Merge #281: fix: Sum value regression

4b83c05 fix: Sum value regression (Christian Lewe)

Pull request description:

  Fixes #275

  I tried the fix [that was recommended](BlockstreamResearch/simfony#114 (comment)) on the Simfony crate and it made all examples pass.

ACKs for top commit:
  apoelstra:
    ACK 4b83c05; successfully ran local tests

Tree-SHA512: aa6710bd7ab1333bc17cec8a57297ca5c455904dea5bab59c01ac3fe37f9109dbd2d231e567e7510513dc2c9a2935f12dbd93a4a9e2d2aa29964a7d4727a86fb

Author: apoelstra

src/value.rs

@@ -358,10 +358,10 @@ impl Value {
         let total_width = cmp::max(inner.ty.bit_width(), right.bit_width());
 
         let (concat, concat_offset) = product(
-            Some((&inner.inner, inner.bit_offset)),
-            inner.ty.bit_width(),
             None,
             total_width - inner.ty.bit_width(),
+            Some((&inner.inner, inner.bit_offset)),
+            inner.ty.bit_width(),
         );
         let (new_inner, new_bit_offset) = right_shift_1(&concat, concat_offset, false);
         Self {