ppx_qt is empty

[clembu]

The opam file for ppx_qt is empty, and nothing is installed. Makes the ppx effectively unavailable, and the library really hard to use.

[Kakadu]

@facelesspanda I did some changes. It seems that a META for executable should exist and I remove it.

Please, check new version, I want more feedback.

[clembu]

will try to update tonight and check again. Thanks.

[clembu]

just tried to pin to master and update fails with

dune build @install
Error: exception Sys_error("_build/log: Read-only file system")
Backtrace:
Raised by primitive operation at file "stdlib.ml", line 324, characters 29-55
Called from file "src/stdune/log.ml", line 23, characters 11-61
Called from file "bin/common.ml", line 73, characters 2-28
Called from file "bin/common.ml" (inlined), line 97, characters 2-39
Called from file "bin/main.ml", line 46, characters 4-37
Called from file "vendor/cmdliner/src/cmdliner_term.ml", line 25, characters 19-24
Called from file "vendor/cmdliner/src/cmdliner.ml", line 146, characters 9-16
Called from file "vendor/cmdliner/src/cmdliner.ml", line 176, characters 18-36
Called from file "vendor/cmdliner/src/cmdliner.ml", line 312, characters 20-46
Called from file "bin/main.ml", line 198, characters 10-51

I must not segfault.  Uncertainty is the mind-killer.  Exceptions are
the little-death that brings total obliteration.  I will fully express
my cases.  Execution will pass over me and through me.  And when it
has gone past, I will unwind the stack along its path.  Where the
cases are handled there will be nothing.  Only I will remain.
make: *** [Makefile:29: install] Error 1

(content of the opam install log pertaining to lablqml)

[Kakadu]

Pinning work for me though. But your error seems quite mysterious (and hardly googlable). Do you use any non-trivial sandboxing software which can mess with access rights?

[clembu]

nope, just opam. I'll see about gaining more info tonight. For some reason this package is the only one that seems to make dune angry for me.

[clembu]

so I tried building locally.

1. Cloned lablqml to a new directory
2. cd lablqml
3. opam switch create . 4.08.1 There opam tries to install the existing local package because there's a lablqml.opam file at the root, and I have this output

   ### output ###
   # dune build @install
   # Error: mkdir: _build: Read-only file system
   # make: *** [Makefile:29: install] Error 1

4. run eval $(opam env) to have the environment in the shell
5. manually run dune build @install That works fine

When I run opam install . from the lablqml repo, I have that error again about _build being read only and dune failing with a huge backtrace. Must come from opam's sandboxing probably?

[Kakadu]

I don't know. I tried the same but it compiles fine. https://gist.github.com/Kakadu/ddfa3d11a159f364ee74998bca13726a

If it is indeed about sanboxing, then you can try to comment out last lines in ~/.opam/config to disable sandboxing

wrap-build-commands:
  ["%{hooks}%/sandbox.sh" "build"] {os = "linux" | os = "macos"}
wrap-install-commands:
  ["%{hooks}%/sandbox.sh" "install"] {os = "linux" | os = "macos"}
wrap-remove-commands:
  ["%{hooks}%/sandbox.sh" "remove"] {os = "linux" | os = "macos"}

[clembu]

hmm. the verbose mode helped me figuring out something that was kinda obvious: there's a build step before the install step

+ /home/odd/.opam/opam-init/hooks/sandbox.sh "build" "dune" "build" "-p" "lablqml" "-j" "3" (CWD=/home/odd/dev/lablqml/_opam/.opam-switch/build/lablqml.0.6.2)
-     discover lib/c_flags.sexp,lib/c_library_flags.sexp,lib/moc.sexp,lib/rcc.sexp
- /usr/bin/moc-qt5
- /usr/bin/rcc-qt5
-          gcc lib/object_ml.o
...... warnings .....
λ compiled  lablqml.0.6.2
+ /home/odd/.opam/opam-init/hooks/sandbox.sh "install" "make" "install" (CWD=/home/odd/dev/lablqml/_opam/.opam-switch/build/lablqml.0.6.2)
- dune build @install
- Error: mkdir: _build: Read-only file system
- make: *** [Makefile:29: install] Error 1

lablqml is built first to /home/odd/dev/lablqml/_opam/.opam-switch/build/lablqml.0.6.2 Yet in the install step there is a dune build @install.

I found that curious so I dug around to see how other packages that install fine are structured.

They don't have a install entry in their .opam file.

I'm gonna try removing it from lablqml's and see if things change.

[clembu]

Sure enough, removing the install entry from the opam file managed to make lablqml install perfectly, ironically as that sounds:

+ /home/odd/.opam/opam-init/hooks/sandbox.sh "build" "dune" "build" "-p" "lablqml" "-j" "3" (CWD=/home/odd/dev/lablqml/_opam/.opam-switch/build/lablqml.0.6.2)
-     discover lib/c_flags.sexp,lib/c_library_flags.sexp,lib/moc.sexp,lib/rcc.sexp
- /usr/bin/moc-qt5
- /usr/bin/rcc-qt5
...... warnings .....
λ compiled  lablqml.0.6.2
∗ installed lablqml.0.6.2
Done.

[clembu]

Okay so now that lablqml installs fine, I can assert that ppx_qt isn't available as a preprocessor. Using

  (preprocess (per_module
               ((pps ppx_qt) Controller)) )

which is the preferred way to preprocess files in dune, from what I've seen, results in dune expecting a library, when ppx_qt is an executable.

I could "workaround" it by using a run stanza, but it'd be a shame and could be fixed if ppx_qt was compiled as a library too.

[Kakadu]

@facelesspanda I will try to look at this at the weekend...

[Kakadu]

run stanza will be required anyway because ppx_qt generates C++ files.

[Kakadu]

@facelesspanda Also, if you manage to upgrade code in https://github.com/Kakadu/lablqml/tree/master/dune_test than pull-request will be appreciated.

[clembu]

Ok, I'll see what I can do.