Re: [PATCH] resolv: Do not build libanl.so for ABIs starting at 2.35

[Stafford Horne <shorne@gmail.com>]

On Thu, Dec 30, 2021 at 11:06:31AM -0300, Adhemerval Zanella via Libc-alpha wrote:
> 
> 
> On 29/12/2021 15:30, Florian Weimer wrote:
> > * Adhemerval Zanella:
> > 
> >> ---
> >>  resolv/Makefile | 11 ++++++++++-
> >>  1 file changed, 10 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/resolv/Makefile b/resolv/Makefile
> >> index 59e599535c..5606eab1fd 100644
> >> --- a/resolv/Makefile
> >> +++ b/resolv/Makefile
> >> @@ -78,8 +78,12 @@ generate := mtrace-tst-leaks.out tst-leaks.mtrace tst-leaks2.mtrace
> >>  
> >>  extra-libs := libresolv libnss_dns
> >>  ifeq ($(have-thread-library),yes)
> >> -extra-libs += libanl
> >>  routines += gai_sigqueue
> >> +endif
> >> +
> >> +ifeq ($(have-GLIBC_2.34)$(have-thread-library),yesyes)
> >> +# Empty compatibility library for old binaries.
> >> +extra-libs += libanl
> >>  
> >>  tests += \
> >>    tst-bug18665 \
> >> @@ -176,6 +180,11 @@ $(libanl-routines-var) += \
> >>  libanl-routines += libanl-compat
> >>  libanl-shared-only-routines += libanl-compat
> >>  
> >> +# Pretend that libanl.so is a linker script, so that the symbolic link
> >> +# is not installed.
> >> +install-lib-ldscripts = libanl.so
> >> +$(inst_libdir)/libanl.so:
> >> +
> > 
> > Looks okay.  But the second hunk should be in a separate commit; I think
> > we should backport it.
> 
> Done.

After this make check fails on the OpenRISC port.

tst-linkall-static fails with:

    make[3]: *** No rule to make target 'build/glibcs/or1k-linux-gnu-soft/glibc/resolv/libanl.a', needed by 'build/glibcs/or1k-linux-gnu-soft/glibc/elf/tst-linkall-static'.  Stop.

We may want to keep libanl.a around as an empty binary for build compatibility
reasons like we did with libutil.  There may be builds wheck hard code -lanl,
maybe not as much as -lutil though.

Never the less, this patch seems to fix it:

diff --git a/elf/Makefile b/elf/Makefile
index 06bfa1642f..71bc2987df 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -1683,7 +1683,6 @@ $(objpfx)tst-linkall-static: \
   $(common-objpfx)resolv/libresolv.a \
   $(common-objpfx)login/libutil.a \
   $(common-objpfx)rt/librt.a \
-  $(common-objpfx)resolv/libanl.a \
   $(static-thread-library)
 
 ifeq ($(build-crypt),yes)
@@ -1704,6 +1703,12 @@ $(objpfx)tst-linkall-static: \
 endif
 endif
 
+# Libanl is only available up to GLIBC_2.34
+ifeq ($(have-GLIBC_2.34)$(have-thread-library),yesyes)
+$(objpfx)tst-linkall-static: \
+  $(common-objpfx)resolv/libanl.a
+endif
+
 # The application depends on the DSO, and the DSO loads the plugin.
 # The plugin also depends on the DSO. This creates the circular
 # dependency via dlopen that we're testing to make sure works.