Rollup merge of #146762 - madsmtm:test-apple-sim, r=jieyouxu

Fix and provide instructions for running test suite on Apple simulators

The following now works:

```sh
./x test --host='' --target aarch64-apple-ios-sim --skip tests/debuginfo
./x test --host='' --target aarch64-apple-tvos-sim --skip tests/debuginfo
./x test --host='' --target aarch64-apple-watchos-sim --skip tests/debuginfo
./x test --host='' --target aarch64-apple-visionos-sim --skip tests/debuginfo
```

I have documented the setup I used [in the `rustc-dev-guide`](https://rustc-dev-guide.rust-lang.org/tests/running.html#testing-on-emulators), it's fairly standard use of `remote-test-server` (with a small fix to library load paths which I've made in the first commit).

I first tried the somewhat simpler `target.aarch64-apple-ios-sim.runner = "xcrun simctl spawn $UDID"`, but that doesn't work as required libraries etc. also need to be copied to the device.

The debuginfo tests fail, I think because the debug info in `.dSYM` isn't available. I am yet unsure exactly how to fix this, either we need to copy that directory to the target as well, or we need to configure `lldb` somehow to read it from the host.

I decided to not add this to our CI, since I suspect we wouldn't gain much from it? Running on the simulator still uses the host Darwin kernel, it's basically just configured to run in another mode with more restricted permissions and different system libraries.

r? jieyouxu
CC ``@simlay,`` you're a lot more familiar with `xcrun simctl` than I.

5 files changed, 96 insertions, 26 deletions

diff --git a/library/std/src/os/unix/process.rs b/library/std/src/os/unix/process.rs
index 09429af06e3..5b7b5a8ea80 100644
--- a/library/std/src/os/unix/process.rs
+++ b/library/std/src/os/unix/process.rs
@@ -406,8 +406,10 @@ pub trait ChildExt: Sealed {
     /// use libc::SIGTERM;
     ///
     /// fn main() -> io::Result<()> {
+    ///     # if cfg!(not(all(target_vendor = "apple", not(target_os = "macos")))) {
     ///     let child = Command::new("cat").stdin(Stdio::piped()).spawn()?;
     ///     child.send_signal(SIGTERM)?;
+    ///     # }
     ///     Ok(())
     /// }
     /// ```
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index 48265de90c4..0883e56342c 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -532,6 +532,7 @@ impl fmt::Debug for ChildStderr {
 /// to be changed (for example, by adding arguments) prior to spawning:
 ///
 /// ```
+/// # if cfg!(not(all(target_vendor = "apple", not(target_os = "macos")))) {
 /// use std::process::Command;
 ///
 /// let output = if cfg!(target_os = "windows") {
@@ -548,6 +549,7 @@ impl fmt::Debug for ChildStderr {
 /// };
 ///
 /// let hello = output.stdout;
+/// # }
 /// ```
 ///
 /// `Command` can be reused to spawn multiple processes. The builder methods
@@ -1348,7 +1350,7 @@ impl Output {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(all(unix, not(target_os = "android")))] {
+    /// # #[cfg(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos")))))] {
     /// use std::process::Command;
     /// assert!(Command::new("false").output().unwrap().exit_ok().is_err());
     /// # }
@@ -1695,7 +1697,7 @@ impl From<io::Stdout> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1724,7 +1726,7 @@ impl From<io::Stderr> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1800,7 +1802,7 @@ impl ExitStatus {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # if cfg!(unix) {
+    /// # if cfg!(all(unix, not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// use std::process::Command;
     ///
     /// let status = Command::new("ls")
@@ -1907,7 +1909,7 @@ impl crate::sealed::Sealed for ExitStatusError {}
 ///
 /// ```
 /// #![feature(exit_status_error)]
-/// # if cfg!(all(unix, not(target_os = "android"))) {
+/// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
 /// use std::process::{Command, ExitStatusError};
 ///
 /// fn run(cmd: &str) -> Result<(), ExitStatusError> {
@@ -1950,7 +1952,7 @@ impl ExitStatusError {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(all(unix, not(target_os = "android")))] {
+    /// # #[cfg(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos")))))] {
     /// use std::process::Command;
     ///
     /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
@@ -1975,7 +1977,7 @@ impl ExitStatusError {
     /// ```
     /// #![feature(exit_status_error)]
     ///
-    /// # if cfg!(all(unix, not(target_os = "android"))) {
+    /// # if cfg!(all(unix, not(target_os = "android"), not(all(target_vendor = "apple", not(target_os = "macos"))))) {
     /// use std::num::NonZero;
     /// use std::process::Command;
     ///
diff --git a/library/std/src/process/tests.rs b/library/std/src/process/tests.rs
index 5879914ca20..12c5130defe 100644
--- a/library/std/src/process/tests.rs
+++ b/library/std/src/process/tests.rs
@@ -5,7 +5,15 @@ use crate::mem::MaybeUninit;
 use crate::str;
 
 fn known_command() -> Command {
-    if cfg!(windows) { Command::new("help") } else { Command::new("echo") }
+    if cfg!(windows) {
+        Command::new("help")
+    } else if cfg!(all(target_vendor = "apple", not(target_os = "macos"))) {
+        // iOS/tvOS/watchOS/visionOS have a very limited set of commandline
+        // binaries available.
+        Command::new("log")
+    } else {
+        Command::new("echo")
+    }
 }
 
