`x perf benchmark` Fails on Windows: Cannot Find `rustc` Executable

[Sol-Ell]

Summary

Running x perf benchmark on Windows fails due to an invalid path to the rustc executable.

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Command Used

./x perf benchmark some-benchmark

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Expected Behavior

The path to rustc should include the platform-specific executable suffix by appending std::env::consts::EXE_SUFFIX.

Reference:

rust/src/bootstrap/src/core/build_steps/perf.rs

Line 163 in a8e4c68

let rustc = sysroot.join("bin/rustc");

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Actual Behavior

Building bootstrap
   Compiling bootstrap v0.0.0 (C:\Users\user\Desktop\projects\rust\src\bootstrap)
    Finished `dev` profile [unoptimized] target(s) in 10.72s
Building stage0 tool collector (x86_64-pc-windows-msvc)
    Finished `release` profile [optimized] target(s) in 1.73s
Creating a sysroot for stage1 compiler (use `rustup toolchain link 'name' build/host/stage1`)
Using database `C:\Users\user\Desktop\projects\rust\build\tmp\rustc-perf\results\results.db`
collector error: failed to canonicalize rustc executable "C:\\Users\\user\\Desktop\\projects\\rust\\build\\x86_64-pc-windows-msvc\\stage1\\bin/rustc"

Caused by:
    The system cannot find the file specified. (os error 2)
Command has failed. Rerun with -v to see more details.

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Bootstrap Configuration (bootstrap.toml)

# See bootstrap.example.toml for documentation of available options
profile = "library"
change-id = 140732

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Operating System

Windows 11

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Git Commit

> git rev-parse HEAD
a8e4c68dcb4dc1e48a0db294c5323cab0227fcb9

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Additional Context

The error seems to be caused by using a forward slash (/) instead of a backslash (\) in the rustc path, and by not appending .exe on Windows. Adding the correct executable suffix should resolve the issue.