avoid dynamically loading the backend in init since it breaks precompilation (#175)

* avoid dynamically loading the backend in init since it breaks precompilation

* update changelog

* avoid loading MicroMamba or pixi_jll if definitely not needed

---------

Co-authored-by: Christopher Doris <github.com/cjdoris>

Author: KristofferC

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+* Bug fix: remove lazy loading for backends, which is incompatible with precompilation.
+
 ## 0.2.27 (2025-04-06)
 * When `add`ing or `rm`ing a dependency, if resolving fails then CondaPkg.toml is now reverted.
 * Bug fixes.

src/CondaPkg.jl

@@ -16,27 +16,12 @@ using Pkg: Pkg
 using Scratch: @get_scratch!
 using TOML: TOML
 
-# these are loaded lazily to avoid downloading the JLLs unless they are needed
-const MICROMAMBA_MODULE = Ref{Module}()
-const PIXI_JLL_MODULE = Ref{Module}()
-
-const MICROMAMBA_PKGID =
-    Base.PkgId(Base.UUID("0b3b1443-0f03-428d-bdfb-f27f9c1191ea"), "MicroMamba")
-const PIXI_JLL_PKGID =
-    Base.PkgId(Base.UUID("4d7b5844-a134-5dcd-ac86-c8f19cd51bed"), "pixi_jll")
-
-function micromamba_module()
-    if !isassigned(MICROMAMBA_MODULE)
-        MICROMAMBA_MODULE[] = Base.require(MICROMAMBA_PKGID)
-    end
-    MICROMAMBA_MODULE[]
+# avoid loading backends which are definitely not used
+if @load_preference("backend", "MicroMamba") == "MicroMamba"
+    using MicroMamba: MicroMamba
 end
-
-function pixi_jll_module()
-    if !isassigned(PIXI_JLL_MODULE)
-        PIXI_JLL_MODULE[] = Base.require(PIXI_JLL_PKGID)
-    end
-    PIXI_JLL_MODULE[]
+if @load_preference("backend", "Pixi") == "Pixi"
+    using pixi_jll: pixi_jll
 end
 
 let toml = TOML.parsefile(joinpath(@__DIR__, "..", "Project.toml"))

src/backend.jl

@@ -14,11 +14,11 @@ function backend()
         env = getpref_env()
         if backend == ""
             if exe == ""
-                if env == "" && invokelatest(pixi_jll_module().is_available)::Bool
+                if env == "" && pixi_jll.is_available()
                     # cannot currently use pixi backend if env preference is set
                     # (see resolve())
                     backend = "Pixi"
-                elseif invokelatest(micromamba_module().available)::Bool
+                elseif MicroMamba.available()
                     backend = "MicroMamba"
                 else
                     error(
@@ -79,7 +79,7 @@ end
 function conda_cmd(args = ``; io::IO = stderr)
     b = backend()
     if b == :MicroMamba
-        invokelatest(micromamba_module().cmd, args, io = io)::Cmd
+        MicroMamba.cmd(args, io = io)
     elseif b in CONDA_BACKENDS
         STATE.condaexe == "" && error("this is a bug")
         `$(STATE.condaexe) $args`
@@ -93,7 +93,7 @@ default_pixi_cache_dir() = @get_scratch!("pixi_cache")
 function pixi_cmd(args = ``; io::IO = stderr)
     b = backend()
     if b == :Pixi
-        pixiexe = invokelatest(pixi_jll_module().pixi)::Cmd
+        pixiexe = pixi_jll.pixi()
         if !haskey(ENV, "PIXI_CACHE_DIR") && !haskey(ENV, "RATTLER_CACHE_DIR")
             # if the cache dirs are not set, use a scratch dir
             pixi_cache_dir = default_pixi_cache_dir()

src/env.jl

@@ -15,8 +15,8 @@ function activate!(e)
     path_sep = Sys.iswindows() ? ';' : ':'
     new_path = join(bindirs(), path_sep)
     if backend() == :MicroMamba
-        e["MAMBA_ROOT_PREFIX"] = invokelatest(micromamba_module().root_dir)::String
-        new_path = "$(new_path)$(path_sep)$(dirname(invokelatest(micromamba_module().executable)::String))"
+        e["MAMBA_ROOT_PREFIX"] = MicroMamba.root_dir()
+        new_path = "$(new_path)$(path_sep)$(dirname(MicroMamba.executable())))"
     end
     if old_path != ""
         new_path = "$(new_path)$(path_sep)$(old_path)"