brew deps --os linux does not report Linux dependencies on macOS ARM

[steveh]

brew doctor output

Your system is ready to brew.

Verification

• My "brew doctor output" above says Your system is ready to brew. and am still able to reproduce my issue.
• I ran brew update twice and am still able to reproduce my issue.
• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

brew config output

HOMEBREW_VERSION: 4.4.14-12-gc723e2f
ORIGIN: https://github.com/Homebrew/brew
HEAD: c723e2fde3ed98f5aa763e8eed152aadfa3bff3a
Last commit: 51 minutes ago
Branch: master
Core tap HEAD: 3f636c3ff7244707e4c13a613f672aaee6cb8582
Core tap last commit: 21 minutes ago
Core tap JSON: 31 Dec 21:01 UTC
Core cask tap HEAD: 21862d9c82c9909995a19df597e27490a16f5f11
Core cask tap last commit: 40 minutes ago
Core cask tap JSON: 31 Dec 21:01 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_BAT_THEME: gruvbox-dark
HOMEBREW_CASK_OPTS: []
HOMEBREW_EDITOR: vim
HOMEBREW_MAKE_JOBS: 10
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.3.6 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.3.6/bin/ruby
CPU: 10-core 64-bit arm_firestorm_icestorm
Clang: 16.0.0 build 1600
Git: 2.47.1 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 15.2-arm64
CLT: 16.2.0.0.1.1733547573
Xcode: N/A
Rosetta 2: false

What were you trying to do (and why)?

List all Linux dependencies for a formula, so I could install on a different machine to create a bottle.

What happened (include all command output)?

$ brew deps --os linux [email protected]
bzip2
ca-certificates
expat
libedit
libffi
libxcrypt
mpdecimal
ncurses
openssl@3
readline
sqlite
unzip
xz
zlib

What did you expect to happen?

The 3 on_linux dependencies to be included in the output. I assume leaving --arch blank means it's using --arch arm on my M1 Mac, but these dependencies are not architecture-dependent on Linux.

depends_on "berkeley-db@5"
depends_on "libnsl"
depends_on "libtirpc"

per https://github.com/Homebrew/homebrew-core/blob/3f636c3ff7244707e4c13a613f672aaee6cb8582/Formula/p/python%403.12.rb#L41C1-L45C6

Step-by-step reproduction instructions (by running brew commands)

1. `brew deps --os linux [email protected]`
2. Note absence of `libnsl`, `berkeley-db@5`, `libtirpc`
3. `brew deps --os linux --arch intel [email protected]`
4. Dependencies are now shown

[cho-m]

Issue is JSON API specific as variations are recorded based on os/arch combination:

❯ curl -sL https://formulae.brew.sh/api/formula/[email protected] | jq .variations
{
  "x86_64_linux": {
    "dependencies": [
      "mpdecimal",
      "openssl@3",
      "sqlite",
      "xz",
      "berkeley-db@5",
      "libnsl",
      "libtirpc"
    ]
  }
}

If run on tap, then behavior is as expected:

❯ HOMEBREW_NO_INSTALL_FROM_API=1 brew deps --os linux [email protected]
berkeley-db@5
bzip2
ca-certificates
expat
krb5
libedit
libffi
libnsl
libtirpc
libxcrypt
mpdecimal
ncurses
openssl@3
readline
sqlite
unzip
xz
zlib

[apainintheneck]

IIRC, we only currently support x86_64 on Linux, right? If that's the case, maybe we could just assume that when the os is Linux and the arch is not provided that it should be x86_64.

[Bo98]

It's unsupported but should still work under at least HOMEBREW_NO_INSTALL_FROM_API. We have maintainers already using arm64 Linux locally.

This is really a API-specific issue because variations don't model the generic case very well unlike the equivalent Ruby DSLs.

So I guess you could force the arch to be x86_64 if under API mode. Bit of a hack.

[apainintheneck]

Are there any plans to add arm64 Linux to the API at some point? If not, I think that the hack you mentioned above might be worth it since that seems to be the expected behavior.

[apainintheneck]

I see some more work being done related to arm64 on Linux so I don't think automatically forcing the arch to be x86_64 when Linux is specified makes that much sense. I wonder if it'd make more sense to not assume the arch at all if the OS is different from the current one in this case.

[carlocab]

Maybe eventually, but it's hard to say when that will happen. It depends largely on how hard it will be to bottle most existing formulae in Homebrew/core. It could be easy, but it could also be a lot of work.