'cargo fix --edition-idioms': more fun macro problems with anonymous lifetimes

[ExpHP]

• Download the hastily-and-poorly-minimized bug5.tar.gz
• cargo fix --edition-idioms --all

warning: failed to automatically apply fixes suggested by rustc to crate `bug4`

after fixes were automatically applied the compiler reported errors within these files:

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see 
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/cargo/issues
quoting the full output of this command we'd be very appreciative!

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation
   |
   = note: `-W elided-lifetimes-in-paths` implied by `-W rust-2018-idioms`

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation
   |
   = note: `-W elided-lifetimes-in-paths` implied by `-W rust-2018-idioms`

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation

warning: hidden lifetime parameters in types are deprecated
  --> src/main.rs:26:35
   |
20 | / gen_each!{
21 | |     [ {V2 X} {V3 X} {V4 X} ]
22 | |     for_each!(
23 | |         {$Cn:ident $T:ident}
...  |
26 | |             fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result
   | |                                   ^^^^^^^^^^^^^^- help: indicate the anonymous lifetime: `<'_>`
...  |
29 | |     }
30 | | }
   | |_- in this macro invocation

    Finished dev [unoptimized + debuginfo] target(s) in 0.34s

The macro call in src/main.rs expands to multiple calls to a callback macro whose body is defined in the macro invocation. (after the for_each!{...} =>). The line producing the warning is in that callback's body.

---

cargo 1.32.0-nightly (b3d0b2e54 2018-11-15)

[ehuss]

Thanks for the report! I believe this is the same as rust-lang/rust#55768

[ExpHP]

Looks like it! (and after working around this example I ran into a much simpler one that is basically exactly the example there)

I will close this one.