Support TypeScript 7.1 API

[Copilot]

This PR migrates ts-loader to fully support and integrate with the TypeScript 7.1+ Native API (powered by the tsgo engine).
The implementation has moved past the initial hybrid/experimental design to route core operations through the native typescript/unstable/sync architecture by default. Historical TypeScript version dependencies have been removed in favor of direct 7.1 alignment.

🚀 What Changed

• Default Native Architecture: The native API path (experimentalNativeApi: true) is now the default behavior for the loader.
• Legacy API Removal: Cleaned up historical TypeScript compiler API dependencies, porting internal compilation machinery to target TypeScript 7 native synchronous entry points directly.
• Async Instance Setup: Maintained async loader instance creation to dynamically resolve and load the native ESM sync compiler APIs at runtime.
• CI Test Suite Updates: Shifted the workflow matrix to target the 7.1 compiler layer, addressing and adapting tests for rootDir, declaration output, watch behaviors, and error formatting (resolveJsonModule, onlyCompileBundledFiles).

📦 Integration Details

• Native Emit Path (/src/native.ts): Opens and manages native snapshots, uses getJavaScriptEmit for file emissions, and registers project dependencies natively with Webpack.
• Diagnostic Mapping: Translates native compiler diagnostics directly into native Webpack module errors.
• Compatibility Layer: Preserves existing source mapping and module completion handling to ensure seamless integration with modern Webpack builds, alongside localized fixes for legacy Webpack 4 setups.

🧪 Verification Status

• yarn build compiles successfully against the native TS7 target architecture.
• Full execution test suites run and pass cleanly against the 7.1.0-dev core matrix.
• (Note: Historic loaderOptions testing has been bypassed or updated to reflect the new default baseline)..

[johnnyreilly]

@copilot update

ts-loader/.github/workflows/push.yml

Line 52 in 53082fb

ts: [5.6.2, 5.7.2, 5.8.2, 5.9.2, 6.0.2] # next excluded for now

and

ts-loader/.github/workflows/push.yml

Line 84 in 53082fb

ts: [5.6.2, 5.7.2, 5.8.2, 5.9.2, 6.0.2] # next excluded for now

to only cater for: 7.1.0-dev.20260725.1 - the existing versions specified do not contain the new API.

We expect execution-tests to pass after this change

[Copilot]

@copilot update

ts-loader/.github/workflows/push.yml

Line 52 in 53082fb

ts: [5.6.2, 5.7.2, 5.8.2, 5.9.2, 6.0.2] # next excluded for now

and https://github.com/TypeStrong/ts-loader/blob/53082fbe1cdeb560b6...

Updated in fcc8a21 to run the execution-test matrix only against 7.1.0-dev.20260725.1. I also verified the native path locally with yarn build && yarn execution-tests -- --single-test nativeApiTranspile.

[johnnyreilly]

@copilot great work! We would like the following to succeed:

yarn build && yarn execution-tests

Remember backwards compatibility is not required - feel free to make changes

[Copilot]

@copilot great work! We would like the following to succeed:

yarn build && yarn execution-tests
...

Verified on fcc8a21: yarn build && yarn execution-tests now succeeds locally (30 execution suites passed).

[johnnyreilly]

@copilot we have explictly removed the historic typescript version from dependencies and moved to use 7.1 directly. This has broken compilation. Please fix it. You will likely need to use new APIs in TypeScript 7 to achieve this. No cheating.

[Copilot]

@copilot we have explictly removed the historic typescript version from dependencies and moved to use 7.1 directly. This has broken compilation. Please fix it. You will likely need to use new APIs i...

Updated in 4706cfe. yarn build now passes against direct TypeScript 7 by routing the loader through typescript/unstable/sync instead of the removed legacy compiler API.

[johnnyreilly]

@copilot make experimentalNativeApi: true the default behaviour and ensure execution-tests pass. We are happy to ignore loaderOptions test for now

[Copilot]

@copilot make experimentalNativeApi: true the default behaviour and ensure execution-tests pass. We are happy to ignore loaderOptions test for now

Addressed in 048c5ce. The native execution test now relies on the default native API path, loaderOptions is skipped for now, and yarn build && yarn execution-tests passes locally.

[johnnyreilly]

TypeScript ESLint cannot pass for now - see typescript-eslint/typescript-eslint#10940