tests: port jobserver-error.rs to rmake.rs

Co-authored-by: Noa <[email protected]>
Co-authored-by: Oneirical <[email protected]>

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -1,5 +1,4 @@
 run-make/cat-and-grep-sanity-check/Makefile
-run-make/jobserver-error/Makefile
 run-make/split-debuginfo/Makefile
 run-make/symbol-mangling-hashed/Makefile
 run-make/translation/Makefile

tests/run-make/jobserver-error/cannot_open_fd.stderr

@@ -1,4 +1,4 @@
-warning: failed to connect to jobserver from environment variable `MAKEFLAGS="--jobserver-auth=5,5"`: cannot open file descriptor 5 from the jobserver environment variable value: Bad file descriptor (os error 9)
+warning: failed to connect to jobserver from environment variable `MAKEFLAGS="--jobserver-auth=1000,1000"`: cannot open file descriptor 1000 from the jobserver environment variable value: Bad file descriptor (os error 9)
   |
   = note: the build environment is likely misconfigured
 

tests/run-make/jobserver-error/rmake.rs

@@ -0,0 +1,47 @@
+// ignore-tidy-linelength
+//! If the environment variables contain an invalid `jobserver-auth`, this used to cause an ICE
+//! until this was fixed in [do not panic on failure to acquire jobserver token
+//! #109694](https://github.com/rust-lang/rust/pull/109694).
+//!
+//! Proper handling has been added, and this test checks that helpful warnings and errors are
+//! printed instead in case of a wrong jobserver. See
+//! <https://github.com/rust-lang/rust/issues/46981>.
+
+//@ only-linux
+//@ ignore-cross-compile
+
+#![deny(warnings)]
+
+use run_make_support::{diff, rustc};
+
+fn main() {
+    let out = rustc()
+        .stdin_buf(("fn main() {}").as_bytes())
+        .env("MAKEFLAGS", "--jobserver-auth=1000,1000")
+        .run_fail()
+        .stderr_utf8();
+    diff().expected_file("cannot_open_fd.stderr").actual_text("actual", out).run();
+
+    let out = rustc()
+        .stdin_buf(("fn main() {}").as_bytes())
+        .input("-")
+        .env("MAKEFLAGS", "--jobserver-auth=3,3")
+        .set_aux_fd(3, std::fs::File::open("/dev/null").unwrap())
+        .run()
+        .stderr_utf8();
+    diff().expected_file("not_a_pipe.stderr").actual_text("actual", out).run();
+
+    // FIXME(#110321): the Makefile version had a disabled check:
+    //
+    // ```makefile
+    // bash -c 'echo "fn main() {}" | MAKEFLAGS="--jobserver-auth=3,3" $(RUSTC) - 3< <(cat /dev/null)' 2>&1 | diff poisoned_pipe.stderr -
+    // ```
+    //
+    // > the jobserver helper thread launched here gets starved out and doesn't run, while the
+    // > coordinator thread continually processes work using the implicit jobserver token, never
+    // > yielding long enough for the jobserver helper to do its work (and process the error).
+    //
+    // but is not necessarily worth fixing as it might require changing coordinator behavior that
+    // might regress performance. See discussion at
+    // <https://github.com/rust-lang/rust/issues/110321#issuecomment-1636914956>.
+}