Tags

Tagging files

To tag files, use the _tags file. See the user manual for more details. You can also use the tag_file function in a plugin or use the -tag option.

Note that some tags, such as link, are not applied to files but are instead part of certain commands. See the solver mechanism for more details.

Tag documentation

If you need more information about a specific tag, use the -documentation option of ocamlbuild. For example, for the thread tag:

$ ocamlbuild -documentation | grep thread
flag {. byte, link, ocaml, thread, toplevel .} "threads.cma"
flag {. link, native, ocaml, thread, toplevel .} "threads.cmxa"
flag {. byte, link, ocaml, program, thread .} "threads.cma"
flag {. link, native, ocaml, program, thread .} "threads.cmxa"
flag {. doc, ocaml, thread .} "-I +threads"
flag {. link, ocaml, thread .} "-thread"
flag {. compile, ocaml, thread .} "-thread"

For example, the last flag says that files with tags compile, ocaml and thread should be compiled using the -thread option. The first flag says that files with tags byte, ocaml and thread, used in commands that have tags link and program, should use the threads library and the -thread option.

You can also know the tags of a file using the -show-tag option of ocamlbuild:

$ ocamlbuild -show-tags test.byte
Warning: the following tags do not include dynamically-generated tags, such as link, compile, pack, byte, native, c, pdf... (this list is by no means exhaustive).
 
Tags for "test.byte":
  {. byte, extension:byte, file:test.byte, ocaml, program, quiet .}
Finished, 0 targets (0 cached) in 00:00:00.

Unfortunately, to get the full semantics of a tag, you need to know in which commands (more precisely, which "holes") it appears. Some tags are always part of some commands: the link tag is always part of the linking commands. Some commands use the tags of their sources and / or the tags of their production. The only precise documentation is the ocamlbuild source code.

List of tags

This list is far from exhaustive. Feel free to extend it!

To get an intuition on the use of the tag, descriptions start with:

  • This produced file...: rules usually add this tag to their command if one of their production has it.
  • This source file...: rules usually add this tag to their command if one of their dependency has it.
  • This command...: rules usually add this tag to their command regardless of the tags of its dependencies and productions.
  • This file..., This directory...: other uses.

A

annot

This source file should be compiled with the -annot flag to produce a .annot file.

B

byte

This produced file is compiled and linked using the bytecode compiler.

bin_annot

This source file should be compiled with the -bin-annot flag to produce a .cmt[i] file (since 4.01).

C

compile

This command is a compilation operation.

D

debug

This produced file should be compiled in debug mode. For OCaml this means using the -g option.

I

include

This directory should be included, as if the -I option were used.

infer_interface

This command infers an interface to generate a .inferred.mli from a .ml file. An example of use can be found in the Ocamlfind plugin.

L

This command is a link operation.

library

This file is a library. By default, *.cma and *.cmxa have this tag.

N

native

This produced file is compiled and linked using ocamlopt.

not_hygienic

This file is not hygienic but won't be scanned by the sanity check.

O

ocaml

This source file is an OCaml source file, or this produced file is produced using an OCaml tool, or this command is an OCaml-related command.

P

precious

This file is precious and won't be deleted by the sanity check.

program

This file is a program. By default, *.byte and *.native have this tags.

T

thread

This source file uses the Thread module. It is compiled and linked using the -thread option, and linked to the threads library.

U

use_bigarray, use_dbm, use_dynlink, use_graphics, use_nums, use_str, use_toplevel, use_unix

This produced file should be linked with the specified library. This can replace the -lib command line option.