First, ensure all ParamDecls that are synthesized from scratch are given
both a contextual type and an interface type.
For ParamDecls written in source, add a new recordParamType() method to
GenericTypeResolver. This calls setType() or setInterfaceType() as
appropriate.
Interestingly enough a handful of diagnostics in the test suite have
improved. I'm not sure why, but I'll take it.
The ParamDecl::createUnboundSelf() method is now only used in the parser,
and no longer sets the type of the self parameter to the unbound generic
type. This was wrong anyway, since the type was always being overwritten.
This allows us to remove DeclContext::getSelfTypeOfContext().
Also, ensure that FuncDecl::getBodyResultTypeLoc() always has an interface
type for synthesized declarations, eliminating a mapTypeOutOfContext()
call when computing the function interface type in configureInterfaceType().
Finally, clean up the logic for resolving the DynamicSelfType. We now
get the interface or contextual type of 'Self' via the resolver, instead
of always getting the contextual type and patching it up inside
configureInterfaceType().
Before we would construct types containing a mix of interface and
contextual types, and then map them in and out. Straighten this out.
Note that I've also had to start untangling the issue where
synthesized ParamDecls do not have an interface type.
The fix for methods to lower the dynamic method type from the substituted AST type of the expression also needed to be applied to the optional chaining, subscript, and property paths.
This also exposed a problem in the Clang importer, where imported subscript accessors would get the unbound generic context type as their Self parameter type instead of the type with the correct generic parameters. Fix this by renaming the all-too-convenient ParamDecl::createSelf factory to `createUnboundSelf`, and introduce a new `createSelf` that uses the bound generic type.
Fixes rdar://problem/26447758.
This class formalizes the common case of the "trailing allocation" idiom we use
frequently. I didn't spot any true bugs while making this change, but I did see
places where we were using the wrong pointer type or casting through void* for
no good reason. This will keep us honest.
I'll get to the other libraries soon.
