fix(sourceMap): use absolute paths in dev for VS Code debugging

[chenjiahan]

Summary

Ensure VS Code and browser debuggers can correctly resolve breakpoints by using POSIX-style absolute paths in source maps during web development.

Related Links

• https://x.com/mrromro/status/1985290786271887481
• fix: use relative paths in source maps #6450
• https://github.com/rspack-contrib/rstack-examples/blob/58120c67e835ef14c5730bdad5ffbfafc350c95a/rspack/source-map-with-vscode-debugging/rspack.config.js#L13

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull Request Overview

This PR updates the source map configuration logic to use a function for devtoolModuleFilenameTemplate during development for web targets, ensuring POSIX-style absolute paths for better debugger compatibility. The test snapshots are updated to reflect that the configuration value is now a function rather than a string.

Key Changes

• Modified devtoolModuleFilenameTemplate to use a function that converts paths to POSIX format during development for web targets
• Added conditional logic based on isDev and target parameters
• Updated comment to clarify the purpose of the processAssets check

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/core/src/plugins/sourceMap.ts	Implements conditional function-based devtoolModuleFilenameTemplate for dev/web builds with POSIX path conversion
packages/core/tests/snapshots/environments.test.ts.snap	Updates snapshot to expect [Function] instead of string template
packages/core/tests/snapshots/default.test.ts.snap	Updates snapshot to expect [Function] instead of string template (3 occurrences)
packages/core/tests/snapshots/builder.test.ts.snap	Updates snapshot to expect [Function] instead of string template
packages/compat/webpack/tests/snapshots/default.test.ts.snap	Updates snapshot to expect [Function] instead of string template

Comments suppressed due to low confidence (1)

packages/core/src/plugins/sourceMap.ts:88

• The processAssets hook checks if devtoolModuleFilenameTemplate !== DEFAULT_SOURCE_MAP_TEMPLATE, but in development mode with web target, the value is now set to a function (lines 45-48), not the string constant. This comparison will always be true when a function is used, causing the hook to incorrectly skip processing source maps in development builds. The check should account for both string templates and function values, or be updated to handle the new function-based approach.

        if (
          compilation.outputOptions.devtoolModuleFilenameTemplate !==
          DEFAULT_SOURCE_MAP_TEMPLATE
        ) {
          return;
        }

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