tracing: fix macro hygiene for `concat!` #1918

teohhanhui · 2022-02-09T20:54:32Z

Re-application of changes made in #1842 which were lost in f1cf1f1

Integration tests added for regression.

Motivation

In my library I define a macro_rules! concat macro, i.e.
callbag::concat.

When I try to call tracing::info!(...), I get error output such as
this:

error output

> RUSTFLAGS='-Z macro-backtrace' cargo +nightly clippy --features trace
    Checking callbag v0.14.0 (/home/teohhanhui/projects/teohhanhui/callbag-rs)
error[E0308]: mismatched types
  --> src/concat.rs:89:9
   |
89 |         info!("from sink: {message:?}");
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&str`, found `u32`

error[E0277]: the trait bound `std::sync::Arc<core::Callbag<never::Never, _>>: std::convert::From<&str>` is not satisfied
    --> src/concat.rs:58:9
     |
56   | / macro_rules! concat {
57   | |     ($($s:expr),* $(,)?) => {
58   | |         $crate::concat(::std::vec![$($s),*].into_boxed_slice())
     | |         ^^^^^^^^^^^^^^ the trait `std::convert::From<&str>` is not implemented for `std::sync::Arc<core::Callbag<never::Never, _>>`
59   | |     };
60   | | }
     | |_- in this expansion of `concat!` (https://github.com/tokio-rs/tracing/issues/5)
...
89   |           info!("from sink: {message:?}");
     |           ------------------------------- in this macro invocation (https://github.com/tokio-rs/tracing/pull/1)
     |
    ::: src/utils/tracing.rs:47:1
     |
47   | / macro_rules! info {
48   | |     ($($arg:tt)+) => {
49   | |         ::cfg_if::cfg_if! {
50   | |             if #[cfg(feature = "trace")] {
51   | |                 ::tracing::info!($($arg)+)
     | |                 -------------------------- in this macro invocation (https://github.com/tokio-rs/tracing/pull/2)
...    |
54   | |     };
55   | | }
     | |_- in this expansion of `info!` (https://github.com/tokio-rs/tracing/pull/1)
     |
    ::: /home/teohhanhui/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/tracing-0.1.29/src/macros.rs:586:1
     |
586  |   macro_rules! event {
     |  _-
     | |_|
     | |
587  | |     (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* } )=> (
588  | |         $crate::__tracing_log!(
589  | |             target: $target,
...    |
644  |                   name: concat!(
     |  _______________________-
645  |                       "event ",
646  |                       file!(),
647  |                       ":",
648  |                       line!()
649  | |                 ),
     | |_________________- in this macro invocation (https://github.com/tokio-rs/tracing/issues/5)
...
667  | /         $crate::event!(
668  |               target: $target,
669  |               $lvl,
670  |               { message = format_args!($($arg)+), $($fields)* }
671  | |         )
     | |_________- in this macro invocation (https://github.com/tokio-rs/tracing/issues/4)
...
791  | |     );
792  | | }
     | | -
     | |_|
     | |_in this expansion of `$crate::event!` (https://github.com/tokio-rs/tracing/pull/3)
     |   in this expansion of `$crate::event!` (https://github.com/tokio-rs/tracing/issues/4)
...
1229 | / macro_rules! info {
1230 |        (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
1231 |           $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($field)* }, $($arg)*)
1232 |       );
...
1398 | /         $crate::event!(
1399 | |             target: module_path!(),
1400 | |             $crate::Level::INFO,
1401 | |             {},
1402 | |             $($arg)+
1403 | |         )
     | |_________- in this macro invocation (https://github.com/tokio-rs/tracing/pull/3)
1404 |       );
1405 | | }
     | |_- in this expansion of `::tracing::info!` (https://github.com/tokio-rs/tracing/pull/2)
     |
     = help: the following implementations were found:
               <std::sync::Arc<B> as std::convert::From<std::borrow::Cow<'a, B>>>
               <std::sync::Arc<T> as std::convert::From<T>>
               <std::sync::Arc<T> as std::convert::From<std::boxed::Box<T>>>
               <std::sync::Arc<[T]> as std::convert::From<&[T]>>
             and 9 others
     = note: required because of the requirements on the impl of `std::convert::Into<std::sync::Arc<core::Callbag<never::Never, _>>>` for `&str`
note: required by a bound in `concat::concat`
    --> src/concat.rs:81:8
     |
72   | pub fn concat<
     |        ------ required by a bound in this
...
81   |     S: Into<Arc<Source<T>>> + Send + Sync,
     |        ^^^^^^^^^^^^^^^^^^^^ required by this bound in `concat::concat`

