Update for extra-link-arg (rust-lang/cargo#8441)

Author: luojia65

gd32vf103-hal/build.rs

@@ -0,0 +1,39 @@
+// Ref: Sha Miao, rv32m1_ri5cy-example/build.rs
+
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+const MISSING_CARGO_ENV: &str = "Missing environment variables provided by Cargo.";
+
+/// Include `.a` files generated by assembly codes
+fn include_a_files(out_dir: &str) {
+    let target = env::var("TARGET").expect(MISSING_CARGO_ENV);
+    let out_dir = PathBuf::from(out_dir);
+    let name = env::var("CARGO_PKG_NAME").expect(MISSING_CARGO_ENV);
+
+    if &target == "riscv32imac-unknown-none-elf" {
+        fs::copy(
+            format!("bin/{}.a", target),
+            out_dir.join(format!("lib{}.a", name)),
+        )
+        .unwrap();
+
+        println!("cargo:rustc-link-lib=static={}", name);
+        println!("cargo:rustc-link-search={}", out_dir.display());
+        println!("cargo:rerun-if-changed=bin/{}.a", target);
+    }
+}
+
+fn linker_script() {
+    println!("cargo:rustc-link-arg-bins=-Tmemory.x");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+}
+
+/// Build script for the crate.
+fn main() {
+    let out_dir = env::var("OUT_DIR").expect(MISSING_CARGO_ENV);
+    include_a_files(&out_dir);
+    linker_script();
+    println!("cargo:rerun-if-changed=build.rs");
+}