[ConstraintSystem] Don't fail in matchTypes when two primary archetype types

are not equal when part of a type requirement. This allows the
SkipSameTypeRequirement constraint fix to be applied instead.

Author: hborla

lib/Sema/CSSimplify.cpp

@@ -3354,8 +3354,10 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
       if (shouldAttemptFixes()) {
         auto last = locator.last();
         // If this happens as part of the argument-to-parameter
-        // conversion, there is a tailored fix/diagnostic.
-        if (last && last->is<LocatorPathElt::ApplyArgToParam>())
+        // conversion or type requirement, there is a tailored
+        // fix/diagnostic.
+        if (last && (last->is<LocatorPathElt::ApplyArgToParam>() ||
+                     last->is<LocatorPathElt::AnyRequirement>()))
           break;
       }
       // If two module types or archetypes were not already equal, there's

test/Generics/conditional_conformances.swift

@@ -11,7 +11,7 @@ protocol P6: P2 {}
 
 protocol Assoc { associatedtype AT }
 
-func takes_P2<X: P2>(_: X) {} // expected-note {{in call to function 'takes_P2'}}
+func takes_P2<X: P2>(_: X) {}
 func takes_P5<X: P5>(_: X) {}
 
 // Skip the first generic signature declcontext dump
@@ -87,6 +87,7 @@ struct SameTypeGeneric<T, U> {}
 extension SameTypeGeneric: P2 where T == U {}
 // expected-note@-1 {{requirement from conditional conformance of 'SameTypeGeneric<U, Int>' to 'P2'}}
 // expected-note@-2 {{requirement from conditional conformance of 'SameTypeGeneric<Int, Float>' to 'P2'}}
+// expected-note@-3 {{requirement from conditional conformance of 'SameTypeGeneric<U, V>' to 'P2'}}
 func same_type_generic_good<U, V>(_: U, _: V)
   where U: Assoc, V: Assoc, U.AT == V.AT
 {
@@ -96,7 +97,7 @@ func same_type_generic_good<U, V>(_: U, _: V)
 }
 func same_type_bad<U, V>(_: U, _: V) {
   takes_P2(SameTypeGeneric<U, V>())
-  // expected-error@-1{{generic parameter 'X' could not be inferred}}
+  // expected-error@-1{{global function 'takes_P2' requires the types 'U' and 'V' be equivalent}}
   takes_P2(SameTypeGeneric<U, Int>())
   // expected-error@-1{{global function 'takes_P2' requires the types 'U' and 'Int' be equivalent}}
   takes_P2(SameTypeGeneric<Int, Float>())

validation-test/compiler_crashers_2_fixed/0158-rdar40165062.swift

@@ -4,11 +4,11 @@ struct Foo<T, U> {
   var value: U
   func bar() -> Foo<T, U> {
     return Foo(value)
-    // expected-error@-1 {{'Foo<T, U>' requires the types 'T' and 'U' be equivalent}}
+    // expected-error@-1 {{referencing initializer 'init(_:)' on 'Foo' requires the types 'T' and 'U' be equivalent}}
   }
 }
 
-extension Foo where T == U {
+extension Foo where T == U { // expected-note {{where 'T' = 'T', 'U' = 'U'}}
   init(_ value: U)  {
     self.value = value
   }