We can't feed resolved DependentMemberTypes into the Requirement Machine
since that will trigger an assertion if there is a missing conformance.
Instead, copy and paste some logic from GenericSignatureBuilder.cpp to
'erase' resolved DependentMemberTypes into unresolved DependentMemberTypes.
If we have a conformance requirement T : P, and a concrete type
requirement T == G<...>, and G _conditionally_ conforms to P,
we would infer the conditional requirements of G needed to
satisfy the conformance.
However, if the conformance requirement T : P was not explicit,
this would mean in practice that we would need to infer an
infinite number of conditional requirements, because there
might be an infinite number of types T for which T : P.
Previously we would infer these up to some limit, based on
how many levels of nested types the GSB had expanded.
Since this is untenable, let's instead change the rules so
that conditional requirement inference is only performed
when the concretizing requirement was explicit.
* Make Range conditionally a Collection
* Convert ClosedRange to conditionally a collection
* De-gyb Range/ClosedRange, refactoring some methods.
* Remove use of Countable{Closed}Range from stdlib
* Remove Countable use from Foundation
* Fix test errors and warnings resulting from Range/CountableRange collapse
* fix prespecialize test for new mangling
* Update CoreAudio use of CountableRange
* Update SwiftSyntax use of CountableRange
* Restore ClosedRange.Index: Hashable conformance
* Move fixed typechecker slowness test for array-of-ranges from slow to fast, yay
* Apply Doug's patch to loosen test to just check for error
Rather than crashing when a generic signature is found to be non-minimal,
report the non-minimal requirement via the normal diagnostics machinery so
we can properly test for it.
Fixes rdar://problem/36912347 by letting us track which cases are
non-minimal in the standard library explicitly, so we can better
decide whether it's worth implementing a complete solution.
Add a verification pass to ensure that all of the generic signatures in
a module are both minimal and canonical. The approach taken is quite
direct: for every (canonical) generic signature in the module, try
removing a single requirement and forming a new generic signature from
the result. If that new generic signature that provide the removed
requirement, then the original signature was not minimal.
Also canonicalize each resulting signature, to ensure that it meets the
requirements for a canonical signature.
Add a test to ensure that all of the generic signatures in the Swift
module are minimal and canonical, since they are ABI.
