Fixes to bitstruct and work on correct behaviour when embedded in structs.

test/test_suite/bitstruct/bitstruct_init.c3

@@ -0,0 +1,63 @@
+// #target
+module foo;
+
+bitstruct Foo : uint
+{
+    int x : 1..3;
+    uint y : 11..13;
+    int z : 15..15;
+}
+
+struct Bar
+{
+    int x;
+    bitstruct baz : int
+    {
+        int x : 1..3;
+    }
+}
+
+struct Bar2
+{
+    int x;
+    bitstruct : int
+    {
+        int z : 1..3;
+    }
+
+}
+fn void testNested()
+{
+    Bar b1 = { 3, { 3 } };
+    Bar b2 = { .x = 3, .baz.x = 3 };
+    Bar2 b3 = { 1, 3 };
+    Bar2 b4 = { .x = 123, .z = 3 };
+    Bar2 b5 = { .x = 123, .z = 4 };  // #error: would be truncated
+    Bar2 b6 = { 1, 3 }; // #error: would be truncated
+    Bar b7 = { 3, { 4 } }; // #error: would be truncated
+    Bar b8 = { .x = 3, .baz.x = 4 }; // #error: would be truncated
+
+}
+
+fn void test()
+{
+    Foo abc = {};
+    abc.x = -4;
+    abc.z = 0;
+    abc.z = -1;
+    abc.x = 3;
+    abc.y = 7;
+    abc.x = -5; // #error: would be truncated
+    abc.x = 4; // #error: would be truncated
+    abc.y = 8; // #error: would be truncated
+}
+
+fn void test2()
+{
+    Foo abc = { -4, 8, 0 }; // #error: would be truncated
+}
+
+fn void test3()
+{
+    Foo abc = { .x = -4, .z = 0, .y = 8 }; // #error: would be truncated
+}