lazily load Pkg (#4955)

* lazily load Pkg

* compat fixes

* use 'pre' in CI

* please formatter

---------

Co-authored-by: Simon Christ <SimonChrist@gmx.de>

Author: KristofferC

.github/workflows/ci.yml

@@ -53,11 +53,7 @@ jobs:
           - os: ubuntu-latest
             experimental: true
             prefix: xvfb-run
-            version: '~1.11.0-0'  # upcoming julia version, next `rc`
-          - os: ubuntu-latest
-            experimental: true
-            prefix: xvfb-run
-            version: 'nightly'
+            version: 'pre'  # upcoming julia version, next `rc`
 
     steps:
       - uses: actions/checkout@v4

Project.toml

@@ -35,6 +35,7 @@ Showoff = "992d4aef-0814-514b-bc4d-f2e9a6c4116f"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
+TOML = "fa267f1f-6049-4f14-aa54-33bafae1ed76"
 UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 UnicodeFun = "1cfade01-22cf-5700-b092-accc4b62d6e1"
 UnitfulLatexify = "45397f5d-5981-4c77-b2b3-fc36d6e9b728"

src/Plots.jl

@@ -7,7 +7,7 @@ if isdefined(Base, :Experimental) && isdefined(Base.Experimental, Symbol("@max_m
     @eval Base.Experimental.@max_methods 1
 end
 
-using Pkg, Dates, Printf, Statistics, Base64, LinearAlgebra, SparseArrays, Random
+using Dates, Printf, Statistics, Base64, LinearAlgebra, SparseArrays, Random, TOML
 using PrecompileTools, Reexport, RelocatableFolders
 using Base.Meta
 @reexport using RecipesBase

src/backends.jl

@@ -1,16 +1,17 @@
 struct NoBackend <: AbstractBackend end
 
-const _plots_project         = Pkg.Types.read_package(normpath(@__DIR__, "..", "Project.toml"))
-const _current_plots_version = _plots_project.version
-const _plots_compats         = _plots_project.compat
+lazyloadPkg() = Base.require(@__MODULE__, :Pkg)
+
+const _current_plots_version = VersionNumber(TOML.parsefile(normpath(@__DIR__, "..", "Project.toml"))["version"])
+const _plots_compats         = TOML.parsefile(normpath(@__DIR__, "..", "Project.toml"))["compat"]
 
 const _backendSymbol        = Dict{DataType,Symbol}(NoBackend => :none)
 const _backendType          = Dict{Symbol,DataType}(:none => NoBackend)
 const _backend_packages     = Dict{Symbol,Symbol}()
 const _initialized_backends = Set{Symbol}()
 const _backends             = Symbol[]
 
-const _plots_deps = let toml = Pkg.TOML.parsefile(normpath(@__DIR__, "..", "Project.toml"))
+const _plots_deps = let toml = TOML.parsefile(normpath(@__DIR__, "..", "Project.toml"))
     merge(toml["deps"], toml["extras"])
 end
 
@@ -38,22 +39,20 @@ function _check_installed(backend::Union{Module,AbstractString,Symbol}; warn = t
     version = if pkg_id === nothing
         nothing
     else
-        get(Pkg.dependencies(), pkg_id.uuid, (; version = nothing)).version
+        pkg = lazyloadPkg()
+        get(Base.invokelatest(pkg.dependencies), pkg_id.uuid, (; version = nothing)).version
     end
     version === nothing && @warn "backend `$str` is not installed."
     version
 end
 
 function _check_compat(m::Module; warn = true)
     (be_v = _check_installed(m; warn)) === nothing && return
-    if (be_c = _plots_compats[string(m)]) isa String  # julia 1.6
-        if be_v ∉ Pkg.Types.semver_spec(be_c)
-            @warn "`$m` $be_v is not compatible with this version of `Plots`. The declared compatibility is $(be_c)."
-        end
-    else
-        if intersect(be_v, be_c.val) |> isempty
-            @warn "`$m` $be_v is not compatible with this version of `Plots`. The declared compatibility is $(be_c.str)."
-        end
+    be_c = _plots_compats[string(m)]
+    pkg = lazyloadPkg()
+    semver = Base.invokelatest(pkg.Types.semver_spec, be_c)
+    if Base.invokelatest(∉, be_v, semver)
+        @warn "`$m` $be_v is not compatible with this version of `Plots`. The declared compatibility is $(be_c)."
     end
     nothing
 end
@@ -214,9 +213,11 @@ function diagnostics(io::IO = stdout)
     else
         be_name = string(backend_package_name(be))
         @info "selected `Plots` backend: $be_name, from $origin"
-        Pkg.status(
+        pkg = lazyloadPkg()
+        Base.invokelatest(
+            pkg.status,
             ["Plots", "RecipesBase", "RecipesPipeline", be_name];
-            mode = Pkg.PKGMODE_MANIFEST,
+            mode = pkg.PKGMODE_MANIFEST,
             io,
         )
     end
@@ -379,7 +380,9 @@ function _initialize_backend(pkg::AbstractBackend)
     @eval name === :GR ? Plots : Main begin
         import $name
         export $name
-        $(_check_compat)($name)
+        if $(QuoteNode(name)) !== :GR
+            $(_check_compat)($name)
+        end
     end
     _post_imports(pkg)
     _runtime_init(pkg)