Set the executable name in ensure_sealed()

[iliana]

If/when process_set_argv0 is stabilized, we can modify ensure_sealed to set argv[0], which is a current limitation of pentacle.

Tracking issue: rust-lang/rust#66510

Diff on 5c1b0e0 that works with rustc 1.43.0-nightly (75cf41afb 2020-03-04):

diff --git a/src/lib.rs b/src/lib.rs
index 57ffcb9..886f473 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -19,12 +19,12 @@
 //! }
 //! ```

+#![feature(process_set_argv0)]
 #![deny(
     missing_copy_implementations,
     missing_debug_implementations,
     missing_docs,
-    rust_2018_idioms,
-    unstable_features
+    rust_2018_idioms
 )]
 #![warn(clippy::pedantic)]

@@ -67,9 +67,13 @@ pub fn ensure_sealed() -> Result<()> {
     if is_sealed_inner(&file) {
         Ok(())
     } else {
-        Err(SealedCommand::new(&mut file)?
-            .args(std::env::args_os().skip(1))
-            .exec())
+        let mut command = SealedCommand::new(&mut file)?;
+        let mut args = std::env::args_os().fuse();
+        if let Some(arg0) = args.next() {
+            command.arg0(arg0);
+        }
+        command.args(args);
+        Err(command.exec())
     }
 }

diff --git a/tests/ensure_sealed.rs b/tests/ensure_sealed.rs
index 185d084..bcda8c6 100644
--- a/tests/ensure_sealed.rs
+++ b/tests/ensure_sealed.rs
@@ -12,4 +12,5 @@
 fn main() {
     pentacle::ensure_sealed().unwrap();
     assert_eq!(pentacle::is_sealed(), true);
+    assert!(std::env::args().next().unwrap().contains("ensure_sealed"));
 }

[oblique]

process_set_argv0 was stabilized in 1.45. Can you apply the patch?

[iliana]

Yes. I'll see if I can do that this week.