Failing to build ocaml/examples

[mohd-akram]

Getting this while building ocaml/examples (on e127edc):

Making all in ocaml/examples
ocamlfind ocamlopt -cclib -L../../lib/.libs -package unix -linkpkg \
          -warn-error A -I .. mlguestfs.cmxa create_disk.ml -o create_disk
ocamlfind ocamlopt -cclib -L../../lib/.libs -package unix -linkpkg \
          -warn-error A -I .. mlguestfs.cmxa debug_logging.ml -o debug_logging
ocamlfind ocamlopt -cclib -L../../lib/.libs -package unix -linkpkg \
          -warn-error A -I .. mlguestfs.cmxa inspect_vm.ml -o inspect_vm
  POD      stamp-guestfs-ocaml.pod
touch stamp-guestfs-ocaml.pod
ld: warning: search path '../lib/.libs' not found
ld: warning: search path '../lib/.libs' not found
ld: warning: search path '../lib/.libs' not found
Undefined symbols for architecture arm64:
Undefined symbols for architecture arm64:
Undefined symbols for architecture arm64:
  "_guestfs_command_out", referenced from:
      _guestfs_int_ocaml_command_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
  "_guestfs_command_out", referenced from:
      _guestfs_int_ocaml_command_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
  "_guestfs_command_out", referenced from:
      _guestfs_int_ocaml_command_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
  "_guestfs_sh_out", referenced from:
      _guestfs_int_ocaml_sh_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
ld: symbol(s) not found for architecture arm64
  "_guestfs_sh_out", referenced from:
      _guestfs_int_ocaml_sh_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
ld: symbol(s) not found for architecture arm64
  "_guestfs_sh_out", referenced from:
      _guestfs_int_ocaml_sh_out in libmlguestfs.a[3](libguestfsocaml_a-guestfs-c-actions.o)
ld: symbol(s) not found for architecture arm64

[rwmjones]

I don't immediately see what's going on here. The problem seems to be that it's trying to link with an old version of libguestfs.so, instead of the version being built in the current build tree. We can guess this because guestfs_command_out and the other one are new APIs only added a few versions ago. The root cause of that could be the error:

ld: warning: search path '../lib/.libs' not found

That error message is itself odd because we're passing -L../../lib/.libs to the C linker (note extra ..).

Does lib/.libs (relative to the top build directory) exist and contain libguestfs.so?

I wonder if libtool acts differently on macOS. Maybe it doesn't create the extra .libs subdirectory. I'm also unclear on where the .. went to.

[mohd-akram]

I don't immediately see what's going on here. The problem seems to be that it's trying to link with an old version of libguestfs.so, instead of the version being built in the current build tree. We can guess this because guestfs_command_out and the other one are new APIs only added a few versions ago.

Thanks, that was it. After uninstalling the system version that part of the build proceeds.

The root cause of that could be the error:

ld: warning: search path '../lib/.libs' not found

That error message is itself odd because we're passing -L../../lib/.libs to the C linker (note extra ..).

Does lib/.libs (relative to the top build directory) exist and contain libguestfs.so?

I wonder if libtool acts differently on macOS. Maybe it doesn't create the extra .libs subdirectory. I'm also unclear on where the .. went to.

It does exist, but it seems to prefer the system version. I ran the command in verbose mode and I get this:

$ ocamlfind ocamlopt -verbose -cclib -L../../lib/.libs -package unix -linkpkg -warn-error A -I .. mlguestfs.cmxa create_disk.ml -o create_disk
Effective set of compiler predicates: pkg_unix,autolink,native
+ ocamlopt.opt -verbose -warn-error A -I .. -o create_disk /opt/local/lib/ocaml/unix.cmxa -cclib -L../../lib/.libs mlguestfs.cmxa create_disk.ml
+ /usr/bin/clang -arch arm64 -Wno-trigraphs -c  -o 'create_disk.o' '/var/folders/v6/r_2fjmg17zgd2mcpd2mjftmh0000gn/T/camlasm445f1c.s'
+ /usr/bin/clang -arch arm64 -Wno-trigraphs -c  -o '/var/folders/v6/r_2fjmg17zgd2mcpd2mjftmh0000gn/T/camlstartup4a12f3.o' '/var/folders/v6/r_2fjmg17zgd2mcpd2mjftmh0000gn/T/camlstartup09474a.s'
+ /usr/bin/clang -arch arm64 -O2 -fno-strict-aliasing -fwrapv -pthread -Wall -Wdeclaration-after-statement -fno-common -pipe -Os -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk -arch arm64  -L/opt/local/lib -Wl,-headerpad_max_install_names -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk -arch arm64 -Wl,-no_compact_unwind -o 'create_disk'  '-L..' '-L/opt/local/lib/ocaml'  '/var/folders/v6/r_2fjmg17zgd2mcpd2mjftmh0000gn/T/camlstartup4a12f3.o' '/opt/local/lib/ocaml/std_exit.o' 'create_disk.o' '../mlguestfs.a' '/opt/local/lib/ocaml/unix.a' '/opt/local/lib/ocaml/stdlib.a' '-lmlguestfs' '-L../lib/.libs' '-lintl' '-lguestfs' '-lunix' '-L../../lib/.libs' '/opt/local/lib/ocaml/libasmrun.a' -lm 

-L../lib/.libs seem to be getting injected from elsewhere.

