fix(lsp): renaming of flag variables (#14890)

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# Description
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This PR fixes a bug: renaming on a flag variable removes the leading
`--` in the signature.

<img width="257" alt="image"
src="https://github.com/user-attachments/assets/767c62de-f3a0-4a07-9786-61b21e8cfcb6"
/>

Gets the following before this PR:

```nushell
export def foooo [
  p: int
] {
  $p
}
```

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

# Tests + Formatting
<!--
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- `cargo fmt --all -- --check` to check standard code formatting (`cargo
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- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
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- `cargo test --workspace` to check that all tests pass (on Windows make
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Cargo.lock

@@ -3202,13 +3202,14 @@ dependencies = [
 
 [[package]]
 name = "lsp-server"
-version = "0.7.7"
+version = "0.7.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "550446e84739dcaf6d48a4a093973850669e13e8a34d8f8d64851041be267cd9"
+checksum = "9462c4dc73e17f971ec1f171d44bfffb72e65a130117233388a0ebc7ec5656f9"
 dependencies = [
  "crossbeam-channel",
  "log",
  "serde",
+ "serde_derive",
  "serde_json",
 ]
 

Cargo.toml

@@ -102,7 +102,7 @@ libproc = "0.14"
 log = "0.4"
 lru = "0.12"
 lscolors = { version = "0.17", default-features = false }
-lsp-server = "0.7.5"
+lsp-server = "0.7.8"
 lsp-types = { version = "0.97.0", features = ["proposed"] }
 lsp-textdocument = "0.4.0"
 mach2 = "0.4"

crates/nu-lsp/src/ast.rs

@@ -198,7 +198,7 @@ fn try_find_id_in_def(
     id_ref: Option<&Id>,
 ) -> Option<(Id, Span)> {
     let call_name = working_set.get_span_contents(call.head);
-    if call_name != "def".as_bytes() && call_name != "export def".as_bytes() {
+    if call_name != b"def" && call_name != b"export def" {
         return None;
     };
     let mut span = None;

crates/nu-lsp/src/workspace.rs

@@ -54,37 +54,18 @@ fn find_reference_in_file(
     file: &FullTextDocument,
     fp: &Path,
     id: &Id,
-) -> Option<Vec<Range>> {
+) -> Option<Vec<Span>> {
-    let fp_str = fp.to_str()?;
     let block = parse(
         working_set,
-        Some(fp_str),
+        fp.to_str(),
         file.get_content(None).as_bytes(),
         false,
     );
-    let file_span = working_set.get_span_for_filename(fp_str)?;
+    let references: Vec<Span> = find_reference_by_id(&block, working_set, id);
-    let offset = file_span.start;
-    let mut references: Vec<Span> = find_reference_by_id(&block, working_set, id);
-
-    // NOTE: for arguments whose declaration is in a signature
-    // which is not covered in the AST
-    if let Id::Variable(vid) = id {
-        let decl_span = working_set.get_variable(*vid).declaration_span;
-        if file_span.contains_span(decl_span)
-            && decl_span.end > decl_span.start
-            && !references.contains(&decl_span)
-        {
-            references.push(decl_span);
-        }
-    }
-    let occurs: Vec<Range> = references
-        .iter()
-        .map(|span| span_to_range(span, file, offset))
-        .collect();
 
     // add_block to avoid repeated parsing
     working_set.add_block(block);
-    (!occurs.is_empty()).then_some(occurs)
+    (!references.is_empty()).then_some(references)
 }
 
 impl LanguageServer {
@@ -284,6 +265,7 @@ impl LanguageServer {
                 .filter_map(|p| p.ok())
                 .collect();
             let len = scripts.len();
+            let definition_span = Self::find_definition_span_by_id(&working_set, &id);
 
             for (i, fp) in scripts.iter().enumerate() {
                 #[cfg(test)]
@@ -324,7 +306,34 @@ impl LanguageServer {
                     }
                     &FullTextDocument::new("nu".to_string(), 0, content_string.into())
                 };
-                let _ = find_reference_in_file(&mut working_set, file, fp, &id).map(|ranges| {
+                let _ = find_reference_in_file(&mut working_set, file, fp, &id).map(|mut refs| {
+                    let file_span = working_set
+                        .get_span_for_filename(fp.to_string_lossy().as_ref())
+                        .unwrap_or(Span::unknown());
+                    // NOTE: for arguments whose declaration is in a signature
+                    // which is not covered in the AST
+                    if let (Id::Variable(_), Some(decl_span)) = (&id, definition_span) {
+                        if file_span.contains_span(decl_span)
+                            && decl_span.end > decl_span.start
+                            && !refs.contains(&decl_span)
+                        {
+                            let leading_dashes = working_set
+                                .get_span_contents(decl_span)
+                                .iter()
+                                // remove leading dashes for flags
+                                .take_while(|c| *c == &b'-')
+                                .count();
+                            let start = decl_span.start + leading_dashes;
+                            refs.push(Span {
+                                start,
+                                end: start + span.end - span.start,
+                            });
+                        }
+                    }
+                    let ranges = refs
+                        .iter()
+                        .map(|span| span_to_range(span, file, file_span.start))
+                        .collect();
                     data_sender
                         .send(InternalMessage::RangeMessage(RangePerDoc { uri, ranges }))
                         .ok();
@@ -693,7 +702,7 @@ mod tests {
                                 "newText": "new"
                             },
                             {
-                                "range": { "start": { "line": 1, "character": 2 }, "end": { "line": 1, "character": 7 } },
+                                "range": { "start": { "line": 1, "character": 4 }, "end": { "line": 1, "character": 9 } },
                                 "newText": "new"
                             }
                         ]

tests/fixtures/lsp/workspace/foo.nu

@@ -1,5 +1,5 @@
 export def foooo [
-  param: int
+  --param(-p): int
 ] {
   $param
 }