Fails to build on Arch Linux without -Wno-discarded-qualifiers

Problem:

Fail to build on Arch Linux without -Wno-discarded-qualifiers.

With the extra cflag above it can build successfully. But I'm not sure if I should suppress the warning blindly.

A rough Googling shows that -Wno-discarded-qualifiers was introduced in GCC 5 which is released roughly 10 years ago. I believe that ruled out Arch Linux being too bleeding edge... Or maybe it is?

Relevant details

AWS-LC commit: 728811e tagged v1.66.2

System information:

CPU architecture: x86-64
CPU name: AMD Ryzen 7 5800X
OS: Arch Linux
C Compiler: gcc 15.2.1 but I believe Arch Linux ships commit=0b99615a8aef011cff76c6caa8c09434f46598b3, not a tagged release. See gcc package in Arch

Build log:
See the gist: https://gist.github.com/5long/be83f0b1ac35b88129ca2dd3228c0c1a

Reproducible:

[174/673] Building C object crypto/CMakeFiles/crypto_objects.dir/rand_extra/urandom.c.o
FAILED: [code=1] crypto/CMakeFiles/crypto_objects.dir/rand_extra/urandom.c.o 
/usr/bin/clang -DBORINGSSL_HAVE_LIBUNWIND -DBORINGSSL_IMPLEMENTATION -DBORINGSSL_RELEASE_BUILD -I/var/tmp/makepkg/aws-lc/src/aws-lc-1.67.0/build/symbol_prefix_include -I/var/tmp/makepkg/aws-lc/src/aws-lc-1.67.0/include -march=native -O2 -pipe -fno-plt -fexceptions         -Wp,-D_FORTIFY_SOURCE=3 -Wformat -Werror=format-security         -fstack-clash-protection -fcf-protection=full         -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -g -ffile-prefix-map=/var/tmp/makepkg/aws-lc/src=/usr/src/debug/aws-lc  -flto=auto -Wextra -Wunused -Wcomment -Wchar-subscripts -Wuninitialized -Wshadow -Wwrite-strings -Wformat-security -Wunused-result -Wno-overlength-strings -Wno-cast-function-type  -Wall -fvisibility=hidden -fno-common -Wno-c11-extensions -Wvla -Wtype-limits -Wno-unused-parameter -Werror -Wformat=2 -Wsign-compare -Wmissing-field-initializers -Wwrite-strings -Wnewline-eof -fcolor-diagnostics -Wstring-concatenation -Wimplicit-fallthrough -Wmissing-prototypes -Wold-style-definition -Wstrict-prototypes -DHAVE_LINUX_RANDOM_H -DAWS_LC_STDALIGN_AVAILABLE -DAWS_LC_BUILTIN_SWAP_SUPPORTED -D_XOPEN_SOURCE=700 -O3  -std=gnu11 -fPIC -MD -MT crypto/CMakeFiles/crypto_objects.dir/rand_extra/urandom.c.o -MF crypto/CMakeFiles/crypto_objects.dir/rand_extra/urandom.c.o.d -o crypto/CMakeFiles/crypto_objects.dir/rand_extra/urandom.c.o -c /var/tmp/makepkg/aws-lc/src/aws-lc-1.67.0/crypto/rand_extra/urandom.c
In file included from /var/tmp/makepkg/aws-lc/src/aws-lc-1.67.0/crypto/rand_extra/urandom.c:70:
/var/tmp/makepkg/aws-lc/src/aws-lc-1.67.0/crypto/rand_extra/../internal.h:939:10: error: returning 'const void *' from a function with result type 'void *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
  939 |   return memchr(s, c, n);
      |          ^~~~~~~~~~~~~~~
/usr/include/string.h:122:3: note: expanded from macro 'memchr'
  122 |   __glibc_const_generic (S, const void *, memchr (S, C, N))
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/sys/cdefs.h:838:3: note: expanded from macro '__glibc_const_generic'
  838 |   _Generic (0 ? (PTR) : (void *) 1,                     \
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  839 |             const void *: (CTYPE) (CALL),               \
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  840 |             default: CALL)
      |             ~~~~~~~~~~~~~~
1 error generated.

Not sure if correct, but fixed with:

sed -i 's/return memchr(s, c, n);/return (void *)memchr(s, c, n);/' crypto/internal.h

Also:
cc1plus: note: unrecognized command-line option ‘-Wno-c11-extensions’ may have been intended to silence earlier diagnostics

Also: cc1plus: note: unrecognized command-line option ‘-Wno-c11-extensions’ may have been intended to silence earlier diagnostics

-Wno-c11-extensions is unrecognized by GCC (it's a Clang flag). This doesn't cause failure but indicates the build system expects Clang. If you're building with GCC, this is expected noise.

Anyway, it's a different issue and you might want to dive a bit deeper (or open a new issue?) to find out why there is a Clang flag in a GCC build environment. Could be hard-coded, could be in the build environment.

Here

aws-lc/CMakeLists.txt

Lines 500 to 510 in 36c64dc

    
               else() 
        
                 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wextra") 
        
                 set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wall -fvisibility=hidden -fno-common") 
        
                 if(CLANG AND MINGW) 
        
                   set(C_CXX_FLAGS "${C_CXX_FLAGS} -fms-extensions") 
        
                 endif() 
        
                 set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -Wno-newline-eof") 
        
               endif() 
        
               set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wunused -Wcomment -Wchar-subscripts -Wuninitialized -Wshadow") 
        
               set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wwrite-strings -Wformat-security -Wunused-result -Wno-overlength-strings") 
        
               set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wno-c11-extensions -Wvla -Wtype-limits -Wno-unused-parameter")

I don't remember I have this warning in my last build, lol

PR #3007

Hello! Sorry, I hadn't noticed this Issue sooner. I'm taking a look.

I posted a PR that I think will address this build failure: #3008

Fix OPENSSL_memchr per C23 (#3008)

@justsmth

@justsmth big thanks for the timely fix!

apacheGH-49601: [C++] Update bundled AWS SDK C++ for C23

GH-49601: [C++] Update bundled AWS SDK C++ for C23 (#49604)

apacheGH-49601: [C++] Update bundled AWS SDK C++ for C23 (apache#49604)

[CHERYPICK FIPS 4.0]Fix OPENSSL_memchr per C23 (#3008) (#3291)

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Fails to build on Arch Linux without -Wno-discarded-qualifiers #2995

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	else()
	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wextra")
	set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wall -fvisibility=hidden -fno-common")
	if(CLANG AND MINGW)
	set(C_CXX_FLAGS "${C_CXX_FLAGS} -fms-extensions")
	endif()
	set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -Wno-newline-eof")
	endif()
	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wunused -Wcomment -Wchar-subscripts -Wuninitialized -Wshadow")
	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wwrite-strings -Wformat-security -Wunused-result -Wno-overlength-strings")
	set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wno-c11-extensions -Wvla -Wtype-limits -Wno-unused-parameter")

Fails to build on Arch Linux without -Wno-discarded-qualifiers #2995

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edmundlod commented on Feb 15, 2026

Ra2-IFV commented on Feb 15, 2026

edmundlod commented on Feb 16, 2026

Ra2-IFV commented on Feb 16, 2026

Ra2-IFV commented on Feb 18, 2026

justsmth commented on Feb 18, 2026

justsmth commented on Feb 18, 2026

5long commented on Feb 21, 2026

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