Fix #52586, cs0121-4.cs.
* decl.cs (MemberCache.DeepCopy): Rename from SetupCache. Take
and return a hashtable.
(MemberCache.ClearDeclaredOnly): New.
(MemberCache.MemberCache): Update to change. Make a deep copy of
the method_hash of a base type too.
(MemberCache.AddMethods): Adapt to having a deep copy of the base
type methods. Overwrite entries with the same MethodHandle so
that the ReflectedType is correct. The process leaves in base
virtual functions and their overrides as distinct entries.
(CacheEntry): Now a class instead of a struct. It shouldn't alter
matters since it was boxed in a ArrayList before.
(CacheEntry.Member, CacheEntry.EntryType): Remove 'readonly'
modifier.
* expression.cs (Invocation.BetterFunction): Simplify. Handle the
case of a virtual function and its override (choose the overload
as better).
(Invocation.OverloadResolve): Avoid 'override' members during
'applicable_type' calculation.
In errors:
* cs0121-4.cs: New test. Ensure that a param method isn't
discarded if the signatures of other normal methods are different.
In tests:
* test-342.cs: New test for #52586.
* test-343.cs: New test. Not a bugfix or regression. Added to
ensure our overloading semantics are right. See
errors/cs0121-4.cs for a counterpart.
(Note that the related bug #59209 is not yet fixed by this)
svn path=/trunk/mcs/; revision=40402
