Rollup merge of #67219 - jsgf:command-argv0-debug, r=joshtriplett

Fix up Command Debug output when arg0 is specified.

PR https://github.com/rust-lang/rust/pull/66512 added the ability to set argv[0] on
Command. As a side effect, it changed the Debug output to print both the program and
argv[0], which in practice results in stuttery output (`"echo" "echo" "foo"`).

This PR reverts the behaviour to the the old one, so that the command is only printed
once - unless arg0 has been set. In that case it emits `"[command]" "arg0" "arg1" ...`.

1 files changed, 104 insertions, 0 deletions

diff --git a/src/test/ui/command/command-exec.rs b/src/test/ui/command/command-exec.rs
new file mode 100644
index 00000000000..568be67abe3
--- /dev/null
+++ b/src/test/ui/command/command-exec.rs
@@ -0,0 +1,104 @@
+// run-pass
+
+#![allow(stable_features)]
+// ignore-windows - this is a unix-specific test
+// ignore-pretty issue #37199
+// ignore-cloudabi no processes
+// ignore-emscripten no processes
+// ignore-sgx no processes
+
+#![feature(process_exec)]
+
+use std::env;
+use std::os::unix::process::CommandExt;
+use std::process::Command;
+
+fn main() {
+    let mut args = env::args();
+    let me = args.next().unwrap();
+
+    if let Some(arg) = args.next() {
+        match &arg[..] {
+            "test1" => println!("passed"),
+
+            "exec-test1" => {
+                let err = Command::new(&me).arg("test1").exec();
+                panic!("failed to spawn: {}", err);
+            }
+
+            "exec-test2" => {
+                Command::new("/path/to/nowhere").exec();
+                println!("passed");
+            }
+
+            "exec-test3" => {
+                Command::new(&me).arg("bad\0").exec();
+                println!("passed");
+            }
+
+            "exec-test4" => {
+                Command::new(&me).current_dir("/path/to/nowhere").exec();
+                println!("passed");
+            }
+
+            "exec-test5" => {
+                env::set_var("VARIABLE", "ABC");
+                Command::new("definitely-not-a-real-binary").env("VARIABLE", "XYZ").exec();
+                assert_eq!(env::var("VARIABLE").unwrap(), "ABC");
+                println!("passed");
+            }
+
+            "exec-test6" => {
+                let err = Command::new("echo").arg("passed").env_clear().exec();
+                panic!("failed to spawn: {}", err);
+            }
+
+            "exec-test7" => {
+                let err = Command::new("echo").arg("passed").env_remove("PATH").exec();
+                panic!("failed to spawn: {}", err);
+            }
+
+            _ => panic!("unknown argument: {}", arg),
+        }
+        return
+    }
+
+    let output = Command::new(&me).arg("exec-test1").output().unwrap();
+    assert!(output.status.success());
+    assert!(output.stderr.is_empty());
+    assert_eq!(output.stdout, b"passed\n");
+
+    let output = Command::new(&me).arg("exec-test2").output().unwrap();
+    assert!(output.status.success());
+    assert!(output.stderr.is_empty());
+    assert_eq!(output.stdout, b"passed\n");
+
+    let output = Command::new(&me).arg("exec-test3").output().unwrap();
+    assert!(output.status.success());
+    assert!(output.stderr.is_empty());
+    assert_eq!(output.stdout, b"passed\n");
+
+    let output = Command::new(&me).arg("exec-test4").output().unwrap();
+    assert!(output.status.success());
+    assert!(output.stderr.is_empty());
+    assert_eq!(output.stdout, b"passed\n");
+
+    let output = Command::new(&me).arg("exec-test5").output().unwrap();
+    assert!(output.status.success());
+    assert!(output.stderr.is_empty());
+    assert_eq!(output.stdout, b"passed\n");
+
+    if cfg!(target_os = "linux") {
+        let output = Command::new(&me).arg("exec-test6").output().unwrap();
+        println!("{:?}", output);
+        assert!(output.status.success());
+        assert!(output.stderr.is_empty());
+        assert_eq!(output.stdout, b"passed\n");
+
+        let output = Command::new(&me).arg("exec-test7").output().unwrap();
+        println!("{:?}", output);
+        assert!(output.status.success());
+        assert!(output.stderr.is_empty());
+        assert_eq!(output.stdout, b"passed\n");
+    }
+}