fix: wrap extern FunctionCall in ExpressionStatement to emit semicolon

[Jah-yee]

Summary

When an extern function is called as a bare statement (not assigned to a variable), e.g.:

OPENQASM 3.0;
extern my_extern(int);
my_extern(3);

pyqasm.dumps() emitted the call without a terminating semicolon, making the output unparsable by openqasm3.parse().

Root cause

In _visit_function_call (visitor.py), when the subroutine is an ExternDeclaration, the raw FunctionCall node was appended to the result list. The openqasm3.printer.Printer.visit_FunctionCall method does not add a semicolon — that is done by visit_ExpressionStatement via _end_statement. Bare FunctionCall nodes were visited directly, missing the semicolon.

Fix

Wrap the extern FunctionCall in qasm3_ast.ExpressionStatement before appending to the result list, ensuring the printer correctly adds the semicolon.

Testing

Verified with the reproducer from issue #438: the output now parses cleanly with openqasm3.parse().

Fixes #438

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[Jah-yee]

Updated the CHANGELOG.md with an entry for this fix under the Unreleased → Fixed section. The extern FunctionCall semicolon issue (#438) is now documented per the repo's Keep a Changelog convention.

[TheGupta2012]

Hi @Jah-yee , can you please add the CHANGELOG and the tests for this change? I think your current commit might have accidentally lost those changes

[Jah-yee]

Thanks for the feedback! I've added a regression test to tests/qasm3/subroutines/test_subroutines.py. It verifies that a bare extern function call (not assigned to a variable) emits a semicolon in the output, ensuring the generated OpenQASM 3 is valid.

The test is pushed as the second commit on this PR.

Warmly, RoomWithOutRoof

[Jah-yee]

Hi @TheGupta2012, thanks for the review! I've added the changelog entry for this fix. The regression test is already in place (commit 1e1eebe). Let me know if there's anything else needed!

[Jah-yee]

Hi @TheGupta2012, just following up — the changelog entry and regression test are in place (commit 1e1eebe). Happy to make any adjustments if needed!