[PATCH v6 2/3] configure: Only use -Wno-discarded-qualifiers iff compiler supports it

[Sam James]

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> The clang analogous option is
> -Wno-incompatible-pointer-types-discards-qualifiers, so add a configure
> option to check which one compiler supports.
> ---
>  configure         | 68 +++++++++++++++++++++++++++++++++++++++++++++++
>  configure.ac      | 20 ++++++++++++++
>  timezone/Makefile |  4 +--
>  3 files changed, 90 insertions(+), 2 deletions(-)
>
> diff --git a/configure b/configure
> index fc36935dd0..878c7cc7e8 100755
> --- a/configure
> +++ b/configure
> @@ -8189,6 +8189,74 @@ test-config-cflags-wno-fortify-source = $libc_cv_test_cflags_wno_fortify_source"
>  
>  
>  
> +saved_CC="$CC"
> +CC="$TEST_CC"
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking -Wno-discarded-qualifiers in testing" >&5
> +printf %s "checking -Wno-discarded-qualifiers in testing... " >&6; }
> +if test ${libc_cv_test_cflags_wno_discarded_qualifiers+y}
> +then :
> +  printf %s "(cached) " >&6
> +else case e in #(
> +  e) if { ac_try='${CC-cc} -Werror -Wno-discarded-qualifiers -xc /dev/null -S -o /dev/null'
> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> +  (eval $ac_try) 2>&5
> +  ac_status=$?
> +  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; }
> +then :
> +  libc_cv_test_cflags_wno_discarded_qualifiers=-Wno-discarded-qualifiers
> +else case e in #(
> +  e) libc_cv_test_cflags_wno_discarded_qualifiers=
> + ;;
> +esac
> +fi ;;
> +esac
> +fi
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_test_cflags_wno_discarded_qualifiers" >&5
> +printf "%s\n" "$libc_cv_test_cflags_wno_discarded_qualifiers" >&6; }
> +
> +CC="$saved_CC"
> +
> +
> +if test -z "$libc_cv_test_cflags_wno_discarded_qualifiers"; then
> +
> +
> +saved_CC="$CC"
> +CC="$TEST_CC"
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking -Wno-incompatible-pointer-types-discards-qualifiers in testing" >&5
> +printf %s "checking -Wno-incompatible-pointer-types-discards-qualifiers in testing... " >&6; }
> +if test ${libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers+y}
> +then :
> +  printf %s "(cached) " >&6
> +else case e in #(
> +  e) if { ac_try='${CC-cc} -Werror -Wno-incompatible-pointer-types-discards-qualifiers -xc /dev/null -S -o /dev/null'
> +  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
> +  (eval $ac_try) 2>&5
> +  ac_status=$?
> +  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; }
> +then :
> +  libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers=-Wno-incompatible-pointer-types-discards-qualifiers
> +else case e in #(
> +  e) libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers=
> +   ;;
> +esac
> +fi ;;
> +esac
> +fi
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers" >&5
> +printf "%s\n" "$libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers" >&6; }
> +
> +CC="$saved_CC"
> +
> +
> +  libc_cv_test_cflags_wno_discarded_qualifiers=$libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers
> +fi
> +config_vars="$config_vars
> +test-config-cflags-wno-discarded-qualifiers = $libc_cv_test_cflags_wno_discarded_qualifiers"
> +
> +
> +
>  saved_CC="$CC"
>  CC="$TEST_CC"
>  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking -finput-charset=ascii in testing" >&5
> diff --git a/configure.ac b/configure.ac
> index 679a4a96cf..589d07f073 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -1633,6 +1633,26 @@ LIBC_TRY_TEST_CC_OPTION([-Wno-fortify-source],
>  LIBC_CONFIG_VAR([test-config-cflags-wno-fortify-source],
>  		[$libc_cv_test_cflags_wno_fortify_source])
>  
> +dnl Check how to suppress C23-qualifier-generic const warnings.  GCC has
> +dnl -Wno-discarded-qualifiers, while clang -Wno-incompatible-pointer-types-discards-qualifiers
> +LIBC_TRY_TEST_CC_OPTION([-Wno-discarded-qualifiers],
> +  [-Werror -Wno-discarded-qualifiers],
> +  libc_cv_test_cflags_wno_discarded_qualifiers,
> +  [libc_cv_test_cflags_wno_discarded_qualifiers=-Wno-discarded-qualifiers],
> +  [libc_cv_test_cflags_wno_discarded_qualifiers=]
> +)

This flag is not being used (exclusively) for tests (timezone/), so we
shouldn't name it such.

> +if test -z "$libc_cv_test_cflags_wno_discarded_qualifiers"; then
> +  LIBC_TRY_TEST_CC_OPTION([-Wno-incompatible-pointer-types-discards-qualifiers],
> +    [-Werror -Wno-incompatible-pointer-types-discards-qualifiers],
> +    libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers,
> +    [libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers=-Wno-incompatible-pointer-types-discards-qualifiers],
> +    [libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers=]
> +  )
> +  libc_cv_test_cflags_wno_discarded_qualifiers=$libc_cv_test_cflags_wno_incompatible_pointer_type_discards_qualifiers
> +fi
> +LIBC_CONFIG_VAR([test-config-cflags-wno-discarded-qualifiers],
> +		[$libc_cv_test_cflags_wno_discarded_qualifiers])
> +
>  dnl Check if TEST_CC supports -finput-charset=ascii.
>  LIBC_TRY_TEST_CC_OPTION([-finput-charset=ascii],
>    [-Werror -finput-charset=ascii],
> diff --git a/timezone/Makefile b/timezone/Makefile
> index c03a68962c..2ff1e92f9d 100644
> --- a/timezone/Makefile
> +++ b/timezone/Makefile
> @@ -73,10 +73,10 @@ tz-cflags = -DTZDIR='"$(zonedir)"' \
>  # The -Wno-unused-variable flag is used to prevent GCC 6
>  # from warning about time_t_min and time_t_max which are
>  # defined in private.h but not used.
> -# -Wno-discarded-qualifiers is because zic is not prepared for C23
> +# $(test-config-cflags-wno-discarded-qualifiers) is because zic is not prepared for C23
>  # -qualifier-generic strchr.
>  CFLAGS-zdump.c += $(tz-cflags)
> -CFLAGS-zic.c += $(tz-cflags) -Wno-unused-variable -Wno-discarded-qualifiers
> +CFLAGS-zic.c += $(tz-cflags) -Wno-unused-variable $(test-config-cflags-wno-discarded-qualifiers)
>  
>  # We have to make sure the data for testing the tz functions is available.
>  # Don't add leapseconds here since test-tz made checks that work only without