Reimplement compiler options checking.

acinclude.m4

@@ -7,6 +7,10 @@ m4_include([m4.include/gnulib/windows-stat-inodes.m4])
 m4_include([m4.include/gnulib/sys_types_h.m4])
 m4_include([m4.include/ax_path_lib_pcre.m4])
 m4_include([m4.include/dx_doxygen.m4])
+m4_include([m4.include/ax_require_defined.m4])
+m4_include([m4.include/ax_check_compile_flag.m4])
+m4_include([m4.include/ax_append_flag.m4])
+m4_include([m4.include/ax_append_compile_flags.m4])
 m4_include([m4.include/mc-cflags.m4])
 m4_include([m4.include/ax_gcc_func_attribute.m4])
 m4_include([m4.include/mc-check-search-type.m4])

configure.ac

@@ -53,7 +53,7 @@ fi
 AC_ARG_ENABLE([werror],
     AS_HELP_STRING([--enable-werror], [Handle all compiler warnings as errors]))
 if test "x$enable_werror" = xyes; then
-    mc_CHECK_ONE_CFLAG([-Werror])
+    AX_APPEND_COMPILE_FLAGS([-Werror], [mc_configured_cflags])
 fi
 
 dnl Compiler can generate warnings for unrecognized flags added to CFLAGS

m4.include/ax_append_compile_flags.m4

@@ -0,0 +1,46 @@
+# ============================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_append_compile_flags.html
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   For every FLAG1, FLAG2 it is checked whether the compiler works with the
+#   flag.  If it does, the flag is added FLAGS-VARIABLE
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  During the check the flag is always added to the
+#   current language's flags.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: This macro depends on the AX_APPEND_FLAG and
+#   AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with
+#   AX_APPEND_LINK_FLAGS.
+#
+# LICENSE
+#
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   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 7
+
+AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
+[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
+AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
+for flag in $1; do
+  AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3], [$4])
+done
+])dnl AX_APPEND_COMPILE_FLAGS

m4.include/ax_append_flag.m4

@@ -0,0 +1,50 @@
+# ===========================================================================
+#      https://www.gnu.org/software/autoconf-archive/ax_append_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+#
+# DESCRIPTION
+#
+#   FLAG is appended to the FLAGS-VARIABLE shell variable, with a space
+#   added in between.
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
+#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
+#   FLAG.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   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 8
+
+AC_DEFUN([AX_APPEND_FLAG],
+[dnl
+AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])
+AS_VAR_SET_IF(FLAGS,[
+  AS_CASE([" AS_VAR_GET(FLAGS) "],
+    [*" $1 "*], [AC_RUN_LOG([: FLAGS already contains $1])],
+    [
+     AS_VAR_APPEND(FLAGS,[" $1"])
+     AC_RUN_LOG([: FLAGS="$FLAGS"])
+    ])
+  ],
+  [
+  AS_VAR_SET(FLAGS,[$1])
+  AC_RUN_LOG([: FLAGS="$FLAGS"])
+  ])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_APPEND_FLAG

m4.include/ax_check_compile_flag.m4

@@ -0,0 +1,53 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   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 6
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS

m4.include/ax_require_defined.m4

@@ -0,0 +1,37 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_require_defined.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_REQUIRE_DEFINED(MACRO)
+#
+# DESCRIPTION
+#
+#   AX_REQUIRE_DEFINED is a simple helper for making sure other macros have
+#   been defined and thus are available for use.  This avoids random issues
+#   where a macro isn't expanded.  Instead the configure script emits a
+#   non-fatal:
+#
+#     ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found
+#
+#   It's like AC_REQUIRE except it doesn't expand the required macro.
+#
+#   Here's an example:
+#
+#     AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
+#
+# LICENSE
+#
+#   Copyright (c) 2014 Mike Frysinger <vapier@gentoo.org>
+#
+#   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 2
+
+AC_DEFUN([AX_REQUIRE_DEFINED], [dnl
+  m4_ifndef([$1], [m4_fatal([macro ]$1[ is not defined; is a m4 file missing?])])
+])dnl AX_REQUIRE_DEFINED

m4.include/mc-cflags.m4

@@ -3,104 +3,88 @@ dnl
 dnl Check flags supported by C compiler
 dnl
 dnl @author Slava Zanko <slavazanko@gmail.com>
-dnl @version 2013-01-16
+dnl @modified by Andrew Borodin <aborodin@vmail.ru>
+dnl @version 2021-09-19
 dnl @license GPL
 dnl @copyright Free Software Foundation, Inc.
 
