[CS] If locator points to a function call, then compare the fn and semanticFn, otherwise fall back to paren check

This is because otherwise we would have false positives, like 'Foo(Bar())' where Foo's init accepts a non-optional Bar and Bar's init returns an IUO

Author: theblixguy

lib/Sema/ConstraintSystem.cpp

@@ -2199,9 +2199,14 @@ void ConstraintSystem::resolveOverload(ConstraintLocator *locator,
     if (!type || !type->is<AnyFunctionType>())
       return false;
 
-    auto paren = getParentExpr(locator->getAnchor());
-    auto result = paren ? isa<ParenExpr>(paren) : false;
-    return result;
+    if (auto call = dyn_cast<CallExpr>(locator->getAnchor()))
+      return call->getSemanticFn() != call->getFn();
+
+    if (auto paren = getParentExpr(locator->getAnchor())) {
+      return isa<ParenExpr>(paren);
+    }
+
+    return false;
   };
 
   // In some cases we already created the appropriate bind constraints.

test/Constraints/iuo.swift

@@ -235,3 +235,14 @@ let sr_10492_int1: Int = (sr_10492_s.foo)() // expected-error {{value of optiona
 // expected-note@-1 {{coalesce}}{{44-44= ?? <#default value#>}}
 // expected-note@-2 {{force-unwrap}}{{44-44=!}}
 let sr_10492_int2: Int? = (sr_10492_s.foo)() // Okay
+
+
+class SR_10492_C1 {
+  init!() {}
+}
+
+class SR_10492_C2 {
+  init(_ foo: SR_10492_C1) {}
+}
+
+let bar = SR_10492_C2(SR_10492_C1()) // Okay