Fix #381559, test-638.cs, test-639.cs

* assign.cs (CompoundAssign.Helper): New wrapper.
(CompoundAssign.DoResolve): Use it to wrap the nested 'target' access.
* ecore.cs (MethodGroupExpr.VerifyArgumentsCompat) <params arguments>:
Pass unconverted expressions to the params array creation expression.
(FieldExpr.EmitAssign): Don't special-case StringConcat.
(PropertyExpr.EmitAssign): Likewise.
* expression.cs (ArrayCreation.ResolveArrayElement): Keep track of the
element if it is of kind CompoundAssign.Helper.
(ArrayCreation.Emit): If we saw a CompoundAssign.Helper, emit it
first before anything else.
(ArrayAccess.EmitAssign): Don't special-case StringConcat.
(ArrayAccess.LoadArrayAndArguments): Simplify.

svn path=/trunk/mcs/; revision=102001

1 files changed, 12 insertions, 0 deletions

diff --git a/mcs/tests/test-639.cs b/mcs/tests/test-639.cs
new file mode 100644
index 00000000000..4d4587dc36f
--- /dev/null
+++ b/mcs/tests/test-639.cs
@@ -0,0 +1,12 @@
+class Foo {
+  bool got;
+  string s {
+    get { got = true; return ""; }
+    set { if (!got || value != "A1B2") throw new System.Exception (); }
+  }
+
+  static void Main ()
+  {
+    (new Foo ()).s += "A" + 1 + "B" + 2;
+  }
+}