-L../../lib/.libs is being detected, but it's coming too late while -L/opt/local/lib takes precedence.

[mohd-akram]

This was a bug in the MacPorts version of ocaml (fixed in macports/macports-ports@293c311).

I still get this warning:

ld: warning: search path '../lib/.libs' not found

It seems that can be resolved with:

diff --git a/ocaml/Makefile.am b/ocaml/Makefile.am
index f7621a8fa..1ab354c5a 100644
--- a/ocaml/Makefile.am
+++ b/ocaml/Makefile.am
@@ -64,16 +64,16 @@ endif
 
 stamp-mlguestfs: libguestfsocaml.a $(guestfs_cmm)
 	$(OCAMLMKLIB) -o mlguestfs \
-	  -ldopt '$(LDFLAGS)' \
+	  -ldopt '$(LDFLAGS) -L../lib/.libs' \
 	  $(libguestfsocaml_a_OBJECTS) guestfs.cmo \
 	  $(LTLIBINTL) \
-	  -L../lib/.libs -lguestfs
+	  -lguestfs
 if HAVE_OCAMLOPT
 	$(OCAMLMKLIB) -o mlguestfs \
-	  -ldopt '$(LDFLAGS)' \
+	  -ldopt '$(LDFLAGS) -L../lib/.libs' \
 	  $(libguestfsocaml_a_OBJECTS) guestfs.cmx \
 	  $(LTLIBINTL) \
-	  -L../lib/.libs -lguestfs
+	  -lguestfs
 endif
 	touch $@
 

Also, it seems -ccopt is preferred for flags other than -l per the man page?

[rwmjones]

Changing that will embed -L/home/... into the final mlguestfs.cma file. (That was actually a pre-existing bug, we embed -L../lib/.libs right now).

This may or may not fix things:

#192

[mohd-akram]

Yeah, I just noticed that. It seems it's best to pass it in -ldopt? Probably this should be done everywhere .libs is used. I tweaked the patch. Nvm, it's not needed at all, your PR works for me.

[rwmjones]

I don't know what -ldopt even does there. It doesn't seem to affect the output of ocamlmklib at all!

If the PR works on macOS let's go with that.

[mohd-akram]

I don't know what -ldopt even does there. It doesn't seem to affect the output of ocamlmklib at all!

It seems it wasn't actually useless. The build fails if the system libguestfs is not installed. Looks like adding -L../lib/.libs to -ldopt as in my patch is in fact correct.

[rwmjones]

What is the error message?

[mohd-akram]

This:

ocamlmklib -o mlguestfs \
	  -ldopt '' \
	  libguestfsocaml_a-guestfs-c.o libguestfsocaml_a-guestfs-c-actions.o libguestfsocaml_a-guestfs-c-errnos.o ../common/utils/libguestfsocaml_a-cleanups.o ../common/utils/libguestfsocaml_a-stringlists-utils.o guestfs.cmo \
	  -lintl -Wl,-framework -Wl,CoreFoundation -Wl,-framework -Wl,CoreServices \
	  -lguestfs
Unknown option -Wl,-framework
Unknown option -Wl,CoreFoundation
Unknown option -Wl,-framework
Unknown option -Wl,CoreServices
ld: warning: -undefined suppress is deprecated
ld: warning: -undefined suppress is deprecated
ld: library 'guestfs' not found

With the patch:

ocamlmklib -o mlguestfs \
	  -ldopt ' -L../lib/.libs' \
	  libguestfsocaml_a-guestfs-c.o libguestfsocaml_a-guestfs-c-actions.o libguestfsocaml_a-guestfs-c-errnos.o ../common/utils/libguestfsocaml_a-cleanups.o ../common/utils/libguestfsocaml_a-stringlists-utils.o guestfs.cmx \
	  -lintl -Wl,-framework -Wl,CoreFoundation -Wl,-framework -Wl,CoreServices \
	  -lguestfs
Unknown option -Wl,-framework
Unknown option -Wl,CoreFoundation
Unknown option -Wl,-framework
Unknown option -Wl,CoreServices
ld: warning: -undefined suppress is deprecated
ld: warning: -undefined suppress is deprecated
touch stamp-mlguestfs

I checked mlguestfs.cmxa after and the path isn't embedded with this, so it seems it's good.

[rwmjones]

I can reproduce that too if system libguestfs isn't installed ...

[rwmjones]

Please try your fix I just added.