common/mlstdutils: Build a bytecode version of this library.

Even if ocamlopt is available, always build a bytecode version of
‘common/mlstdutils’.

Furthermore, because this library is pure OCaml, we should not be
using ‘ocamlmklib’.  We should use ‘ocaml{c,opt} -a’ instead.  This
doesn't make any difference for native code, but for bytecode it was
building a broken library.

The original reason for making this change is because the generator is
always built as bytecode, and it depended on
‘../common/mlstdutils/guestfs_config.cmo’ and
‘../common/mlstdutils/std_utils.cmo’.  On native code platforms these
were not built before the generator and so the generator races to
build the .cmi and .cmo files.  Since the generator doesn't have
correct dependencies covering the ‘common/mlstdutils’ directory you
can get a broken link on fast machines:

  File "../common/mlstdutils/std_utils.ml", line 1:
  Error: Corrupted compiled interface
  ../common/mlstdutils/guestfs_config.cmi
  make[2]: *** [Makefile:1993: ../common/mlstdutils/std_utils.cmo] Error 2
  make[2]: *** Waiting for unfinished jobs....
  make[2]: Leaving directory '/builddir/build/BUILD/libguestfs-1.37.17/generator'

common/mlstdutils/Makefile.am

@@ -48,7 +48,12 @@ else
 MLSTDUTILS_CMA = mlstdutils.cmxa
 endif
 
-noinst_DATA = $(MLSTDUTILS_CMA)
+# Just for this library, we need to build both bytecode and native
+# code because the generator always requires the bytecode version.
+noinst_DATA = mlstdutils.cma
+if HAVE_OCAMLOPT
+noinst_DATA += mlstdutils.cmxa
+endif
 
 libmlstdutils_a_SOURCES = dummy.c
 libmlstdutils_a_CPPFLAGS = \
@@ -79,8 +84,13 @@ endif
 
 libmlstdutils_a_DEPENDENCIES = $(OBJECTS)
 
-$(MLSTDUTILS_CMA): $(OBJECTS)
-	$(OCAMLFIND) mklib $(OCAMLPACKAGES) $(OBJECTS) -o mlstdutils
+mlstdutils.cma: $(BOBJECTS)
+	$(OCAMLFIND) ocamlc $(OCAMLPACKAGES) -a $^ -o $@
+
+if HAVE_OCAMLOPT
+mlstdutils.cmxa: $(XOBJECTS)
+	$(OCAMLFIND) ocamlopt $(OCAMLPACKAGES) -a $^ -o $@
+endif
 
 # This OCaml module has to be generated by make (configure will put
 # unexpanded prefix macro in).

generator/Makefile.am

@@ -114,9 +114,6 @@ sources = \
 
 # In build dependency order.
 objects = \
-	$(OCAML_BYTES_COMPAT_CMO) \
-	../common/mlstdutils/guestfs_config.cmo \
-	../common/mlstdutils/std_utils.cmo \
 	types.cmo \
 	utils.cmo \
 	proc_nr.cmo \
@@ -178,7 +175,12 @@ OCAMLFLAGS = $(OCAML_FLAGS) $(OCAML_WARN_ERROR)
 noinst_PROGRAM = generator
 
 generator: $(objects)
-	$(OCAMLFIND) ocamlc $(OCAMLFLAGS) $(OCAMLPACKAGES) -linkpkg $^ -o $@
+#	We need the recursive make here because the generator is
+#	rebuilt in ‘make clean’.
+	$(MAKE) -C $(top_builddir)/common/mlstdutils mlstdutils.cma
+	$(OCAMLFIND) ocamlc $(OCAMLFLAGS) \
+	    $(OCAMLPACKAGES) -linkpkg mlstdutils.cma \
+	    $^ -o $@
 
 # Dependencies.
 depend: .depend