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Add case insensitive comparison, besides Levenstein for DYM #46347

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Merged
merged 3 commits into from
Dec 2, 2017
Merged

Add case insensitive comparison, besides Levenstein for DYM #46347

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6506f9c
Add case insensitive comparison, besides Levenstein
Nov 28, 2017
537f2a6
move comparator into +find_best_match_name+ function
Nov 30, 2017
f18446e
add magic comment for ui test, remove newline
Dec 1, 2017
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12 changes: 12 additions & 0 deletions src/librustc_resolve/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3212,6 +3212,18 @@ impl<'a> Resolver<'a> {
let name = path[path.len() - 1].node.name;
// 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());
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case_insensitive_match would be a less-misleading name.

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This should be the following to account for @petrochenkov's comment

names.iter().find(|x| {
    x.as_str().to_uppercase() == name.as_str().to_uppercase() && x.as_str() != name.as_str()
})

// 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,
}
}
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Less nesting:

if case_insensitive_match.is_some() {
    return case_insensitive_match.cloned()
}

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This code can be written as

if let Some(found) = exact_match {
    return Some(found.clone());
}


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It occurs to me that we should likely be making this change as a "tiebreaker" in syntax::util::lev_distance::find_best_match_for_name itself: the only time case-insensitive match is going to do better than minimizing Levenshtein distance is when there's a tie for the minimum and the method makes an unlucky choice among the minima, as in the motivating example (TyInt and TyUint are both Levenshtein-distance 1 away from TyUInt).

match find_best_match_for_name(names.iter(), &name.as_str(), None) {
Some(found) if found != name => Some(found),
_ => None,
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14 changes: 14 additions & 0 deletions src/test/ui/issue46332.rs
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@@ -0,0 +1,14 @@
// Original problem is Levenstein distance.

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issue-46332.rs (with the hyphen) as a file name would conform more with most of the other test file names. The license also needs to be at the top of the file (the build system will check).

fn TyUint() {
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(An enum variant rather than a function is closer to the spirit of the example in the issue (which isn't to say that we shouldn't test functions, too, but those are snake_case_in_standard_style, unlike TyUint).)

println!("TyUint");
}

fn TyInt() {
println!("TyInt");
}


fn main() {
TyUInt();
}
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You're missing the .stderr file in this PR.