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-rw-r--r--m4/woe32-dll.m445
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diff --git a/m4/woe32-dll.m4 b/m4/woe32-dll.m4
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+# woe32-dll.m4 serial 2
+dnl Copyright (C) 2005-2006 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 Bruno Haible.
+
+# Add --disable-auto-import to the LDFLAGS if the linker supports it.
+# GNU ld has an --enable-auto-import option, and it is the default on Cygwin
+# since July 2005. But it has three fatal drawbacks:
+# - It produces executables and shared libraries with relocations in the
+# .text segment, defeating the principles of virtual memory.
+# - For some constructs such as
+# extern int var;
+# int * const b = &var;
+# it creates an executable that will give an error at runtime, rather
+# than either a compile-time or link-time error or a working executable.
+# (This is with both gcc and g++.) Whereas this code, not relying on
+# auto-import:
+# extern __declspec (dllimport) int var;
+# int * const b = &var;
+# gives a compile-time error with gcc and works with g++.
+# - It doesn't work in some cases (references to a member field of an
+# exported struct variable, or to a particular element of an exported
+# array variable), requiring code modifications. One platform
+# dictates code modifications on all platforms.
+AC_DEFUN([gl_WOE32_DLL],
+[
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ case "$host_os" in
+ mingw* | cygwin*)
+ AC_MSG_CHECKING([for auto-import of symbols])
+ AC_CACHE_VAL([gl_cv_ld_autoimport], [
+ gl_save_LDFLAGS="$LDFLAGS"
+ LDFLAGS="$LDFLAGS -Wl,--disable-auto-import"
+ AC_TRY_LINK([], [], [gl_cv_ld_autoimport=yes], [gl_cv_ld_autoimport=no])
+ LDFLAGS="$gl_save_LDFLAGS"])
+ AC_MSG_RESULT([$gl_cv_ld_autoimport])
+ if test $gl_cv_ld_autoimport = yes; then
+ LDFLAGS="$LDFLAGS -Wl,--disable-auto-import"
+ fi
+ ;;
+ esac
+])