Added two helper macros to manipulate *FLAGS vars

m4/mhd_append_flag_to_var.m4

@@ -0,0 +1,46 @@
+# SYNOPSIS
+#
+#   MHD_APPEND_FLAG_TO_VAR([VARIABLE-TO-EXTEND], [FLAG-TO-APPEND])
+#
+# DESCRIPTION
+#
+#   This macro sets VARIABLE-TO-EXTEND to the value of VARIABLE-TO-EXTEND with
+#   appended FLAG-TO-APPEND. If current value of VARIABLE-TO-EXTEND and
+#   FLAG-TO-APPEND are both non-empty strings then space is added between them.
+#
+#   Example usage:
+#
+#     MHD_APPEND_FLAG_TO_VAR([my_CFLAGS], [-Wall])
+#
+#
+# LICENSE
+#
+#   Copyright (c) 2022 Karlson2k (Evgeny Grin) <[email protected]>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+AC_DEFUN([MHD_APPEND_FLAG_TO_VAR],[dnl
+m4_ifblank([$1],[m4_fatal([$0: First macro argument must not be empty])])dnl
+m4_bmatch([$1], [\$], [m4_fatal([$0: First macro argument must not contain '$'])])dnl
+m4_bmatch([$1], [,], [m4_fatal([$0: First macro argument must not contain ','])])dnl
+m4_bmatch(_mhd_norm_expd([$1]), [\s],dnl
+[m4_fatal([$0: First macro argument must not contain whitespaces])])dnl
+m4_pushdef([varExtd],_mhd_norm_expd([$1]))dnl
+m4_bmatch([$2],[\$],dnl
+[dnl The second parameter is a variable value
+AS_IF([test -z "_mhd_norm_expd([$2])"],dnl
+[varExtd="${varExtd}"],dnl
+[AS_IF([test -z "${varExtd}"],[varExtd="_mhd_norm_expd([$2])"],[varExtd="${varExtd} _mhd_norm_expd([$2])"])])
+],dnl
+[dnl The second parameter is not a variable value
+m4_ifnblank(_mhd_norm_expd([$2]),dnl
+[AS_IF([test -z "${varExtd}"],[varExtd="_mhd_norm_expd([$2])"],[varExtd="${varExtd} _mhd_norm_expd([$2])"])
+],dnl
+[m4_n([varExtd="${varExtd}"])])])dnl m4_ifnblank m4_bmatch
+m4_popdef([varExtd])dnl
+])dnl AC_DEFUN

m4/mhd_prepend_flag_to_var.m4

@@ -0,0 +1,46 @@
+# SYNOPSIS
+#
+#   MHD_PREPEND_FLAG_TO_VAR([VARIABLE-TO-EXTEND], [FLAG-TO-PREPEND])
+#
+# DESCRIPTION
+#
+#   This macro sets VARIABLE-TO-EXTEND to the value of VARIABLE-TO-EXTEND with
+#   appended FLAG-TO-APPEND. If current value of VARIABLE-TO-EXTEND and
+#   FLAG-TO-APPEND are both non-empty strings then space is added between them.
+#
+#   Example usage:
+#
+#     MHD_PREPEND_FLAG_TO_VAR([my_CFLAGS], [-Wall])
+#
+#
+# LICENSE
+#
+#   Copyright (c) 2022 Karlson2k (Evgeny Grin) <[email protected]>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+AC_DEFUN([MHD_PREPEND_FLAG_TO_VAR],[dnl
+m4_ifblank([$1],[m4_fatal([$0: First macro argument must not be empty])])dnl
+m4_bmatch([$1], [\$], [m4_fatal([$0: First macro argument must not contain '$'])])dnl
+m4_bmatch([$1], [,], [m4_fatal([$0: First macro argument must not contain ','])])dnl
+m4_bmatch(_mhd_norm_expd([$1]), [\s],dnl
+[m4_fatal([$0: First macro argument must not contain whitespaces])])dnl
+m4_pushdef([varExtd],_mhd_norm_expd([$1]))dnl
+m4_bmatch([$2],[\$],dnl
+[dnl The second parameter is a variable value
+AS_IF([test -z "_mhd_norm_expd([$2])"],dnl
+[varExtd="${varExtd}"],dnl
+[AS_IF([test -z "${varExtd}"],[varExtd="_mhd_norm_expd([$2])"],[varExtd="_mhd_norm_expd([$2]) ${varExtd}"])])
+],dnl
+[dnl The second parameter is not a variable value
+m4_ifnblank(_mhd_norm_expd([$2]),dnl
+[AS_IF([test -z "${varExtd}"],[varExtd="_mhd_norm_expd([$2])"],[varExtd="_mhd_norm_expd([$2]) ${varExtd}"])
+],dnl
+[m4_n([varExtd="${varExtd}"])])])dnl m4_ifnblank m4_bmatch
+m4_popdef([varExtd])dnl
+])dnl AC_DEFUN