error[E0308]: mismatched types
    --> src/concat.rs:58:9
     |
56   | / macro_rules! concat {
57   | |     ($($s:expr),* $(,)?) => {
58   | |         $crate::concat(::std::vec![$($s),*].into_boxed_slice())
     | |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&str`, found struct `core::Callbag`
59   | |     };
60   | | }
     | |_- in this expansion of `concat!` (https://github.com/tokio-rs/tracing/issues/5)
...
89   |           info!("from sink: {message:?}");
     |           ------------------------------- in this macro invocation (https://github.com/tokio-rs/tracing/pull/1)
     |
    ::: src/utils/tracing.rs:47:1
     |
47   | / macro_rules! info {
48   | |     ($($arg:tt)+) => {
49   | |         ::cfg_if::cfg_if! {
50   | |             if #[cfg(feature = "trace")] {
51   | |                 ::tracing::info!($($arg)+)
     | |                 -------------------------- in this macro invocation (https://github.com/tokio-rs/tracing/pull/2)
...    |
54   | |     };
55   | | }
     | |_- in this expansion of `info!` (https://github.com/tokio-rs/tracing/pull/1)
     |
    ::: /home/teohhanhui/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/tracing-0.1.29/src/macros.rs:586:1
     |
586  |   macro_rules! event {
     |  _-
     | |_|
     | |
587  | |     (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* } )=> (
588  | |         $crate::__tracing_log!(
589  | |             target: $target,
...    |
644  |                   name: concat!(
     |  _______________________-
645  |                       "event ",
646  |                       file!(),
647  |                       ":",
648  |                       line!()
649  | |                 ),
     | |_________________- in this macro invocation (https://github.com/tokio-rs/tracing/issues/5)
...
667  | /         $crate::event!(
668  |               target: $target,
669  |               $lvl,
670  |               { message = format_args!($($arg)+), $($fields)* }
671  | |         )
     | |_________- in this macro invocation (https://github.com/tokio-rs/tracing/issues/4)
...
791  | |     );
792  | | }
     | | -
     | |_|
     | |_in this expansion of `$crate::event!` (https://github.com/tokio-rs/tracing/pull/3)
     |   in this expansion of `$crate::event!` (https://github.com/tokio-rs/tracing/issues/4)
...
1229 | / macro_rules! info {
1230 |        (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => (
1231 |           $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($field)* }, $($arg)*)
1232 |       );
...
1398 | /         $crate::event!(
1399 | |             target: module_path!(),
1400 | |             $crate::Level::INFO,
1401 | |             {},
1402 | |             $($arg)+
1403 | |         )
     | |_________- in this macro invocation (https://github.com/tokio-rs/tracing/pull/3)
1404 |       );
1405 | | }
     | |_- in this expansion of `::tracing::info!` (https://github.com/tokio-rs/tracing/pull/2)
     |
     = note: expected reference `&'static str`
                   found struct `core::Callbag<never::Never, _>`

Some errors have detailed explanations: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.
error: could not compile `callbag` due to 3 previous errors

This is because of my concat macro being in scope.

Solution

Change all the tracing macros to use the re-export of core::concat!
in the __macro_support module, rather than using an un-namespaced
concat!. The re-export ensures that everything still works even in a
crate that redefines the core name to something else.

hawkw

looks good to me, thanks for the tests too!

hawkw · 2022-02-09T23:30:43Z

CI failure is due to a regression in the latest nightly (rust-lang/rust#93821), nothing we can do about it, so I'm going to go ahead and merge this.

@QnnOkabayashi

# 0.1.31 (February 17th, 2022) This release increases the minimum supported Rust version (MSRV) to 1.49.0. In addition, it fixes some relatively rare macro bugs. ### Added - Added `tracing-forest` to the list of related crates ([#1935]) ### Changed - Updated minimum supported Rust version (MSRV) to 1.49.0 ([#1913]) ### Fixed - Fixed the `warn!` macro incorrectly generating an event with the `TRACE` level ([#1930]) - Fixed macro hygiene issues when used in a crate that defines its own `concat!` macro, for real this time ([#1918]) Thanks to @QnnOkabayashi, @nicolaasg, and @teohhanhui for contributing to this release! [#1935]: #1935 [#1913]: #1913 [#1930]: #1930 [#1918]: #1918

@QnnOkabayashi

# 0.1.31 (February 17th, 2022) This release increases the minimum supported Rust version (MSRV) to 1.49.0. In addition, it fixes some relatively rare macro bugs. ### Added - Added `tracing-forest` to the list of related crates ([#1935]) ### Changed - Updated minimum supported Rust version (MSRV) to 1.49.0 ([#1913]) ### Fixed - Fixed the `warn!` macro incorrectly generating an event with the `TRACE` level ([#1930]) - Fixed macro hygiene issues when used in a crate that defines its own `concat!` macro, for real this time ([#1918]) Thanks to @QnnOkabayashi, @nicolaasg, and @teohhanhui for contributing to this release! [#1935]: #1935 [#1913]: #1913 [#1930]: #1930 [#1918]: #1918

