Use to_string() instead of write!(&mut text, "{}", ....

lib/filetests/src/test_postopt.rs

@@ -7,7 +7,6 @@ use cretonne_codegen::ir::Function;
 use cretonne_codegen::print_errors::pretty_error;
 use cretonne_reader::TestCommand;
 use std::borrow::Cow;
-use std::fmt::Write;
 use subtest::{run_filecheck, Context, Result, SubTest};
 
 struct TestPostopt;
@@ -39,8 +38,7 @@ impl SubTest for TestPostopt {
             .postopt(isa)
             .map_err(|e| pretty_error(&comp_ctx.func, context.isa, Into::into(e)))?;
 
-        let mut text = String::new();
-        write!(&mut text, "{}", &comp_ctx.func).map_err(|e| e.to_string())?;
+        let text = comp_ctx.func.to_string();
         run_filecheck(&text, context)
     }
 }