AST: Fix DeclContext::getAsTypeOrTypeExtensionContext() for extensions of typealiases

Author: slavapestov

lib/AST/DeclContext.cpp

@@ -61,17 +61,10 @@ DeclContext::getAsTypeOrTypeExtensionContext() const {
     auto ED = cast<ExtensionDecl>(this);
     auto type = ED->getExtendedType();
 
-    if (type.isNull() || type->hasError())
+    if (!type)
       return nullptr;
 
-    if (auto ND = type->getNominalOrBoundGenericNominal())
-      return ND;
-
-    if (auto unbound = dyn_cast<UnboundGenericType>(type.getPointer())) {
-      return unbound->getDecl();
-    }
-
-    return nullptr;
+    return type->getAnyNominal();
   }
 
   case DeclContextKind::GenericTypeDecl:

test/decl/ext/generic.swift

@@ -158,3 +158,9 @@ struct S5<Q> {
 }
 
 extension S5 : P4 {}
+
+// rdar://problem/21607421
+public typealias Array2 = Array
+extension Array2 where QQQ : VVV {}
+// expected-error@-1 {{use of undeclared type 'QQQ'}}
+// expected-error@-2 {{use of undeclared type 'VVV'}}

validation-test/compiler_crashers/28738-impl-genericparams-empty-key-depth-impl-genericparams-back-getdepth-key-index-im.swift renamed to validation-test/compiler_crashers_fixed/28738-impl-genericparams-empty-key-depth-impl-genericparams-back-getdepth-key-index-im.swift

@@ -6,5 +6,5 @@
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
 // REQUIRES: asserts
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 protocol P}extension P{{}typealias a:P}extension P.a{protocol P