Re-application of changes made in tokio-rs#1842 which were lost in f1cf1f1 Integration tests added for regression. --- ## Motivation In my library I define a `macro_rules! concat` macro, i.e. [`callbag::concat`](https://docs.rs/callbag/latest/callbag/macro.concat.html). When I try to call `tracing::info!(...)`, I get error output such as this: <details> <summary>error output</summary>  ``` > RUSTFLAGS='-Z macro-backtrace' cargo +nightly clippy --features trace Checking callbag v0.14.0 (/home/teohhanhui/projects/teohhanhui/callbag-rs) error[E0308]: mismatched types --> src/concat.rs:89:9 | 89 | info!("from sink: {message:?}"); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&str`, found `u32` error[E0277]: the trait bound `std::sync::Arc<core::Callbag<never::Never, _>>: std::convert::From<&str>` is not satisfied --> src/concat.rs:58:9 | 56 | / macro_rules! concat { 57 | | ($($s:expr),* $(,)?) => { 58 | | $crate::concat(::std::vec![$($s),*].into_boxed_slice()) | | ^^^^^^^^^^^^^^ the trait `std::convert::From<&str>` is not implemented for `std::sync::Arc<core::Callbag<never::Never, _>>` 59 | | }; 60 | | } | |_- in this expansion of `concat!` (tokio-rs#5) ... 89 | info!("from sink: {message:?}"); | ------------------------------- in this macro invocation (tokio-rs#1) | ::: src/utils/tracing.rs:47:1 | 47 | / macro_rules! info { 48 | | ($($arg:tt)+) => { 49 | | ::cfg_if::cfg_if! { 50 | | if #[cfg(feature = "trace")] { 51 | | ::tracing::info!($($arg)+) | | -------------------------- in this macro invocation (tokio-rs#2) ... | 54 | | }; 55 | | } | |_- in this expansion of `info!` (tokio-rs#1) | ::: /home/teohhanhui/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/tracing-0.1.29/src/macros.rs:586:1 | 586 | macro_rules! event { | _- | |_| | | 587 | | (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* } )=> ( 588 | | $crate::__tracing_log!( 589 | | target: $target, ... | 644 | name: concat!( | _______________________- 645 | "event ", 646 | file!(), 647 | ":", 648 | line!() 649 | | ), | |_________________- in this macro invocation (tokio-rs#5) ... 667 | / $crate::event!( 668 | target: $target, 669 | $lvl, 670 | { message = format_args!($($arg)+), $($fields)* } 671 | | ) | |_________- in this macro invocation (tokio-rs#4) ... 791 | | ); 792 | | } | | - | |_| | |_in this expansion of `$crate::event!` (tokio-rs#3) | in this expansion of `$crate::event!` (tokio-rs#4) ... 1229 | / macro_rules! info { 1230 | (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => ( 1231 | $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($field)* }, $($arg)*) 1232 | ); ... 1398 | / $crate::event!( 1399 | | target: module_path!(), 1400 | | $crate::Level::INFO, 1401 | | {}, 1402 | | $($arg)+ 1403 | | ) | |_________- in this macro invocation (tokio-rs#3) 1404 | ); 1405 | | } | |_- in this expansion of `::tracing::info!` (tokio-rs#2) | = help: the following implementations were found: <std::sync::Arc<B> as std::convert::From<std::borrow::Cow<'a, B>>> <std::sync::Arc<T> as std::convert::From<T>> <std::sync::Arc<T> as std::convert::From<std::boxed::Box<T>>> <std::sync::Arc<[T]> as std::convert::From<&[T]>> and 9 others = note: required because of the requirements on the impl of `std::convert::Into<std::sync::Arc<core::Callbag<never::Never, _>>>` for `&str` note: required by a bound in `concat::concat` --> src/concat.rs:81:8 | 72 | pub fn concat< | ------ required by a bound in this ... 81 | S: Into<Arc<Source<T>>> + Send + Sync, | ^^^^^^^^^^^^^^^^^^^^ required by this bound in `concat::concat` error[E0308]: mismatched types --> src/concat.rs:58:9 | 56 | / macro_rules! concat { 57 | | ($($s:expr),* $(,)?) => { 58 | | $crate::concat(::std::vec![$($s),*].into_boxed_slice()) | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&str`, found struct `core::Callbag` 59 | | }; 60 | | } | |_- in this expansion of `concat!` (tokio-rs#5) ... 89 | info!("from sink: {message:?}"); | ------------------------------- in this macro invocation (tokio-rs#1) | ::: src/utils/tracing.rs:47:1 | 47 | / macro_rules! info { 48 | | ($($arg:tt)+) => { 49 | | ::cfg_if::cfg_if! { 50 | | if #[cfg(feature = "trace")] { 51 | | ::tracing::info!($($arg)+) | | -------------------------- in this macro invocation (tokio-rs#2) ... | 54 | | }; 55 | | } | |_- in this expansion of `info!` (tokio-rs#1) | ::: /home/teohhanhui/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/tracing-0.1.29/src/macros.rs:586:1 | 586 | macro_rules! event { | _- | |_| | | 587 | | (target: $target:expr, parent: $parent:expr, $lvl:expr, { $($fields:tt)* } )=> ( 588 | | $crate::__tracing_log!( 589 | | target: $target, ... | 644 | name: concat!( | _______________________- 645 | "event ", 646 | file!(), 647 | ":", 648 | line!() 649 | | ), | |_________________- in this macro invocation (tokio-rs#5) ... 667 | / $crate::event!( 668 | target: $target, 669 | $lvl, 670 | { message = format_args!($($arg)+), $($fields)* } 671 | | ) | |_________- in this macro invocation (tokio-rs#4) ... 791 | | ); 792 | | } | | - | |_| | |_in this expansion of `$crate::event!` (tokio-rs#3) | in this expansion of `$crate::event!` (tokio-rs#4) ... 1229 | / macro_rules! info { 1230 | (target: $target:expr, parent: $parent:expr, { $($field:tt)* }, $($arg:tt)* ) => ( 1231 | $crate::event!(target: $target, parent: $parent, $crate::Level::INFO, { $($field)* }, $($arg)*) 1232 | ); ... 1398 | / $crate::event!( 1399 | | target: module_path!(), 1400 | | $crate::Level::INFO, 1401 | | {}, 1402 | | $($arg)+ 1403 | | ) | |_________- in this macro invocation (tokio-rs#3) 1404 | ); 1405 | | } | |_- in this expansion of `::tracing::info!` (tokio-rs#2) | = note: expected reference `&'static str` found struct `core::Callbag<never::Never, _>` Some errors have detailed explanations: E0277, E0308. For more information about an error, try `rustc --explain E0277`. error: could not compile `callbag` due to 3 previous errors ``` </details> This is because of my `concat` macro being in scope. ## Solution Change all the `tracing` macros to use the re-export of `core::concat!` in the `__macro_support` module, rather than using an un-namespaced `concat!`. The re-export ensures that everything still works even in a crate that redefines the `core` name to something else.

