dtolnay/cxx

Implement glob import semantics for builtin type names

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#682 opened on 2021年1月16日

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 (6 comments) (0 reactions) (0 assignees)Rust (4,472 stars) (253 forks)batch import
help wanted

説明

Currently we disallow any user-defined type name that collides with one of the builtin type names.

error[cxxbridge]: reserved name
  ┌─ src/main.rs:3:12
  │
3 │     struct UniquePtr { broken: bool }
  │            ^^^^^^^^^ reserved name

error[cxxbridge]: reserved name
  ┌─ src/main.rs:5:12
  │
5 │     struct c_char { broken: bool }
  │            ^^^^^^ reserved name

However, this is bad because it makes it a breaking change for us to add new builtin bindings, such as #681. If the user already had their own type with the same name as the new binding, that code needs to continue to work.

We need to implement basically the same semantics that Rust has for prelude types and glob imports — a user-defined type replaces any builtin binding of the same name.

コントリビューターガイド

技術スタック
rust
領域
developer experiencetooling
Issue 種別
feature
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
4
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
3-5 days
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
stale
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
mostly clear
前提条件
Rust programmingUnderstanding of cxx crate APIFamiliarity with Rust's glob imports
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
30
調査方針
Examine the cxx crate's source code for the reserved name validation logic (likely around the code generation step). Study how Rust implements glob import semantics for prelude types, and design a similar mechanism where user defined types shadow builtin bindings. The issue mentions #681 as an example of a new builtin binding that could break existing code; review that PR for context. Look at the error message output and the parsing of type names to understand where to implement the fallback.