Fix a bug on 32-bit platforms that caused Position::max_altitude to…

… return

the wrong value, as a result of assuming that `usize` is 64 bits.
fixes #56

Signed-off-by: Daira Hopwood <[email protected]>

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to Rust's notion of
 
 ## [Unreleased]
 
+### Fixed
+
+- A bug affecting 32-bit platforms caused `Position::max_altitude` to return the wrong
+  value. This typically manifested as failures to add commitments to the tree.
+
 ## [0.3.0] - 2022-05-10
 
 ### Added

proptest-regressions/lib.txt

@@ -0,0 +1,8 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 713580b935d97377d97711c7f126ad2ef82c961bc4b64b538c551d1b2e8b1cdb # shrinks to ops = [Append("a"), Append("a"), Append("a")]
+cc db0c5a37f69e8824f0680d595aaf803e15b207d5571d07db464d8178037d8798 # shrinks to ops = [Append(SipHashable(0)), Append(SipHashable(0)), Authpath(Position(0), 0)]

src/lib.rs

@@ -106,7 +106,7 @@ impl Position {
         Altitude(if self.0 == 0 {
             0
         } else {
-            63 - self.0.leading_zeros() as u8
+            (usize::BITS - 1 - self.0.leading_zeros()) as u8
         })
     }