[PATCH v2] selftests/net: suppress clang's "variable-sized type not at the end" warning

[PATCH v2] selftests/net: suppress clang's "variable-sized type not at the end" warning

[John Hubbard]

When building with clang, via:

    make LLVM=1 -C tools/testing/selftest

...clang warns that "a variable sized type not at the end of a struct or
class is a GNU extension".

These cases are not easily changed, because they involve structs that
are part of the API. Fortunately, however, the tests seem to be doing
just fine (specifically, neither affected test runs any differently with
gcc vs. clang builds, on my test system) regardless of the warning. So,
all the warning is doing is preventing a clean build of selftests/net.

Fix this by suppressing this particular clang warning for the
selftests/net suite.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

Changes since the first version:

1) Rebased onto Linux 6.10-rc1

thanks,
John Hubbard


 tools/testing/selftests/net/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index bd01e4a0be2c..9a3b766c8781 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -6,6 +6,10 @@ CFLAGS += -I../../../../usr/include/ $(KHDR_INCLUDES)
 # Additional include paths needed by kselftest.h
 CFLAGS += -I../
 
+ifneq ($(LLVM),)
+    CFLAGS += -Wno-gnu-variable-sized-type-not-at-end
+endif
+
 TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \
 	      rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh
 TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh

base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b
-- 
2.45.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v2] selftests/net: suppress clang's "variable-sized type not at the end" warning

[Nathan Chancellor]

On Mon, May 27, 2024 at 02:36:41PM -0700, John Hubbard wrote:
> When building with clang, via:
> 
>     make LLVM=1 -C tools/testing/selftest
> 
> ...clang warns that "a variable sized type not at the end of a struct or
> class is a GNU extension".
> 
> These cases are not easily changed, because they involve structs that
> are part of the API. Fortunately, however, the tests seem to be doing
> just fine (specifically, neither affected test runs any differently with
> gcc vs. clang builds, on my test system) regardless of the warning. So,
> all the warning is doing is preventing a clean build of selftests/net.
> 
> Fix this by suppressing this particular clang warning for the
> selftests/net suite.
> 
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
> 
> Changes since the first version:
> 
> 1) Rebased onto Linux 6.10-rc1
> 
> thanks,
> John Hubbard
> 
> 
>  tools/testing/selftests/net/Makefile | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index bd01e4a0be2c..9a3b766c8781 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -6,6 +6,10 @@ CFLAGS += -I../../../../usr/include/ $(KHDR_INCLUDES)
>  # Additional include paths needed by kselftest.h
>  CFLAGS += -I../
>  
> +ifneq ($(LLVM),)
> +    CFLAGS += -Wno-gnu-variable-sized-type-not-at-end

For what it's worth, the main kernel has -Wno-gnu because there is
little point in warning about the use of GNU extensions when building
with '-std=gnu...'. It may be worth doing this anywhere that uses a GNU
standard in the selftests but I guess it depends on how noisy things
are.

> +endif
> +
>  TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \
>  	      rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh
>  TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh
> 
> base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b
> -- 
> 2.45.1
> 
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v2] selftests/net: suppress clang's "variable-sized type not at the end" warning

[John Hubbard]

On 5/28/24 1:39 PM, Nathan Chancellor wrote:
> On Mon, May 27, 2024 at 02:36:41PM -0700, John Hubbard wrote:
...
>> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
>> index bd01e4a0be2c..9a3b766c8781 100644
>> --- a/tools/testing/selftests/net/Makefile
>> +++ b/tools/testing/selftests/net/Makefile
>> @@ -6,6 +6,10 @@ CFLAGS += -I../../../../usr/include/ $(KHDR_INCLUDES)
>>   # Additional include paths needed by kselftest.h
>>   CFLAGS += -I../
>>   
>> +ifneq ($(LLVM),)
>> +    CFLAGS += -Wno-gnu-variable-sized-type-not-at-end
> 
> For what it's worth, the main kernel has -Wno-gnu because there is
> little point in warning about the use of GNU extensions when building
> with '-std=gnu...'. It may be worth doing this anywhere that uses a GNU
> standard in the selftests but I guess it depends on how noisy things
> are.

I think there might be one or two other cases like this that I haven't
gotten around to, so yes you are right, this probably should be moved
into lib.mk instead.

I'll do that in a v3.

> 
>> +endif
>> +
>>   TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \
>>   	      rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh
>>   TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh
>>
>> base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b
>> -- 
>> 2.45.1
>>
>>

thanks,
-- 
John Hubbard
NVIDIA


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel