Tests for while loops that may invalidate constraints

Wrote some small test cases that use while loops and moves, to
make sure the poststate for the loop body gets propagated into the
new prestate and deinitialization gets reflected.

Along with that, rewrite the code for intersecting states. I still
find it dodgy, but I guess I'll continue trying to add more tests.
Also, I'll probably feel better about it once I start formalizing
the algorithm.

3 files changed, 50 insertions, 0 deletions

diff --git a/src/test/compile-fail/do-while-constraints.rs b/src/test/compile-fail/do-while-constraints.rs
new file mode 100644
index 00000000000..c9c557320a0
--- /dev/null
+++ b/src/test/compile-fail/do-while-constraints.rs
@@ -0,0 +1,17 @@
+// xfail-stage0
+// error-pattern: Unsatisfied precondition constraint (for example, init(y
+fn main() {
+
+  let int y = 42;
+  let int x;
+  do {
+    log y;
+    do {
+      do {
+	do {
+	  x <- y;
+	} while (true);
+      } while (true);
+    } while (true);
+  } while (true);
+}
\ No newline at end of file
diff --git a/src/test/compile-fail/while-loop-constraints.rs b/src/test/compile-fail/while-loop-constraints.rs
new file mode 100644
index 00000000000..981a555ff30
--- /dev/null
+++ b/src/test/compile-fail/while-loop-constraints.rs
@@ -0,0 +1,17 @@
+// xfail-stage0
+// error-pattern: Unsatisfied precondition constraint (for example, init(y
+fn main() {
+
+  let int y = 42;
+  let int x;
+  while (true) {
+    log y;
+    while (true) {
+      while (true) {
+	while (true) {
+	  x <- y;
+	}
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/test/run-pass/while-loop-constraints-2.rs b/src/test/run-pass/while-loop-constraints-2.rs
new file mode 100644
index 00000000000..c1550ad2d08
--- /dev/null
+++ b/src/test/run-pass/while-loop-constraints-2.rs
@@ -0,0 +1,16 @@
+// xfail-stage0
+fn main() {
+
+  let int y = 42;
+  let int z = 42;
+  let int x;
+  while (z < 50) {
+    z += 1; 
+    while (false) {
+      x <- y;
+      y = z;
+    }
+    log y;
+  }
+  assert (y == 42 && z == 50);
+}
\ No newline at end of file