Check for / or \ on windows

Author: Veykril

crates/rust-analyzer/src/handlers/request.rs

@@ -2003,7 +2003,9 @@ fn run_rustfmt(
                     // approach: if the command name contains a path seperator, join it with the workspace root.
                     // however, if the path is absolute, joining will result in the absolute path being preserved.
                     // as a fallback, rely on $PATH-based discovery.
-                    let cmd_path = if command.contains(std::path::MAIN_SEPARATOR_STR) {
+                    let cmd_path = if cfg!(windows) && command.contains(&[std::path::MAIN_SEPARATOR_STR, '/']) {
+                        spec.workspace_root.join(cmd).into()
+                    } else if command.contains(std::path::MAIN_SEPARATOR_STR) {
                         spec.workspace_root.join(cmd).into()
                     } else {
                         cmd