Ensure Rustc::print use in rmake tests

tests/run-make/print-cfg/rmake.rs

@@ -6,7 +6,6 @@
 //! It also checks that some targets have the correct set cfgs.
 
 use std::collections::HashSet;
-use std::ffi::OsString;
 use std::iter::FromIterator;
 use std::path::PathBuf;
 
@@ -91,10 +90,8 @@ fn check_(output: &str, includes: &[&str], disallow: &[&str]) {
     // --print=cfg=PATH
     {
         let tmp_path = PathBuf::from(format!("{target}.cfg"));
-        let mut print_arg = OsString::from("--print=cfg=");
-        print_arg.push(tmp_path.as_os_str());
 
-        rustc().target(target).arg(print_arg).run();
+        rustc().target(target).print(&format!("cfg={}", tmp_path.display())).run();
 
         let output = rfs::read_to_string(&tmp_path);
 

tests/run-make/print-check-cfg/rmake.rs

@@ -87,7 +87,7 @@ fn main() {
 
 fn check(CheckCfg { args, contains }: CheckCfg) {
     let output =
-        rustc().input("lib.rs").arg("-Zunstable-options").arg("--print=check-cfg").args(args).run();
+        rustc().input("lib.rs").arg("-Zunstable-options").print("check-cfg").args(args).run();
 
     let stdout = output.stdout_utf8();
 

tests/run-make/print-to-output/rmake.rs

@@ -1,7 +1,6 @@
 //! This checks the output of some `--print` options when
 //! output to a file (instead of stdout)
 
-use std::ffi::OsString;
 use std::path::PathBuf;
 
 use run_make_support::{rfs, rustc, target};
@@ -44,10 +43,8 @@ fn check_(output: &str, includes: &[&str]) {
     // --print={option}=PATH
     let output = {
         let tmp_path = PathBuf::from(format!("{}.txt", args.option));
-        let mut print_arg = OsString::from(format!("--print={}=", args.option));
-        print_arg.push(tmp_path.as_os_str());
 
-        rustc().target(args.target).arg(print_arg).run();
+        rustc().target(args.target).print(&format!("{}={}", args.option, tmp_path.display())).run();
 
         rfs::read_to_string(&tmp_path)
     };

tests/run-make/rustdoc-scrape-examples-macros/rmake.rs

@@ -11,8 +11,7 @@ fn main() {
     let dylib_name = rustc()
         .crate_name(proc_crate_name)
         .crate_type("dylib")
-        .arg("--print")
+        .print("file-names")
-        .arg("file-names")
         .arg("-")
         .run()
         .stdout_utf8();