frame-support build fails with latest rust nightly-2020-05-26

[mnaamani]

cargo build --release

Compiler error building WASM runtime with latest nightly-2020-05-26

error[E0424]: expected value, found module `self`
   --> /Users/mokhtar/joystream/substrate/frame/support/src/traits.rs:913:11
    |
911 | / bitmask! {
912 | |     /// Reasons for moving funds out of an account.
913 | |     #[derive(Encode, Decode)]
    | |              ^^^^^^ `self` value is a keyword only available in methods with a `self` parameter
914 | |     pub mask WithdrawReasons: i8 where
...   |
929 | |     }
930 | | }
    | |_- this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters
    |
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0424`.
error: could not compile `frame-support`.

Reverting to earlier version of nightly from a few days prior does not show same error.

[duval1024]

stable version 1.43.1 (8d69840ab 2020-05-04) also show the same error :

   Compiling frame-support v2.0.0-rc2 (/Users/duval/workspace/blockchain/substrate/frame/support)
error[E0424]: expected value, found module `self`
   --> /Users/duval/workspace/blockchain/substrate/frame/support/src/traits.rs:913:11
    |
911 | / bitmask! {
912 | |     /// Reasons for moving funds out of an account.
913 | |     #[derive(Encode, Decode)]
    | |              ^^^^^^ `self` value is a keyword only available in methods with a `self` parameter
914 | |     pub mask WithdrawReasons: i8 where
...   |
929 | |     }
930 | | }
    | |_- this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters
    |
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0424`.
error: could not compile `frame-support`.

~/workspace/blockchain/substrate   master  rustup show
Default host: x86_64-apple-darwin
rustup home:  /Users/duval/.rustup

installed toolchains
--------------------

stable-x86_64-apple-darwin (default)
nightly-x86_64-apple-darwin
1.12.0-x86_64-apple-darwin
1.43.1-x86_64-apple-darwin

active toolchain
----------------

stable-x86_64-apple-darwin (default)
rustc 1.43.1 (8d69840ab 2020-05-04)

[duval1024]

I reinstalled all installed toolchains , and then fixed this problem.

[bkchr]

This is fixed by this pr: rust-lang/rust#72724

Installing rust nightly rustc 1.45.0-nightly (74e804683 2020-05-30) fixes it.

We also merged a pr to fix the underlying bug, so, if the feature is re-added to the compiler we should not run into the same problems.

[danforbes]

For people following our tutorials, will this problems always be present in Substrate v2.0.0-rc2? If so I can update the instructions for that version of the tutorial to add an extra step to make sure you're on the correct nightly. I guess I'm unclear if this is an ephemeral upstream issue with Rust or if this is something that will always be the case on v2.0.0-rc.

[bkchr]

No, the compiler reverted the code that lead to this compilation error. Until the code is re-added, the tutorial should work without any problems.

[JoshOrndorff]

A tutorial user reported the same error in sp-consensus-babe when trying to build subkey. polkadot-developers/tutorials#53

I know the compiler itself reverted so this is not an immediate problem anymore, but I wonder if the underlying issue in sp-consensus-babe was fixed as @bkchr described for the one in frame-support

We also merged a pr to fix the underlying bug, so, if the feature is re-added to the compiler we should not run into the same problems.