Artifacts: Improve type-stability

This improves Artifacts.jl to make `_artifact_str` full type-stable,
which allows `artifact"..."` to be used with `juliac`.

This is a requirement for JLL support w/ trimmed executables.

Dependent on JuliaLang#55016

stdlib/Artifacts/src/Artifacts.jl

@@ -175,13 +175,11 @@ function load_overrides(;force::Bool = false)::Dict{Symbol, Any}
         end
     end
 
-    overrides = Dict{Symbol,Any}(
-        # Overrides by UUID
-        :UUID => overrides_uuid,
-
-        # Overrides by hash
-        :hash => overrides_hash
-    )
+    overrides = Dict{Symbol,Any}()
+    # Overrides by UUID
+    overrides[:UUID] = overrides_uuid
+    # Overrides by hash
+    overrides[:hash] = overrides_hash
 
     ARTIFACT_OVERRIDES[] = overrides
     return overrides
@@ -351,7 +349,7 @@ function process_overrides(artifact_dict::Dict, pkg_uuid::Base.UUID)
 
             # If we've got a platform-specific friend, override all hashes:
             artifact_dict_name = artifact_dict[name]
-            if isa(artifact_dict_name, Array)
+            if isa(artifact_dict_name, Vector{Any})
                 for entry in artifact_dict_name
                     entry = entry::Dict{String,Any}
                     hash = SHA1(entry["git-tree-sha1"]::String)
@@ -544,7 +542,7 @@ function jointail(dir, tail)
     end
 end
 
-function _artifact_str(__module__, artifacts_toml, name, path_tail, artifact_dict, hash, platform, @nospecialize(lazyartifacts))
+function _artifact_str(__module__, artifacts_toml, name, path_tail, artifact_dict, hash, platform, ::Val{LazyArtifacts}) where LazyArtifacts
     pkg = Base.PkgId(__module__)
     if pkg.uuid !== nothing
         # Process overrides for this UUID, if we know what it is
@@ -563,11 +561,11 @@ function _artifact_str(__module__, artifacts_toml, name, path_tail, artifact_dic
     # If not, try determining what went wrong:
     meta = artifact_meta(name, artifact_dict, artifacts_toml; platform)
     if meta !== nothing && get(meta, "lazy", false)
-        if lazyartifacts isa Module && isdefined(lazyartifacts, :ensure_artifact_installed)
-            if nameof(lazyartifacts) in (:Pkg, :Artifacts)
+        if LazyArtifacts isa Module && isdefined(LazyArtifacts, :ensure_artifact_installed)
+            if nameof(LazyArtifacts) in (:Pkg, :Artifacts)
                 Base.depwarn("using Pkg instead of using LazyArtifacts is deprecated", :var"@artifact_str", force=true)
             end
-            return jointail(lazyartifacts.ensure_artifact_installed(string(name), meta, artifacts_toml; platform), path_tail)
+            return jointail(LazyArtifacts.ensure_artifact_installed(string(name), meta, artifacts_toml; platform), path_tail)
         end
         error("Artifact $(repr(name)) is a lazy artifact; package developers must call `using LazyArtifacts` in $(__module__) before using lazy artifacts.")
     end
@@ -699,10 +697,10 @@ macro artifact_str(name, platform=nothing)
 
     # Check if the user has provided `LazyArtifacts`, and thus supports lazy artifacts
     # If not, check to see if `Pkg` or `Pkg.Artifacts` has been imported.
-    lazyartifacts = nothing
+    LazyArtifacts = nothing
     for module_name in (:LazyArtifacts, :Pkg, :Artifacts)
         if isdefined(__module__, module_name)
-            lazyartifacts = GlobalRef(__module__, module_name)
+            LazyArtifacts = GlobalRef(__module__, module_name)
             break
         end
     end
@@ -714,7 +712,7 @@ macro artifact_str(name, platform=nothing)
         platform = HostPlatform()
         artifact_name, artifact_path_tail, hash = artifact_slash_lookup(name, artifact_dict, artifacts_toml, platform)
         return quote
-            Base.invokelatest(_artifact_str, $(__module__), $(artifacts_toml), $(artifact_name), $(artifact_path_tail), $(artifact_dict), $(hash), $(platform), $(lazyartifacts))::String
+            Base.invokelatest(_artifact_str, $(__module__), $(artifacts_toml), $(artifact_name), $(artifact_path_tail), $(artifact_dict), $(hash), $(platform), Val($(LazyArtifacts)))::String
         end
     else
         if platform === nothing
@@ -723,7 +721,7 @@ macro artifact_str(name, platform=nothing)
         return quote
             local platform = $(esc(platform))
             local artifact_name, artifact_path_tail, hash = artifact_slash_lookup($(esc(name)), $(artifact_dict), $(artifacts_toml), platform)
-            Base.invokelatest(_artifact_str, $(__module__), $(artifacts_toml), artifact_name, artifact_path_tail, $(artifact_dict), hash, platform, $(lazyartifacts))::String
+            Base.invokelatest(_artifact_str, $(__module__), $(artifacts_toml), artifact_name, artifact_path_tail, $(artifact_dict), hash, platform, Val($(LazyArtifacts)))::String
         end
     end
 end