Improve MinGW building

.cirrus.yml

@@ -146,7 +146,6 @@ task:
   env:
     EXEC_CMD: wine
     HOST: x86_64-w64-mingw32
-    CXXFLAGS: -O2 -static -static-libgcc -static-libstdc++
     BUILD:
   << : *MERGE_BASE
   test_script:

build-aux/m4/ax_check_link_flag.m4

@@ -0,0 +1,53 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the linker 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 linker's default flags
+#   when the check is done.  The check is thus made with the flags: "LDFLAGS
+#   EXTRA-FLAGS FLAG".  This can for example be used to force the linker to
+#   issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_LINK_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,COMPILE}_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_LINK_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
+AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
+  ax_check_save_flags=$LDFLAGS
+  LDFLAGS="$LDFLAGS $4 $1"
+  AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  LDFLAGS=$ax_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_LINK_FLAGS

configure.ac

@@ -88,6 +88,17 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
   ]
 )
 
+case $host in
+  *mingw*)
+     dnl -static is interpreted by libtool, where it has a different meaning.
+     dnl In libtool-speak, it's -all-static.
+#     AX_CHECK_COMPILE_FLAG([[-static-libgcc]],[CXXFLAGS="-static-libgcc $CXXFLAGS";LDFLAGS="-static-libgcc $LDFLAGS"])
+     AX_CHECK_COMPILE_FLAG([[-static-libstdc++]],[CXXFLAGS="-static-libstdc++ $CXXFLAGS"])
+#     AX_CHECK_LINK_FLAG([[-static]],[LIBTOOL_APP_LDFLAGS="$LIBTOOL_APP_LDFLAGS -all-static";CXXFLAGS="-static $CXXFLAGS";LDFLAGS="-static $LDFLAGS"])
+     AX_CHECK_LINK_FLAG([[-static]],[LIBTOOL_APP_LDFLAGS="$LIBTOOL_APP_LDFLAGS -all-static"])
+     ;;
+esac
+
 AX_CHECK_COMPILE_FLAG([-Wall],[WARN_CXXFLAGS="$WARN_CXXFLAGS -Wall"],,[[$CXXFLAG_WERROR]])
 ## Some compilers (gcc) ignore unknown -Wno-* options, but warn about all
 ## unknown options if any other warning is produced. Test the -Wfoo case, and