disable debug assertions in the standard library

Author: RalfJung

cargo-miri/bin.rs

@@ -353,6 +353,8 @@ path = "lib.rs"
     // to the sysroot either.
     command.env_remove("RUSTC_WRAPPER");
     command.env_remove("RUSTFLAGS");
+    // Disable debug assertions in the standard library -- Miri is already slow enough.
+    command.env("RUSTFLAGS", "-Cdebug-assertions=off");
     // Finally run it!
     if command.status().expect("failed to run xargo").success().not() {
         show_error(format!("failed to run xargo"));

tests/run-pass/panic/catch_panic.rs

@@ -78,7 +78,6 @@ fn main() {
     // Assertion and debug assertion
     test(None, |_old_val| { assert!(false); loop {} });
     test(None, |_old_val| { debug_assert!(false); loop {} });
-    test(None, |_old_val| { unsafe { std::char::from_u32_unchecked(0xFD10000); } loop {} }); // trigger debug-assertion in libstd
 
     eprintln!("Success!"); // Make sure we get this in stderr
 }

tests/run-pass/panic/catch_panic.stderr

@@ -23,6 +23,4 @@ thread 'main' panicked at 'assertion failed: false', $DIR/catch_panic.rs:LL:29
 Caught panic message (&str): assertion failed: false
 thread 'main' panicked at 'assertion failed: false', $DIR/catch_panic.rs:LL:29
 Caught panic message (&str): assertion failed: false
-thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', $LOC
-Caught panic message (&str): called `Option::unwrap()` on a `None` value
 Success!