This reverts commit 25985cb764. For now,
we're trying to avoid spurious non-structural changes to the mangling,
so that the /old/ mangling doesn't appear to change. That doesn't mean
no changes at all, but we can save this one for later.
It also uses the new mangling for type names in meta-data (except for top-level non-generic classes).
lldb has now support for new mangled metadata type names.
This reinstates commit 21ba292943.
For this we are linking the new re-mangler instead of the old one into the swift runtime library.
Also we are linking the new de-mangling into the swift runtime library.
It also switches to the new mangling for class names of generic swift classes in the metadata.
Note that for non-generic class we still have to use the old mangling, because the ObjC runtime in the OS depends on it (it de-mangles the class names).
But names of generic classes are not handled by the ObjC runtime anyway, so there should be no problem to change the mangling for those.
The reason for this change is that it avoids linking the old re-mangler into the runtime library.
Previously we had two separate mechanisms to turn a metatype
into a string. The swift_typeName() function was used to print
the metatype in a human-readable fashion, whereas the
_swift_buildDemanglingForMetadata() was used when naming
generated generic Objective-C classes.
Unify them, since what swift_typeName() does is redundant;
instead of going directly from the metatype to a human-readable
string, we can get the mangling, and print that using the
demangler.
This fixes some issues with unnecessary parenthesis when
printing function types, and also allows Objective-C classes
to be instantiated with nested generic types as parameters.
From the Swift documentation:
"If you define an optional variable without providing a default value,
the variable is automatically set to nil for you."
