[CSSimplify] Produce tailored fixes for a few generic argument mismatches

- Mismatch in tuple element position should reference whole tuple
  with a note for mismatch position;
- Situations where optional object type is not a class but matched
  against `AnyObject` have a tailored fix.

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -6942,12 +6942,19 @@ bool ConstraintSystem::repairFailures(
     path.pop_back();
 
     ConstraintFix *fix = nullptr;
-    if (!path.empty() && path.back().is<LocatorPathElt::AnyRequirement>()) {
+    auto *fixLoc = getConstraintLocator(anchor, path);
+
+    if (fixLoc->isLastElement<LocatorPathElt::AnyRequirement>()) {
       fix = fixRequirementFailure(*this, fromType, toType, anchor, path);
+    } else if (fixLoc->isLastElement<LocatorPathElt::TupleElement>()) {
+      return repairFailures(lhs, rhs, matchKind, flags, conversionsOrFixes,
+                            fixLoc);
+    } else if (!lhs->mayHaveSuperclass() && rhs->isAnyObject()) {
+      fix = AllowNonClassTypeToConvertToAnyObject::create(*this, fromType,
+                                                          fixLoc);
     } else {
       fix = GenericArgumentsMismatch::create(
-          *this, fromType, toType, {genericArgElt.getIndex()},
-          getConstraintLocator(anchor, path));
+          *this, fromType, toType, {genericArgElt.getIndex()}, fixLoc);
     }
 
     if (!fix)
@@ -15687,7 +15694,8 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyFixConstraint(
   case FixKind::AllowFunctionSpecialization:
   case FixKind::IgnoreGenericSpecializationArityMismatch:
   case FixKind::IgnoreKeyPathSubscriptIndexMismatch:
-  case FixKind::AllowMemberRefOnExistential: {
+  case FixKind::AllowMemberRefOnExistential:
+  case FixKind::AllowNonClassTypeToConvertToAnyObject: {
     return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
   }
 
@@ -15938,7 +15946,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyFixConstraint(
   case FixKind::DefaultGenericArgument:
   case FixKind::AllowMutatingMemberOnRValueBase:
   case FixKind::AllowTupleSplatForSingleParameter:
-  case FixKind::AllowNonClassTypeToConvertToAnyObject:
   case FixKind::SpecifyClosureParameterType:
   case FixKind::SpecifyClosureReturnType:
   case FixKind::AddQualifierToAccessTopLevelName: