fix: Respect sort in custom completions (#14424)

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# Description

This PR makes it so that when a custom completer sets `options.sort` to
true, completions aren't sorted. Previously, in #13311, I'd made it so
that setting `sort` to true would sort in alphabetical order, while
omitting it or setting it to false would sort it in the default order
for the chosen match algorithm (alphabetical for prefix matching, fuzzy
match score for fuzzy matching). I'd assumed that you'd always want to
sort completions and the important thing was choosing alphabetical
sorting vs the default sort order for your match algorithm. However,
this assumption was incorrect (see #13696 and [this
thread](https://discord.com/channels/601130461678272522/1302332259227144294)
in Discord).

An alternative would be to make `sort` accept `"alphabetical"`,
`"smart"`, and `"none"`/`null` rather than keeping it a boolean. But
that would be a breaking change and require more discussion, and I
wanted to keep this PR simple/small so that we can go back to the
sensible behavior as soon as possible.

# User-Facing Changes
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Here are the different scenarios:
- If your custom completer returns a record with an `options` field
that's a record:
- If `options` contains `sort: true`, completions **will be sorted
according to the order set in the user's config**. Previously, they
would have been sorted in alphabetical order. This does mean that
**custom completers cannot explicitly choose to sort in alphabetical
order** anymore. I think that's an acceptable trade-off, though.
- If `options` contains `sort: false`, completions will not be sorted.
#13311 broke things so they would be sorted in the default order for the
match algorithm used. Before that PR, completions would not have been
sorted.
- If there's no `sort` option, that **will be treated as `sort: true`**.
Previously, this would have been treated as `sort: false`.
- Otherwise, nothing changes. Completions will still be sorted.

# Tests + Formatting
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Added 1 test to make sure that completions aren't sorted with `sort:
false` explicitly set.

# After Submitting
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crates/nu-cli/src/completions/custom_completions.rs

@@ -1,13 +1,12 @@
 use crate::completions::{
-    completer::map_value_completions, Completer, CompletionOptions, MatchAlgorithm,
-    SemanticSuggestion,
+    completer::map_value_completions, Completer, CompletionOptions, SemanticSuggestion,
 };
 use nu_engine::eval_call;
 use nu_protocol::{
     ast::{Argument, Call, Expr, Expression},
     debugger::WithoutDebug,
     engine::{Stack, StateWorkingSet},
-    CompletionSort, DeclId, PipelineData, Span, Type, Value,
+    DeclId, PipelineData, Span, Type, Value,
 };
 use std::collections::HashMap;
 
@@ -68,6 +67,7 @@ impl Completer for CustomCompletion {
         );
 
         let mut custom_completion_options = None;
+        let mut should_sort = true;
 
         // Parse result
         let suggestions = result
@@ -85,10 +85,9 @@ impl Completer for CustomCompletion {
                     let options = val.get("options");
 
                     if let Some(Value::Record { val: options, .. }) = &options {
-                        let should_sort = options
-                            .get("sort")
-                            .and_then(|val| val.as_bool().ok())
-                            .unwrap_or(false);
+                        if let Some(sort) = options.get("sort").and_then(|val| val.as_bool().ok()) {
+                            should_sort = sort;
+                        }
 
                         custom_completion_options = Some(CompletionOptions {
                             case_sensitive: options
@@ -98,20 +97,16 @@ impl Completer for CustomCompletion {
                             positional: options
                                 .get("positional")
                                 .and_then(|val| val.as_bool().ok())
-                                .unwrap_or(true),
+                                .unwrap_or(completion_options.positional),
                             match_algorithm: match options.get("completion_algorithm") {
                                 Some(option) => option
                                     .coerce_string()
                                     .ok()
                                     .and_then(|option| option.try_into().ok())
-                                    .unwrap_or(MatchAlgorithm::Prefix),
+                                    .unwrap_or(completion_options.match_algorithm),
                                 None => completion_options.match_algorithm,
                             },
-                            sort: if should_sort {
-                                CompletionSort::Alphabetical
-                            } else {
-                                CompletionSort::Smart
-                            },
+                            sort: completion_options.sort,
                         });
                     }
 
@@ -124,9 +119,17 @@ impl Completer for CustomCompletion {
 
         let options = custom_completion_options.unwrap_or(completion_options.clone());
         let mut matcher = NuMatcher::new(String::from_utf8_lossy(prefix), options);
+
+        if should_sort {
             for sugg in suggestions {
                 matcher.add_semantic_suggestion(sugg);
             }
             matcher.results()
+        } else {
+            suggestions
+                .into_iter()
+                .filter(|sugg| matcher.matches(&sugg.suggestion.value))
+                .collect()
+        }
     }
 }

crates/nu-cli/tests/completions/mod.rs

@@ -88,6 +88,27 @@ fn completer_strings_with_options() -> NuCompleter {
     NuCompleter::new(Arc::new(engine), Arc::new(stack))
 }
 
+#[fixture]
+fn completer_strings_no_sort() -> NuCompleter {
+    // Create a new engine
+    let (_, _, mut engine, mut stack) = new_engine();
+    let command = r#"
+        def animals [] {
+            {
+                completions: ["zzzfoo", "foo", "not matched", "abcfoo" ],
+                options: {
+                    completion_algorithm: "fuzzy",
+                    sort: false,
+                }
+            }
+        }
+        def my-command [animal: string@animals] { print $animal }"#;
+    assert!(support::merge_input(command.as_bytes(), &mut engine, &mut stack).is_ok());
+
+    // Instantiate a new completer
+    NuCompleter::new(Arc::new(engine), Arc::new(stack))
+}
+
 #[fixture]
 fn custom_completer() -> NuCompleter {
     // Create a new engine
@@ -210,6 +231,13 @@ fn customcompletions_case_insensitive(mut completer_strings_with_options: NuComp
     match_suggestions(&expected, &suggestions);
 }
 
+#[rstest]
+fn customcompletions_no_sort(mut completer_strings_no_sort: NuCompleter) {
+    let suggestions = completer_strings_no_sort.complete("my-command foo", 14);
+    let expected: Vec<String> = vec!["zzzfoo".into(), "foo".into(), "abcfoo".into()];
+    match_suggestions(&expected, &suggestions);
+}
+
 #[test]
 fn dotnu_completions() {
     // Create a new engine