OpenQASM Missing Language Features

[orpuente-MS]

The following features are missing in our OpenQASM implementation, and we plan to implement them in the near future:

• Index sets arr[{2, 6, 8}].
  • need some clarification from the spec. issue filed
• Support for OpenQASM 3.2 with nop instructions
• Extern functions. Adding extern compilation for OpenQASM #2680
• input arrays. [Array type variables are clarified to be supported as inputs.] OpenQASM input and output interop #2678 (https://openqasm.com/release_notes.html#bug-fixes)
  • Parser and Lowerer
  • Compiler
  • Python
• Array concatenation Add support for array concatenation in OpenQASM #2676
• durationof calls. Lower duration and stretch #2611
• Mutable array references as parameters allowed by lowerer and used accordingly. (See below as they aren't supported past the lowerer) Allow indexing into array references in OpenQASM #2616
• Alias declarations for qubits. Add support for qubit alias decls #2665
• Built-in functions (sin, cos, etc.)
  • Foundation and mod implementation Add support for builtin functions #2508
  • Implementation of builtin functions Implement builtin functions #2521
  • pow edge case: pow builtin collides with pow gate modifier.
• box statement. Adding box pragma support to QASM compiler #2571
• sizeof calls. Add sizeof bultin to qasm #2586
• Array references (passing arrays as readonly parameters). Add sizeof bultin to qasm #2586
• Index into sized types. Classical types indexing in OpenQASM #2564
• Importing files other than "stdgates.inc". Consolidate OpenQASM project loading and include handling #2512
• Ranges with open start or end: [:1:5], [0:1:]. Support omitted start and stop in ranges #2472

These features require work in the Q# compiler and we may implement them at some point, but not in the near future:

• break keyword.
• continue keyword.
• Array references (passing arrays as mutable parameters).
• alias declarations for bitarrays
• register concatenation

These features are not planned for full compilation support:

• Hardware qubit ids.
• Duration type value, this includes supplying durations on gate and box instructions.
• Stretch type values.
• Calibration statements.
• Calibration grammar statements.
• Defcal statements.
• Delay statements.