ocaml-cstruct-1.7.0 fails to build documentation

[tomboy-64]

I wrote an ebuild (gentoo package) for a couple of packages and included support for bruild the documentation. ocaml-cstruct failed to build those. This is reproducible without the package-manager environment.

The effective command run is

        ocaml setup.ml -doc

after

        ocaml setup.ml -build

This is the output:

 * Package:    dev-ml/ocaml-cstruct-1.7.0
 * Repository: tbc
 * USE:        abi_x86_64 amd64 camlp4 doc elibc_glibc kernel_linux lwt ocamlopt userland_GNU
 * FEATURES:   preserve-libs sandbox userpriv usersandbox
>>> Unpacking source...
>>> Unpacking ocaml-cstruct-1.7.0.tar.gz to /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work
>>> Source unpacked in /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work
>>> Preparing source in /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work/ocaml-cstruct-1.7.0 ...
>>> Source prepared.
>>> Configuring source in /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work/ocaml-cstruct-1.7.0 ...

Configuration: 
ocamlfind: ........................................... /usr/bin/ocamlfind
ocamlc: .............................................. /usr/bin/ocamlc.opt
ocamlopt: ............................................ /usr/bin/ocamlopt.opt
ocamlbuild: .......................................... /usr/bin/ocamlbuild
Package name: ........................................ cstruct
Package version: ..................................... 1.7.0
os_type: ............................................. Unix
system: .............................................. linux
architecture: ........................................ amd64
ccomp_type: .......................................... cc
ocaml_version: ....................................... 4.02.3
standard_library_default: ............................ /usr/lib64/ocaml
standard_library: .................................... /usr/lib64/ocaml
standard_runtime: .................................... /usr/bin/ocamlrun
bytecomp_c_compiler: ................................. x86_64-pc-linux-gnu-gcc -march=core-avx2 -O2 -pipe -O -fno-defer-pop -Wall -D_FILE_OFFSET_BITS=64 -D_REENTRANT -O -fPIC
native_c_compiler: ................................... x86_64-pc-linux-gnu-gcc -march=core-avx2 -O2 -pipe -O  -D_FILE_OFFSET_BITS=64 -D_REENTRANT
model: ............................................... default
ext_obj: ............................................. .o
ext_asm: ............................................. .s
ext_lib: ............................................. .a
ext_dll: ............................................. .so
default_executable_name: ............................. a.out
systhread_supported: ................................. true
Install architecture-independent files dir: .......... /usr
Install architecture-dependent files in dir: ......... $prefix
User executables: .................................... $exec_prefix/bin
System admin executables: ............................ $exec_prefix/sbin
Program executables: ................................. $exec_prefix/libexec
Read-only single-machine data: ....................... $prefix/etc
Modifiable architecture-independent data: ............ $prefix/com
Modifiable single-machine data: ...................... $prefix/var
Object code libraries: ............................... /usr/lib64
Read-only arch-independent data root: ................ $prefix/share
Read-only architecture-independent data: ............. $datarootdir
Info documentation: .................................. $datarootdir/info
Locale-dependent data: ............................... $datarootdir/locale
Man documentation: ................................... $datarootdir/man
Documentation root: .................................. /usr/share/doc/ocaml-cstruct-1.7.0/html
HTML documentation: .................................. $docdir
DVI documentation: ................................... $docdir
PDF documentation: ................................... $docdir
PS documentation: .................................... $docdir
Prepend a path when installing package: .............. /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/image/
findlib_version: ..................................... 1.5.5
is_native: ........................................... true
suffix_program: ...................................... 
Remove a file.: ...................................... rm -f
Remove a directory.: ................................. rm -rf
Turn ocaml debug flag on: ............................ false
Turn ocaml profile flag on: .......................... false
Compiler support generation of .cmxs.: ............... true
OCamlbuild additional flags: ......................... 
build the Lwt library: ............................... true
build the Async_unix library: ........................ false
build the UNIX library: .............................. true
build the camlp4 syntax extension: ................... true
Create documentations: ............................... true
Compile tests executable and library and run them: ... false
pkg_bigarray: ........................................ /usr/lib64/ocaml
pkg_ocplib_endian: ................................... /usr/lib64/ocaml/ocplib-endian
pkg_ocplib_endian_bigstring: ......................... /usr/lib64/ocaml/ocplib-endian
pkg_sexplib: ......................................... /usr/lib64/ocaml/sexplib
pkg_sexplib_syntax: .................................. /usr/lib64/ocaml/sexplib
pkg_lwt_unix: ........................................ /usr/lib64/ocaml/lwt
pkg_unix: ............................................ /usr/lib64/ocaml
pkg_camlp4_lib: ...................................... /usr/lib64/ocaml/camlp4
pkg_camlp4_quotations_r: ............................. /usr/lib64/ocaml/camlp4
pkg_camlp4_extend: ................................... /usr/lib64/ocaml/camlp4
ocamldoc: ............................................ /usr/bin/ocamldoc

>>> Source configured.
>>> Compiling source in /tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work/ocaml-cstruct-1.7.0 ...
Finished, 1 target (0 cached) in 00:00:00.
+ /usr/bin/ocamlfind ocamlc -c -g -annot -bin-annot -principal -ccopt -O3 -ccopt -Wall -package bigarray -package ocplib-endian -package ocplib-endian.bigstring -package sexplib -syntax camlp4o -package sexplib.syntax -I lib -o lib/cstruct.cmo lib/cstruct.ml
File "lib/cstruct.ml", line 160, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 286, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 314, characters 10-23:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 417, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
+ /usr/bin/ocamlfind ocamlopt -c -g -annot -bin-annot -principal -ccopt -O3 -ccopt -Wall -package bigarray -package ocplib-endian -package ocplib-endian.bigstring -package sexplib -syntax camlp4o -package sexplib.syntax -I lib -o lib/cstruct.cmx lib/cstruct.ml
File "lib/cstruct.ml", line 160, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 286, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 314, characters 10-23:
Warning 3: deprecated: String.create
Use Bytes.create instead.
File "lib/cstruct.ml", line 417, characters 12-25:
Warning 3: deprecated: String.create
Use Bytes.create instead.
Finished, 33 targets (0 cached) in 00:00:03.
Finished, 0 targets (0 cached) in 00:00:00.
Solver failed:
  Ocamlbuild knows of no rules that apply to a target named Cstruct.odoc. This can happen if you ask Ocamlbuild to build a target with the wrong extension (e.g. .opt instead of .native) or if the source files live in directories that have not been specified as include directories.
Compilation unsuccessful after building 0 targets (0 cached) in 00:00:00.
E: Failure("Command ''/usr/bin/ocamlbuild' doc/api.docdir/index.html' terminated with error code 6")
 * ERROR: dev-ml/ocaml-cstruct-1.7.0::tbc failed (compile phase):
 *   (no error message)
 *
 * Call stack:
 *     ebuild.sh, line   93:  Called src_compile
 *   environment, line 2078:  Called oasis_src_compile
 *   environment, line 1858:  Called die
 * The specific snippet of code:
 *           ocaml setup.ml -doc || die;
 *
 * If you need support, post the output of `emerge --info '=dev-ml/ocaml-cstruct-1.7.0::tbc'`,
 * the complete build log and the output of `emerge -pqv '=dev-ml/ocaml-cstruct-1.7.0::tbc'`.
 * The complete build log is located at '/var/log/portage/dev-ml:ocaml-cstruct-1.7.0:20150905-104457.log'.
 * For convenience, a symlink to the build log is located at '/tmp/portage/dev-ml/ocaml-cstruct-1.7.0/temp/build.log'.
 * The ebuild environment file is located at '/tmp/portage/dev-ml/ocaml-cstruct-1.7.0/temp/environment'.
 * Working directory: '/tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work/ocaml-cstruct-1.7.0'
 * S: '/tmp/portage/dev-ml/ocaml-cstruct-1.7.0/work/ocaml-cstruct-1.7.0'
 *
 * The following package has failed to build, install, or execute postinst:
 *
 *  (dev-ml/ocaml-cstruct-1.7.0:0/0::tbc, ebuild scheduled for merge), Log file:
 *   '/var/log/portage/dev-ml:ocaml-cstruct-1.7.0:20150905-104457.log'
 *

The respective ebuild (gentoo build script) can be found here.