相同代码的货物构建:虚假编译时错误? [英] cargo build of the same code: spurious compile time errors?
问题描述
我有依赖于 B 和 B 的箱子 A 依赖于 rust-nmea 箱子.
I have crate A that depend on B and B depend on rust-nmea crate.
如果我构建 crate A 我在构建 use std::error::Error;)"https://github.com/Dushistov/rust-nmea" rel="nofollow noreferrer">rust-nmea 依赖:
If I build crate A I got bunch of errors (all of them that missed use std::error::Error;) during build of rust-nmea dependency:
error[E0599]: no method named `description` found for type `nom::Err<&[u8]>` in the current scope
--> /home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/src/parse.rs:100:44
|
100 | IError::Error(e) => e.description().to_string(),
| ^^^^^^^^^^^
|
= help: items from traits can only be used if the trait is in scope
= note: the following trait is implemented but not in scope, perhaps add a `use` for it:
candidate #1: `use std::error::Error;`
但是如果我去 B crate 的源代码树并运行 cargo build，所有构建都没有任何错误(如果你跟着我 A 依赖于 B 而 B 依赖于 rust-nmea),
But if I go to source tree of B crate and run cargo build,
all build without any error (if you follow me A depend on B and B depend on rust-nmea),
如果去/home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/(见编译错误)并运行cargo build 那么一切都很好.
also if go to /home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/ (see compile error) and run cargo build then all good.
A 的货物树展示:
│ ├── chrono v0.4.0
│ │ ├── num v0.1.40
│ │ │ ├── num-integer v0.1.35
│ │ │ │ └── num-traits v0.1.40
│ │ │ ├── num-iter v0.1.34
│ │ │ │ ├── num-integer v0.1.35 (*)
│ │ │ │ └── num-traits v0.1.40 (*)
│ │ │ └── num-traits v0.1.40 (*)
│ │ └── time v0.1.38
│ │ └── libc v0.2.27
├── nmea v0.0.6
│ ├── chrono v0.4.0 (*)
│ └── nom v3.2.0
│ └── memchr v1.0.1 (*)
以及由 cargo 缓存 rust-nmea:
├── chrono v0.4.0
│ ├── num v0.1.40
│ │ ├── num-integer v0.1.35
│ │ │ └── num-traits v0.1.40
│ │ ├── num-iter v0.1.34
│ │ │ ├── num-integer v0.1.35 (*)
│ │ │ └── num-traits v0.1.40 (*)
│ │ └── num-traits v0.1.40 (*)
│ └── time v0.1.38
│ └── libc v0.2.27
└── nom v3.2.0
└── memchr v1.0.1
└── libc v0.2.27 (*)
所以无论好坏都使用相同的依赖项.
so for both good and bad case used the same dependencies.
如果运行 cargo build -v -j1，我得到了两种情况下的 rustc 命令行.
If run cargo build -v -j1, I got rustc command line for both cases.
好坏的唯一区别是这部分:
The only difference for good and bad case is this part:
-L dependency=/home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/target/debug/deps --extern chrono=/home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/target/debug/deps/libchrono-8e9e54e691d9b988.rlib --extern nom=/home/evgeniy/.cargo/registry/src/github.com-1ecc6299db9ec823/nmea-0.0.6/target/debug/deps/libnom-b72336f662b090c1.rlib
坏情况有不同的库路径和libnom-e2ec53418967eac0.rlib 而不是libnom-b72336f662b090c1.rlib，而libchrono-8e9e54e691d9b988.rlib> 匹配.
bad case have different path to libraries and libnom-e2ec53418967eac0.rlib instead of libnom-b72336f662b090c1.rlib, while libchrono-8e9e54e691d9b988.rlib match.
板条箱 A 和 B 是近源的，我无法将问题简化为更简单的情况.nom 未在 A 和 B 中使用的 crate除了通过 rust-nmea.rust-nmea 使用简单，只需 nmea = 0.0.6在 Cargo.toml 中.没有标志之类的东西.
The crates A and B are close sourced and I can not reduce problem to more simple case. nom crates not used in A and B except via rust-nmea.
rust-nmea is used in simple way, just nmea = 0.0.6 in Cargo.toml.
No flags or so on things.
知道为什么使用相同标志的 crate 依赖(根本没有标志)可能产生或不产生语法错误?
Any idea why crate dependecy with the same flags (no flags at all) may produce or not produce syntax error?
推荐答案
我找到了问题的根源，crate A 与 ceexpr 有二级依赖关系，cexpr 在 Cargo.toml 中有 nom = {version = "^3", features = ["verbose-errors"] }，rust-nmea 也依赖于 nom，所以我们有编译时错误.
I found source of problem,
crate A has second level dependicies with cexpr,
cexpr has nom = {version = "^3", features = ["verbose-errors"] } in Cargo.toml,
rust-nmea also depend on nom, so we have compile time error.
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