Re: [PATCH] meson: remove -no-pie linker flag

[Paolo Bonzini]

On Mon, May 22, 2023 at 4:39 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
> > +  # What about linker flags?  For a static build, no PIE is implied by 
> > -static
> > +  # which we added above.
>
> Is it though?  That was the major problem at the time: it wasn't.

It's what configure was doing:

if test "$static" = "yes"; then
  if test "$pie" != "no" && compile_prog "-Werror -fPIE -DPIE"
"-static-pie"; then
    CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
    pie="yes"
  elif test "$pie" = "yes"; then
    error_exit "-static-pie not available due to missing toolchain support"
  else
    pie="no"
    QEMU_CFLAGS="-fno-pie $QEMU_CFLAGS"
  fi
elif test "$pie" = "no"; then
  if compile_prog "-Werror -fno-pie" "-no-pie"; then
    CONFIGURE_CFLAGS="-fno-pie $CONFIGURE_CFLAGS"
    CONFIGURE_LDFLAGS="-no-pie $CONFIGURE_LDFLAGS"
    QEMU_CFLAGS="-fno-pie -no-pie $QEMU_CFLAGS"
   fi
fi

Note that the code to use -no-pie is only used if test "$static" = no.

> Trying both now, e.g. '--static --disable-system --disable-tools 
> --disable-docs',
> a link line contains
>
> ... -Wl,--as-needed -Wl,--no-undefined -pie -Wl,--whole-archive libhwcore.fa 
> ...
>                                         ^^^^
>
> Where does that come from, and why isn't -no-pie the antidote?

That comes from Meson's -Db_pie=true, but it is followed by
-static-pie later in the command line so all is good.

In other words, whatever we add second in the command line wins and
that is good for executables; but it is a problem when -no-pie
overrides -shared, thus messing up compilation of any shared library.

Paolo