[replace] does not replace metadata (dependencies)

[SimonSapin]

I have a branch of Servo with this override:

[replace]
"hyper:0.8.1" = {git = "https://github.com/servo/hyper", branch = "url-1.0"}

In that git branch, the Cargo.toml for hyper contains:

[dependencies]
url = "1.0"

However, hyper with my replaced sourced is built with url 0.5.9, which is the dependency declared in the original un-replaced hyper. Cargo.lock even shows this:

[[package]]
name = "hyper"
version = "0.8.1"
source = "git+https://github.com/servo/hyper?branch=url-1.0#353217402264578933dca89c0e7f210052c552a5"
dependencies = [
 […]
 "url 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
]

Where dependencies does not match what’s in the Cargo.toml file at source.

(Specifying an additional replacement for "url:0.5.9" = {git = "https://github.com/servo/rust-url", branch = "1.0.0-pretending-to-be-0.5.9"} worked, but I was trying to remove it now that url 1.0.0 is on crates.io.)

[alexcrichton]

I unfortunately can't seem to reproduce this situation in a test case of Cargo. Is there a branch I could check out or an easy way for me to reproduce this locally?

[behnam]

I'm facing a similar issue and ./mach clean doesn't help either. Here's my situation in short:

git clone https://github.com/servo/unicode-bidi
git clone https://github.com/servo/servo

then:

1. Edit unicode-bidi/Cargo.toml and bump the version
2. Update dependency version in components/layout/text.rs
3. Add following line to [replace] table in servo/Cargo.toml:

"unicode-bidi:0.3.0" = { path = "../servo-unicode-bidi" }

Here's the result:

$ ./mach clean

$ ./mach build --dev
    Updating registry `https://github.com/rust-lang/crates.io-index`
error: no matching version `^0.3` found for package `unicode-bidi` (required by `layout`)
location searched: registry https://github.com/rust-lang/crates.io-index
versions found: 0.2.5, 0.2.4, 0.2.3, ...
Build FAILED in 0:00:03

[alexcrichton]

@behnam currently [replace] only works with crates that already exist on crates.io, and it looks like 0.3.0 doesn't exist on crates.io?

[behnam]

Right, @alexcrichton. The 0.3.0 version is something I have locally and want to test servo against before publishing.

In servo/Cargo.toml, I see this:

[replace]
# If you need to temporarily test Servo with a local fork of some upstream
# crate, add that here. Use the form:
#
#     "<crate>:<version>" = { path = "/path/to/local/checkout" }

which sounds like exactly what I need [replace] for: overriding the source (path instead of crates.io) for the specific version for the whole build.

[behnam]

Interesting part is that I get a warning: package replacement is not used: https://github.com/rust-lang/crates.io-index#... if I add a replace entry with a version that's not required. But, when the version is required by some of the components, the warning goes away, but a few seconds into the ./mach build I get the error: no matching version ... error.

[alexcrichton]

@behnam ah yeah if you want to work with unpublished crates currently Cargo doesn't have support for that, but you may be interested in rust-lang/rfcs#1969 which adds support.

[behnam]

Okay, got it. Thanks. But wondering what this comment in servo/Cargo.toml means, then:

# If you need to temporarily test Servo with a local fork of some upstream
# crate, add that here. Use the form:

Does it mean that local path works as long as the version is published to crates.io? If so, maybe we should point it out in the comment. I can submit a PR for it.

[alexcrichton]

Yeah as long as the version of the crate listed in path is the same as it is in the lock file, then you should be good to go.

[carols10cents]

I unfortunately can't seem to reproduce this situation in a test case of Cargo. Is there a branch I could check out or an easy way for me to reproduce this locally?

Closing due to inactivity, if this is still an issue, please reopen with more details.

[SimonSapin]

I think that the solution to this is often to use [patch] instead of [replace]