Added example using rand crate to ensure no_std compatibility

Signed-off-by: Daniel Egger <[email protected]>

Author: therealprof

cortex-m-rt/Cargo.toml

@@ -19,6 +19,10 @@ cortex-m = "0.5.4"
 panic-abort = "0.3.0"
 panic-semihosting = "0.4.0"
 
+[dev-dependencies.rand]
+default-features = false
+version = "0.5.5"
+
 [target.'cfg(not(target_os = "none"))'.dev-dependencies]
 compiletest_rs = "0.3.14"
 

cortex-m-rt/ci/script.sh

@@ -20,11 +20,12 @@ main() {
         minimal
         override-exception
         pre_init
+        rand
         state
         unsafe-default-handler
-        unsafe-hard-fault
         unsafe-entry
         unsafe-exception
+        unsafe-hard-fault
     )
     local fail_examples=(
         data_overflow

cortex-m-rt/examples/rand.rs

@@ -0,0 +1,24 @@
+//! Use rand crate to ensure it's configured for no_std compatbility
+
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate cortex_m_rt as rt;
+use rt::entry;
+
+extern crate panic_semihosting;
+
+extern crate rand;
+use rand::Rng;
+use rand::SeedableRng;
+
+// the program entry point
+#[entry]
+fn main() -> ! {
+    let seed: [u8; 32] = [0; 32];
+    let mut rng = rand::ChaChaRng::from_seed(seed);
+    let _ = rng.gen::<u32>();
+
+    loop {}
+}