-AC_DEFUN([mc_CHECK_ONE_CFLAG],[
-
-  AC_MSG_CHECKING([whether ${CC} accepts $1])
-
-  safe_CFLAGS=$CFLAGS
-
-  case "$CC" in
-    clang*)
-      CFLAGS="-Werror $1"
-      ;;
-    *)
-      CFLAGS="$1"
-      ;;
-  esac
-
-  AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([], [[return 0;]])],
-    [mc_check_one_cflag=yes],
-    [mc_check_one_cflag=no])
-
-  CFLAGS=$safe_CFLAGS
-  AC_MSG_RESULT([$mc_check_one_cflag])
-
-  if test x$mc_check_one_cflag = xyes; then
-    mc_configured_cflags="$mc_configured_cflags $1"
-  fi
-])
-
 AC_DEFUN([mc_CHECK_CFLAGS],[
     AC_LANG_PUSH(C)
 
     mc_configured_cflags=""
 
-dnl Sorted -f options:
+dnl    AC_MSG_CHECKING([CC is $CC])
-dnl AC_MSG_CHECKING([CC is $CC])
-case "$CC" in
-  gcc*)
-    mc_CHECK_ONE_CFLAG([-fdiagnostics-show-option])
-dnl    mc_CHECK_ONE_CFLAG([-fno-stack-protector])
-    ;;
-  *)
-    ;;
-esac
 
