Merge pull request #328 from manavgabhawala/master

Fixes [SR-78] swift compiler seg fault

Author: rudkx

lib/IRGen/GenType.cpp

@@ -2031,17 +2031,19 @@ SILType irgen::getSingletonAggregateFieldType(IRGenModule &IGM,
 
     // If there's only one stored property, we have the layout of its field.
     auto allFields = structDecl->getStoredProperties();
+    
     auto field = allFields.begin();
-    if (std::next(field) == allFields.end())
+    if (!allFields.empty() && std::next(field) == allFields.end())
       return t.getFieldType(*field, *IGM.SILMod);
 
     return SILType();
   }
 
   if (auto enumDecl = t.getEnumOrBoundGenericEnum()) {
     auto allCases = enumDecl->getAllElements();
+    
     auto theCase = allCases.begin();
-    if (std::next(theCase) == allCases.end()
+    if (!allCases.empty() && std::next(theCase) == allCases.end()
         && (*theCase)->hasArgumentType())
       return t.getEnumElementType(*theCase, *IGM.SILMod);
 

test/IRGen/generic_enums.swift

@@ -0,0 +1,9 @@
+// RUN: %target-swift-frontend -primary-file %s -emit-ir
+
+struct Bar<A1, A2> {
+  var a: A1
+  var b: Foo<A1>
+}
+
+enum Foo<A>{
+}

test/IRGen/generic_structs.swift

@@ -0,0 +1,27 @@
+// RUN: %target-swift-frontend -primary-file %s -emit-ir
+
+struct A<T1, T2>
+{
+  var b: T1
+  var c: T2
+  var d: B<T1, T2>
+}
+struct B<T1, T2>
+{
+  var c: T1
+  var d: T2
+}
+
+struct C<T1>
+{}
+struct D<T2>
+{}
+
+struct Foo<A1, A2>
+{
+  var a: A1
+  var b: Bar<A1, A2>
+}
+
+struct Bar<A1, A2> {
+}