fix(v2/linux,darwin): plug Calloc leak caused by value receivers

[4RH1T3CT0R7]

Calloc.String and Calloc.Free in the v2 linux and darwin frontends take the receiver by value, so String appends each C.CString to a copy of the pool that is dropped on return. The caller's pool stays nil, Free iterates nothing, and every string allocated for dialogs, menus, single-instance messaging and window setup leaks. On darwin defer c.Free() even captures the empty copy up front.

NewCalloc now returns a pointer and both methods use pointer receivers, the same shape v3 already has in linux_cgo.go. Call sites keep c := NewCalloc(); defer c.Free() unchanged. The windows frontend has no cgo allocator and is unaffected. Changelog entry added under Unreleased.

Fixes #6059
Fixes #6058

Summary by CodeRabbit

• Bug Fixes

  • Fixed a memory leak affecting C strings used during dialog, menu, and window setup on macOS and Linux.

• Documentation

  • Added an unreleased changelog entry describing the memory-leak fix.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Team

Run ID: 79e30b17-6e60-4e15-af1a-c106c1553fdb

📥 Commits

Reviewing files that changed from the base of the PR and between 5bce785 and b39d41c.

📒 Files selected for processing (3)

• v2/internal/frontend/desktop/darwin/calloc.go
• v2/internal/frontend/desktop/linux/calloc.go
• website/src/pages/changelog.mdx

Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review.

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Walkthrough

The Darwin and Linux Calloc implementations now use pointer-based allocation pools. The changelog documents the resulting C-string memory-leak fix.

Changes

Calloc lifecycle

Layer / File(s)	Summary
Pointer-backed allocator lifecycle v2/internal/frontend/desktop/{darwin,linux}/calloc.go, website/src/pages/changelog.mdx	NewCalloc returns *Calloc, and String and Free use pointer receivers so allocated C strings remain in the shared pool until cleanup. The changelog records the fix.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 54281

Darwin and Linux C-string allocations are now retained by the shared allocator and released during cleanup, fixing the reported frontend memory leak with no remaining merge-blocking risk.

Suggested reviewers: leaanthony

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the bug, affected platforms, implementation, linked issues, and call-site compatibility. It does not include the required change type, testing details, test configuration, or …	Add the required description sections. Select the applicable change type, document tests and platform details, provide wails doctor output or environment details, and complete the checklist.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the Linux and Darwin Calloc memory leak fix caused by value receivers.
Linked Issues check	✅ Passed	The changes satisfy both linked issues [#6059] and [#6058]. The Linux and Darwin implementations now return *Calloc and use pointer receivers, which preserves allocations in the pool and allows `Fre…
Out of Scope Changes check	✅ Passed	All changes are within scope. The code changes fix the linked Linux and Darwin memory leaks, and the Unreleased changelog entry documents the fix.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1 …

Full details: Description check

Explanation

The description explains the bug, affected platforms, implementation, linked issues, and call-site compatibility. It does not include the required change type, testing details, test configuration, or checklist responses.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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_{A rabbit found strings in a C-shaped haystack
Pointer paws kept each one on the track
The pool held them tight
Then freed them just right
No leaks hopped away through a crack}

_{Comment @coderabbitai help to get the list of available commands.}

[leaanthony]

Reviewed the allocator change and native string lifetimes. Pointer receivers fix allocation tracking and deferred cleanup on both v2 platforms; the changelog entry is included. Required checks pass. The equivalent v3 GTK4 and GTK3 fixes are already present from #5466.