fix: Multiple fixes to the pytket encoder

[aborgna-q]

Fixes all issues reported in #1514, as well as ones detected in #1558 and others seen when processing the guppy-exports test set.
(Best viewed as separate commits)

• Fixes ClExpr encoding so expression inputs exclude output-only bits. 2bbe580

• Emits Hugr barriers as pytket Barriers only when every barrier input/output type is pytket-encodable. 9bb239b

• Allows the decoder to reconstruct tuple-typed wires from individually tracked pytket values. 89e1b34

• Fixes standalone decoding dropping target signature info when reconstructing parameter inputs. 40ebba9

• Avoids double-freeing qubits when opaque subgraph outputs are consumed near the decoded region output. 9ac277d

• Uses the patched tket-json-rs handling for pytket commands with "args": null. 47bc7a8

• Treats Future<T> as unsupported by pytket encoding, instead of unwrapping known types. 2f823ff

• Fixes translation of LoadConstants for values that cannot be statically loaded by the encoder (e.g. with external definitions). 958c9e3

• Makes the region traversal in reassemble_inplace deterministic. Fixes [Bug]: Invalid Hugr during RemoveBarriers tket pass on simple guppy program #1577. d466e94

Ai usage: Used codex to create repro cases and find the bug locations.

[codecov]

Codecov Report

❌ Patch coverage is 71.78218% with 57 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.09%. Comparing base (394a610) to head (524150a).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
tket/src/serialize/pytket/decoder/wires.rs	63.15%	24 Missing and 4 partials ⚠️
tket/src/serialize/pytket/decoder.rs	69.44%	18 Missing and 4 partials ⚠️
tket/src/serialize/pytket/encoder.rs	79.16%	4 Missing and 1 partial ⚠️
tket-qsystem/src/pytket/qsystem.rs	0.00%	1 Missing ⚠️
tket/src/serialize/pytket/circuit.rs	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1566      +/-   ##
==========================================
+ Coverage   83.81%   84.09%   +0.27%     
==========================================
  Files         188      188              
  Lines       29062    29283     +221     
  Branches    27936    28157     +221     
==========================================
+ Hits        24359    24625     +266     
+ Misses       3541     3479      -62     
- Partials     1162     1179      +17     

Flag	Coverage Δ
python	92.39% <ø> (ø)
qis-compiler	91.66% <ø> (ø)
rust	83.76% <71.78%> (+0.28%)	⬆️

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[cqc-alec]

The changes look reasonable; however, when I tried the procedure described in #1514 with this branch I encountered some more errors.

Specifically:

1. In the guppylang repo (main branch), run just export-integration-tests.

2. On this branch of tket2, run:

import os
from hugr import Hugr
from hugr.passes.scope import GlobalScope
from pytket.passes import FullPeepholeOptimise
from tket.passes import PytketHugrPass

p = PytketHugrPass(FullPeepholeOptimise()).with_scope(GlobalScope.PRESERVE_ENTRYPOINT)

hugr_dir = os.path.join("/home", "alec", "r", "guppylang", "guppy-exports") # edit as appropriate
for hugr_file in os.listdir(hugr_dir):
    hugr_path = os.path.join(hugr_dir, hugr_file)
    with open(hugr_path, "rb") as f:
        h = Hugr.from_bytes(f.read())
    try:
        h1 = p(h)
    except:
        print(f"*** Failed for {hugr_file}")

Running this script gives:

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(11), src_offset: Port(Outgoing, 0) } }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
*** Failed for tests.integration.test_inout-test_move_back_branch.hugr

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(18), src_offset: Port(Outgoing, 0) } }
*** Failed for tests.integration.test_linear-test_while_move_back.hugr
*** Failed for tests.integration.test_qsystem-test_measure_leaked.hugr
*** Failed for tests.integration.test_qsystem-test_lazy_measure_array.hugr
*** Failed for tests.integration.test_quantum-test_barrier.hugr

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(85), src_offset: Port(Outgoing, 0) } }
*** Failed for tests.integration.test_inout-test_move_back.hugr

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(47), src_offset: Port(Outgoing, 0) } }
*** Failed for tests.integration.test_linear-test_struct_reassign2.hugr
*** Failed for tests.integration.test_extern-test_extern_float.hugr

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(191), src_offset: Port(Outgoing, 0) } }
*** Failed for tests.integration.test_tuples-test_control_flow2.hugr
*** Failed for tests.integration.std.test_futures-test_read.hugr
*** Failed for tests.integration.test_qsystem-test_lazy_measure_conditional.hugr

thread '<unnamed>' (390845) panicked at tket/src/serialize/pytket/decoder.rs:485:18:
called `Result::unwrap()` on an `Err` value: OperationWiring { op: ExtensionOp(ExtensionOp { def: OpDef { extension: IdentList("tket.quantum"), extension_ref: (Weak), name: "QFree", description: "QFree", misc: {"commutation": Array []}, signature_func: PolyFuncTypeBase { params: [], body: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }, lower_funcs: [], constant_folder: None }, args: [], signature: FuncTypeBase { input: TypeRowBase { types: [TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear)] }, output: TypeRowBase { types: [] } } }), error: NoCopyLinear { typ: TypeBase(Extension(CustomType { extension: IdentList("prelude"), extension_ref: (Weak), id: "qubit", args: [], bound: Linear }), Linear), src: Node(51), src_offset: Port(Outgoing, 0) } }
*** Failed for tests.integration.test_comprehension-test_linear_discard_struct.hugr

Some of these decoding errors seem to be for cases that succeeded previously (though I haven't double-checked this and there may have been changes in guppylang).

[aborgna-q]

Ok, there were more fixes needed -.-'

Fixed them all in separate per-bug commits, and made a release of tket-json-rs to fix the JSON decoding error (Quantinuum/tket-json-rs#185).

I'll update the PR description

[cqc-alec]

Thanks! This solves almost all of the issues. I still see two errors, which look like the same thing, coming from the files tests.integration.test_poly_py312-test_copy_and_drop_bound.hugr and tests.integration.test_poly_py312-test_copy_bound.hugr:

Traceback (most recent call last):
  File "/home/alec/play/tket2/1514.py", line 28, in <module>
    test("tests.integration.test_poly_py312-test_copy_bound.hugr")
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alec/play/tket2/1514.py", line 15, in test
    h1 = p(h)
  File "/home/alec/r/tket2/.venv/lib/python3.14/site-packages/hugr/passes/composable.py", line 26, in __call__
    return self.run(hugr, inplace=inplace).hugr
           ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alec/r/tket2/tket-py/tket/passes/__init__.py", line 58, in run
    return implement_pass_run(
        self,
    ...<2 lines>...
        copy_call=lambda h: self._run_pytket_pass_on_hugr(h, inplace),
    )
  File "/home/alec/r/tket2/.venv/lib/python3.14/site-packages/hugr/passes/composable.py", line 81, in implement_pass_run
    pass_result = copy_call(hugr)
  File "/home/alec/r/tket2/tket-py/tket/passes/__init__.py", line 62, in <lambda>
    copy_call=lambda h: self._run_pytket_pass_on_hugr(h, inplace),
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/home/alec/r/tket2/tket-py/tket/passes/__init__.py", line 78, in _run_pytket_pass_on_hugr
    _passes.tket1_pass(tk_program._inner, pass_json, scope=self._scope)
    ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
tket.PyTK1DecodeError: Could not find a wire with type [bool] that contains pytket bit arguments [c[1], c[0], c[2], c[3]]. While decoding a pytket Barrier

Any ideas on this? Otherwise we can merge as-is and leave this for later.

[aborgna-q]

I haven't been able to reproduce that last issue :/

I added a small PR swapping out a HashMap with an IndexMap to fix #1577.

I say let's merge this and fill in a new issue if we can reproduce that last error.