1# 2# Copyright (c) 2023, Luke Mewburn <lukem@NetBSD.org> 3# 4# Copying and distribution of this file, with or without modification, 5# are permitted in any medium without royalty provided the copyright 6# notice and this notice are preserved. This file is offered as-is, 7# without any warranty. 8# 9 10# 11# _NB_CHECK_CC_FLAG_PREPARE 12# Check for flags to force a compiler (e.g., clang) to fail 13# if given an unknown -WWARN, and set $nb_cv_check_cc_flags 14# to that flag for NB_CHECK_CC_FLAG() to use. 15# 16AC_DEFUN([_NB_CHECK_CC_FLAG_PREPARE], [dnl 17nb_cv_check_cc_flags= 18AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option], 19 [AS_VAR_SET([nb_cv_check_cc_flags], [-Werror=unknown-warning-option])]) 20]) dnl _NB_CHECK_CC_FLAG_PREPARE 21 22# 23# NB_CHECK_CC_FLAG(FLAG, [VAR=FLAG_DERIVED]) 24# Determine if the C compiler supports FLAG, 25# and sets output variable VAR to FLAG if FLAG is supported. 26# 27# If VAR is not provided, default to FLAG_DERIVED, which is 28# FLAG converted to upper-case and all special characters 29# replaced with "_", and the result prepended with "CC_". 30# FLAG_DERIVED is appended to the m4 macro NB_CHECK_CC_FLAG_VARS. 31# E.g., if FLAG is "-Wexample=yes", FLAG_DERIVED is "CC_WEXAMPLE_YES". 32# 33# Compiler-specific notes: 34# clang Uses _NB_CHECK_CC_FLAG_PREPARE() to determine if 35# -Werror=unknown-warning-option. 36# gcc Check for -WFLAG if FLAG is -Wno-FLAG, to work around 37# gcc silently ignoring unknown -Wno-FLAG. 38# 39AC_DEFUN([NB_CHECK_CC_FLAG], [dnl 40AC_REQUIRE([_NB_CHECK_CC_FLAG_PREPARE])dnl 41m4_ifblank([$1], [m4_fatal([Usage: $0(FLAG,[VAR=FLAG_DERIVED])])])dnl 42m4_pushdef([NB_flag], [$1])dnl 43m4_ifblank([$2], [dnl 44m4_pushdef([NB_var], [CC]m4_translit(NB_flag, [-=a-z], [__A-Z]))dnl 45m4_append([NB_CHECK_CC_FLAG_VARS], NB_var, [ ])dnl 46], [dnl 47m4_pushdef([NB_var], [$2])dnl 48])dnl 49m4_pushdef([NB_wflag], m4_bpatsubst(NB_flag, [^-Wno-], [-W]))dnl 50AX_CHECK_COMPILE_FLAG(NB_wflag, [AS_VAR_SET(NB_var,NB_flag)], [], [$nb_cv_check_cc_flags]) 51AC_SUBST(NB_var) 52m4_popdef([NB_flag])dnl 53m4_popdef([NB_wflag])dnl 54m4_popdef([NB_var])dnl 55]) dnl NB_CHECK_CC_FLAG 56