Re: [bug-libsigsegv] mingw failure

[Eric Blake]

On 08/23/2011 03:18 PM, Sam Steingold wrote:
> > * Eric Blake<address@hidden>  [2011-08-23 15:02:52 -0600]:
> >
> > On 08/23/2011 02:52 PM, Sam Steingold wrote:
> > > ../configure --prefix=/cygdrive/c/sds/src/top-mingw/ CC=i686-pc-mingw32-gcc
> > > ...
> > > libtool: link: i686-pc-mingw32-gcc -g -O2 -o cygwin1.exe cygwin1.o
> >
> > Why is a mingw build trying to compile a cygwin-specific test?  You
> > didn't call configure correctly to let it know that you intended to do
> > cross-compilation.  Try this:
> >
> > ./configure --prefix=/cygdrive/c/sds/src/top-mingw \
> >    --host=i686-pc-mingw32 --build-i686-pc-mingw32

Typo: I meant --build=, not --build-.

> > That will automatically tell configure that you are doing cross
> > compilation, and default to finding CC=i686-poc-mingw32-gcc without you
> > having to explicitly request $CC.
>
> I thought that setting CC would take care of this, i.e., configure
> should call CC with -dumpmachine and compare that with the output of
> uname (or whatever)...  Sorry.

Nope.  Doesn't work that way.  -dumpmachine is gcc-specific, but not all 
cross-compilers are gcc, so there is no portable way to tell if an 
arbitrary $CC is a cross-compiler by using options to $CC.  Rather, the 
autoconf way (as documented in the generic INSTALL file in so many 
packages) has _always_ been that to specify cross-compilation, you 
specify the --host argument to ./configure; and to avoid warnings, you 
also specify the --build argument (the --build argument is the one that 
is auto-probed by running config.guess, but for compatibility reasons, 
./configure emits a warning if you specify --host without --build).

> > The only way to expect sane results when cross-compiling for mingw from
> > a cygwin environment is to not lie to configure about the fact that you
> > are cross-compiling.
>
>
> still I see this:
>
> checking whether we are cross compiling... no

Huh?  Oh, maybe you hit my typo.  What was your exact command line? 
When I do:

$ ../configure --host=i686-w64-mingw32 --build=i686-pc-cygwin
...
checking for i686-w64-mingw32-strip... i686-w64-mingw32-strip
...
checking whether we are cross compiling... yes

so it properly found my cross-toolchain, and detected cross compilation.

After that, I got flawless test results:

Test passed.
PASS: sigsegv1.exe
Test passed.
PASS: sigsegv2.exe
Doing SIGSEGV pass 1.
Stack overflow 1 caught.
Doing SIGSEGV pass 2.
Stack overflow 2 caught.
Test passed.
PASS: sigsegv3.exe
Starting recursion pass 1.
Stack overflow 1 caught.
Starting recursion pass 2.
Stack overflow 2 caught.
Test passed.
PASS: stackoverflow1.exe
Starting recursion pass 1.
Stack overflow 1 caught.
Starting recursion pass 2.
Stack overflow 2 caught.
Segmentation violation correctly detected.
Segmentation violation correctly detected.
Test passed.
PASS: stackoverflow2.exe
==================
All 5 tests passed
==================

libsigsegv: i686-w64-mingw32 | yes | yes | 2.10

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org