fix(codegen): use safe_pop for loop body lowering; use fadd/fsub for float unary inc and dec

[omsherikar]

• Replace raw .pop() with safe_pop() in WhileStmt, ForCountLoopStmt, and ForRangeLoopStmt body handling
• Remove broken if not body_val: return guard in WhileStmt that skipped branch-back on falsy values
• Add regression test with a void-only loop body
  solves Fix: WhileStmt body pop crashes on empty result stack #241

[Copilot]

Pull request overview

This PR addresses codegen crashes and incorrect control-flow in loop lowering by ensuring loop bodies don’t underflow result_stack and by removing a guard that incorrectly treated valid “falsy” LLVM values as missing results.

Changes:

• Replace raw result_stack.pop() with safe_pop() for loop body result handling in WhileStmt, ForCountLoopStmt, and ForRangeLoopStmt.
• Remove the if not body_val: return guard in WhileStmt so codegen doesn’t skip the back-edge on falsy values.
• Add a regression test intended to cover loops whose body doesn’t leave a value on the stack.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/irx/builders/llvmliteir.py	Makes loop codegen tolerant to empty body results by using safe_pop() and modernizes some type annotations.
tests/test_while.py	Adds a new regression test aimed at preventing WhileStmt crashes when the loop body doesn’t produce a value.

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[omsherikar]

@yuvimittal I have made the changes can you have a look?

[Jaskirat-s7]

Hey @omsherikar, i was going through your PR and i analyzed that the safe_pop change in all three loop types makes good sense, and good call removing the if not body_val: return guard ->that would also break loops when the body produced a falsy value like 0, not just on empty stacks.

but there were a couple of things I noticed:

first is that regression test only covers WhileStmt — since ForCountLoopStmt and ForRangeLoopStmt were also changed to use safe_pop,i think it would be good to add similar void-body tests for those two as well , what do you think and the Optional → X | None type hint changes are valid modernization but maybe unrelated to the bug fix — might be cleaner as a separate commit to keep the fix-focused diff small.

rest of the code change looks good overall 👍

[omsherikar]

Hii @yuvimittal can you review this pr please

[yuvimittal]

i am sorry @omsherikar , i missed that these are the exact changes you made!

[omsherikar]

hii @yuvimittal I have made the changes as discussed, resolved the merge conflicts . ready for review

[xmnlab]

thanks @omsherikar

[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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