Use CommandExt::exec for cargo run on Unix (#2343)

Before, we would spawn a child process for the program. One of the
problems with that is when killing the cargo process, the program
continues running.

With this change, the cargo process is replaced by the program, and
killing it works.

Author: robinst

src/cargo/ops/cargo_run.rs

@@ -52,5 +52,5 @@ pub fn run(ws: &Workspace,
     process.args(args).cwd(config.cwd());
 
     try!(config.shell().status("Running", process.to_string()));
-    Ok(process.exec().err())
+    Ok(process.exec_replace().err())
 }

src/cargo/util/process_builder.rs

@@ -89,6 +89,22 @@ impl ProcessBuilder {
         }
     }
 
+    #[cfg(unix)]
+    pub fn exec_replace(&self) -> Result<(), ProcessError> {
+        use std::os::unix::process::CommandExt;
+
+        let mut command = self.build_command();
+        let error = command.exec();
+        Err(process_error(&format!("could not execute process `{}`",
+                                   self.debug_string()),
+                          Some(Box::new(error)), None, None))
+    }
+
+    #[cfg(windows)]
+    pub fn exec_replace(&self) -> Result<(), ProcessError> {
+        self.exec()
+    }
+
     pub fn exec_with_output(&self) -> Result<Output, ProcessError> {
         let mut command = self.build_command();
 

tests/run.rs

@@ -126,14 +126,18 @@ fn exit_code() {
             fn main() { std::process::exit(2); }
         "#);
 
-    assert_that(p.cargo_process("run"),
-                execs().with_status(2)
-                       .with_stderr("\
+    let mut output = String::from("\
 [COMPILING] foo v0.0.1 (file[..])
 [FINISHED] debug [unoptimized + debuginfo] target(s) in [..]
 [RUNNING] `target[..]`
+");
+    if !cfg!(unix) {
+        output.push_str("\
 [ERROR] process didn't exit successfully: `target[..]foo[..]` (exit code: 2)
-"));
+");
+    }
+    assert_that(p.cargo_process("run"),
+                execs().with_status(2).with_stderr(output));
 }
 
 #[test]
@@ -149,15 +153,20 @@ fn exit_code_verbose() {
             fn main() { std::process::exit(2); }
         "#);
 
-    assert_that(p.cargo_process("run").arg("-v"),
-                execs().with_status(2)
-                       .with_stderr("\
+    let mut output = String::from("\
 [COMPILING] foo v0.0.1 (file[..])
 [RUNNING] `rustc [..]`
 [FINISHED] debug [unoptimized + debuginfo] target(s) in [..]
 [RUNNING] `target[..]`
+");
+    if !cfg!(unix) {
+        output.push_str("\
 [ERROR] process didn't exit successfully: `target[..]foo[..]` (exit code: 2)
-"));
+");
+    }
+
+    assert_that(p.cargo_process("run").arg("-v"),
+                execs().with_status(2).with_stderr(output));
 }
 
 #[test]