diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs index ea74dffd9fd..fdee469a3fb 100644 --- a/src/librustc_resolve/lib.rs +++ b/src/librustc_resolve/lib.rs @@ -3213,17 +3213,6 @@ impl<'a> Resolver<'a> { // Make sure error reporting is deterministic. names.sort_by_key(|name| name.as_str()); - - // Ugly code, just to see if using case insensitive comparison will help - let exact_match = names.iter().find(|x| x.as_str().to_uppercase() == name.as_str().to_uppercase()); - // do not use Levenstein, just return the value we found (if any) - if exact_match.is_some() { - return match exact_match { - Some(found) => Some(found.clone()), - _ => None, - } - } - match find_best_match_for_name(names.iter(), &name.as_str(), None) { Some(found) if found != name => Some(found), _ => None, diff --git a/src/libsyntax/util/lev_distance.rs b/src/libsyntax/util/lev_distance.rs index 9307f3c58d4..e429791f2bd 100644 --- a/src/libsyntax/util/lev_distance.rs +++ b/src/libsyntax/util/lev_distance.rs @@ -44,23 +44,45 @@ pub fn lev_distance(a: &str, b: &str) -> usize { /// To find the best match for a given string from an iterator of names /// As a loose rule to avoid the obviously incorrect suggestions, it takes /// an optional limit for the maximum allowable edit distance, which defaults -/// to one-third of the given word +/// to one-third of the given word. +/// Besides Levenshtein, we use case insensitive comparison to improve accuracy on an edge case with +/// a lower(upper)case letters mismatch. pub fn find_best_match_for_name<'a, T>(iter_names: T, lookup: &str, dist: Option) -> Option where T: Iterator { let max_dist = dist.map_or_else(|| cmp::max(lookup.len(), 3) / 3, |d| d); - iter_names + + let (case_insensitive_match, levenstein_match) = iter_names .filter_map(|&name| { let dist = lev_distance(lookup, &name.as_str()); - if dist <= max_dist { // filter the unwanted cases + if dist <= max_dist { Some((name, dist)) } else { None } }) - .min_by_key(|&(_, val)| val) // extract the tuple containing the minimum edit distance - .map(|(s, _)| s) // and return only the string + // Here we are collecting the next structure: + // (case_insensitive_match, (levenstein_match, levenstein_distance)) + .fold((None, None), |result, (candidate, dist)| { + ( + if candidate.as_str().to_uppercase() == lookup.to_uppercase() { + Some(candidate) + } else { + result.0 + }, + match result.1 { + None => Some((candidate, dist)), + Some((c, d)) => Some(if dist < d { (candidate, dist) } else { (c, d) }) + } + ) + }); + + if let Some(candidate) = case_insensitive_match { + Some(candidate) // exact case insensitive match has a higher priority + } else { + if let Some((candidate, _)) = levenstein_match { Some(candidate) } else { None } + } } #[test] diff --git a/src/test/ui/issue-46332.rs b/src/test/ui/issue-46332.rs new file mode 100644 index 00000000000..32cd5d39dc3 --- /dev/null +++ b/src/test/ui/issue-46332.rs @@ -0,0 +1,20 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// Original Levenshtein distance for both of this is 1. We improved accuracy with +// additional case insensitive comparison. + +struct TyUint {} + +struct TyInt {} + +fn main() { + TyUInt {}; +} diff --git a/src/test/ui/issue-46332.stderr b/src/test/ui/issue-46332.stderr new file mode 100644 index 00000000000..6aef8456835 --- /dev/null +++ b/src/test/ui/issue-46332.stderr @@ -0,0 +1,8 @@ +error[E0422]: cannot find struct, variant or union type `TyUInt` in this scope + --> $DIR/issue-46332.rs:19:5 + | +19 | TyUInt {}; + | ^^^^^^ did you mean `TyUint`? + +error: aborting due to previous error + diff --git a/src/test/ui/issue46332.rs b/src/test/ui/issue46332.rs deleted file mode 100644 index 79de1600ae2..00000000000 --- a/src/test/ui/issue46332.rs +++ /dev/null @@ -1,14 +0,0 @@ -// Original problem is Levenstein distance. - -fn TyUint() { - println!("TyUint"); -} - -fn TyInt() { - println!("TyInt"); -} - - -fn main() { - TyUInt(); -}