fix: Every workspace should have a proc-macro server - #23111
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fetch_proc_macros() zips proc_macro_clients with a per-workspace vec. We therefore require proc_macro_clients to have an item for every workspace, or we get "proc-macro-srv is not running" and no macro expansion for some workspaces. This issue is more noticeable when using a discovery command, where it's common to have have several workspaces, but it can occur in plain cargo repositories too. The logic was essentially `if !same_workspaces`, but this doesn't actually work. When a new workspace is added, switch_workspaces() updates self.workspaces, pushes to fetch_build_data_queue, and returns early. When we actually check the proc macro clients, on the second invocation, we're seeing the *new* self.workspaces already and it looks like nothing has changed! This was broken in rust-lang#22766, and only partially fixed in rust-lang#22865. Revert the code, and expand the doc comments. A better solution would be to track proc macro initialisation state properly, but this fixes r-a on the >1 workspaces case today. AI disclosure: Bisected with help by AI.
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fetch_proc_macros() zips proc_macro_clients with a per-workspace vec. We therefore require proc_macro_clients to have an item for every workspace, or we get "proc-macro-srv is not running" and no macro expansion for some workspaces.
This issue is more noticeable when using a discovery command, where it's common to have have several workspaces, but it can occur in plain cargo repositories too.
The logic was essentially
if !same_workspaces, but this doesn't actually work. When a new workspace is added, switch_workspaces() updates self.workspaces, pushes to fetch_build_data_queue, and returns early.When we actually check the proc macro clients, on the second invocation, we're seeing the new self.workspaces already and it looks like nothing has changed!
This was broken in #22766, and only partially fixed in #22865. Revert the code, and expand the doc comments.
A better solution would be to track proc macro initialisation state properly, but this fixes r-a on the >1 workspaces case today.
AI disclosure: Bisected with help by AI.