Deprecate basepri/basepri_max on thumbv8m.base

First step in resolving #155

Author: JJJollyjim

build.rs

@@ -29,6 +29,7 @@ fn main() {
     } else if target.starts_with("thumbv8m.base") {
         println!("cargo:rustc-cfg=cortex_m");
         println!("cargo:rustc-cfg=armv8m");
+        println!("cargo:rustc-cfg=armv8m_base");
     } else if target.starts_with("thumbv8m.main") {
         println!("cargo:rustc-cfg=cortex_m");
         println!("cargo:rustc-cfg=armv8m");

src/register/mod.rs

@@ -26,10 +26,24 @@
 //!
 //! - Cortex-M* Devices Generic User Guide - Section 2.1.3 Core registers
 
-#[cfg(not(armv6m))]
+#[cfg(all(not(armv6m), not(armv8m_base)))]
 pub mod basepri;
 
-#[cfg(not(armv6m))]
+#[cfg(armv8m_base)]
+#[deprecated(
+    since = "0.6.2",
+    note = "basepri is unavailable on armv8m.base, and will be removed in the next release"
+)]
+pub mod basepri;
+
+#[cfg(all(not(armv6m), not(armv8m_base)))]
+pub mod basepri_max;
+
+#[cfg(armv8m_base)]
+#[deprecated(
+    since = "0.6.2",
+    note = "basepri is unavailable on armv8m.base, and will be removed in the next release"
+)]
 pub mod basepri_max;
 
 pub mod control;