v0.5 requires rustc v1.21.0 minimum

[kbknapp]

I see the readme says 1.17 is required, but it looks like unicode-normilization has been updated to now require 1.21.0 minimum rustc.

To reproduce:

$ git clone https://github.com/mgeisler/version-sync
[.. snip ..]
$ cd version-sync
$ rustup override add 1.20.0
$ cargo build
   Compiling unicode-normalization v0.1.7
error[E0597]: borrowed value does not live long enough
    --> /home/kevin/.cargo/registry/src/github.com-1ecc6299db9ec823/unicode-normalization-0.1.7/src/tables.rs:7533:30
     |
7533 |         '\u{1F248}' => Some(&['\u{3014}', '\u{6557}', '\u{3015}']),
     |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- temporary value only lives until here
     |                              |
     |                              does not live long enough
     |
     = note: borrowed value must be valid for the static lifetime...

error[E0597]: borrowed value does not live long enough
    --> /home/kevin/.cargo/registry/src/github.com-1ecc6299db9ec823/unicode-normalization-0.1.7/src/tables.rs:7534:30
     |
7534 |         '\u{1F250}' => Some(&['\u{5F97}']),
     |                              ^^^^^^^^^^^^- temporary value only lives until here
     |                              |
     |                              does not live long enough
     |
     = note: borrowed value must be valid for the static lifetime...

error[E0597]: borrowed value does not live long enough
    --> /home/kevin/.cargo/registry/src/github.com-1ecc6299db9ec823/unicode-normalization-0.1.7/src/tables.rs:7535:30
     |
7535 |         '\u{1F251}' => Some(&['\u{53EF}']),
     |                              ^^^^^^^^^^^^- temporary value only lives until here
     |                              |
     |                              does not live long enough
     |
     = note: borrowed value must be valid for the static lifetime...

error: aborting due to 5738 previous errors

error: Could not compile `unicode-normalization`.

To learn more, run the command again with --verbose.
$ rustup override add 1.21.0
$ cargo build
[.. snip ..]
   Compiling unicode-normalization v0.1.7
    Finished dev [unoptimized + debuginfo] target(s) in 25.18 secs

[mgeisler]

Hey Kevin... and yet my build with Rust 1.17 is green: https://travis-ci.org/mgeisler/version-sync/jobs/373680042 :-D

You're of course right, it fails after a cargo update. I guess I should see if I can disable the caching in Travis for that build...

Do you think

diff --git a/Cargo.toml b/Cargo.toml
index d6755b2..9a1d1af 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,4 +24,5 @@ semver-parser = "0.7"
 syn = { version = "0.11", features = ["full"] }
 toml = "0.4"
 url = "1.5.1"
+unicode-normalization = "=0.1.5"
 itertools = "0.7"

is a sensible way to handle this? It looks quite hacky to me and I'm not sure how me pinning the dependency like this impacts crates that depend on version-sync? (Here it might be okay since nobody should depend on version-sync outside of an integration test.)

Thanks for catching this!

[mgeisler]

I asked the question on the users forum: https://users.rust-lang.org/t/impact-of-pinning-dependencies/17634 -- I'll see what the consensus is there.

[kbknapp]

I think the problem is for libraries there is no lock file, so it's essentially a cargo update at every fresh Travis build, or for any user that doesn't previously have a lock file from a prior build.

[mgeisler]

Let's say this is fixed by #40 and #46.