[WIP] Make Cargo warn about unrecognized sections and possibly give suggestions

[iancormac84]

Closes #5264.

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[iancormac84]

I intend to make this code more flexible so that it will give potentially useful suggestions about current or future recognized keys in Cargo.toml files. I'm thinking that to do so, I need to have a list of keys that are recognized by cargo. The best option I can think of is to have a static list of the keys that are recognized, which incurs a maintenance cost. What do you guys think?

[matklad]

@iancormac84 but dost it warn that path is unused in the first place? From the description of #5264 I've got the idea that patch misspellings don't trigger this particular logic at all...

Could you add a test from #5264 somewhere near this place:

cargo/tests/testsuite/bad_config.rs

Line 812 in dfaba34

fn unused_keys() {

That way, it should be easier to see what is going on here. Perhaps we do warn about misspelled patch already?

As for making this code general, I suggest that, at first, we just produce the usual unused key warning here, without elaboration, because that'll get us 80% of the benefits. a lev-distance solution is excellent, but we need to add it in such way that it handles all the keys.

[iancormac84]

@matklad It indeed does mention unused manifest key 'path', for example, but no mention of the remaining ."https://github.com/foo/bar". So I'm guessing that's what I need to work towards it outputting something like

warning: unused manifest key: path."https://github.com/foo/bar"
?

[alexcrichton]

@iancormac84 did you have any luck extending this to handle all the keys?

[alexcrichton]

Ok I'm gonna close this due to inactivity, but feel fre of course to resubmit!