将暂时的git依赖补丁到一个特定的版本

Question

我依赖于板条箱a和b，在那里我修补了b到一个git依赖于reffoo:

# Cargo.toml of my crate
[dependencies]
a = "1.0.0"
b = "1.0.0"
[patch.crates-io]
b = { git = "https://github.com/user/example", rev = "foo" }

a也依赖于b作为git依赖，但没有特定的ref:

# Cargo.toml of a
[dependencies]
b = { git = "https://github.com/user/example" }

我想强制a为b使用相同的ref，我认为我可以这样做:

# The ideal Cargo.toml of my crate
[dependencies]
a = "1.0.0"
b = "1.0.0"
# patch local dependency
[patch.crates-io]
b = { git = "https://github.com/user/example", rev = "foo" }
# patch transient dependency
[patch.'https://github.com/user/example']
b = { git = "https://github.com/user/example", rev = "foo" }

这不起作用，但是，因为我正在修补的源仍然指向相同的源，只是在不同的rev:

error: failed to resolve patches for `https://github.com/user/example`
Caused by:
patch for `b` in `https://github.com/user/example` points to the same source, but patches must point to different sources
[Finished running. Exit status: 101]

---

到目前为止，我的解决方案是分叉b并像这样修补:

# Cargo.toml of my crate using a work around
[dependencies]
a = "1.0.0"
b = "1.0.0"
[patch.crates-io]
b = { git = "https://github.com/me/example", rev = "foo" } # Using my fork
[patch.'https://github.com/user/example']
b = { git = "https://github.com/me/example", rev = "foo" } # Using my fork

这是可行的，但分叉实际上是无用的。有更好的方法吗?

---

我试过这个hack，但它不工作，因为它只是忽略了rev。整个GitHub问题使它看起来像我正在尝试的目前不支持，但很难说，因为它不是完全相同的功能。

Answer 1

根据这个GitHub问题，这个功能目前不支持，因为git依赖项是通过URL而不是修订来区分的。一些url被视为相同的，例如.git结尾总是被剥离，但货物仍然只是比较url，而不是其他。
我们可以使用这个"特性"。对我们有利:在URL的末尾添加?ref=foo将使它看起来像一个新的源代码:

# Fixed Cargo.toml
[dependencies]
a = "1.0.0"
b = "1.0.0"
# patch local dependency
[patch.crates-io]
b = { git = "https://github.com/user/example?rev=foo" }
# patch transient dependency
[patch.'https://github.com/user/example']
b = { git = "https://github.com/user/example?rev=foo" }

---

注意在两个补丁中使用URL hack，否则你会创建一个损坏的Cargo.lock和b的两个定义:

# Corrupt Cargo.toml
[dependencies]
a = "1.0.0"
b = "1.0.0"
# patch local dependency
[patch.crates-io]
b = { git = "https://github.com/user/example", rev = "foo" } # mistake!
# patch transient dependency
[patch.'https://github.com/user/example']
b = { git = "https://github.com/user/example?rev=foo" }

---

虽然我没有测试它，但这种方法原则上也应该通过将/tree/<branch>附加到URL来处理分支上的补丁。