grin_wallet compilation error - `impl Trait` in return position is experimental (see issue #34511)

[Thireus]

   Compiling grin_wallet v0.2.0 (file:///home/thireus/grin/wallet)
error[E0658]: `impl Trait` in return position is experimental (see issue #34511)
  --> wallet/src/grinwallet/selection.rs:39:34
   |
39 | ) -> Result<(transaction::Slate, impl FnOnce() -> Result<(), Error>), Error> {
   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0658]: `impl Trait` in return position is experimental (see issue #34511)
   --> wallet/src/grinwallet/selection.rs:110:26
    |
110 | ) -> Result<(Identifier, impl FnOnce() -> Result<(), Error>), Error> {
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused import: `rand::thread_rng`
  --> wallet/src/grinwallet/keys.rs:16:5
   |
16 | use rand::thread_rng;
   |     ^^^^^^^^^^^^^^^^
   |
   = note: #[warn(unused_imports)] on by default

warning: unused import: `uuid::Uuid`
  --> wallet/src/grinwallet/keys.rs:17:5
   |
17 | use uuid::Uuid;
   |     ^^^^^^^^^^

warning: unused imports: `Committed`, `Transaction`, `amount_to_hr_string`
  --> wallet/src/grinwallet/keys.rs:19:18
   |
19 | use core::core::{amount_to_hr_string, Committed, Transaction};
   |                  ^^^^^^^^^^^^^^^^^^^  ^^^^^^^^^  ^^^^^^^^^^^

warning: unused import: `failure::ResultExt`
  --> wallet/src/grinwallet/keys.rs:20:5
   |
20 | use failure::ResultExt;
   |     ^^^^^^^^^^^^^^^^^^

warning: unused imports: `BlindSum`, `BlindingFactor`
  --> wallet/src/grinwallet/keys.rs:21:16
   |
21 | use keychain::{BlindSum, BlindingFactor, Identifier, Keychain};
   |                ^^^^^^^^  ^^^^^^^^^^^^^^

warning: unused imports: `aggsig`, `build`
  --> wallet/src/grinwallet/keys.rs:22:17
   |
22 | use libwallet::{aggsig, build};
   |                 ^^^^^^  ^^^^^

warning: unused import: `util::secp::Signature`
  --> wallet/src/grinwallet/keys.rs:24:5
   |
24 | use util::secp::Signature;
   |     ^^^^^^^^^^^^^^^^^^^^^

warning: unused imports: `PublicKey`, `SecretKey`
  --> wallet/src/grinwallet/keys.rs:25:23
   |
25 | use util::secp::key::{PublicKey, SecretKey};
   |                       ^^^^^^^^^  ^^^^^^^^^

warning: unused imports: `LOGGER`, `secp`
  --> wallet/src/grinwallet/keys.rs:26:12
   |
26 | use util::{secp, LOGGER};
   |            ^^^^  ^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::sign_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:293:12
    |
293 |     let sig = aggsig::sign_single(secp, &msg, &skey, None, None, None)?;
    |               ^^^^^^^^^^^^^^^^^^^
    |
    = note: #[warn(deprecated)] on by default

warning: use of deprecated item 'util::<unnamed>::aggsig::verify_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:307:2
    |
307 |     aggsig::verify_single(secp, &sig, &msg, None, &pubkey, false)
    |     ^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::verify_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:331:2
    |
331 |     aggsig::verify_single(secp, sig, msg, pubnonce, pubkey, is_partial)
    |     ^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::add_signatures_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:341:12
    |
341 |     let sig = aggsig::add_signatures_single(&secp, part_sigs, &nonce_sum)?;
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::sign_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:352:12
    |
352 |     let sig = aggsig::sign_single(secp, &msg, skey, None, None, None)?;
    |               ^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::export_secnonce_single': underlying aggsig api still subject to review and change
  --> wallet/src/libwallet/aggsig.rs:95:17
   |
95 |                     sec_nonce: aggsig::export_secnonce_single(secp).unwrap(),
   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::sign_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:165:13
    |
165 |         let sig = aggsig::sign_single(secp, msg, &self.sec_key, secnonce, pubnonce, nonce_sum)?;
    |                   ^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::aggsig::add_signatures_single': underlying aggsig api still subject to review and change
   --> wallet/src/libwallet/aggsig.rs:253:13
    |
253 |         let sig = aggsig::add_signatures_single(&secp, part_sigs, &nonce_sum)?;
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::pedersen::<impl util::<unnamed>::Secp256k1>::bullet_proof': Experimental - underlying code unreviewed and subject to change
  --> wallet/src/libwallet/proof.rs:53:22
   |
53 |         return Ok(k.secp().bullet_proof(amount, skey, nonce, extra_data, None));
   |                            ^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::pedersen::<impl util::<unnamed>::Secp256k1>::bullet_proof': Experimental - underlying code unreviewed and subject to change
  --> wallet/src/libwallet/proof.rs:63:4
   |
63 |         .bullet_proof(amount, skey, nonce, extra_data, Some(msg)));
   |          ^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::pedersen::<impl util::<unnamed>::Secp256k1>::verify_bullet_proof': Experimental - underlying code unreviewed and subject to change
  --> wallet/src/libwallet/proof.rs:72:20
   |
72 |     let result = secp.verify_bullet_proof(commit, proof, extra_data);
   |                       ^^^^^^^^^^^^^^^^^^^

warning: use of deprecated item 'util::<unnamed>::pedersen::<impl util::<unnamed>::Secp256k1>::unwind_bullet_proof': Experimental - underlying code unreviewed and subject to change
  --> wallet/src/libwallet/proof.rs:89:4
   |
89 |         .unwind_bullet_proof(commit, skey, nonce, extra_data, proof);
   |          ^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

error: Could not compile `grin_wallet`.

For reference:

rustc --version
rustc 1.25.0 (84203cac6 2018-03-25)

[hashmap]

@Thireus you need 1.26, please run rustup update to get it.

[Thireus]

I know, but:

• Grin Requirements states
  rust 1.24+ from https://github.com/mimblewimble/grin/blob/master/doc/build.md

• Rust 1.26 isn't working on ARM atm: Rust 1.26.0 fails to install on ARM rust-lang/rustup#1410.

[sesam]

TL;DR of rust-lang/rustup#1410 is

• 1.25 works on ARM - with minor complications
• 1.26 fails, fixed in latest beta Rust 1.26.0 fails to install on ARM rust-lang/rustup#1410 (comment)
• 1.27 for ARM will have the fix

There are nice features in 1.26 - aka latest stable - mentioned as OK to use before ARM rustc troubles were known.

Solution seem to be to wait for 1.27, then hardcode rustc to 1.27 and hope everything works everywhere.

Then do some testing each time we want to raise rustc version. I.e. more work.

I think this would be a great topic to debate today at 22.00 UTC in https://gitter.im/grin_community/dev

[hashmap]

I'd also test nightly on ARM

[clefru]

Rust 1.26 is 14 days old and hasn't even hit the bleeding edge branch of my distro[1]. rustup might work for individual installations but doesn't for packaging. As a general rule, I would welcome a softer requirement on being up-to-date.

[1] NixOS/nixpkgs#40356 was opened around 24h after 1.26 was released, so my distro isn't really slacking on this.

[ignopeverell]

We'll definitely soften that requirement when we get closer to release, and as you mention, packaging. But at this stage aggressive update is actually good.