Sema: Hacky fix for infinite recursion if a class inherits from itself

This seems to come up a lot; we need to consolidate and clean up
inheritance circularity breaks.

Author: slavapestov

lib/Sema/ITCNameLookup.cpp

@@ -75,6 +75,10 @@ bool IterativeTypeChecker::isQualifiedLookupInDeclContextSatisfied(
 
     if (auto superclass = classDecl->getSuperclass()) {
       if (auto superclassDecl = superclass->getAnyNominal()) {
+        // Hack.
+        if (superclassDecl == nominal)
+          return true;
+
         if (!isSatisfied(requestQualifiedLookupInDeclContext({ superclassDecl,
                                                                payload.Name,
                                                                payload.Loc })))

validation-test/compiler_crashers/28462-segfault-0xcdc361-0xd051ef-0xcdc361-0xd051ef.swift renamed to validation-test/compiler_crashers_fixed/28462-segfault-0xcdc361-0xd051ef-0xcdc361-0xd051ef.swift

@@ -5,5 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 typealias e=A.G{}{}class A:A

validation-test/compiler_crashers/28506-swift-iterativetypechecker-issatisfied-swift-typecheckrequest.swift renamed to validation-test/compiler_crashers_fixed/28506-swift-iterativetypechecker-issatisfied-swift-typecheckrequest.swift

@@ -5,5 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 typealias e:A.d)class A:A}a

validation-test/compiler_crashers/28524-swift-iterativetypechecker-issatisfied-swift-typecheckrequest.swift renamed to validation-test/compiler_crashers_fixed/28524-swift-iterativetypechecker-issatisfied-swift-typecheckrequest.swift

@@ -5,6 +5,6 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 typealias d:A.a
 class A:A