Add note if method is called on a function object #32053
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Fixes issue #29124. If method is called on a function type a note is generated to suggest that the developer may have forgotten to call it. e.g. fn main() { let mut guess = String::new(); std::io::stdin.read_line(&mut guess); } will generate the note: note: called method on function type. did you mean `std::io::stdin().read_line(..)`?
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r? @Manishearth |
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Hey, this is my first code pull request so any advice to get it up to standard would be great. |
| @@ -37,6 +37,42 @@ use std::cmp::Ordering; | |||
| use super::{MethodError, NoMatchData, CandidateSource, impl_item, trait_item}; | |||
| use super::probe::Mode; | |||
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| fn is_fn_ty<'a, 'tcx>(ty: &Ty<'tcx>, fcx: &FnCtxt<'a, 'tcx>, span: Span) -> bool { | |||
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Mostly looks good, some minor issues. Also, this needs a test. See https://github.com/Nashenas88/rust/blob/bae1df65aaabf6129636364d86d918c76ed52b6b/src/test/compile-fail/issue-2392.rs for an example of a test for #26305 . You can run a particular test by using |
Split `fileline_note` into a `file_line note` and `span_suggestion` as per @Manishearth's suggestions. Change nested `match`es to `if let`s.
| if let Ok (expr_string) = cx.sess.codemap().span_to_snippet(expr.span) { | ||
| err.fileline_note( | ||
| expr.span, | ||
| &format!("{} is a function, perhaps you wish to call it?", |
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in case the snippet doesn't exist, we should check if it's an ExprKind::Path, and use the last path segment as the function name. No suggestion in this case.
Also, still needs tests, but then it should be good to go
| //~^^ NOTE obj::func is a function, perhaps you wish to call it | ||
| func.x(); | ||
| //~^ ERROR no method named `x` found for type `fn() -> ret {func}` in the current scope | ||
| //~^^ NOTE func is a function, perhaps you wish to call it |
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For some reason these pass without referencing the help note in the comments. The help note does show when this file is manually compiled though.
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compiletest only errors for unexpected errors and warnings, if it gets a help that wasn't expected it silently pushes ahead. It only errors for helps when there is an expected help which doesn't match the found help.
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You should add //~| SUGGESTION as well (see other instances of this in the tests)
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One last nit, otherwise looks good! |
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☔ The latest upstream changes (presumably #31710) made this pull request unmergeable. Please resolve the merge conflicts. |
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Apologies for the delayed fix. I've been on holiday for the last week. |
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☔ The latest upstream changes (presumably #32351) made this pull request unmergeable. Please resolve the merge conflicts. |
| @@ -1 +1 @@ | |||
| Subproject commit 57315f7e07d09b6f0341ebbcd50dded6c20d782f | |||
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These shouldn't have changed. You may have done a git add * here. I can rebase it and fix it if you want.
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Yes please, Manishearth. If you could rebase it for me that would be great. I'm away with terrible internet and no dev machine at the moment.
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r=me post rebase |
Split `fileline_note` into a `file_line note` and `span_suggestion` as per @Manishearth's suggestions. Change nested `match`es to `if let`s.
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superseded by #32358 |
Add note if method is called on a function object rebase of #32053
Fixes issue #29124.
If method is called on a function type a note is generated to suggest
that the developer may have forgotten to call the base function.
e.g.
will generate the note: