internal: Don't parse files unnecessarily in scope_for_offset

Cargo.lock

@@ -1318,9 +1318,9 @@ checksum = "49b3de9ec5dc0a3417da371aab17d729997c15010e7fd24ff707773a33bddb64"
 
 [[package]]
 name = "rowan"
-version = "0.15.5"
+version = "0.15.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ce1f383129e417a6265b16ed78e6e9307748f0863b2ba75f78ff14717db5b017"
+checksum = "e88acf7b001007e9e8c989fe7449f6601d909e5dd2c56399fc158977ad6c56e8"
 dependencies = [
  "countme",
  "hashbrown",

crates/hir/src/source_analyzer.rs

@@ -650,9 +650,7 @@ fn scope_for_offset(
         .filter_map(|(id, scope)| {
             let InFile { file_id, value } = source_map.expr_syntax(*id).ok()?;
             if from_file == file_id {
-                let root = db.parse_or_expand(file_id)?;
-                let node = value.to_node(&root);
-                return Some((node.syntax().text_range(), scope));
+                return Some((value.text_range(), scope));
             }
 
             // FIXME handle attribute expansion

crates/syntax/Cargo.toml

@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 cov-mark = "2.0.0-pre.1"
 itertools = "0.10.3"
-rowan = "0.15.5"
+rowan = "0.15.8"
 rustc_lexer = { version = "725.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 once_cell = "1.12.0"

crates/syntax/src/ptr.rs

@@ -14,6 +14,8 @@ use std::{
     marker::PhantomData,
 };
 
+use rowan::TextRange;
+
 use crate::{syntax_node::RustLanguage, AstNode, SyntaxNode};
 
 /// A "pointer" to a [`SyntaxNode`], via location in the source code.
@@ -60,6 +62,10 @@ impl<N: AstNode> AstPtr<N> {
         self.raw.clone()
     }
 
+    pub fn text_range(&self) -> TextRange {
+        self.raw.text_range()
+    }
+
     pub fn cast<U: AstNode>(self) -> Option<AstPtr<U>> {
         if !U::can_cast(self.raw.kind()) {
             return None;