Set/override `os-distribution`

vsiles · December 17, 2022, 12:43pm

Hi !
On my system, I have both brew and port installed, and sometimes, I have libraries present in both of them. For example I have the gmp library installed in both of them, so when I install zarith, the detection will select the library from brew (my understanding is that brew is always checked first).

Is it possible to by-pass this and make opam select the library in port instead ? Maybe by setting or overriding manually os-distribution ? At the moment, I have to temporarily “hide” homebrew from opam while I install zarith to make it choose the right library.

dbuenzli · December 17, 2022, 1:10pm

You are asking for trouble.

You might succeed by setting up the C toolchain LIBRARY_PATH and C_INCLUDE_PATH environment variables appropriately before installing (or if gmp uses pkg-config, the PKG_CONFIG_PATH variable).

vsiles · December 17, 2022, 1:51pm

Not by choice I assure you

Do you mean that by setting these I could prevent opam to use the os-distribution variable ?

dbuenzli · December 17, 2022, 1:52pm

No you could make it lookup the right library.

kit-ty-kate · December 17, 2022, 2:57pm

This is possible with the (hopefully) soon to be released opam 2.2.0. See:

github.com/ocaml/opam

os-distribution

opened 05:21PM - 03 Nov 21 UTC

closed 08:06AM - 04 Aug 22 UTC

diremy

KIND: BUG

``` $ opam --version 2.1.0 ``` opam has a global configuration variable `os-…distribution`, but this variable seems to be ignored at least in most (if not all) cases, instead trying to guess the its value dynamically by checking which one of the two commands `brew` or `port` (in this order) is executable. Here is my global config: ``` $ opam var | grep os os macos # Inferred from system os-distribution macports # Set through 'opam config set-global' os-family bsd # Set through 'opam config set-global' os-version 11.6 # Inferred from system ``` However, opam seems to bypass this configuration: ``` $ opam config report | grep system # system arch=x86_64 os=macos os-distribution=homebrew os-version=11.6 ``` The reason is that (for some reason) I have both `port` and `brew` binaries installed. Indeed, removing the executable rights to the `brew` command ``` $ chmod -x /usr/local/bin/brew ``` fixes the problem: ``` $ opam config report | grep system # system arch=x86_64 os=macos os-distribution=macports os-version=11.6 ``` But I consider this to be a bug since the global `os-distribution` variable seems to be always overriden. As a result, `opam` - always wants to install external dependencies with `brew`, which I must refuse. - fails to install most `conf-*` packages even when these are correctly installed with macports. My only solution is thus to make `brew` non-executable.

You just need to be careful to change both os-family and os-distribution:

opam var --global os-distribution=macports
opam var --global os-family=macports

You can install opam master fairly easily by compiling it from source:

git clone https://github.com/ocaml/opam
cd opam
make cold
sudo install ./opam /usr/local/bin/opam

make cold does everything for you and does not require you to install any of opam’s dependencies.