Keep track of compiler info during build

[nojaf]

Fixes #7436

It produces a lib/bs/compiler-info.json file which contains:

{
  "version": "12.0.0-beta.12",
  "bsc_path": "/Users/nojaf/Projects/vrindelycker/node_modules/@rescript/darwin-arm64/bin/bsc.exe",
  "bsc_hash": "7d113813ca550965be97771da2ce2d47f85d297eda9e568763e54d31e0b8098d",
  "rescript_config_hash": "226055db0876bea957f7b3b597478f95fdaefb4547704d6557c5dceb64772a1b",
  "runtime_path": "/Users/nojaf/Projects/vrindelycker/node_modules/@rescript/runtime",
  "generated_at": "1757936814848"
}

"runtime_path" and "bsc_path" might be interesting for tooling to pick up.

That hash compare is also really useful when working with a local compiler.

[pkg-pr-new]

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rescript

npm i https://pkg.pr.new/rescript-lang/rescript@7889

@rescript/darwin-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-arm64@7889

@rescript/darwin-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-x64@7889

@rescript/linux-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-arm64@7889

@rescript/linux-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-x64@7889

@rescript/runtime

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@7889

@rescript/win32-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/win32-x64@7889

commit: bef0e40

[Copilot]

Pull Request Overview

This PR implements compiler tracking functionality during builds to detect compiler changes and trigger necessary package cleaning. It adds compiler metadata including version, BSC path/hash, and runtime path to facilitate build invalidation when the compiler environment changes.

Key changes:

• Introduces a CompilerInfo struct containing BSC path, hash, and runtime path
• Adds compiler verification logic that compares current compiler info with stored metadata
• Implements automatic package cleaning when compiler changes are detected

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
rewatch/src/build/compiler_info.rs	New module implementing compiler info verification and metadata file writing
rewatch/src/build/build_types.rs	Adds CompilerInfo struct and updates BuildState to use it
rewatch/src/build.rs	Integrates compiler verification into build initialization
rewatch/src/build/packages.rs	Adds method to get compiler info file path
rewatch/src/build/parse.rs	Updates AST generation to use compiler info
rewatch/src/build/compile.rs	Refactors runtime path handling and updates compilation
rewatch/src/build/clean.rs	Updates cleaning logic and adds compiler info cleanup

Comments suppressed due to low confidence (1)

rewatch/src/build/compiler_info.rs:1

• This TODO comment appears to be in the wrong location. It's placed in the compile.rs diff but seems unrelated to the compiler info functionality being added.

use crate::helpers;

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