run-make-support: add support for passing stdin bytes in rustdoc

Author: Urgau

src/tools/run-make-support/src/rustdoc.rs

@@ -1,6 +1,7 @@
 use std::env;
+use std::io::Write;
 use std::path::Path;
-use std::process::{Command, Output};
+use std::process::{Command, Output, Stdio};
 
 use crate::{handle_failed_output, set_host_rpath};
 
@@ -62,6 +63,26 @@ impl Rustdoc {
         self
     }
 
+    /// Run the constructed command and assert that it is successfully run.
+    #[track_caller]
+    pub fn run_with_stdin<I: AsRef<[u8]>>(&mut self, input: I) -> ::std::process::Output {
+        let caller_location = ::std::panic::Location::caller();
+        let caller_line_number = caller_location.line();
+
+        self.cmd.stdin(Stdio::piped());
+        let mut child = self.cmd.spawn().unwrap();
+        let mut stdin = child.stdin.take().unwrap();
+        stdin.write_all(input.as_ref()).unwrap();
+        drop(stdin);
+
+        let output = child.wait_with_output().unwrap();
+
+        if !output.status.success() {
+            handle_failed_output(&self.cmd, output, caller_line_number);
+        }
+        output
+    }
+
     #[track_caller]
     pub fn run_fail_assert_exit_code(&mut self, code: i32) -> Output {
         let caller_location = std::panic::Location::caller();