Fix issue where rename doesn't work on variable declaration sites

Author: themkat

server/src/main/kotlin/org/javacs/kt/CompiledFile.kt

@@ -6,6 +6,7 @@ import org.javacs.kt.compiler.CompilationKind
 import org.javacs.kt.position.changedRegion
 import org.javacs.kt.position.location
 import org.javacs.kt.position.position
+import org.javacs.kt.position.range
 import org.javacs.kt.util.findParent
 import org.javacs.kt.util.nullResult
 import org.javacs.kt.util.toPath
@@ -193,6 +194,22 @@ class CompiledFile(
         }
     }
 
+    /**
+     * Find the declaration of the element at the cursor.
+     * Works even in cases where the element at the cursor might not be a reference, so works for declaration sites.
+     */
+    fun findDeclarationCursorSite(cursor: Int): Pair<KtNamedDeclaration, Location>? {
+        // current symbol might be a declaration. This function is used as a fallback when
+        // findDeclaration fails
+        val declaration = elementAtPoint(cursor)?.findParent<KtNamedDeclaration>()
+
+        return declaration?.let {
+            Pair(it,
+                 Location(it.containingFile.name,
+                          range(content, it.nameIdentifier?.textRange ?: return null)))
+        }
+    }
+
     /**
      * Find the lexical-scope surrounding `cursor`.
      * This may be out-of-date if the user is typing quickly.

server/src/main/kotlin/org/javacs/kt/highlight/DocumentHighlight.kt

@@ -23,18 +23,4 @@ fun documentHighlightsAt(file: CompiledFile, cursor: Int): List<DocumentHighligh
     } + references.map { DocumentHighlight(it, DocumentHighlightKind.Text) }
 }
 
-private fun CompiledFile.findDeclarationCursorSite(cursor: Int): Pair<KtNamedDeclaration, Location>? {
-    // current symbol might be a declaration. This function is used as a fallback when
-    // findDeclaration fails
-    val declaration = elementAtPoint(cursor)?.findParent<KtNamedDeclaration>()
-
-    return declaration?.let {
-        // in this scenario we know that the declaration will be at the cursor site, so uri is not
-        // important
-        Pair(it,
-             Location("",
-                      range(content, it.nameIdentifier?.textRange ?: return null)))
-    }
-}
-
 private fun KtNamedDeclaration.isInFile(file: KtFile) = this.containingFile == file

server/src/main/kotlin/org/javacs/kt/rename/Rename.kt

@@ -7,7 +7,7 @@ import org.javacs.kt.SourcePath
 import org.javacs.kt.references.findReferences
 
 fun renameSymbol(file: CompiledFile, cursor: Int, sp: SourcePath, newName: String): WorkspaceEdit? {
-    val (declaration, location) = file.findDeclaration(cursor) ?: return null
+    val (declaration, location) = file.findDeclaration(cursor) ?: file.findDeclarationCursorSite(cursor) ?: return null
     return declaration.let {
         val declarationEdit = Either.forLeft<TextDocumentEdit, ResourceOperation>(TextDocumentEdit(
             VersionedTextDocumentIdentifier().apply { uri = location.uri },