Fix #305 Implement Debug for many types

[imor]

For most types it was a simple matter of adding #[derive(Debug)] but
ParseOptions needed a manual implementation because the type of
log_syntax_violation is Option<&'a Fn(&'static str)> and Fn doesn't
implement Debug. log_syntax_violation is formatted as Some(Fn(&'static
str)) or None depending upon its value.

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This change is 

[saghm]

Review status: 0 of 6 files reviewed at latest revision, 1 unresolved discussion.

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src/encoding.rs, line 98 at r1 (raw file):

        write!(f, "EncodingOverride {{ encoding: ")?;
        match self.encoding {
            Some(_) => write!(f, "Some(EncodingOverride) }}"),

Could this instead call name on the wrapped encoding ref? I think it might be useful to be able to see the the type of the encoding if it's present.

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Comments from Reviewable

[saghm]

Reviewed 6 of 6 files at r1.
Review status: all files reviewed at latest revision, 1 unresolved discussion.

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Comments from Reviewable

[turnage]

The body of this function can just be

(self.base_url, self.encoding_override).fmt(f)

Edit: I've never done a github review before so if this comment blocks or something feel free to close it with a garbage comment.

[imor]

What about the log_syntax_violation field? Shouldn't it be included? And as it includes a Fn in the type, how is it usually formatted?

[turnage]

You can just derive Debug on the structs compiled for each feature.

[imor]

Can't derive Debug in this case because encoding field has type Option<EncodingRef> and EncodingRef trait isn't Debug

[turnage]

You need to derive Debug in the encoding set macro to get the rest of *_ENCODE_SET types.

[imor]

Right, will do.

[imor]

Done.

[dtolnay]

The write! approach isn't a great way to do Debug implementations because it doesn't respect the various flags on the Formatter.

use std::fmt::{self, Debug};

struct Good { imor: i32 }
impl Debug for Good {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        formatter.debug_struct("Good")
            .field("imor", &self.imor)
            .finish()
    }
}

struct Bad { imor: i32 }
impl Debug for Bad {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "Bad {{ imor: {:?} }}", self.imor)
    }
}

fn main() {
    let good = Good { imor: 0 };
    let bad = Bad { imor: 0 };
    println!("default: {:?}", good);
    println!("indented: {:#?}", good);
    println!();
    println!("default: {:?}", bad);
    println!("indented: {:#?}", bad);
}

default: Good { imor: 0 }
indented: Good {
    imor: 0
}

default: Bad { imor: 0 }
indented: Bad { imor: 0 }

Is there a way to do these only using derive(Debug) and debug_struct?

[imor]

Review status: 5 of 6 files reviewed at latest revision, 4 unresolved discussions.

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src/encoding.rs, line 98 at r1 (raw file):

Previously, saghm (Saghm Rossi) wrote…

Could this instead call name on the wrapped encoding ref? I think it might be useful to be able to see the the type of the encoding if it's present.

Done.

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Comments from Reviewable

[SimonSapin]

Thanks!

@bors-servo r+

[bors-servo]

📌 Commit 81fdb30 has been approved by SimonSapin

[bors-servo]

⌛️ Testing commit 81fdb30 with merge 4083375...

[bors-servo]

☀️ Test successful - status-travis
Approved by: SimonSapin
Pushing 4083375 to master...