E0277 on complex tuple omits essential info and is duplicated #142592
Description
Code
use nom::{ character::complete::anychar, combinator::recognize, bytes::tag, IResult, Parser, }; pub fn parse(s: &str) -> IResult<&str, &str> { recognize(( anychar, anychar, anychar, tag, anychar, )).parse(s) }Current output
error[E0277]: the trait bound `(..., ..., ..., ..., ...): Parser<_>` is not satisfied --> src/lib.rs:11:15 | 11 | recognize(( | _____---------_^ | | | | | required by a bound introduced by this call 12 | | anychar, 13 | | anychar, 14 | | anychar, 15 | | tag, 16 | | anychar, 17 | | )).parse(s) | |_____^ the trait `Parser<_>` is not implemented for `(fn(_) -> ... {anychar::<_, _>}, ..., ..., ..., ...)` | = help: the following other types implement trait `Parser<Input>`: (P1, P2) (P1, P2, P3) (P1, P2, P3, P4) (P1, P2, P3, P4, P5) (P1, P2, P3, P4, P5, P6) (P1, P2, P3, P4, P5, P6, P7) (P1, P2, P3, P4, P5, P6, P7, P8) (P1, P2, P3, P4, P5, P6, P7, P8, P9) and 13 others note: required by a bound in `recognize` --> /home/binarycat/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nom-8.0.0/src/combinator/mod.rs:635:6 | 631 | pub fn recognize<I: Clone + Offset + Input, E: ParseError<I>, F>( | --------- required by a bound in this function ... 635 | F: Parser<I, Error = E>, | ^^^^^^^^^^^^^^^^^^^^ required by this bound in `recognize` = note: the full name for the type has been written to '/tmp/bug-repro/target/debug/deps/bug_repro-39cf7f6b883a22b4.long-type-13436936027012102670.txt' = note: consider using `--verbose` to print the full type name to the console error[E0277]: the trait bound `(..., ..., ..., ..., ...): Parser<_>` is not satisfied --> src/lib.rs:11:5 | 11 | / recognize(( 12 | | anychar, 13 | | anychar, 14 | | anychar, 15 | | tag, 16 | | anychar, 17 | | )).parse(s) | |______^ the trait `Parser<_>` is not implemented for `(fn(_) -> ... {anychar::<_, _>}, ..., ..., ..., ...)` | = help: the following other types implement trait `Parser<Input>`: (P1, P2) (P1, P2, P3) (P1, P2, P3, P4) (P1, P2, P3, P4, P5) (P1, P2, P3, P4, P5, P6) (P1, P2, P3, P4, P5, P6, P7) (P1, P2, P3, P4, P5, P6, P7, P8) (P1, P2, P3, P4, P5, P6, P7, P8, P9) and 13 others note: required by a bound in `recognize` --> /home/binarycat/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nom-8.0.0/src/combinator/mod.rs:635:6 | 631 | pub fn recognize<I: Clone + Offset + Input, E: ParseError<I>, F>( | --------- required by a bound in this function ... 635 | F: Parser<I, Error = E>, | ^^^^^^^^^^^^^^^^^^^^ required by this bound in `recognize` = note: the full name for the type has been written to '/tmp/bug-repro/target/debug/deps/bug_repro-39cf7f6b883a22b4.long-type-13436936027012102670.txt' = note: consider using `--verbose` to print the full type name to the console error[E0277]: the trait bound `(..., ..., ..., ..., ...): Parser<_>` is not satisfied --> src/lib.rs:11:5 | 11 | / recognize(( 12 | | anychar, 13 | | anychar, 14 | | anychar, 15 | | tag, 16 | | anychar, 17 | | )).parse(s) | |_______________^ the trait `Parser<_>` is not implemented for `(fn(_) -> ... {anychar::<_, _>}, ..., ..., ..., ...)` | = help: the following other types implement trait `Parser<Input>`: (P1, P2) (P1, P2, P3) (P1, P2, P3, P4) (P1, P2, P3, P4, P5) (P1, P2, P3, P4, P5, P6) (P1, P2, P3, P4, P5, P6, P7) (P1, P2, P3, P4, P5, P6, P7, P8) (P1, P2, P3, P4, P5, P6, P7, P8, P9) and 13 others note: required by a bound in `recognize` --> /home/binarycat/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nom-8.0.0/src/combinator/mod.rs:635:6 | 631 | pub fn recognize<I: Clone + Offset + Input, E: ParseError<I>, F>( | --------- required by a bound in this function ... 635 | F: Parser<I, Error = E>, | ^^^^^^^^^^^^^^^^^^^^ required by this bound in `recognize` = note: the full name for the type has been written to '/tmp/bug-repro/target/debug/deps/bug_repro-39cf7f6b883a22b4.long-type-13436936027012102670.txt' = note: consider using `--verbose` to print the full type name to the console For more information about this error, try `rustc --explain E0277`.Desired output
error[E0277]: the trait bound `(..., ..., ..., ..., ...): Parser<_>` is not satisfied --> src/lib.rs:11:15 | 11 | recognize(( | _____---------_^ | | | | | required by a bound introduced by this call 12 | | anychar, 13 | | anychar, 14 | | anychar, 15 | | tag, 16 | | anychar, 17 | | )).parse(s) | |_____^ the trait `Parser<_>` is not implemented for `(fn(_) -> ... {anychar::<_, _>}, ..., ..., ..., ...)` | = help: the 4th element of this tuple does not implement Parser<_> = note: the full name for the type has been written to '/tmp/bug-repro/target/debug/deps/bug_repro-39cf7f6b883a22b4.long-type-13436936027012102670.txt' = note: consider using `--verbose` to print the full type name to the console note: required by a bound in `recognize` --> /home/binarycat/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/nom-8.0.0/src/combinator/mod.rs:635:6 | 631 | pub fn recognize<I: Clone + Offset + Input, E: ParseError<I>, F>( | --------- required by a bound in this function ... 635 | F: Parser<I, Error = E>, | ^^^^^^^^^^^^^^^^^^^^ required by this bound in `recognize`Rationale and extra context
I initially didn't even see the long type disclaimer, since there was so much noise and because it was targeting the span of the function definition, not the main error span.
It would be very handy to know which element of the tuple is actually causing the problem.
nice ordinals (eg. 4th) should be possible since we're already using fluent.
Also confusing is that cargo --verbose does not set rustc --verbose.
Other cases
Rust Version
rustc 1.86.0 (05f9846f8 2025-03-31) binary: rustc commit-hash: 05f9846f893b09a1be1fc8560e33fc3c815cfecb commit-date: 2025-03-31 host: x86_64-unknown-linux-gnu release: 1.86.0 LLVM version: 19.1.7Anything else?
latest nightly isn't any better