Workspace Cargo.toml support + overhaul examples

[cormacrelf]

Fixes #51 by

• Running cargo commands in current dir & prefixing vendor with third-party/...
• Adding --manifest-path flag
• Adding manifest_path = "..." + third_party_dir = "..." to reindeer.toml, allowing it to live at your workspace root and just point to where the output should go.
  • (This always bugged me about reindeer, the only real way to use it was with a wrapper script. No longer.)
• Remaining compatible with the old CLI ways, hopefully.
• Now that you can run on a workspace toml, filter out workspace members from the BUCK file by default; include_workspace_members = false (default false) because you often want to write your own BUCK files for those instead of having them mixed into a huge generated BUCK file.
• Overhauls the example, now it's 3 examples with much more documentation. Browse the tree at https://github.com/cormacrelf/reindeer/tree/workspace_cargo_toml/examples to see how it looks.

Altogether you get reindeer --manifest-path ./Cargo.toml --third-party-dir subdirectory buckify, and because this is not something I expect people will want to type, the new config parameters get that down to just reindeer buckify. The layout is as as below.

; cat reindeer.toml

manifest_path = "Cargo.toml"
third_party_dir = "third-party/rust"
...

; reindeer buckify
.
├── Cargo.lock
├── Cargo.toml
├── reindeer.toml
└── third-party
    └── rust
        ├── .cargo/...
        ├── BUCK
        └── vendor

Includes a cargo fmt, let me know if this is wrong, maybe there is configuration drift between this repo & others at meta.

[cormacrelf]

Also fixes CI, hopefully.

[cormacrelf]

Ok, everything works except windows, and I don't have a windows machine to dig any further into that at the moment. I'm using the exact same blake3/fixups.toml as the buck2 repository, but note that this PR upgrades blake3 to the latest version 1.5.5 (it was 0.1.5 here before). And we get

error[E0433]: failed to resolve: could not find `sse2` in the crate root
   --> .\third-party\blake3-1.5.5.crate\src\platform.rs:123:24
    |
123 |                 crate::sse2::compress_in_place(cv, block, block_len, counter, flags)
    |                        ^^^^ could not find `sse2` in the crate root
    |
note: found an item that was configured out
   --> .\third-party\blake3-1.5.5.crate\src\lib.rs:119:5
    |
119 | mod sse2;
    |     ^^^^
note: the item is gated here
   --> .\third-party\blake3-1.5.5.crate\src\lib.rs:117:1
    |
117 | #[cfg(blake3_sse2_rust)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
note: found an item that was configured out
   --> .\third-party\blake3-1.5.5.crate\src\lib.rs:122:5
    |
122 | mod sse2;
    |     ^^^^
note: the item is gated here
   --> .\third-party\blake3-1.5.5.crate\src\lib.rs:120:1
    |
120 | #[cfg(blake3_sse2_ffi)]
    | ^^^^^^^^^^^^^^^^^^^^^^^

Even though

• the x86 shared cfgs from the fixups toml (e.g. --cfg=blake3_sse2_ffi) are applied on mac and linux just fine it seems?
• Certainly it applies the neon cfgs on an M1 mac.
• Somehow not there on windows?
• https://github.com/facebookincubator/reindeer/actions/runs/12807517757/job/35708280984?pr=54

[cormacrelf]

Edit, figured out what that was and documented it in the reindeer.toml. Mismatch between prelude's platform names and the ones in this file.