Fix nightly CI by adding --check-cfg flags

Emit `cargo::rustc-check-cfg=CHECK_CFG` in build.rs so that they can be
cross-checked even if cfg option itself isn't set.

riscv-rt/build.rs

@@ -76,6 +76,13 @@ fn main() {
     let cargo_flags = env::var("CARGO_ENCODED_RUSTFLAGS").unwrap();
     let _name = env::var("CARGO_PKG_NAME").unwrap();
 
+    println!("cargo:rustc-check-cfg=cfg(riscv)");
+    println!("cargo:rustc-check-cfg=cfg(riscv32)");
+    println!("cargo:rustc-check-cfg=cfg(riscv64)");
+    for ext in ['i', 'e', 'm', 'a', 'f', 'd', 'g', 'c'] {
+        println!("cargo:rustc-check-cfg=cfg(riscv{})", ext);
+    }
+
     // set configuration flags depending on the target
     if target.starts_with("riscv") {
         println!("cargo:rustc-cfg=riscv");

riscv-semihosting/build.rs

@@ -3,6 +3,10 @@ use std::env;
 fn main() {
     let target = env::var("TARGET").unwrap();
 
+    println!("cargo:rustc-check-cfg=cfg(riscv)");
+    println!("cargo:rustc-check-cfg=cfg(riscv32)");
+    println!("cargo:rustc-check-cfg=cfg(riscv64)");
+
     if target.starts_with("riscv") {
         println!("cargo:rustc-cfg=riscv");
     }

riscv/CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Add `Mstatus::from(usize)` for use in unit tests
 - Add `Mstatus.bits()`
 - Export `riscv::register::macros` module macros for external use
+- Add --check-cfg options to fix nightly CI
 
 ### Fixed
 

riscv/build.rs

@@ -3,6 +3,10 @@ use std::env;
 fn main() {
     let target = env::var("TARGET").unwrap();
 
+    println!("cargo:rustc-check-cfg=cfg(riscv)");
+    println!("cargo:rustc-check-cfg=cfg(riscv32)");
+    println!("cargo:rustc-check-cfg=cfg(riscv64)");
+
     if target.starts_with("riscv32") {
         println!("cargo:rustc-cfg=riscv");
         println!("cargo:rustc-cfg=riscv32");