rules in a separate pass after homotopy reduction.
RewriteSystem::propagateExplicitBits was too eager in propagating
IDs from explicit rules within rewrite loops, which resulted in bogus
redundancy warnings when the canonical form of an explicit rule was
given a different requirement ID. Instead, propagate requirement IDs
after homotopy reduction when redundant rules are computed and rewrite
loops are simplified.
See the comment at the top of ConcreteContraction.cpp for a detailed explanation.
This can be turned off with the -disable-requirement-machine-concrete-contraction
pass, mostly meant for testing. A few tests now run with this pass both enabled
and disabled, to exercise code paths which are otherwise trivially avoided by
concrete contraction.
Fixes rdar://problem/88135912.
If a type parameter is subject to both a conformance requirement
and a concrete type requirement, the concrete type might conform
conditionally.
In this case, introduce new requirements to satisfy the conditional
conformance.
Since this can add new hitherto-unseen protocols to the rewrite
system, restrict this feature to top-level generic signatures, and
not protocol requirement signatures. Allowing this to occur in
protocol requirement signatures would change the connectivity of
the protocol dependency graph (and hence the connected components)
during completion, which would be a major complication in the
design. The GSB already enforces this restriction.
I changed the existing conditional_requirement_inference.swift test
to run with -requirement-machine-inferred-signatures=verify. Since
one of the test cases there triggers an unrelated bug in the
Requirement Machine, I split it off into a new file named
conditional_requirement_inference_2.swift which still runs with
the GSB. Once the bug is fixed I'll merge the files again.
