error: failed to select a version for libc (required by appname):

[CBSears]

rustc 1.15.0-beta.3 (a035041ba 2017-01-07)
clap = "2.20.0"

I'm developing on OSX, latest and greatest.

I am only just starting to use clap. So I'm including essentially three lines in my project and I can't even get it to build. I'm not even calling clap.

In my Cargo.toml:

clap = "2.20.0"
libc = "0.2.20"

I've also tried libc 0.2.19 and 0.2.18 as well with the same error message. When I build my code:

% cargo clean; cargo build
Updating registry https://github.com/rust-lang/crates.io-index
error: failed to select a version for libc (required by appname):
all possible versions conflict with previously selected versions of libc
version 0.2.19 in use by libc v0.2.19
possible versions to select: 0.2.20

In particular, this line makes no sense to me:

version 0.2.19 in use by libc v0.2.19

My entire Cargo.toml is:

[package]
name = "appname"
version = "0.1.0"
authors = ["chris"]

build = "build.rs"

[dependencies]

time = "0.1"
clap = "2.20.0"
libc = "0.2.20"
rustc-serialize = "0.3"

[CBSears]

The problem persisted after I commented out "extern crate clap;" and "clap = "2.20.0"
It went away after cargo update. But returned when I uncommented these lines.

[kbknapp]

Thanks for reporting this! I saw this mentioned on the subreddit as well. I'll do some tests and see where it lies, if it's as simple as bumping the pinned libc version I'll do that.

[kbknapp]

Alright this should be fixed, I'm uploading the PR now

[CBSears]

Can you explain what it was since I wasn't understanding what the problem was at all. Newish to Rust and I thought it was pilot error. C

On Sun, Jan 29, 2017 at 3:40 PM Kevin K. ***@***.***> wrote: Alright this should be fixed, I'm uploading the PR now — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#826 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFJM0ReCOhPTlH6xQi2Kt9ecX0jWJl9Uks5rXSNdgaJpZM4Lwkkr> .

-- Ite Ursi

[kbknapp]

To be honest I'm not 100% sure since cargo should allow for multiple versions of a dep to exist in the dep graph.

The way it went down is clap required exactly version 0.2.18 of libc, while one of claps deps required "up to" version 0.2.20 and cargo didn't like that for some reason.

I've relaxed claps version requirements and also updated that dep of claps (term_size-rs) so it shouldn't happen again. Now both of those crates require anything semver compatible with 0.2.20 and above.

[kbknapp]

As soon as #830 merges I'll put v2.20.1 on crates.io

[kbknapp]

Closed with #830