From 3003050d473abd13d56c7e7966b971bd7443194f Mon Sep 17 00:00:00 2001
From: Noratrieb <48135649+Noratrieb@users.noreply.github.com>
Date: Mon, 23 Jun 2025 21:01:08 +0200
Subject: [PATCH] Fix hang in --print=file-names in bootstrap

In an interactive context, the subprocess inherited a real tty stdin,
which lead it it waiting for something to happen, even though nothing
happened. By explicitly passing null as stdin we make sure an empty file
is passed, which achieves the desired behavior.
---
 src/bootstrap/src/core/builder/cargo.rs | 1 +
 src/bootstrap/src/utils/exec.rs         | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index 1e9af68a92df6..5cbd4b7ac00f1 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -683,6 +683,7 @@ impl Builder<'_> {
                         .arg("--print=file-names")
                         .arg("--crate-type=proc-macro")
                         .arg("-")
+                        .stdin(std::process::Stdio::null())
                         .run_capture(self)
                         .stderr();
 
diff --git a/src/bootstrap/src/utils/exec.rs b/src/bootstrap/src/utils/exec.rs
index 64e46f105638f..26deb38717181 100644
--- a/src/bootstrap/src/utils/exec.rs
+++ b/src/bootstrap/src/utils/exec.rs
@@ -120,6 +120,11 @@ impl BootstrapCommand {
         self
     }
 
+    pub fn stdin(&mut self, stdin: std::process::Stdio) -> &mut Self {
+        self.command.stdin(stdin);
+        self
+    }
+
     #[must_use]
     pub fn delay_failure(self) -> Self {
         Self { failure_behavior: BehaviorOnFailure::DelayFail, ..self }