[ConstraintSystem] Extend function type conversion mismatch coverage

Originally type mismatches associated with conversions between
function types were only covered for coercions and assignments
but fix coverage grew since then and now it makes sense
to remove special case and let `repairFailures` take care of it.

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -4083,21 +4083,8 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
 
       auto result = matchFunctionTypes(func1, func2, kind, flags, locator);
 
-      if (shouldAttemptFixes() && result.isFailure()) {
-        // If this is a contextual type mismatch failure
-        // let's give the solver a chance to "fix" it.
-        if (auto last = locator.last()) {
-          if (last->is<LocatorPathElt::ContextualType>())
-            break;
-        }
-
-        // If this is a type mismatch in assignment, we don't really care
-        // (yet) was it argument or result type mismatch, let's produce a
-        // diagnostic which mentions both function types.
-        auto *anchor = locator.getAnchor();
-        if (anchor && isa<AssignExpr>(anchor))
-          break;
-      }
+      if (shouldAttemptFixes() && result.isFailure())
+        break;
 
       return result;
     }

test/Constraints/enum_cases.swift

@@ -22,14 +22,14 @@ let _ = arr.map(E.bar) // Ok
 let _ = arr.map(E.two) // expected-error {{cannot invoke 'map' with an argument list of type '(@escaping (Int, Int) -> E)'}}
 // expected-note@-1{{expected an argument list of type '((Self.Element) throws -> T)'}}
 
-let _ = arr.map(E.tuple) // expected-error {{cannot invoke 'map' with an argument list of type '(@escaping ((x: Int, y: Int)) -> E)'}}
-// expected-note@-1{{expected an argument list of type '((Self.Element) throws -> T)'}}
+let _ = arr.map(E.tuple) // expected-error {{cannot convert value of type '((x: Int, y: Int)) -> E' to expected argument type '(String) throws -> T'}}
+// expected-error@-1 {{generic parameter 'T' could not be inferred}}
 
 let _ = arr.map(G_E<String>.foo) // Ok
 let _ = arr.map(G_E<String>.bar) // Ok
 let _ = arr.map(G_E<String>.two) // expected-error {{cannot convert value of type '(String, String) -> G_E<String>' to expected argument type '(String) throws -> G_E<String>'}}
-let _ = arr.map(G_E<Int>.tuple) // expected-error {{cannot invoke 'map' with an argument list of type '(@escaping ((x: Int, y: Int)) -> G_E<Int>)'}}
-// expected-note@-1{{expected an argument list of type '((Self.Element) throws -> T)'}}
+let _ = arr.map(G_E<Int>.tuple) // expected-error {{cannot convert value of type '((x: Int, y: Int)) -> G_E<Int>' to expected argument type '(String) throws -> T'}}
+// expected-error@-1 {{generic parameter 'T' could not be inferred}}
 
 let _ = E.foo("hello") // expected-error {{missing argument label 'bar:' in call}}
 let _ = E.bar("hello") // Ok

test/Constraints/tuple_arguments.swift

@@ -1702,7 +1702,8 @@ _ = x.map { (_: ()) in () }
 // https://bugs.swift.org/browse/SR-9470
 do {
   func f(_: Int...) {}
-  let _ = [(1, 2, 3)].map(f) // expected-error {{cannot invoke 'map' with an argument list of type '(@escaping (Int...) -> ())'}}
+  let _ = [(1, 2, 3)].map(f) // expected-error {{cannot convert value of type '(Int...) -> ()' to expected argument type '((Int, Int, Int)) throws -> T'}}
+  // expected-error@-1 {{generic parameter 'T' could not be inferred}}
 }
 
 // rdar://problem/48443263 - cannot convert value of type '() -> Void' to expected argument type '(_) -> Void'