Merge remote-tracking branch 'origin/master' into master-rebranch

Author: swift-ci

lib/Sema/CSDiagnostics.cpp

@@ -310,7 +310,12 @@ Type RequirementFailure::getOwnerType() const {
 const GenericContext *RequirementFailure::getGenericContext() const {
   if (auto *genericCtx = AffectedDecl->getAsGenericContext())
     return genericCtx;
-  return AffectedDecl->getDeclContext()->getAsDecl()->getAsGenericContext();
+
+  auto parentDecl = AffectedDecl->getDeclContext()->getAsDecl();
+  if (!parentDecl)
+    return nullptr;
+
+  return parentDecl->getAsGenericContext();
 }
 
 const Requirement &RequirementFailure::getRequirement() const {

lib/Sema/CSDiagnostics.h

@@ -236,6 +236,10 @@ class RequirementFailure : public FailureDiagnostic {
     assert(locator);
     assert(isConditional() || Signature);
     assert(AffectedDecl);
+    assert(getRequirementDC() &&
+           "Couldn't find where the requirement came from?");
+    assert(getGenericContext() &&
+           "Affected decl not within a generic context?");
 
     auto reqElt = locator->castLastElementTo<LocatorPathElt::AnyRequirement>();
     assert(reqElt.getRequirementKind() == kind);

lib/Sema/CSSimplify.cpp

@@ -1629,11 +1629,18 @@ ConstraintSystem::matchSuperclassTypes(Type type1, Type type2,
   TypeMatchOptions subflags = getDefaultDecompositionOptions(flags);
 
   auto classDecl2 = type2->getClassOrBoundGenericClass();
+  SmallPtrSet<ClassDecl *, 4> superclasses1;
   for (auto super1 = type1->getSuperclass();
        super1;
        super1 = super1->getSuperclass()) {
-    if (super1->getClassOrBoundGenericClass() != classDecl2)
+    auto superclass1 = super1->getClassOrBoundGenericClass();
+    if (superclass1 != classDecl2) {
+      // Break if we have circular inheritance.
+      if (superclass1 && !superclasses1.insert(superclass1).second)
+        break;
+
       continue;
+    }
 
     return matchTypes(super1, type2, ConstraintKind::Bind,
                       subflags, locator);

lib/Sema/ConstraintSystem.cpp

@@ -425,7 +425,8 @@ ConstraintLocator *ConstraintSystem::getCalleeLocator(Expr *expr) {
     // For an apply of a metatype, we have a short-form constructor. Unlike
     // other locators to callees, these are anchored on the apply expression
     // rather than the function expr.
-    if (simplifyType(getType(fnExpr))->is<AnyMetatypeType>()) {
+    auto fnTy = getFixedTypeRecursive(getType(fnExpr), /*wantRValue*/ true);
+    if (fnTy->is<AnyMetatypeType>()) {
       auto *fnLocator =
           getConstraintLocator(applyExpr, ConstraintLocator::ApplyFunction);
       return getConstraintLocator(fnLocator,

test/Constraints/generics.swift

@@ -714,7 +714,7 @@ protocol Q {
 }
 
 struct SR10694 {
-  init<T : P>(_ x: T) {} // expected-note 2{{where 'T' = 'T'}}
+  init<T : P>(_ x: T) {} // expected-note 3{{where 'T' = 'T'}}
   func bar<T>(_ x: T, _ s: SR10694, _ q: Q) {
     SR10694.self(x) // expected-error {{initializer 'init(_:)' requires that 'T' conform to 'P'}}
 
@@ -726,6 +726,10 @@ struct SR10694 {
 
     type(of: q)(x)  // expected-error {{initializer 'init(_:)' requires that 'T' conform to 'P'}}
     // expected-error@-1 {{initializing from a metatype value must reference 'init' explicitly}}
+
+    var srTy = SR10694.self
+    srTy(x) // expected-error {{initializer 'init(_:)' requires that 'T' conform to 'P'}}
+    // expected-error@-1 {{initializing from a metatype value must reference 'init' explicitly}}
   }
 }
 

test/decl/class/circular_inheritance_2.swift

@@ -0,0 +1,8 @@
+// RUN: %target-typecheck-verify-swift
+
+// rdar://problem/54296278 - infinite loop
+class Foo {}
+class Bar: Bar {} // expected-error{{'Bar' inherits from itself}}
+func foo(_ o: AnyObject) -> Foo? {
+    return o as? Bar // expected-error{{cannot convert return expression of type 'Bar?' to return type 'Foo?'}}
+}