@QnnOkabayashi

# 0.1.31 (February 17th, 2022) This release increases the minimum supported Rust version (MSRV) to 1.49.0. In addition, it fixes some relatively rare macro bugs. ### Added - Added `tracing-forest` to the list of related crates ([tokio-rs#1935]) ### Changed - Updated minimum supported Rust version (MSRV) to 1.49.0 ([tokio-rs#1913]) ### Fixed - Fixed the `warn!` macro incorrectly generating an event with the `TRACE` level ([tokio-rs#1930]) - Fixed macro hygiene issues when used in a crate that defines its own `concat!` macro, for real this time ([tokio-rs#1918]) Thanks to @QnnOkabayashi, @nicolaasg, and @teohhanhui for contributing to this release! [tokio-rs#1935]: tokio-rs#1935 [tokio-rs#1913]: tokio-rs#1913 [tokio-rs#1930]: tokio-rs#1930 [tokio-rs#1918]: tokio-rs#1918

tracing: fix macro hygiene for concat!

b8014f5

teohhanhui requested review from hawkw and a team as code owners February 9, 2022 20:54

hawkw approved these changes Feb 9, 2022

View reviewed changes

hawkw merged commit 3e5318d into tokio-rs:v0.1.x Feb 9, 2022

teohhanhui deleted the fix/macro-hygiene-again branch February 10, 2022 08:14

hawkw mentioned this pull request Feb 17, 2022

tracing: prepare to release v0.1.31 #1937

Merged

davidbarsky mentioned this pull request Sep 26, 2023

chore: backport roughly a year's worth of changes #2728

Merged

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tracing: fix macro hygiene for `concat!` #1918

tracing: fix macro hygiene for `concat!` #1918

teohhanhui commented Feb 9, 2022

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hawkw commented Feb 9, 2022

tracing: fix macro hygiene for concat! #1918

tracing: fix macro hygiene for concat! #1918

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teohhanhui commented Feb 9, 2022

Motivation

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hawkw commented Feb 9, 2022

tracing: fix macro hygiene for `concat!` #1918

tracing: fix macro hygiene for `concat!` #1918