collect e.g. weak deps from project even if it is not a package

src/Operations.jl

@@ -245,17 +245,14 @@ function reset_all_compat!(proj::Project)
     return nothing
 end
 
-function collect_project(pkg::PackageSpec, path::String)
+function collect_project(pkg::Union{PackageSpec, Nothing}, path::String)
     deps = PackageSpec[]
     weakdeps = Set{UUID}()
     project_file = projectfile_path(path; strict=true)
-    if project_file === nothing
-        pkgerror("could not find project file for package $(err_rep(pkg)) at `$path`")
-    end
-    project = read_package(project_file)
+    project = project_file === nothing ?  Project() : read_project(project_file)
     julia_compat = get_compat(project, "julia")
     if !isnothing(julia_compat) && !(VERSION in julia_compat)
-        pkgerror("julia version requirement from Project.toml's compat section not satisfied for package $(err_rep(pkg)) at `$path`")
+        pkgerror("julia version requirement from Project.toml's compat section not satisfied for package at `$path`")
     end
     for (name, uuid) in project.deps
         path, repo = get_path_repo(project, name)
@@ -267,11 +264,13 @@ function collect_project(pkg::PackageSpec, path::String)
         push!(deps, PackageSpec(name, uuid, vspec))
         push!(weakdeps, uuid)
     end
-    if project.version !== nothing
-        pkg.version = project.version
-    else
-        # @warn("project file for $(pkg.name) is missing a `version` entry")
-        pkg.version = VersionNumber(0)
+    if pkg !== nothing
+        if project.version !== nothing
+            pkg.version = project.version
+        else
+            # @warn("project file for $(pkg.name) is missing a `version` entry")
+            pkg.version = VersionNumber(0)
+        end
     end
     return deps, weakdeps
 end
@@ -309,13 +308,13 @@ end
 function collect_fixed!(env::EnvCache, pkgs::Vector{PackageSpec}, names::Dict{UUID, String})
     deps_map = Dict{UUID,Vector{PackageSpec}}()
     weak_map = Dict{UUID,Set{UUID}}()
-    if env.pkg !== nothing
-        pkg = env.pkg
-        deps, weakdeps = collect_project(pkg, dirname(env.project_file))
-        deps_map[pkg.uuid] = deps
-        weak_map[pkg.uuid] = weakdeps
-        names[pkg.uuid] = pkg.name
-    end
+
+    uuid = Types.project_uuid(env)
+    deps, weakdeps = collect_project(env.pkg, dirname(env.project_file))
+    deps_map[uuid] = deps
+    weak_map[uuid] = weakdeps
+    names[uuid] = env.pkg === nothing ? "project" : env.pkg.name
+
     for pkg in pkgs
         # add repo package if necessary
         if (pkg.repo.rev !== nothing || pkg.repo.source !== nothing) && pkg.tree_hash === nothing
@@ -345,7 +344,8 @@ function collect_fixed!(env::EnvCache, pkgs::Vector{PackageSpec}, names::Dict{UU
             idx = findfirst(pkg -> pkg.uuid == uuid, pkgs)
             fix_pkg = pkgs[idx]
         end
-        fixed[uuid] = Resolve.Fixed(fix_pkg.version, q, weak_map[uuid])
+        fixpkgversion = fix_pkg === nothing ? v"0.0.0" : fix_pkg.version
+        fixed[uuid] = Resolve.Fixed(fixpkgversion, q, weak_map[uuid])
     end
     return fixed
 end

src/Types.jl

@@ -417,7 +417,7 @@ Base.@kwdef mutable struct Context
     julia_version::Union{VersionNumber,Nothing} = VERSION
 end
 
-project_uuid(env::EnvCache) = env.pkg === nothing ? nothing : env.pkg.uuid
+project_uuid(env::EnvCache) = env.pkg === nothing ? Base.dummy_uuid(env.project_file) : env.pkg.uuid
 collides_with_project(env::EnvCache, pkg::PackageSpec) =
     is_project_name(env, pkg.name) || is_project_uuid(env, pkg.uuid)
 is_project(env::EnvCache, pkg::PackageSpec) = is_project_uuid(env, pkg.uuid)

test/extensions.jl

@@ -1,5 +1,6 @@
 using  .Utils
 using Test
+using UUIDs
 
 @testset "weak deps" begin
     he_root = joinpath(@__DIR__, "test_packages", "ExtensionExamples", "HasExtensions.jl")
@@ -93,4 +94,15 @@ using Test
             @test proj.extras == Dict{String, Base.UUID}("Example" => Base.UUID("7876af07-990d-54b4-ab0e-23690620f79a"))
         end
     end
+
+    isolate(loaded_depot=false) do
+        mktempdir() do dir
+            Pkg.Registry.add("General")
+            path = joinpath(@__DIR__, "test_packages", "TestWeakDepProject")
+            cp(path, joinpath(dir, "TestWeakDepProject"))
+            Pkg.activate(joinpath(dir, "TestWeakDepProject"))
+            Pkg.resolve()
+            @test Pkg.dependencies()[UUID("2ab3a3ac-af41-5b50-aa03-7779005ae688")].version == v"0.3.26"
+        end
+    end
 end

test/test_packages/TestWeakDepProject/Project.toml

@@ -0,0 +1,9 @@
+[deps]
+ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
+
+[weakdeps]
+LogExpFunctions = "2ab3a3ac-af41-5b50-aa03-7779005ae688"
+
+[compat]
+ForwardDiff = "=0.10.36"
+LogExpFunctions = "=0.3.26"