1 files changed, 51 insertions, 0 deletions
diff --git a/tests/ui/mir-dataflow/def-inits-1.rs b/tests/ui/mir-dataflow/def-inits-1.rs
new file mode 100644
index 00000000000..30460824a16
--- /dev/null
+++ b/tests/ui/mir-dataflow/def-inits-1.rs
@@ -0,0 +1,51 @@
+// General test of maybe_uninits state computed by MIR dataflow.
+
+#![feature(core_intrinsics, rustc_attrs)]
+
+use std::intrinsics::rustc_peek;
+use std::mem::{drop, replace};
+
+struct S(i32);
+
+#[rustc_mir(rustc_peek_definite_init,stop_after_dataflow)]
+fn foo(test: bool, x: &mut S, y: S, mut z: S) -> S {
+    let ret;
+    // `ret` starts off uninitialized
+    rustc_peek(&ret);  //~ ERROR rustc_peek: bit not set
+
+    // All function formal parameters start off initialized.
+
+    rustc_peek(&x);
+    rustc_peek(&y);
+    rustc_peek(&z);
+
+    ret = if test {
+        ::std::mem::replace(x, y)
+    } else {
+        z = y;
+        z
+    };
+
+    // `z` may be uninitialized here.
+    rustc_peek(&z); //~ ERROR rustc_peek: bit not set
+
+    // `y` is definitely uninitialized here.
+    rustc_peek(&y); //~ ERROR rustc_peek: bit not set
+
+    // `x` is still (definitely) initialized (replace above is a reborrow).
+    rustc_peek(&x);
+
+    ::std::mem::drop(x);
+
+    // `x` is *definitely* uninitialized here
+    rustc_peek(&x); //~ ERROR rustc_peek: bit not set
+
+    // `ret` is now definitely initialized (via `if` above).
+    rustc_peek(&ret);
+
+    ret
+}
+fn main() {
+    foo(true, &mut S(13), S(14), S(15));
+    foo(false, &mut S(13), S(14), S(15));
+}