Error reporting of bad description definition

[tailhook]

When description is defined in wrong way:

description("error decoding file name {:?}", path)

(i.e. this is clearly should be displayed, you can't format anything with description, and description has only one field)
The error is like the following:

<quick_error macros>:37:23: 37:34 error: no rules expected the token `ERROR_CHECK`
<quick_error macros>:37 ; $ ( quick_error ! ( ERROR_CHECK $ ( $ ifuncs ) * ) ; ) * } ; (
                                              ^~~~~~~~~~~

I. e. it's very misleading. Rust version is 1.3

[colin-kiegel]

I just stumbled upon it too, and I observed the following it makes a difference, whether the error occurs inside a foreign crate, or inside the quick-error crate which defines the macro. Take this example:

quick_error! {
    #[derive(Debug)]
    pub enum Wrapper {
        Foo(err: Foo) {
            __some_typo_in_description("Foo")
        }
    }
}

Inside crate quick-error it yields a nice and descriptive error:

src/lib.rs:735:17: 735:43 error: no rules expected the token `__some_typo_in_description`
src/lib.rs:735                 __some_typo_in_description("Foo")
                               ^~~~~~~~~~~~~~~~~~~~~~~~~~

Outside crate quick-error exactly the same error is presented quite differently and very obscure. In this case it even seems wrong, where the '^~~~' is pointing at.

<quick_error macros>:86:26: 86:41 error: no rules expected the token `TUPLE`
<quick_error macros>:86 $ ( # [ $ bmeta ] ) * => $ bitem : TUPLE [ $ ( $ qvar : $ qtyp ) , * ] ] queue
                                                 ^~~~~~~~~~~~~~~

It is the same with your example - inside crate quick-error

src/lib.rs:735:60: 735:61 error: no rules expected the token `,`
src/lib.rs:735                 description("error decoding file name {:?}", path)
                                                                          ^

Outside

<quick_error macros>:86:26: 86:41 error: no rules expected the token `TUPLE`
<quick_error macros>:86 $ ( # [ $ bmeta ] ) * => $ bitem : TUPLE [ $ ( $ qvar : $ qtyp ) , * ] ] queue
                                                 ^~~~~~~~~~~~~~~

I would say the macro is good, but rust needs some improvement for presentation of these kinds of errors if the macro is used and defined in different crates.

I will file an issue, I think it is quite important. ... :-)

[colin-kiegel]

rust-lang/rust#30576

[0xpr03]

as of colin-kiegel's post this issue should be fixed

[tailhook]

Great! Thanks for reporting.