Issue #748: Fix arithmetic for loops in bash mode

[bhumikamittal7]

Problem

When running bash scripts with arithmetic for loops through PaSh with --bash flag, the following error occurred:

KeyError: 'Could not find appropriate preprocessor for arithfor'

Root Cause: The AST node type is ArithFor which gets lowercased to arithfor, but the preprocessor function was named preprocess_node_arith_for (with underscore). The dynamic dispatch in preprocess_node() couldn't find a matching handler.

Fix

Renamed preprocess_node_arith_for → preprocess_node_arithfor to match the naming convention.

Testing

Before fix:

./pa.sh --bash script_with_arith_for.sh
# KeyError: 'Could not find appropriate preprocessor for arithfor'

After fix:

$ cat test.sh
for (( x=0; x < 3; ++x )); do
  echo "iteration $x"
done

$ ./pa.sh --bash test.sh
iteration 0
iteration 1
iteration 2

Discovery Results

Ran discovery on all 268 commented-out bash tests:

Category	Count
Passed (exact match)	55
Partial (runs, output differs)	163
Failed	50

This fix enables 55 tests to be uncommented immediately and allows 163 more tests to at least compile and run (with minor output differences).

---

Remark: Script to find passing tests: scripts/discover_passing_bash_tests.sh

[angelhof]

Thanks for the change, it looks good but I am not sure why the tests are failing. Could you take a look?

[angelhof]

Actually, let me take a look since I see that CI/CD is somewhat broken in general, I will let you know once I fix it.

[angelhof]

@bhumikamittal7 I have been refactoring the project a lot but now I have a good sense of what is failing or not with the tests. Could you rebase your commit over main? Also, instead of pushing the script that discovers the new tests that pass, you should instead just push a commit that uncomments all the new tests that pass :) When you do that ping me and I can merge the PR!

[angelhof]

@bhumikamittal7 Since your change was just one line of code you could also just remake the change in a new branch forking off main!

[angelhof]

Fixes #748

[github-actions]

OS:ubuntu-24.04
Mon Feb 2 16:27:33 UTC 2026
intro: 3/3 tests passed.
interface: 43/43 tests passed.
compiler: 100/100 tests passed.

[github-actions]

OS:ubuntu-24.04
Mon Feb 2 17:19:44 UTC 2026
intro: 3/3 tests passed.
interface: 43/43 tests passed.
compiler: 100/100 tests passed.

[github-actions]

OS:ubuntu-24.04
Mon Feb 2 18:56:34 UTC 2026
intro: 3/3 tests passed.
interface: 43/43 tests passed.
compiler: 100/100 tests passed.

[github-actions]

OS:ubuntu-24.04
Mon Feb 2 19:02:09 UTC 2026
intro: 3/3 tests passed.
interface: 43/43 tests passed.
compiler: 100/100 tests passed.

[github-actions]

OS:ubuntu-24.04
Mon Feb 2 19:04:36 UTC 2026
intro: 3/3 tests passed.
interface: 43/43 tests passed.
compiler: 100/100 tests passed.

[bhumikamittal7]

@angelhof Thanks for the comments and updates! Sorry for the delayed response on my end — I was swamped with work for the last few weeks and only got a chance to look into this today.

I am closing this PR and have opened a new one from a branch forked off main:
#784