flag && add_cflags $1
>>>  }
>>>
>>>  check_disable_warning -Wno-parentheses
>>
>> Ping. This or a similar solution has been annoying Clang users for some
>> days now and should be part of the 3.4 release.
> 
> I wonder if a general -Werror is really "safer", do these tests really
> execute without any other warnings, which might trigger a false
> negative? We're not exactly making it compile a proper source file, so
> it might warn about random things.
> 
> - Hendrik

Ok, what about the attached patch, then?

Both -Werror=unused-command-line-argument and
-Werror=unknown-warning-option are not supported by gcc, so they
generate an error and would break every check.
This hopefully only uses them where they exist.
-------------- next part --------------
From 0e305676e6b30ed3274fcbb4f31e318d41cac66d Mon Sep 17 00:00:00 2001
From: James Almer <jamrial at gmail.com>
Date: Fri, 13 Oct 2017 12:34:34 -0300
Subject: [PATCH] configure: force erroring out in check_disable_warning() if
 an option doesn't exists

Should prevent some options from being added to cflags when they
don't exist and the compiler only warns about it.

Signed-off-by: James Almer <jamrial at gmail.com>
---
 configure | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index 64fd088208..87087f02e4 100755
--- a/configure
+++ b/configure
@@ -6370,9 +6370,14 @@ fi
 
 check_disable_warning(){
     warning_flag=-W${1#-Wno-}
-    test_cflags $warning_flag && add_cflags $1
+    test_cflags $unknown_warning_flags $warning_flag && add_cflags $1
 }
 
+test_cflags -Werror=unused-command-line-argument &&
+    append unknown_warning_flags "-Werror=unused-command-line-argument"
+test_cflags -Werror=unknown-warning-option &&
+    append unknown_warning_flags "-Werror=unknown-warning-option"
+
 check_disable_warning -Wno-parentheses
 check_disable_warning -Wno-switch
 check_disable_warning -Wno-format-zero-length
-- 
2.14.2