Changing a source in `Project.toml` doesn't trigger a full resolution of the environment

[giordano]

Consider the following Project.toml

[deps]
Example = "7876af07-990d-54b4-ab0e-23690620f79a"

[sources]
Example = {url = "https://github.com/JuliaLang/Example.jl.git", rev = "9eafbe382ffe5bf31d674cd3d7bfd7dbaf3f4b29"}

Resolve the environment and you get the following Manifest.toml:

# This file is machine-generated - editing it directly is not advised

julia_version = "1.13.0-DEV"
manifest_format = "2.0"
project_hash = "2ba095eea143434854ea510082d0697aa2bcd3f3"

[[deps.Example]]
git-tree-sha1 = "f5f048e73ccd0bdfbddd9bd556d9eca360135609"
repo-rev = "9eafbe382ffe5bf31d674cd3d7bfd7dbaf3f4b29"
repo-url = "https://github.com/JuliaLang/Example.jl.git"
uuid = "7876af07-990d-54b4-ab0e-23690620f79a"
version = "0.5.5"

Now change the project to (note the change of the rev attribute of the Example package)

[deps]
Example = "7876af07-990d-54b4-ab0e-23690620f79a"

[sources]
Example = {url = "https://github.com/JuliaLang/Example.jl.git", rev = "82d1224c32990c0105898fa44009864f5648e98d"}

and re-resolving the environment changes the Manifest.toml to

# This file is machine-generated - editing it directly is not advised

julia_version = "1.13.0-DEV"
manifest_format = "2.0"
project_hash = "2ba095eea143434854ea510082d0697aa2bcd3f3"

[[deps.Example]]
git-tree-sha1 = "f5f048e73ccd0bdfbddd9bd556d9eca360135609"
repo-rev = "82d1224c32990c0105898fa44009864f5648e98d"
repo-url = "https://github.com/JuliaLang/Example.jl.git"
uuid = "7876af07-990d-54b4-ab0e-23690620f79a"
version = "0.5.5"

Note that only deps.Example.repo-rev changed, but not deps.Example.git-tree-sha1, nor project_hash.

julia> versioninfo()
Julia Version 1.13.0-DEV.63
Commit f5f6d4115b* (2025-02-14 21:22 UTC)
Platform Info:
  OS: macOS (arm64-apple-darwin23.4.0)
  CPU: 8 × Apple M1
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, apple-m1)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 4 virtual cores)

[KristofferC]

Might be related to #4086.

[KristofferC]

It wasn't the case that you could change rev / repo / path without a corresponding Pkg command so there are some cases (like in resolve) where this causes Pkg to miss that information has been updated directly in the project file.

[KristofferC]

The project hash not updating seems to be due to

Pkg.jl/src/Types.jl

Lines 601 to 602 in d2c81db

	# only hash the deps and compat fields as they are the only fields that affect a resolve
	function workspace_resolve_hash(env::EnvCache)

where it claims that only compact + deps affect resolve (which is no longer true with sources).

[KristofferC]

We do not enter the repo handling here:

Pkg.jl/src/Operations.jl

Lines 410 to 418 in d2c81db

	source = source_path(env.manifest_file, pkg)
	path = source === nothing ? nothing : project_rel_path(env, source)
	if (path === nothing || !isdir(path)) && (pkg.repo.rev !== nothing || pkg.repo.source !== nothing)
	# ensure revved package is installed
	# pkg.tree_hash is set in here
	Types.handle_repo_add!(Types.Context(env=env), pkg)
	# Recompute path
	path = project_rel_path(env, source_path(env.manifest_file, pkg))
	end

because we see that we have already downloaded the package with the tree hash recorded in the manifest (failing to see that information is no longer valid due to the updated rev in the project sources).