Fix indent for move_guard_to_arm_body

Input:

```rust
fn main() {
    match 92 {
        x $0if true
            && true
            && true =>
        {
            {
                false
            }
        },
        _ => true
    }
}
```

Old output:

```rust
fn main() {
    match 92 {
        x =>
        if true
                    && true
                    && true {
            {
                    {
                        false
                    }
                }
        },
        _ => true
    };
}
```

This PR fixed:

```rust
fn main() {
    match 92 {
        x => if true
            && true
            && true {
            {
                {
                    false
                }
            }
        },
        _ => true
    }
}
```

1 files changed, 57 insertions, 13 deletions

diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/move_guard.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/move_guard.rs
index 644d1f6cafe..6b50718424c 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/move_guard.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/move_guard.rs
@@ -40,28 +40,34 @@ pub(crate) fn move_guard_to_arm_body(acc: &mut Assists, ctx: &AssistContext<'_>)
         return None;
     }
     let space_before_guard = guard.syntax().prev_sibling_or_token();
+    let space_after_arrow = match_arm.fat_arrow_token()?.next_sibling_or_token();
 
-    let guard_condition = guard.condition()?;
+    let guard_condition = guard.condition()?.reset_indent();
     let arm_expr = match_arm.expr()?;
-    let if_expr =
-        make::expr_if(guard_condition, make::block_expr(None, Some(arm_expr.clone())), None)
-            .indent(arm_expr.indent_level());
+    let then_branch = make::block_expr(None, Some(arm_expr.reset_indent().indent(1.into())));
+    let if_expr = make::expr_if(guard_condition, then_branch, None).indent(arm_expr.indent_level());
 
     let target = guard.syntax().text_range();
     acc.add(
         AssistId::refactor_rewrite("move_guard_to_arm_body"),
         "Move guard to arm body",
         target,
-        |edit| {
-            match space_before_guard {
-                Some(element) if element.kind() == WHITESPACE => {
-                    edit.delete(element.text_range());
-                }
-                _ => (),
-            };
+        |builder| {
+            let mut edit = builder.make_editor(match_arm.syntax());
+            if let Some(element) = space_before_guard
+                && element.kind() == WHITESPACE
+            {
+                edit.delete(element);
+            }
+            if let Some(element) = space_after_arrow
+                && element.kind() == WHITESPACE
+            {
+                edit.replace(element, make::tokens::single_space());
+            }
 
-            edit.delete(guard.syntax().text_range());
-            edit.replace_ast(arm_expr, if_expr.into());
+            edit.delete(guard.syntax());
+            edit.replace(arm_expr.syntax(), if_expr.syntax());
+            builder.add_file_edits(ctx.vfs_file_id(), edit);
         },
     )
 }
@@ -299,6 +305,44 @@ fn main() {
     }
 
     #[test]
+    fn move_multiline_guard_to_arm_body_works() {
+        check_assist(
+            move_guard_to_arm_body,
+            r#"
+fn main() {
+    match 92 {
+        x $0if true
+            && true
+            && true =>
+        {
+            {
+                false
+            }
+        },
+        _ => true
+    }
+}
+"#,
+            r#"
+fn main() {
+    match 92 {
+        x => if true
+            && true
+            && true {
+            {
+                {
+                    false
+                }
+            }
+        },
+        _ => true
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
     fn move_guard_to_arm_body_works_complex_match() {
         check_assist(
             move_guard_to_arm_body,