1 files changed, 24 insertions, 0 deletions
diff --git a/src/test/ui/numbers-arithmetic/overflowing-rsh-4.rs b/src/test/ui/numbers-arithmetic/overflowing-rsh-4.rs
new file mode 100644
index 00000000000..ce7f818e330
--- /dev/null
+++ b/src/test/ui/numbers-arithmetic/overflowing-rsh-4.rs
@@ -0,0 +1,24 @@
+// build-fail
+// compile-flags: -C debug-assertions
+
+// This function is checking that our (type-based) automatic
+// truncation does not sidestep the overflow checking.
+
+#![deny(arithmetic_overflow, const_err)]
+
+fn main() {
+    // this signals overflow when checking is on
+    let x = 2_i8 >> 17;
+    //~^ ERROR: this arithmetic operation will overflow
+
+    // ... but when checking is off, the fallback will truncate the
+    // input to its lower three bits (= 1). Note that this is *not*
+    // the behavior of the x86 processor for 8- and 16-bit types,
+    // but it is necessary to avoid undefined behavior from LLVM.
+    //
+    // We check that here, by ensuring the result is not zero; if
+    // overflow checking is turned off, then this assertion will pass
+    // (and the compiletest driver will report that the test did not
+    // produce the error expected above).
+    assert_eq!(x, 1_i8);
+}