Fix <rdar://23248290> Name lookup: "Cannot convert type 'Int' to expected argument type 'Int'" while trying to initialize ivar of generic type in class scope

Type resolution wasn't looking through property initializer decl contexts
to find out whether an unbound generic type reference was referring to the
enclosing type.  Previously we'd reject this with:

error: cannot convert value of type 'Int' to specified type 'Int'
  private var data: Int = Matrix4.size()
                          ~~~~~~~~^~~~~~

which was super confusing.  The problem was that we weren't resolving
Matrix4 to Matrix4<T>.

Author: lattner

lib/Sema/TypeCheckType.cpp

@@ -224,9 +224,14 @@ Type TypeChecker::resolveTypeInContext(
         case DeclContextKind::Module:
         case DeclContextKind::FileUnit:
         case DeclContextKind::TopLevelCodeDecl:
-        case DeclContextKind::Initializer:
           break;
 
+        case DeclContextKind::Initializer:
+          // If this is a property initializer, we may be referring to the
+          // type initializing the property.
+          continue;
+
+            
         case DeclContextKind::NominalTypeDecl:
           // If this is our nominal type, return its type within its context.
           // FIXME: Just produce the type structure when TR_ResolveStructure.

test/NameBinding/name-binding.swift

@@ -207,3 +207,17 @@ func questionablyValidForwardReference() { print(qvfrVar, terminator: ""); }; va
 // FIXME: This should warn too.
 print(forwardReferenceVar, terminator: ""); var forwardReferenceVar: Int = 0
 
+
+
+// <rdar://problem/23248290> Name lookup: "Cannot convert type 'Int' to expected argument type 'Int'" while trying to initialize ivar of generic type in class scope
+// https://gist.github.com/erynofwales/61768899502b7ac83c6e
+struct Matrix4<T: FloatingPointType>  {
+  static func size() -> Int {}
+  
+  private var data: Int = Matrix4.size()   // Ok: Matrix4<T>
+  
+  init() {
+    data = Matrix4.size()  // Ok: Matrix4<T>
+  }
+}
+

test/expr/delayed-ident/static_var.swift

@@ -18,7 +18,7 @@ acceptInOutX1(&(.AnX1))
 
 // Generic struct types
 struct X2<T> {
-  static var AnX2 = X2() // expected-error{{generic parameter 'T' could not be inferred}}
+  static var AnX2 = X2() // expected-error{{static stored properties not yet supported in generic types}}
   static var NotAnX2 = 0 // expected-error {{static stored properties not yet supported in generic types}}
 }