fix(pilota-build): incorrect merge function signature for cycled-enum

[shenyj3]

Motivation

Fix the compile error of the pb generated code caused by nested enum.

For nested enum, pilota-build will use ::std::option::Option and ::std::boxed::Box to wrap the real enum type in struct field declaration. But the merge method of the enum type only accept ::std::option::Option<Self>.

error[E0308]: mismatched types
   --> /data00/home/shenyuji/tmp/rust-test/target/debug/build/pb-gen-229d3f2befcfa45d/out/pb_gen.rs:37:37
    |
 37 |                         a::B::merge(&mut _inner_pilota_value, tag, wire_type, buf, ctx).map_err(
    |                         ----------- ^^^^^^^^^^^^^^^^^^^^^^^^ expected `&mut Option<B>`, found `&mut &mut Option<Box<B>>`
    |                         |
    |                         arguments to this function are incorrect
    |
    = note: expected mutable reference `&mut std::option::Option<B>`
               found mutable reference `&mut &mut std::option::Option<Box<B>>`
note: associated function defined here
   --> /data00/home/shenyuji/tmp/rust-test/target/debug/build/pb-gen-229d3f2befcfa45d/out/pb_gen.rs:662:24
    |
662 |                 pub fn merge(
    |                        ^^^^^
663 |                     field: &mut ::core::option::Option<Self>,
    |                     ----------------------------------------

Solution

Change the type of the first param of the nested-enum merge method from &mut Option<Self> to &mut Option<Box<T>>.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.59%. Comparing base (67eb3ec) to head (b414ff1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #360      +/-   ##
==========================================
+ Coverage   66.37%   66.59%   +0.22%     
==========================================
  Files          88       88              
  Lines       24577    24710     +133     
==========================================
+ Hits        16312    16456     +144     
+ Misses       8265     8254      -11     

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[PureWhiteWu]

@cursor run

[cursor]

我已检查 pilota-build/src/codegen/pb/mod.rs，目前针对 cycled enum 的 merge 签名已经是 &mut Option<Box<Self>>，并且对应的分支逻辑与 Box 使用一致，这与 PR 描述的修复点一致。因此当前分支没有需要再修改的代码。
测试未运行（如果需要我执行某个测试/复现流程，请给出具体命令或用例）。

  

[shenyj3]

@cursor run

known issue, already fix in another pr.

let me cherry-pick to this pr.