Fix overflow checking in unsigned pow()

The pow() method for unsigned integers produced 0 instead of trapping
overflow for certain inputs. Calls such as 2u32.pow(1024) produced 0
when they should trap an overflow. This also adds tests for the
correctly handling overflow in unsigned pow().

For issue number #34913

2 files changed, 16 insertions, 0 deletions

diff --git a/src/test/run-fail/overflowing-pow.rs b/src/test/run-fail/overflowing-pow-signed.rs
index b0ff0df5577..b0ff0df5577 100644
--- a/src/test/run-fail/overflowing-pow.rs
+++ b/src/test/run-fail/overflowing-pow-signed.rs
diff --git a/src/test/run-fail/overflowing-pow-unsigned.rs b/src/test/run-fail/overflowing-pow-unsigned.rs
new file mode 100644
index 00000000000..5dca7795462
--- /dev/null
+++ b/src/test/run-fail/overflowing-pow-unsigned.rs
@@ -0,0 +1,16 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// error-pattern:thread 'main' panicked at 'attempted to multiply with overflow'
+// compile-flags: -C debug-assertions
+
+fn main() {
+    let _x = 2u32.pow(1024);
+}