implement null aware ops, fixes #249

test/codegen/language/conditional_property_increment_decrement_test.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Verify semantics of the ?. operator when it appears in a postincrement or
+// preincrement expression (or a postdecrement or predecrement expression).
+
+import "package:expect/expect.dart";
+import "conditional_access_helper.dart" as h;
+
+class C {
+  int v;
+  C(this.v);
+  static int staticInt;
+}
+
+class D {
+  E v;
+  D(this.v);
+  static E staticE;
+}
+
+class E {
+  G operator+(int i) => new I();
+  G operator-(int i) => new I();
+}
+
+class F {}
+
+class G extends E implements F {}
+
+class H {}
+
+class I extends G implements H {}
+
+C nullC() => null;
+
+main() {
+  // Make sure the "none" test fails if assignment to "?." is not implemented.
+  // This makes status files easier to maintain.
+  nullC()?.v = 1;
+
+  // e1?.v++ is equivalent to ((x) => x == null ? null : x.v++)(e1).
+  Expect.equals(null, nullC()?.v++); /// 01: ok
+  { C c = new C(1); Expect.equals(1, c?.v++); Expect.equals(2, c.v); } /// 02: ok
+
+  // C?.v++ is equivalent to C.v++.
+  { C.staticInt = 1; Expect.equals(1, C?.staticInt++); Expect.equals(2, C.staticInt); } /// 17: ok
+  { h.C.staticInt = 1; Expect.equals(1, h.C?.staticInt++); Expect.equals(2, h.C.staticInt); } /// 18: ok
+
+  // The static type of e1?.v++ is the same as the static type of e1.v.
+  { E e1 = new E(); D d = new D(e1); E e2 = d?.v++; Expect.identical(e1, e2); } /// 03: ok
+  { G g = new G(); D d = new D(g); F f = d?.v++; Expect.identical(f, g); } /// 04: static type warning
+  { E e1 = new E(); D.staticE = e1; E e2 = D?.staticE++; Expect.identical(e1, e2); } /// 19: ok
+  { h.E e1 = new h.E(); h.D.staticE = e1; h.E e2 = h.D?.staticE++; Expect.identical(e1, e2); } /// 20: ok
+  { G g = new G(); D.staticE = g; F f = D?.staticE++; Expect.identical(f, g); } /// 21: static type warning
+  { h.G g = new h.G(); h.D.staticE = g; h.F f = h.D?.staticE++; Expect.identical(f, g); } /// 22: static type warning
+
+  // e1?.v-- is equivalent to ((x) => x == null ? null : x.v--)(e1).
+  Expect.equals(null, nullC()?.v--); /// 05: ok
+  { C c = new C(1); Expect.equals(1, c?.v--); Expect.equals(0, c.v); } /// 06: ok
+
+  // C?.v-- is equivalent to C.v--.
+  { C.staticInt = 1; Expect.equals(1, C?.staticInt--); Expect.equals(0, C.staticInt); } /// 23: ok
+  { h.C.staticInt = 1; Expect.equals(1, h.C?.staticInt--); Expect.equals(0, h.C.staticInt); } /// 24: ok
+
+  // The static type of e1?.v-- is the same as the static type of e1.v.
+  { E e1 = new E(); D d = new D(e1); E e2 = d?.v--; Expect.identical(e1, e2); } /// 07: ok
+  { G g = new G(); D d = new D(g); F f = d?.v--; Expect.identical(f, g); } /// 08: static type warning
+  { E e1 = new E(); D.staticE = e1; E e2 = D?.staticE--; Expect.identical(e1, e2); } /// 25: ok
+  { h.E e1 = new h.E(); h.D.staticE = e1; h.E e2 = h.D?.staticE--; Expect.identical(e1, e2); } /// 26: ok
+  { G g = new G(); D.staticE = g; F f = D?.staticE--; Expect.identical(f, g); } /// 27: static type warning
+  { h.G g = new h.G(); h.D.staticE = g; h.F f = h.D?.staticE--; Expect.identical(f, g); } /// 28: static type warning
+
+  // ++e1?.v is equivalent to e1?.v += 1.
+  Expect.equals(null, ++nullC()?.v); /// 09: ok
+  { C c = new C(1); Expect.equals(2, ++c?.v); Expect.equals(2, c.v); } /// 10: ok
+
+  // ++C?.v is equivalent to C?.v += 1.
+  { C.staticInt = 1; Expect.equals(2, ++C?.staticInt); Expect.equals(2, C.staticInt); } /// 29: ok
+  { h.C.staticInt = 1; Expect.equals(2, ++h.C?.staticInt); Expect.equals(2, h.C.staticInt); } /// 30: ok
+
+  // The static type of ++e1?.v is the same as the static type of e1.v + 1.
+  { D d = new D(new E()); F f = ++d?.v; Expect.identical(d.v, f); } /// 11: ok
+  { D d = new D(new E()); H h = ++d?.v; Expect.identical(d.v, h); } /// 12: static type warning
+  { D.staticE = new E(); F f = ++D?.staticE; Expect.identical(D.staticE, f); } /// 31: ok
+  { h.D.staticE = new h.E(); h.F f = ++h.D?.staticE; Expect.identical(h.D.staticE, f); } /// 32: ok
+  { D.staticE = new E(); H h = ++D?.staticE; Expect.identical(D.staticE, h); } /// 33: static type warning
+  { h.D.staticE = new h.E(); h.H hh = ++h.D?.staticE; Expect.identical(h.D.staticE, hh); } /// 34: static type warning
+
+  // --e1?.v is equivalent to e1?.v -= 1.
+  Expect.equals(null, --nullC()?.v); /// 13: ok
+  { C c = new C(1); Expect.equals(0, --c?.v); Expect.equals(0, c.v); } /// 14: ok
+
+  // --C?.v is equivalent to C?.v -= 1.
+  { C.staticInt = 1; Expect.equals(0, --C?.staticInt); Expect.equals(0, C.staticInt); } /// 35: ok
+  { h.C.staticInt = 1; Expect.equals(0, --h.C?.staticInt); Expect.equals(0, h.C.staticInt); } /// 36: ok
+
+  // The static type of --e1?.v is the same as the static type of e1.v - 1.
+  { D d = new D(new E()); F f = --d?.v; Expect.identical(d.v, f); } /// 15: ok
+  { D d = new D(new E()); H h = --d?.v; Expect.identical(d.v, h); } /// 16: static type warning
+  { D.staticE = new E(); F f = --D?.staticE; Expect.identical(D.staticE, f); } /// 37: ok
+  { h.D.staticE = new h.E(); h.F f = --h.D?.staticE; Expect.identical(h.D.staticE, f); } /// 38: ok
+  { D.staticE = new E(); H h = --D?.staticE; Expect.identical(D.staticE, h); } /// 39: static type warning
+  { h.D.staticE = new h.E(); h.H hh = --h.D?.staticE; Expect.identical(h.D.staticE, hh); } /// 40: static type warning
+}