Usage of Span was temporarily behind an experimental feature flag. Now
that SE-0447 has been accepted, remove the experimental feature flag and
allow Span usage everywhere.
Implements rdar://144819992.
Unfortunately, this was not discovered earlier as swift-ide-test is not
invoking the SIL passes that produce this diagnostic. When creating
Swift spans from C++ spans we have no lifetime dependency information to
propagate as C++ spans are modeled as escapable types. Hence, this PR
introduces a helper function to bypass the lifetime checks triggered by
this discepancy. Hopefully, the new utility will go away as the lifetime
analysis matures on the Swift side and we get standardized way to deal
with unsafe lifetimes.
When we generate a safe wrapper that only differs in the return type we
might introduce ambiguities as some callers might not have enough
information to disambiguate between the overloads. This PR makes sure
the newly generated declarations are marked as @_disfavoredOverload so
the compiler can keep calling the old functions without a source break
when the feature is turned on.
rdar://139074571
We do not need to borrow from view objects passed by value but we need
to borrow from owners taken by const reference regardless of whether it
was annotated using lifetimebound or lifetime_capture_by.
Support adding safe wrappers for APIs returning std::span depending on
the this object. This also fixes an issue for APIs with 0 parameters.
rdar://139074571
A previous PR already added support to the SwiftifyImport macro to
generate safe wrappers. This PR makes ClangImporter emit the macro to do
the transformation.
