Many tests that use `-parse-stdlib` only do so because they want access
to the Builtin module. Now that we have the flag and ability to import
it, use that instead.
"Function builders" are being renamed to "result builders". Add the
corresponding `@resultBuilder` attribute, with `@_functionBuilder` as
an alias for it, Update test cases to use @resultBuilder.
Before 09db2902d2, the function builder
transform used to try to detect when the builder type wasn't fully
resolved. In such a case, rather than fail the solution set as we do
currently, it would construct a null TypeLoc, then stash the type-
variable-laden builder type inside of a TypeExpr and rely on CSGen
to reinterpret that as a request to read the stashed type as it was
constructing the rest of the system. This used to rely on the ability to construct
an implicit TypeExpr node with a null type but now such a thing is
banned by the TypeExpr interface.
Instead, we have to detect this case and construct an *explicit*
TypeExpr node pointing to all the usual fake data. This node's type will
be used to resolve the build* member, but the final applied type of the
node will be the builder type we stashed earlier - hopefully with
outstanding type variables solved.
rdar://65116204
Previously we would only gather one-way constraints
if they were found through a type variable in their
right hand side. However we would incorrectly check
this against the type variable that we started the
search at. This meant that if the constraint was
found through a fixed binding, we would never
return it, and could therefore fail to re-activate
it, leaving it unsolved.
Fix this issue by simply removing the check for
the RHS, and letting the constraint system handle
it instead.
Resolves rdar://64890308.
