fix: FunctionDef does not emit a return for void functions

[Fizza-Mukhtar]

Pull Request description

Fixes #244

When visit(FunctionDef) finishes walking the function body, if no
FunctionReturn node was encountered the current basic block is left
without a terminator. llvmlite raises an AssertionError during module
verification for void functions, and silently produces malformed IR for
non-void functions that fall off the end.

Fix: after self.visit(node.body), check is_terminated on the
current block:

• void return type → emit ret_void()
• non-void return type → emit ret <zero> as a safe fallback

How to test these changes

pytest tests/test_void_function.py -v

Pull Request checklists

This PR is a:

• bug-fix
• new feature
• maintenance

About this PR:

• it includes tests.
• the tests are executed on CI.
• the tests generate log file(s) (path).
• pre-commit hooks were executed locally.
• this PR requires a project documentation update.

Author's checklist:

• I have reviewed the changes and it contains no misspelling.
• The code is well commented, especially in the parts that contain more complexity.
• New and old tests passed locally.

[Jaskirat-s7]

Hey @yuvimittal , I tested the changes locally — all 5 tests pass .
the is_terminated check after self.visit(node.body) is a very clean approach, and it is good that it handles both void (ret_void()) and non-void (ret 0 fallback) cases. The test for explicit return not producing a duplicate terminator is a nice edge case to cover too.

hey @Fizza-Mukhtar ,same as your other PR , the branch is a bit behind main so you'll probably need a rebase to avoid conflicts

[yuvimittal]

@Fizza-Mukhtar , overall tests are good, just one comment

[yuvimittal]

This does not guarantee correct IR, only that it didn’t crash.

[Fizza-Mukhtar]

Updated the test to verify ret void is present in the emitted IR
instead of only checking that the build did not crash. Also rebased
onto latest main.

[github-actions]

🎉 This PR is included in version 1.9.0 🎉

The release is available on:

• 1.9.0
• GitHub release

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