Instead of passing around a TypeChecker and three Decls (the nominal type, the
protocol, and the decl declaring the conformance) everywhere, we can just pass
one object.
This should be [NFC].
This has three principal advantages:
- It gives some additional type-safety when working
with known accessors.
- It makes it significantly easier to test whether a declaration
is an accessor and encourages the use of a common idiom.
- It saves a small amount of memory in both FuncDecl and its
serialized form.
With the introduction of special decl names, `Identifier getName()` on
`ValueDecl` will be removed and pushed down to nominal declarations
whose name is guaranteed not to be special. Prepare for this by calling
to `DeclBaseName getBaseName()` instead where appropriate.
A lot of files transitively include Expr.h, because it was
included from SILInstruction.h, SILLocation.h and SILDeclRef.h.
However in reality most of these files don't do anything
with Exprs, especially not anything in IRGen or the SILOptimizer.
Now we're down to 171 files in the frontend which depend on
Expr.h, which is still a lot but much better than before.
- The DeclContext versions of these methods have equivalents
on the DeclContext class; use them instead.
- The GenericEnvironment versions of these methods are now
static methods on the GenericEnvironment class. Note that
these are not made redundant by the instance methods on
GenericEnvironment, since the static methods can also be
called with a null GenericEnvironment, in which case they
just assert that the type is fully concrete.
- Remove some unnecessary #includes of ArchetypeBuilder.h
and GenericEnvironment.h. Now changes to these files
result in a lot less recompilation.
Rather than having Sema provide a default implementation of
Error._code when needed, introduce a runtime function to extract the
default code, so that we can provide a default implementation via a
protocol extension in the standard library.
When synthesizing the witness for Error._code, synthesize it as
final. This isn't meant to be user-visible (and, therefore, isn't
meant to be user-overridable), so it's a minor efficiency
win. Moreover, we weren't making sure this member got synthesized in
in cross-module situations, leading to runtime crashes. Fixes
rdar://problem/27335637.
