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Autoconf Macro: ax_dll_string
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<h1>
ax_dll_string
</h1>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>AX_DLL_STRING</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
Tests for a bug currently in g++ 3.4.4 on Cygwin (maybe other targets with
statically linked libstdc++?) where passing an empty std::string to a dll
will cause a crash on destruction due to incorrect memory handling. See bug
24196 in gcc's bugzilla for more details: <a href=
"http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24196">http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24196</a>
</p>
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<h2>
Author
</h2>
<p class="indent">
Steven Brown <swbrown@variadic.org>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2006-04-08
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
dnl Plan: compile conftest-dll.cc, conftest-exe.cc. It has a 'crash' param
dnl that can be passed. Verify the compile worked and we can run it normally
dnl ok. Then, pass 'crash', test if it crashed, fail.
AC_DEFUN([AX_DLL_STRING],
[
AC_MSG_CHECKING(if the dll string test can be compiled)
cat << EOF > conftest-dll.cc
[
#include <string>
using namespace std;
void testit(std::string (*contentGet)()) {
contentGet();
}
]
EOF
cat << EOF > conftest-exe.cc
[
#include <string>
#include <cstring>
using namespace std;
extern void testit(std::string (*contentGet)());
std::string contentGet() {
return string(""); // Anything other than empty string works.
}
int main(int argc, char *argv[]) {
if(argc == 2 && strcmp(argv[1], "crash") == 0) {
testit(&contentGet);
}
return 0;
}
]
EOF
$CXX -shared $CFLAGS $CPPFLAGS conftest-dll.cc -o conftest-dll.dll >&AS_MESSAGE_LOG_FD && $CXX $CFLAGS $CPPFLAGS conftest-exe.cc conftest-dll.dll -o conftest-exe.exe >& AS_MESSAGE_LOG_FD
if test x"$?" = x"0"; then
AC_MSG_RESULT(yes)
dnl Make sure it runs normally first.
AC_MSG_CHECKING(if the dll string test is usable)
if /bin/sh -c "(LD_LIBRARY_PATH=\"$PWD\" ./conftest-exe.exe)" >& AS_MESSAGE_LOG_FD 2>&1; then
AC_MSG_RESULT(yes)
dnl Now we can check for the bug.
AC_MSG_CHECKING(if the dll string test is affected by gcc bug 24196)
if ! /bin/sh -c "(LD_LIBRARY_PATH=\"$PWD\" ./conftest-exe.exe crash)" >& AS_MESSAGE_LOG_FD 2>&1; then
AC_MSG_RESULT(yes)
dnl We have the bug, user'll need to fix it.
AC_MSG_ERROR([*** This toolchain is affected by gcc bug 24196. For Cygwin as of 4/8/2006, you can downgrade to gcc/g++ 3.3.3 or check if there is a newer compiler available that's fixed.])
else
AC_MSG_RESULT(no)
fi
else
AC_MSG_RESULT(no)
fi
else
AC_MSG_RESULT(no)
fi
])
</pre>
</div>
<h2>
License
</h2>
<div class="indent">
<span style="white-space:nowrap;">Copyright © 2006 Steven Brown
<swbrown@variadic.org></span>
<p>
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.
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