# warnings.m4 serial 11

dnl Copyright (C) 2008-2017 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl From Simon Josefsson

# gl_AS_VAR_APPEND(VAR, VALUE)

# ----------------------------

# Provide the functionality of AS_VAR_APPEND if Autoconf does not have it.

m4_ifdef([AS_VAR_APPEND],

[m4_copy([AS_VAR_APPEND], [gl_AS_VAR_APPEND])],

[m4_define([gl_AS_VAR_APPEND],

[AS_VAR_SET([$1], [AS_VAR_GET([$1])$2])])])

# gl_COMPILER_OPTION_IF(OPTION, [IF-SUPPORTED], [IF-NOT-SUPPORTED],

#                       [PROGRAM = AC_LANG_PROGRAM()])

# -----------------------------------------------------------------

# Check if the compiler supports OPTION when compiling PROGRAM.

#

# FIXME: gl_Warn must be used unquoted until we can assume Autoconf

# 2.64 or newer.

AC_DEFUN([gl_COMPILER_OPTION_IF],

[AS_VAR_PUSHDEF([gl_Warn], [gl_cv_warn_[]_AC_LANG_ABBREV[]_$1])dnl

AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl

AS_LITERAL_IF([$1],

  [m4_pushdef([gl_Positive], m4_bpatsubst([$1], [^-Wno-], [-W]))],

  [gl_positive="$1"

case $gl_positive in

  -Wno-*) gl_positive=-W`expr "X$gl_positive" : 'X-Wno-\(.*\)'` ;;

esac

m4_pushdef([gl_Positive], [$gl_positive])])dnl

AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], m4_defn([gl_Warn]), [

  gl_save_compiler_FLAGS="$gl_Flags"

  gl_AS_VAR_APPEND(m4_defn([gl_Flags]),

    [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positive])["])

  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([])])],

                 [AS_VAR_SET(gl_Warn, [yes])],

                 [AS_VAR_SET(gl_Warn, [no])])

  gl_Flags="$gl_save_compiler_FLAGS"

])

AS_VAR_IF(gl_Warn, [yes], [$2], [$3])

m4_popdef([gl_Positive])dnl

AS_VAR_POPDEF([gl_Flags])dnl

AS_VAR_POPDEF([gl_Warn])dnl

])

# gl_UNKNOWN_WARNINGS_ARE_ERRORS

# ------------------------------

# Clang doesn't complain about unknown warning options unless one also

# specifies -Wunknown-warning-option -Werror.  Detect this.

AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],

[gl_COMPILER_OPTION_IF([-Werror -Wunknown-warning-option],

   [gl_unknown_warnings_are_errors='-Wunknown-warning-option -Werror'],

   [gl_unknown_warnings_are_errors=])])

# gl_WARN_ADD(OPTION, [VARIABLE = WARN_CFLAGS],

#             [PROGRAM = AC_LANG_PROGRAM()])

# ---------------------------------------------

# Adds parameter to WARN_CFLAGS if the compiler supports it when

# compiling PROGRAM.  For example, gl_WARN_ADD([-Wparentheses]).

#

# If VARIABLE is a variable name, AC_SUBST it.

AC_DEFUN([gl_WARN_ADD],

[AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS])

gl_COMPILER_OPTION_IF([$1],

  [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_CFLAGS]], [[$2]]), [" $1"])],

  [],

  [$3])

m4_ifval([$2],

         [AS_LITERAL_IF([$2], [AC_SUBST([$2])])],

         [AC_SUBST([WARN_CFLAGS])])dnl

])

# Local Variables:

# mode: autoconf

# End: