Qiskit / qiskit / 35909882113

88%

main: 88%

Build Type

push

github

Committed by web-flow

Commit Message

Add `ProgramFunction` to the providers crate (#16922)

* Add a program function, one typed dataflow graph

Instructions are the only entity a function holds. A value is an output slot of
the instruction that produces it, and a function's parameters and results are
instructions too, so every value has a producer and every operand refers to one.
Three properties then follow from how a function is built rather than needing to
be maintained: an instruction stores exactly as many operands as its arity, so it
cannot be half-wired; its result types are inferred and kept as it is added, so a
signature is a table read; and its operands must already exist, so storage order
is topological, evaluation is one forward walk with nothing to sort, and a cycle
is not representable.

Instructions carry no labels. An instruction is identified by its index and
described by its type name, and those are what a diagnostic names.

A function holds ops of different concrete types, so it stores them behind `dyn`.
`ErasedOpNodeType` is `OpNodeType` with its error type boxed, blanket implemented
for every op that is `Clone`, `Send` and `Sync`. `Clone` is not dyn-compatible,
so it is reached through a sealed helper trait whose blanket implementation asks
an implementor for nothing but `Clone`.

An instruction records both its operand types and its result types, so the
coercions in a built program remain reconstructible as explicit conversions.

* Assert on error variants rather than on error messages

A test that reads an error's `Display` output has to change whenever the wording
does. Each one now matches on the variant, downcasting where the source is boxed.
Also applies four doc-comment suggestions from review.

Coverage Stats

738 of 795 new or added lines in 2 files covered. (92.83%)

8 existing lines in 3 files now uncovered.

120447 of 136939 relevant lines covered (87.96%)

959283.11 hits per line