RequirementMachine: Preserve sugar in desugarSameTypeRequirement()

Author: slavapestov

lib/AST/RequirementMachine/RequirementLowering.cpp

@@ -73,13 +73,13 @@ static void desugarSameTypeRequirement(Type lhs, Type rhs, SourceLoc loc,
 
       if (secondType->isTypeParameter()) {
         result.emplace_back(RequirementKind::SameType,
-                            secondType, firstType);
+                            secondType, sugaredFirstType);
         recordedRequirements = true;
         return true;
       }
 
       errors.push_back(
-          RequirementError::forConcreteTypeMismatch(firstType,
+          RequirementError::forConcreteTypeMismatch(sugaredFirstType,
                                                     secondType,
                                                     loc));
       recordedErrors = true;

test/Generics/requirement_machine_diagnostics.swift

@@ -19,7 +19,7 @@ typealias NotAnInt = Double
 
 protocol X {}
 
-// expected-error@+1{{generic signature requires types 'Double' and 'Int' to be the same}}
+// expected-error@+1{{generic signature requires types 'NotAnInt' (aka 'Double') and 'Int' to be the same}}
 extension X where NotAnInt == Int {}
 
 protocol EqualComparable {