fix(runtime): use typed pthread attributes for Linux stack bounds

[proggeramlug]

Linux builds fail -D warnings because the GC and Error.stack paths redeclare three pthread functions with incompatible pointer types. The ARM64 GC frame walker repeats the byte-buffer variant. Replace all three implementations with one Linux-only helper using libc::pthread_attr_t and libc's declarations.

The shared helper has target-correct storage alignment and size, destroys attributes after a successful lookup, and returns zero if bounds cannot be read or overflow. GC and frame walkers retain their existing zero-bound fallback. Two runtime tests check current-thread bounds and workers with different requested stack sizes.

Validation:

• On pristine 12efed1222, Linux RUSTFLAGS="-D warnings" cargo check -p perry-runtime --lib fails with the three conflicting-declaration errors; the same command passes with this change.
• The actual helper source passes standalone main-thread and unit-test probes on x86_64 glibc and musl, plus an ARM64 Linux compile check, all with warnings denied.
• All 3,125 Linux runtime unit tests pass (4 ignored), run single-threaded.
• Formatting, file-size, test registration, address-classification, store-site and holder-inventory checks pass.

This removes the pre-existing Linux warnings failure reported on #9746, #9747, #9748 and #9750. The separate baseline raw-TLS policy failure is addressed by #9750. No version bump.

Summary by CodeRabbit

• Bug Fixes
  • Improved stack boundary detection on Linux for garbage collection and error reporting.
  • Increased reliability of stack walking on Linux, including aarch64 systems.
  • Corrected handling for thread stacks with custom sizes and unusual boundary conditions.
  • Added safeguards to stop stack processing safely when valid stack boundaries cannot be determined.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Team

Run ID: 058cb6aa-29dc-4ddf-a15a-396358254253

📥 Commits

Reviewing files that changed from the base of the PR and between 12efed1 and 1cf5077.

📒 Files selected for processing (6)

• changelog.d/9752-linux-pthread-stack-attributes.md
• crates/perry-runtime/src/error_stack_frames.rs
• crates/perry-runtime/src/gc/roots.rs
• crates/perry-runtime/src/gc/roots/stack_maps.rs
• crates/perry-runtime/src/lib.rs
• crates/perry-runtime/src/native_stack.rs

Included review availability: Your plan provides up to 8 included reviews per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The runtime adds a validated Linux pthread stack-bound helper. GC roots, error-stack frames, and frame-pointer walking now use the shared helper. Tests cover current-thread and custom-thread stack bounds.

Changes

Linux stack-bound handling

Layer / File(s)	Summary
Add validated native stack helper crates/perry-runtime/src/lib.rs, crates/perry-runtime/src/native_stack.rs	The Linux-only native_stack module provides stack_top(). The helper validates pthread results, null addresses, zero sizes, and overflow. Tests cover current-thread and custom-thread stack bounds.
Route runtime consumers through helper crates/perry-runtime/src/gc/roots.rs, crates/perry-runtime/src/error_stack_frames.rs, crates/perry-runtime/src/gc/roots/stack_maps.rs, changelog.d/9752-linux-pthread-stack-attributes.md	Linux GC roots, error-stack frame discovery, and frame-pointer walking now delegate stack-bound lookup to native_stack::stack_top(). The changelog records the pthread attribute fix.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 1cf50

Linux stack-bound discovery is consolidated behind a validated pthread helper for GC and error-stack walking, preserving safe fallback behavior. No current merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: using typed pthread attributes for Linux stack-bound handling.
Description check	✅ Passed	The description explains the problem, implementation, affected runtime paths, issue references, validation steps, test results, and versioning status. It does not follow every template heading or incl…
Docstring Coverage	✅ Passed	Docstring coverage is 85.71% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 5 files. (1 skipped: 1 u…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[proggeramlug]

Landed on main via merge train #9798 (rebase-merged, so your commits keep their authorship). Thanks!