Using -Ztrim-paths with -Zbuild-std gives bad version numbers for standard library paths

[Nemo157]

I tried this code:

> cargo new foo && cd foo
     Created binary (application) `foo` package
> sed -i s/println/panic/ src/main.rs
> RUST_BACKTRACE=1 cargo run --release -Ztrim-paths -Zbuild-std --config=profile.release.debug='"line-tables-only"'
   Compiling foo v0.1.0 (/tmp/tmp.VBGvfipbYa/foo)
    Finished release [optimized + debuginfo] target(s) in 0.63s
     Running `/run/user/1000/cargo-home/target/shared/x86_64-unknown-linux-gnu/release/foo`
thread 'main' panicked at src/main.rs:2:5:
Hello, world!
stack backtrace:
   0: begin_panic_handler
             at std-0.0.0/src/panicking.rs:645:5
   1: panic_fmt
             at core-0.0.0/src/panicking.rs:72:14
   2: main
             at src/main.rs:2:5
   3: call_once<fn(), ()>
             at core-0.0.0/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

I expected to see this happen: std/core version numbers matching rustc's version number

Instead, this happened: std/core have version number 0.0.0

This may be a cargo bug, but I assume it's just using the version numbers from the packaged Cargo.toml so would be fixed here.

Meta

rustc --version --verbose:

rustc 1.76.0-nightly (2c1b65ee1 2023-11-11)
binary: rustc
commit-hash: 2c1b65ee1431f8d3fe2142e821eb13c623bbf8a0
commit-date: 2023-11-11
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.4

cc #111540 (and I can't find a tracking issue for -Zbuild-std)

[Nemo157]

Using -v I see it is actually trying to use the /rustc/<commit hash> path, but also adds the crate path overriding it:

--remap-path-prefix=[toolchain]/lib/rustlib/src/rust=/rustc/2c1b65ee1431f8d3fe2142e821eb13c623bbf8a0
--remap-path-prefix=[toolchain]/lib/rustlib/src/rust/library/core=core-0.0.0

If that path is preferred then this looks more like a cargo bug around flag order, cc @weihanglo you seem likely to have more context about the preferred result.

[weihanglo]

Interactions with -Zbuild-std are out of scope of RFC 3127, but agree with that showing 0.0.0 doesn't make any sense. Just posted a PR for this rust-lang/cargo#13065

I expect the following remap is better and meet what people want?

thread 'main' panicked at src/main.rs:2:5:
Hello, world!
stack backtrace:
   0: begin_panic_handler
             at /rustc/49b3924bd4a34d3cf9c37b74120fba78d9712ab8/library/std/src/panicking.rs:645:5
   1: panic_fmt
             at /rustc/49b3924bd4a34d3cf9c37b74120fba78d9712ab8/library/core/src/panicking.rs:72:14
   2: main
             at src/main.rs:2:5
   3: call_once<fn(), ()>
             at /rustc/49b3924bd4a34d3cf9c37b74120fba78d9712ab8/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace