Bun: fix issue with sourcemap shim

[jhaynie]

in production, the bundle isn't included correctly

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of source map support for projects using the "bunjs" runtime, ensuring more reliable debugging.
• Refactor
  • Streamlined the bundling process for JavaScript, resulting in more maintainable and efficient internal plugin logic.

[coderabbitai]

Walkthrough

The changes update the JavaScript bundling workflow to handle source map shimming internally within a plugin. The createPlugin function now takes additional parameters for the directory and a shim flag, and registers an extra handler when shimming is needed. The explicit post-build shim string logic has been removed from the build options.

Changes

File(s)	Change Summary
internal/bundler/bundler.go	Refactored to use a shimSourceMap flag and pass directory and flag to createPlugin; removed post-build shim string logic.
internal/bundler/patch.go	Updated createPlugin to accept directory and shim flag; registers extra OnLoad handler for source map shimming when needed.

Poem

In the warren where code is spun,
The bundler's dance is nearly done.
No more shims tacked on with glue—
Now plugins know just what to do!
With flags and paths, they hop along,
Making source maps neat and strong.
🐇✨

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between e18a483 and 1ad8596.

📒 Files selected for processing (2)

• internal/bundler/bundler.go (2 hunks)
• internal/bundler/patch.go (2 hunks)

🧰 Additional context used

🧬 Code Graph Analysis (1)

internal/bundler/bundler.go (1)

internal/project/project.go (1)

• Bundler (456-465)

🔇 Additional comments (7)

internal/bundler/patch.go (3)

6-6: LGTM: Import added for path operations.

The path import is appropriately added to support the path.Join operation used in the new shimming logic.

---

72-72:

Details

✅ Verification successful

Verify function signature change is consistent across codebase.

The function signature has been updated to accept additional parameters. This is a breaking change that requires all call sites to be updated.

I can see from the bundler.go file that the call site has been updated, but let me verify there are no other usages:

---

🏁 Script executed:

#!/bin/bash
# Description: Verify all calls to createPlugin have been updated to match the new signature
# Expected: Only the updated call in bundler.go should be found

rg -A 3 "createPlugin\(" --type go

Length of output: 599

---

✅ createPlugin signature update verified

A repo-wide search for createPlugin( reveals only one usage in internal/bundler/bundler.go, which has already been updated to:

createPlugin(ctx.Logger, dir, shimSourceMap)

No other call sites exist—no further changes are required.

---

76-90:

Details

✅ Verification successful

Verify sourceMapShim variable is defined and accessible.

The new shimming logic looks well-structured, but it references sourceMapShim which is not defined in this file. Please ensure this variable is accessible in the current scope.

---

🏁 Script executed:

#!/bin/bash
# Description: Find the definition of sourceMapShim variable
# Expected: Should find where sourceMapShim is defined

rg "sourceMapShim" --type go -B 2 -A 2

Length of output: 644

---

sourceMapShim is already defined and accessible

The sourceMapShim variable is declared in internal/bundler/shim.go as:

// NOTE: this shim is only used in bun since node has built-in source map support
var sourceMapShim = `…
(function () {
  const { SourceMapConsumer… } = require('source-map-js');
  …
})();
`

Since both shim.go and patch.go reside in the same internal/bundler package, sourceMapShim is in scope and no further action is needed.

internal/bundler/bundler.go (4)

156-156: LGTM: Clean variable initialization.

The shimSourceMap boolean variable is properly initialized to false, providing a clear default state.

---

162-162: LGTM: Conditional shimming for Bun runtime.

Setting shimSourceMap = true specifically for the "bunjs" runtime after ensuring source-map-js is installed is a logical approach that aligns with Bun's specific requirements for source map handling.

---

235-235: LGTM: Function call updated to match new signature.

The createPlugin call correctly passes the new parameters (dir and shimSourceMap) that match the updated function signature in patch.go.

---

239-239:

Details

✅ Verification successful

Verify that removing postShim doesn't break existing functionality.

The Banner field has been simplified to exclude postShim, which suggests the source map shimming logic has been moved from a post-build banner approach to the plugin-based approach. This architectural change looks sound, but please verify that no existing functionality is broken.

---

🏁 Script executed:

#!/bin/bash
# Description: Search for any remaining references to postShim to ensure it's been properly removed
# Expected: Should find minimal or no references if the migration is complete

rg "postShim" --type go -B 2 -A 2

Length of output: 33

---

🏁 Script executed:

#!/bin/bash
# Search for any remaining references to postShim across the entire repository
rg -n "postShim"

Length of output: 16

---

postShim removal verified

A repository-wide search shows no remaining references to postShim, confirming it has been fully removed in favor of the plugin-based approach. Everything looks in order—please ensure the existing test suite (and any end-to-end tests) passes to catch any integration regressions.

✨ Finishing Touches

• 📝 Generate Docstrings

---

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