Fix add-required-import with multi-line offsets (#2946)

crates/ruff/resources/test/fixtures/isort/required_imports/multiline_docstring.py

@@ -0,0 +1,4 @@
+"""a
+b"""
+# b
+import os

crates/ruff/src/rules/isort/helpers.rs

@@ -110,7 +110,7 @@ pub fn find_splice_location(body: &[Stmt], locator: &Locator) -> Location {
 
     // Find the first token that isn't a comment or whitespace.
     let contents = locator.skip(splice);
-    for (.., tok, end) in lexer::make_tokenizer(contents).flatten() {
+    for (.., tok, end) in lexer::make_tokenizer_located(contents, splice).flatten() {
         if matches!(tok, Tok::Comment(..) | Tok::Newline) {
             splice = end;
         } else {

crates/ruff/src/rules/isort/mod.rs

@@ -620,6 +620,7 @@ mod tests {
 
     #[test_case(Path::new("docstring.py"))]
     #[test_case(Path::new("docstring_only.py"))]
+    #[test_case(Path::new("multiline_docstring.py"))]
     #[test_case(Path::new("empty.py"))]
     fn required_import(path: &Path) -> Result<()> {
         let snapshot = format!("required_import_{}", path.to_string_lossy());

crates/ruff/src/rules/isort/snapshots/ruff__rules__isort__tests__required_import_multiline_docstring.py.snap

@@ -0,0 +1,24 @@
+---
+source: crates/ruff/src/rules/isort/mod.rs
+expression: diagnostics
+---
+- kind:
+    MissingRequiredImport: from __future__ import annotations
+  location:
+    row: 1
+    column: 0
+  end_location:
+    row: 1
+    column: 0
+  fix:
+    content:
+      - ""
+      - from __future__ import annotations
+    location:
+      row: 3
+      column: 3
+    end_location:
+      row: 3
+      column: 3
+  parent: ~
+