test that build scripts do not run in Miri

Author: RalfJung

test-cargo-miri/Cargo.toml

@@ -3,6 +3,7 @@ name = "cargo-miri-test"
 version = "0.1.0"
 authors = ["Oliver Schneider <git-spam-no-reply9815368754983@oli-obk.de>"]
 edition = "2018"
+build = "build.rs"
 
 [dependencies]
 byteorder = "1.0"

test-cargo-miri/build.rs

@@ -0,0 +1,15 @@
+#![feature(asm)]
+
+fn not_in_miri() -> i32 {
+    // Inline assembly definitely does not work in Miri.
+    let dummy = 42;
+    unsafe {
+        asm!("" : : "r"(&dummy));
+    }
+    return dummy;
+}
+
+fn main() {
+    not_in_miri();
+    println!("cargo:rerun-if-changed=build.rs");
+}