Merge pull request #16163 from slavapestov/typevar-leak

Sema: Fix another type variable leak with closures

Author: slavapestov

lib/Sema/CSDiag.cpp

@@ -6532,18 +6532,18 @@ bool FailureDiagnosis::diagnoseClosureExpr(
     }
 
     expectedResultType = fnType->getResult();
-  } else {
-    // Defend against type variables from our constraint system leaking into
-    // recursive constraints systems formed when checking the body of the
-    // closure.  These typevars come into them when the body does name
-    // lookups against the parameter decls.
-    //
-    // Handle this by rewriting the arguments to UnresolvedType().
-    for (auto VD : *CE->getParameters()) {
-      if (VD->getType()->hasTypeVariable() || VD->getType()->hasError()) {
-        VD->setType(CS.getASTContext().TheUnresolvedType);
-        VD->setInterfaceType(VD->getType()->getInOutObjectType());
-      }
+  }
+
+  // Defend against type variables from our constraint system leaking into
+  // recursive constraints systems formed when checking the body of the
+  // closure.  These typevars come into them when the body does name
+  // lookups against the parameter decls.
+  //
+  // Handle this by rewriting the arguments to UnresolvedType().
+  for (auto VD : *CE->getParameters()) {
+    if (VD->getType()->hasTypeVariable() || VD->getType()->hasError()) {
+      VD->setType(CS.getASTContext().TheUnresolvedType);
+      VD->setInterfaceType(VD->getType()->getInOutObjectType());
     }
   }
 

test/Constraints/closures.swift

@@ -690,3 +690,24 @@ func rdar37790062() {
   _ = S({ bzz(C1()) }, { bar() }) // expected-warning {{result of call to 'bzz' is unused}}
   _ = S({ faz(C2()) }, { bar() }) // expected-warning {{result of call to 'faz' is unused}}
 }
+
+// <rdar://problem/39489003>
+typealias KeyedItem<K, T> = (key: K, value: T)
+
+protocol Node {
+  associatedtype T
+  associatedtype E
+  associatedtype K
+  var item: E {get set}
+  var children: [(key: K, value: T)] {get set}
+}
+
+extension Node {
+  func getChild(for key:K)->(key: K, value: T) {
+    return children.first(where: { (item:KeyedItem) -> Bool in
+        return item.key == key
+        // expected-error@-1 {{binary operator '==' cannot be applied to operands of type '_' and 'Self.K'}}
+        // expected-note@-2 {{overloads for '==' exist with these partially matching parameter lists:}}
+      })
+  }
+}