Fix build on big-endian hosts?

[he32]

Description

jj fails to build on big-endian hosts.

Steps to Reproduce the Problem

Try to build jj on a big-endian host, watch it fail because e.g. put_i16_be is not defined.

Expected Behavior

The build ought to succeed.

Actual Behavior

   Compiling serde_bser v0.4.0
error[E0599]: no method named `put_i16_be` found for struct `Vec<u8>` in the current scope
   --> /home/builder/work/devel/jj/work/vendor/serde_bser-0.4.0/src/ser/mod.rs:136:22
    |
136 |         self.scratch.put_i16_be(v);
    |                      ^^^^^^^^^^
    |
help: there is a method `put_i16_le` with a similar name
    |
136 -         self.scratch.put_i16_be(v);
136 +         self.scratch.put_i16_le(v);
    |

error[E0599]: no method named `put_i32_be` found for struct `Vec<u8>` in the current scope
   --> /home/builder/work/devel/jj/work/vendor/serde_bser-0.4.0/src/ser/mod.rs:146:22
    |
146 |         self.scratch.put_i32_be(v);
    |                      ^^^^^^^^^^
    |
help: there is a method `put_i32_le` with a similar name
    |
146 -         self.scratch.put_i32_be(v);
146 +         self.scratch.put_i32_le(v);
    |

error[E0599]: no method named `put_i64_be` found for struct `Vec<u8>` in the current scope
   --> /home/builder/work/devel/jj/work/vendor/serde_bser-0.4.0/src/ser/mod.rs:156:22
    |
156 |         self.scratch.put_i64_be(v);
    |                      ^^^^^^^^^^
    |
help: there is a method `put_i64_le` with a similar name
    |
156 -         self.scratch.put_i64_be(v);
156 +         self.scratch.put_i64_le(v);
    |

error[E0599]: no method named `put_f64_be` found for struct `Vec<u8>` in the current scope
   --> /home/builder/work/devel/jj/work/vendor/serde_bser-0.4.0/src/ser/mod.rs:258:22
    |
258 |         self.scratch.put_f64_be(v);
    |                      ^^^^^^^^^^
    |
help: there is a method `put_f64_le` with a similar name
    |
258 -         self.scratch.put_f64_be(v);
258 +         self.scratch.put_f64_le(v);
    |

For more information about this error, try `rustc --explain E0599`.
error: could not compile `serde_bser` (lib) due to 4 previous errors

The reason appears that the vendored version of serde_bser does not
have this particular pull request included: facebook/watchman#1238.

I'll admit that I'm a bit confused by the versioning of the serde_bser crate, as HEAD
at the source is 0.4.0 and includes this fix, and the same version (0.4.0) is apparently
used by jj, but there this fix is not included.

Specifications

• Platform: Build issue experienced on NetBSD/macppc 11.0 w/ rust 1.97.0.
• Version: jj version 0.44.

[botovq]

I've been carrying this patch in the OpenBSD port for a long time (and so has FreeBSD where it originally came from). I've been using jj on sparc64 extensively with no issues for the last two years.

The patch landed in serde_bser on August 6, 2024, a few weeks after the release of 0.4.0 (June 19, 2024), so in order for jj to pick up that fix, a new release of serde_bser would be needed. I guess we could try opening an issue there and hope that something will happen, but I would not hold my breath.

There is the option of patching crates, but my understanding is that jj tries hard to avoid this.

[he32]

I've scratched my immediate itch by adding the patch to NetBSD's pkgsrc, but it would be nice to get movement on this "upstream", so that we may eventually remove the patch, so welcome any assistance to make that happen.

[botovq]

Well. We can always ask... facebook/watchman#1361