chore: add explicit UTF-8 encoding for FFI doc generation

[xdustinface]

Add encoding='utf-8' to all file open operations in the FFI documentation generation scripts since the default Windows encoding doesnt seem to go well with it and lets the relevant pre-commit step fail for Windows in #253.

Also improved error visibility in verify_ffi.py by capturing stderr when the subprocess fails.

Summary by CodeRabbit

• Bug Fixes
  • Improved error reporting to capture and display failure messages during documentation generation processes.
  • Ensured proper UTF-8 text encoding to guarantee consistent character handling across all platforms.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Three Python scripts updated: one to capture stderr instead of stdout on subprocess failures for improved error reporting, and two to explicitly specify UTF-8 encoding for file I/O operations in documentation generation scripts.

Changes

Cohort / File(s)	Summary
Error Handling contrib/verify_ffi.py	Modified generate_ffi_docs() to return stderr from subprocess when exit code is non-zero; previously always returned stdout regardless of failure status
UTF-8 Encoding Specification dash-spv-ffi/scripts/generate_ffi_docs.py, key-wallet-ffi/scripts/generate_ffi_docs.py	Added explicit encoding='utf-8' parameter to file open operations in extract_ffi_functions() (reading) and main() (writing) to ensure consistent Unicode handling across platforms

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 Stderr now whispers what stdout won't tell,
UTF-8 encoded in every shell,
No more encoding guesses in the dark,
Error messages shine—a helpful spark! ✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: adding explicit UTF-8 encoding for FFI documentation generation scripts, which aligns with the primary objectives of the PR.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch chore/ffi-utf8

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3884314 and fdfe8ce.

📒 Files selected for processing (3)

• contrib/verify_ffi.py
• dash-spv-ffi/scripts/generate_ffi_docs.py
• key-wallet-ffi/scripts/generate_ffi_docs.py

🧰 Additional context used

🧠 Learnings (7)

📓 Common learnings

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/src/**/*.rs : Input strings in FFI functions are `*const c_char` (borrowed, not freed by C caller)

📚 Learning: 2025-12-01T07:59:58.608Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/src/**/*.rs : Input strings in FFI functions are `*const c_char` (borrowed, not freed by C caller)

Applied to files:

• dash-spv-ffi/scripts/generate_ffi_docs.py

📚 Learning: 2025-12-01T07:59:58.608Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/src/**/*.rs : Add cbindgen annotations for complex types in FFI functions

Applied to files:

• dash-spv-ffi/scripts/generate_ffi_docs.py

📚 Learning: 2025-12-01T07:59:58.608Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/src/**/*.rs : Use `#[no_mangle] extern "C"` attribute when implementing new FFI functions in Rust

Applied to files:

• dash-spv-ffi/scripts/generate_ffi_docs.py

📚 Learning: 2025-12-01T07:59:58.608Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/tests/unit/**/*.rs : Add corresponding unit tests in `tests/unit/` for each new FFI function

Applied to files:

• dash-spv-ffi/scripts/generate_ffi_docs.py

📚 Learning: 2025-12-01T07:59:58.608Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: dash-spv-ffi/CLAUDE.md:0-0
Timestamp: 2025-12-01T07:59:58.608Z
Learning: Applies to dash-spv-ffi/tests/c_tests/**/*.{c,h} : Add corresponding C tests in `tests/c_tests/` for each new FFI function

Applied to files:

• dash-spv-ffi/scripts/generate_ffi_docs.py

📚 Learning: 2025-12-22T17:59:37.849Z

Learnt from: CR
Repo: dashpay/rust-dashcore PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-22T17:59:37.849Z
Learning: Applies to **/*-ffi/**/*.rs : Exercise careful handling at FFI boundaries for memory safety

Applied to files:

• key-wallet-ffi/scripts/generate_ffi_docs.py

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (20)

• GitHub Check: fuzz (dash_deserialize_block)
• GitHub Check: fuzz (dash_deserialize_witness)
• GitHub Check: fuzz (dash_outpoint_string)
• GitHub Check: fuzz (hashes_json)
• GitHub Check: fuzz (hashes_sha512_256)
• GitHub Check: fuzz (hashes_ripemd160)
• GitHub Check: fuzz (dash_deserialize_amount)
• GitHub Check: fuzz (hashes_sha256)
• GitHub Check: fuzz (dash_script_bytes_to_asm_fmt)
• GitHub Check: fuzz (hashes_cbor)
• GitHub Check: fuzz (dash_deser_net_msg)
• GitHub Check: fuzz (dash_deserialize_script)
• GitHub Check: fuzz (hashes_sha512)
• GitHub Check: fuzz (dash_deserialize_address)
• GitHub Check: Pre-commit (ubuntu-latest)
• GitHub Check: Pre-commit (macos-latest)
• GitHub Check: SPV Components Tests
• GitHub Check: RPC Tests (stable, true)
• GitHub Check: Core Components Tests
• GitHub Check: Key Wallet Components Tests

🔇 Additional comments (3)

key-wallet-ffi/scripts/generate_ffi_docs.py (1)

31-31: LGTM! Explicit UTF-8 encoding ensures cross-platform compatibility.

Adding encoding='utf-8' to both read and write operations prevents platform-specific encoding issues, particularly on Windows where the default is cp1252. This directly addresses the issue referenced in the PR objectives.

Also applies to: 312-312

contrib/verify_ffi.py (1)

38-41: LGTM! Improved error visibility by surfacing stderr on subprocess failures.

The logic now correctly prioritizes stderr when the subprocess exits with a non-zero code, making it easier to diagnose documentation generation failures. The fallback to stdout when stderr is empty is a reasonable default.

dash-spv-ffi/scripts/generate_ffi_docs.py (1)

32-32: LGTM! Consistent UTF-8 encoding across both FFI documentation generators.

These changes mirror the encoding fixes in key-wallet-ffi, ensuring both documentation generation scripts handle UTF-8 consistently across platforms and avoid Windows default encoding issues.

Also applies to: 373-373

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