-dnl Sorted -W options:
+    dnl https://stackoverflow.com/questions/52557417/how-to-check-support-compile-flag-in-autoconf-for-clang
-    mc_CHECK_ONE_CFLAG([-Wassign-enum])
+    case "$CC" in
-    mc_CHECK_ONE_CFLAG([-Wbad-function-cast])
+    clang*)
-    mc_CHECK_ONE_CFLAG([-Wcomment])
+        EXTRA_OPTION="-Werror"
-    mc_CHECK_ONE_CFLAG([-Wconditional-uninitialized])
+        ;;
-    mc_CHECK_ONE_CFLAG([-Wdeclaration-after-statement])
+    *)
-    mc_CHECK_ONE_CFLAG([-Wfloat-conversion])
+        EXTRA_OPTION=""
-    mc_CHECK_ONE_CFLAG([-Wfloat-equal])
+        ;;
-    mc_CHECK_ONE_CFLAG([-Wformat])
+    esac
-    mc_CHECK_ONE_CFLAG([-Wformat-security])
+
-    mc_CHECK_ONE_CFLAG([-Wformat-signedness])
+    dnl Sorted -f options:
-    mc_CHECK_ONE_CFLAG([-Wimplicit])
+    case "$CC" in
-    mc_CHECK_ONE_CFLAG([-Wimplicit-fallthrough])
+    gcc*)
-    mc_CHECK_ONE_CFLAG([-Wignored-qualifiers])
+        AX_APPEND_COMPILE_FLAGS([-fdiagnostics-show-option], [mc_configured_cflags])
-    mc_CHECK_ONE_CFLAG([-Wlogical-not-parentheses])
+dnl        AX_APPEND_COMPILE_FLAGS([-fno-stack-protector], [mc_configured_cflags])
-    mc_CHECK_ONE_CFLAG([-Wmaybe-uninitialized])
+        ;;
-    mc_CHECK_ONE_CFLAG([-Wmissing-braces])
+    *)
-    mc_CHECK_ONE_CFLAG([-Wmissing-declarations])
+        ;;
-    mc_CHECK_ONE_CFLAG([-Wmissing-field-initializers])
+    esac
-    mc_CHECK_ONE_CFLAG([-Wmissing-format-attribute])
+
-    mc_CHECK_ONE_CFLAG([-Wmissing-parameter-type])
+    dnl Sorted -W options:
-    mc_CHECK_ONE_CFLAG([-Wmissing-prototypes])
+    AX_APPEND_COMPILE_FLAGS([-Wassign-enum], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wmissing-variable-declarations])
+    AX_APPEND_COMPILE_FLAGS([-Wbad-function-cast], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wnested-externs])
+    AX_APPEND_COMPILE_FLAGS([-Wcomment], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wno-long-long])
+    AX_APPEND_COMPILE_FLAGS([-Wconditional-uninitialized], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wno-unreachable-code])
+    AX_APPEND_COMPILE_FLAGS([-Wdeclaration-after-statement], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wparentheses])
+    AX_APPEND_COMPILE_FLAGS([-Wfloat-conversion], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wpointer-arith])
+    AX_APPEND_COMPILE_FLAGS([-Wfloat-equal], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wpointer-sign])
+    AX_APPEND_COMPILE_FLAGS([-Wformat], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wredundant-decls])
+    AX_APPEND_COMPILE_FLAGS([-Wformat-security], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wreturn-type])
+    AX_APPEND_COMPILE_FLAGS([-Wformat-signedness], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wsequence-point])
+    AX_APPEND_COMPILE_FLAGS([-Wimplicit], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wshadow])
+    AX_APPEND_COMPILE_FLAGS([-Wimplicit-fallthrough], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wsign-compare])
+    AX_APPEND_COMPILE_FLAGS([-Wignored-qualifiers], [mc_configured_cflags], [$EXTRA_OPTION])
-dnl  mc_CHECK_ONE_CFLAG([-Wstrict-aliasing])
+    AX_APPEND_COMPILE_FLAGS([-Wlogical-not-parentheses], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wstrict-prototypes])
+    AX_APPEND_COMPILE_FLAGS([-Wmaybe-uninitialized], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wswitch])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-braces], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wswitch-default])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-declarations], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wtype-limits])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-field-initializers], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wundef])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-format-attribute], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wuninitialized])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-parameter-type], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunreachable-code])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-prototypes], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-but-set-variable])
+    AX_APPEND_COMPILE_FLAGS([-Wmissing-variable-declarations], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-function])
+    AX_APPEND_COMPILE_FLAGS([-Wnested-externs], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-label])
+    AX_APPEND_COMPILE_FLAGS([-Wno-long-long], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-parameter])
+    AX_APPEND_COMPILE_FLAGS([-Wno-unreachable-code], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-result])
+    AX_APPEND_COMPILE_FLAGS([-Wparentheses], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-value])
+    AX_APPEND_COMPILE_FLAGS([-Wpointer-arith], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wunused-variable])
+    AX_APPEND_COMPILE_FLAGS([-Wpointer-sign], [mc_configured_cflags], [$EXTRA_OPTION])
-    mc_CHECK_ONE_CFLAG([-Wwrite-strings])
+    AX_APPEND_COMPILE_FLAGS([-Wredundant-decls], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wreturn-type], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wsequence-point], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wshadow], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wsign-compare], [mc_configured_cflags], [$EXTRA_OPTION])
+dnl    AX_APPEND_COMPILE_FLAGS([-Wstrict-aliasing], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wstrict-prototypes], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wswitch], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wswitch-default], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wtype-limits], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wundef], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wuninitialized], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunreachable-code], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-but-set-variable], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-function], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-label], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-parameter], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-result], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-value], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wunused-variable], [mc_configured_cflags], [$EXTRA_OPTION])
+    AX_APPEND_COMPILE_FLAGS([-Wwrite-strings], [mc_configured_cflags], [$EXTRA_OPTION])
 
     AC_LANG_POP()
 ])