In #69257, we modified `ObjCReason` to carry a pointer to the @implementation attribute for the `MemberOfObjCImplementationExtension` kind. This made it mark the @implementation attribute as invalid, suppressing diagnostics from the ObjCImplementationChecker.
However, invalidating the attribute *also* causes it to be skipped by serialization. That isn’t a problem if the diagnostics are errors, since we’ll never emit the serialized module, but #74135 softened these diagnostics to warnings for early adopters.
The upshot was that if Swift emitted one of these warnings when it compiled a library, clients of that library would see the objcImpl extension as a normal extension instead. This would cause various kinds of mischief: ambiguous name lookups because implementations weren’t being excluded, overrides failing because an implementation was `public` instead of `open`, asserts and crashes in SILGen and IRGen because stored properties were found in seemingly normal extensions, etc.
Fix this by setting a separate bit on ObjCImplementationAttr, rather than the invalid bit, and modifying the implementation checker to manually suppress many diagnostics when that bit is set.
Fixes rdar://134730183.
This PR ensures library-evolution is enabled for Package CMO; without it,
it previously fell back to regular CMO, which caused mismatching serialization
attributes if importing another module that had Package CMO enbaled, causing
an assert fail for loadable types.
Resolves rdar://135308288
Some requirement machine work
Rename requirement to Value
Rename more things to Value
Fix integer checking for requirement
some docs and parser changes
Minor fixes
When looking up the decl context of a type, ASTDemangler has to take
into account that there are multiple different modules where that type
could've come from. This is due to two facts:
- Thanks to the `-module-abi-name` flag, multiple modules can share
the same ABI name (which is the module name that is usually used when
mangling a type).
- In some situations mangling can use the module's real name, for
example, when mangling for the debugger or USRs coupled with @_originallyDefinedIn.
rdar://134095412
