[Conformance checking] Cleanup renaming check, fix a test.

Author: DougGregor

lib/Sema/TypeCheckProtocol.cpp

@@ -806,7 +806,7 @@ matchWitness(TypeChecker &tc,
   }
 
   SmallVector<OptionalAdjustment, 2> optionalAdjustments;
-  bool anyRenaming = false;
+  bool anyRenaming = req->getFullName() != witness->getFullName();
   if (decomposeFunctionType) {
     // Decompose function types into parameters and result type.
     auto reqFnType = reqType->castTo<AnyFunctionType>();
@@ -853,12 +853,6 @@ matchWitness(TypeChecker &tc,
       if (reqParams[i].isVararg() != witnessParams[i].isVararg())
         return RequirementMatch(witness, MatchKind::TypeConflict, witnessType);
 
-      // Check the parameter names.
-      if (reqParams[i].getName() != witnessParams[i].getName()) {
-        // A parameter has been renamed.
-        anyRenaming = true;
-      }
-
       // Gross hack: strip a level of unchecked-optionality off both
       // sides when matching against a protocol imported from Objective-C.
       auto types = getTypesToCompare(req, reqParams[i].getType(),

test/attr/attr_objc.swift

@@ -2033,6 +2033,7 @@ class ConformsToProtocolThrowsObjCName2 : ProtocolThrowsObjCName {
   // expected-warning@-1{{instance method 'doThing' nearly matches optional requirement 'doThing' of protocol 'ProtocolThrowsObjCName'}}
   // expected-note@-2{{move 'doThing' to an extension to silence this warning}}
   // expected-note@-3{{make 'doThing' private to silence this warning}}{{9-9=private }}
+  // expected-note@-4{{candidate has non-matching type '(Int) throws -> String'}}
 }
 
 @objc class DictionaryTest {