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Include type of missing trait methods in error #24626

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aij opened this issue Apr 20, 2015 · 0 comments
Closed

Include type of missing trait methods in error #24626

aij opened this issue Apr 20, 2015 · 0 comments
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A-diagnostics Area: Messages for errors, warnings, and lints

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@aij
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aij commented Apr 20, 2015

Feature request (improved diagnostics):

This is what the error currently looks like:

src/sha256.rs:48:1: 50:2 error: not all trait items implemented, missing: `fmt` [E0046]
src/sha256.rs:48 impl core::fmt::Display for Sha256 {
src/sha256.rs:49 
src/sha256.rs:50 }
error: aborting due to previous error

In order to implement the missing method I need to double check the type in the documentation, even though I already know what the function needs to do. It would be really convenient if the compiler could print out the required type for me.
@jdm jdm added I-papercut A-diagnostics Area: Messages for errors, warnings, and lints labels Apr 20, 2015
@birkenfeld birkenfeld mentioned this issue May 2, 2016
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@estebank estebank mentioned this issue Sep 10, 2016
Closed
estebank added a commit to estebank/rust that referenced this issue Sep 10, 2016
@estebank
Include type of missing trait methods in error
cc0c258 
For a given file `foo.rs`:

```rust
use std::str::FromStr;

struct A {}

trait X<T> {
    type Foo;
    const BAR: u32 = 128;

    fn foo() -> T;
    fn bar();
    fn    bay<
        'lifetime,    TypeParameterA
            >(  a   : usize,
                b: u8  );
}

impl std::fmt::Display for A {
}
impl FromStr for A{}

impl X<usize> for A {
}
```

Provide the following output:

```bash
error: main function not found

error[E0046]: not all trait items implemented, missing: `fmt`
  --> file2.rs:18:1
   |
18 | impl std::fmt::Display for A {
   | ^ missing `fmt` in implementation
   |
   = note: fn fmt(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>;

error[E0046]: not all trait items implemented, missing: `Err`, `from_str`
  --> file2.rs:20:1
   |
20 | impl FromStr for A{}
   | ^^^^^^^^^^^^^^^^^^^^ missing `Err`, `from_str` in implementation
   |
   = note: type Err;
   = note: fn from_str(&str) -> std::result::Result<Self, <Self as std::str::FromStr>::Err>;

error[E0046]: not all trait items implemented, missing: `Foo`, `foo`, `bar`, `bay`
  --> file2.rs:22:1
   |
22 | impl X<usize> for A {
   | ^ missing `Foo`, `foo`, `bar`, `bay` in implementation
   |
   = note: type Foo;
   = note: fn foo() -> T;
   = note: fn bar();
   = note: fn bay<'lifetime, TypeParameterA>(a: usize, b: u8);

error: aborting due to 3 previous errors
```

Fixes rust-lang#24626
estebank added a commit to estebank/rust that referenced this issue Oct 1, 2016
@estebank
Show type of missing/incorrect trait methods
f9c0319 
For a given file `foo.rs`:

```rust
use std::str::FromStr;

struct A {}

trait X<T> {
    type Foo;
    const BAR: u32 = 128;

    fn foo() -> T;
    fn bar();
    fn    bay<
        'lifetime,    TypeParameterA
            >(  a   : usize,
                b: u8  );
}

impl std::fmt::Display for A {
}
impl FromStr for A{}

impl X<usize> for A {
}
```

Provide the following output:

```bash
error: main function not found

error[E0046]: not all trait items implemented, missing: `fmt`
  --> foo.rs:18:1
   |
18 | impl std::fmt::Display for A {
   | ^ missing `fmt` in implementation
   |
   = note: fn fmt(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>;

error[E0046]: not all trait items implemented, missing: `Err`, `from_str`
  --> foo.rs:20:1
   |
20 | impl FromStr for A{}
   | ^^^^^^^^^^^^^^^^^^^^ missing `Err`, `from_str` in implementation
   |
   = note: type Err;
   = note: fn from_str(&str) -> std::result::Result<Self, <Self as std::str::FromStr>::Err>;

error[E0046]: not all trait items implemented, missing: `Foo`, `foo`, `bar`, `bay`
  --> foo.rs:22:1
   |
22 | impl X<usize> for A {
   | ^ missing `Foo`, `foo`, `bar`, `bay` in implementation
   |
   = note: type Foo;
   = note: fn foo() -> T;
   = note: fn bar();
   = note: fn bay<'lifetime, TypeParameterA>(a: usize, b: u8);

error: aborting due to 3 previous errors
```

Fixes rust-lang#24626

For a given file `foo.rs`:

```rust
struct A {}

impl std::fmt::Display for A {
    fn fmt() -> () {}
}
```

provide the expected method signature:

```bash
error: main function not found

error[E0186]: method `fmt` has a `&self` declaration in the trait, but not in the impl
 --> foo.rs:4:5
  |
4 |     fn fmt() -> () {}
  |     ^^^^^^^^^^^^^^^^^ expected `&self` in impl
  |
  = note: Expected signature: fn fmt(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>;
  = note:    Found signature: fn fmt();

error: aborting due to previous error
```

Fixes rust-lang#28011
@estebank estebank mentioned this issue Oct 24, 2016
Merged
eddyb added a commit to eddyb/rust that referenced this issue Nov 9, 2016
@eddyb
Rollup merge of rust-lang#37370 - estebank:signature-2-empire-strikes…
7f2853f 
…-back, r=nikomatsakis

Include type of missing trait methods in error

Provide either a span pointing to the original definition of missing
trait items, or a message with the inferred definitions.

Fixes rust-lang#24626. Follow up to PR rust-lang#36371.

If PR rust-lang#37369 lands, missing trait items that present a multiline span will be able to show the entirety of the item definition on the error itself, instead of just the first line.
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@jdm @aij