regression: assert_eq cannot find panic with no_implicit_prelude #61567
Labels
regression-from-stable-to-beta
Performance or correctness regression from stable to beta.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
Comments
Mark-Simulacrum
added
T-compiler
Centril
added a commit
to Centril/rust
that referenced
this issue
Jun 12, 2019
Hygienize macros in the standard library Same as rust-lang#55597, but for all macros in the standard library. Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site. Technically this is a breaking change, so crater run would probably be useful. --- One exception that is not hygienized is calls to `panic!(...)`. Macros defined in libcore do not want to call `core::panic`. What they really want to call is either `std::panic` or `core::panic` depending on `no_std` settings. EDIT: After some thought, recursive calls to `panic` from `panic` itself probably do want to use `$crate` (UPDATE: done). Calling `std::panic` from macros defined in std and "whatever `panic` is in scope" from macros defined in libcore is probably even worse than always calling "whatever `panic` is in scope", so I kept the existing code. The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to `std::panic` or `core::panic` using compiler magic. Then standard library macros could delegate to this built-in macro. The macro could be named `panic` too, that would fix rust-lang#61567. (This PR doesn't do that.) --- cc rust-lang#56389 cc rust-lang#61567 Fixes rust-lang#61699 r? @alexcrichton
Centril
added a commit
to Centril/rust
that referenced
this issue
Jun 12, 2019
Hygienize macros in the standard library Same as rust-lang#55597, but for all macros in the standard library. Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site. Technically this is a breaking change, so crater run would probably be useful. --- One exception that is not hygienized is calls to `panic!(...)`. Macros defined in libcore do not want to call `core::panic`. What they really want to call is either `std::panic` or `core::panic` depending on `no_std` settings. EDIT: After some thought, recursive calls to `panic` from `panic` itself probably do want to use `$crate` (UPDATE: done). Calling `std::panic` from macros defined in std and "whatever `panic` is in scope" from macros defined in libcore is probably even worse than always calling "whatever `panic` is in scope", so I kept the existing code. The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to `std::panic` or `core::panic` using compiler magic. Then standard library macros could delegate to this built-in macro. The macro could be named `panic` too, that would fix rust-lang#61567. (This PR doesn't do that.) --- cc rust-lang#56389 cc rust-lang#61567 Fixes rust-lang#61699 r? @alexcrichton
|
#61971 implements a temporary solution, but I'd rather leave this as wontfix. |
|
Discussed at T-compiler meeting. Closing as wont-fix. |
|
#62002 provides a proper solution. |
|
#78343 would fix this. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
This only works on 2015 edition. This code sample will fail to compile on beta but succeed on stable.
cc @petrochenkov
The text was updated successfully, but these errors were encountered: