Use a private field instead of #[non_exhaustive]

Author: jonas-schievink

src/peripheral/mod.rs

@@ -89,7 +89,6 @@ mod test;
 
 /// Core peripherals
 #[allow(non_snake_case)]
-#[non_exhaustive]
 pub struct Peripherals {
     /// Cache and branch predictor maintenance operations (not present on Cortex-M0 variants)
     pub CBP: CBP,
@@ -126,6 +125,10 @@ pub struct Peripherals {
 
     /// Trace Port Interface Unit (not present on Cortex-M0 variants)
     pub TPIU: TPIU,
+
+    // Private field making `Peripherals` non-exhaustive. We don't use `#[non_exhaustive]` so we
+    // can support older Rust versions.
+    _priv: (),
 }
 
 // NOTE `no_mangle` is used here to prevent linking different minor versions of this crate as that
@@ -188,6 +191,7 @@ impl Peripherals {
             TPIU: TPIU {
                 _marker: PhantomData,
             },
+            _priv: (),
         }
     }
 }