 #[cfg(target_os = "android")]
@@ -19,7 +27,10 @@ fn shell_cmd() -> Command {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn smoke() {
     let p = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 0"]).spawn()
@@ -41,7 +52,10 @@ fn smoke_failure() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn exit_reported_right() {
     let p = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn()
@@ -56,7 +70,10 @@ fn exit_reported_right() {
 
 #[test]
 #[cfg(unix)]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn signal_reported_right() {
     use crate::os::unix::process::ExitStatusExt;
 
@@ -80,7 +97,10 @@ pub fn run_output(mut cmd: Command) -> String {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn stdout_works() {
     if cfg!(target_os = "windows") {
         let mut cmd = Command::new("cmd");
@@ -94,7 +114,11 @@ fn stdout_works() {
 }
 
 #[test]
-#[cfg_attr(any(windows, target_os = "vxworks"), ignore)]
+#[cfg_attr(windows, ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn set_current_dir_works() {
     // On many Unix platforms this will use the posix_spawn path.
     let mut cmd = shell_cmd();
@@ -116,7 +140,11 @@ fn set_current_dir_works() {
 }
 
 #[test]
-#[cfg_attr(any(windows, target_os = "vxworks"), ignore)]
+#[cfg_attr(windows, ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn stdin_works() {
     let mut p = shell_cmd()
         .arg("-c")
@@ -134,7 +162,10 @@ fn stdin_works() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn child_stdout_read_buf() {
     let mut cmd = if cfg!(target_os = "windows") {
         let mut cmd = Command::new("cmd");
@@ -165,7 +196,10 @@ fn child_stdout_read_buf() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_status() {
     let mut status = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).status().unwrap()
@@ -191,7 +225,10 @@ fn test_process_output_fail_to_start() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_output_output() {
     let Output { status, stdout, stderr } = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "echo hello"]).output().unwrap()
@@ -206,7 +243,10 @@ fn test_process_output_output() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_process_output_error() {
     let Output { status, stdout, stderr } = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "mkdir ."]).output().unwrap()
@@ -221,7 +261,10 @@ fn test_process_output_error() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_finish_once() {
     let mut prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn().unwrap()
@@ -232,7 +275,10 @@ fn test_finish_once() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_finish_twice() {
     let mut prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "exit 1"]).spawn().unwrap()
@@ -244,7 +290,10 @@ fn test_finish_twice() {
 }
 
 #[test]
-#[cfg_attr(any(target_os = "vxworks"), ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_wait_with_output_once() {
     let prog = if cfg!(target_os = "windows") {
         Command::new("cmd").args(&["/C", "echo hello"]).stdout(Stdio::piped()).spawn().unwrap()
@@ -279,7 +328,10 @@ pub fn env_cmd() -> Command {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_override_env() {
     use crate::env;
 
@@ -302,7 +354,10 @@ fn test_override_env() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_add_to_env() {
     let result = env_cmd().env("RUN_TEST_NEW_ENV", "123").output().unwrap();
     let output = String::from_utf8_lossy(&result.stdout).to_string();
@@ -314,7 +369,10 @@ fn test_add_to_env() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no shell available"
+)]
 fn test_capture_env_at_spawn() {
     use crate::env;
 
@@ -378,7 +436,10 @@ fn test_interior_nul_in_current_dir_is_error() {
 
 // Regression tests for #30862.
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no `env` cmd available"
+)]
 fn test_interior_nul_in_env_key_is_error() {
     match env_cmd().env("has-some-\0\0s-inside", "value").spawn() {
         Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
@@ -387,7 +448,10 @@ fn test_interior_nul_in_env_key_is_error() {
 }
 
 #[test]
-#[cfg_attr(target_os = "vxworks", ignore)]
+#[cfg_attr(
+    any(target_os = "vxworks", all(target_vendor = "apple", not(target_os = "macos"))),
+    ignore = "no `env` cmd available"
+)]
 fn test_interior_nul_in_env_value_is_error() {
     match env_cmd().env("key", "has-some-\0\0s-inside").spawn() {
         Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
diff --git a/library/std/src/sys/process/unix/unix/tests.rs b/library/std/src/sys/process/unix/unix/tests.rs
index f4d6ac6b4e3..663ba61f966 100644
--- a/library/std/src/sys/process/unix/unix/tests.rs
+++ b/library/std/src/sys/process/unix/unix/tests.rs
@@ -51,6 +51,7 @@ fn exitstatus_display_tests() {
 
 #[test]
 #[cfg_attr(target_os = "emscripten", ignore)]
+#[cfg_attr(any(target_os = "tvos", target_os = "watchos"), ignore = "fork is prohibited")]
 fn test_command_fork_no_unwind() {
     let got = catch_unwind(|| {
         let mut c = Command::new("echo");
diff --git a/library/std/tests/process_spawning.rs b/library/std/tests/process_spawning.rs
index 43b45cb2d2b..93f73ccad3e 100644
--- a/library/std/tests/process_spawning.rs
+++ b/library/std/tests/process_spawning.rs
@@ -7,6 +7,7 @@ mod common;
 #[test]
 // Process spawning not supported by Miri, Emscripten and wasi
 #[cfg_attr(any(miri, target_os = "emscripten", target_os = "wasi"), ignore)]
+#[cfg_attr(any(target_os = "tvos", target_os = "watchos"), ignore = "fork is prohibited")]
 fn issue_15149() {
     // If we're the parent, copy our own binary to a new directory.
     let my_path = env::current_exe().unwrap();