[simon1hofmann]

🤖 AI text below 🤖

Description

Fixes #2593. Based on main; array-valued outputs (#2592) remain separate.

• Add nonrecursive classical def functions with by-value scalar parameters, local variables, and an optional scalar result. Mutable bit vectors use independent local storage.
• Borrow readonly/mutable arrays with fixed shapes or fixed-rank runtime dimensions (#dim), including strided and rank-reduced views. Passing arguments does not copy their elements; writes reach caller storage.
• Check types, widths, ranks, shapes, initialization, and mutable aliasing. All selected elements must be initialized on entry; unresolved mutable overlap is rejected. References cannot escape.
• Preserve supported calls through QC/QCO and OpenQASM export. QIR uses existing inlining; jeff inlines borrowed helpers and retains scalar helpers. CBit inlining and constant folding before dead-value cleanup preserve backend semantics and quantum linearity.

Only final top-level returns are supported. Early/nested returns, recursion, externs, runtime scalar angle signatures, quantum statements/parameters, local arrays, and mutable-global capture are diagnosed. Angle array elements are supported. Empty views require statically known retained extents. Existing runtime bounds/shape preconditions and backend storage limits remain; no new host-result ABI or dependencies.

Review also fixed repeated evaluation in values[next(counter)] += value, strengthened the backend stride test to inspect caller storage, and removed redundant test checks and plan text.

Validation

501 focused tests passed: 214 OpenQASM target, 239 translation, 11 compiler pipeline, 28 jeff round-trip, and 9 DD/memref/call tests. These cover borrowing, initialization/alias rejection, scalar-copy isolation, empty/strided views, single-evaluation compound indices, QIR JIT, and serialized jeff execution. The compound-index regression failed before the fix and passes after it.

Whole-file C++ lint passed for all 15 changed sources against origin/main; repository lint passed. Additional frontend-header checks found only the existing redundant indices{} initializer in Frontend.h, unchanged from main. No full suite, benchmarks, or automation were run. CI is not being monitored.

Codex assisted with implementation, tests, review, and this description. Human review is still required.

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

If PR contains AI-assisted content:

• Any agent that created, edited, or submitted GitHub content was explicitly authorized for that scope, as required by our AI Usage Guidelines.
• Every agent-authored or agent-edited public text body begins with the visible disclosure 🤖 *AI text below* 🤖 (titles are exempt).
• I have disclosed AI assistance in the PR description.
• I confirm that I have personally reviewed and understood all AI-generated content, and accept full responsibility for it.

[codecov]

Codecov Report

❌ Patch coverage is 92.09402% with 74 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...nclude/mqt/Target/OpenQASM/Detail/OpenQASMParser.h	85.2%	22 Missing ⚠️
mlir/lib/Target/OpenQASM/OpenQASMSemantics.cpp	94.7%	17 Missing ⚠️
mlir/lib/Target/OpenQASM/OpenQASMToQCEmitter.cpp	90.5%	16 Missing ⚠️
...lir/lib/Target/OpenQASM/TranslateQCToOpenQASM3.cpp	93.7%	16 Missing ⚠️
mlir/lib/Dialect/QCO/Utils/DDFunctionality.cpp	50.0%	2 Missing ⚠️
mlir/lib/Target/OpenQASM/OpenQASMSyntax.cpp	92.8%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!