Improve target gen

* Show an error message when the build script is unable to run
  rustfmt.

* Don't generate a struct without values for the JEP106 code in the
  target generation. The whole struct should be `None` in that case.

probe-rs-t2rust/src/lib.rs

@@ -3,6 +3,9 @@ use std::fs::{read_dir, read_to_string};
 use std::io;
 use std::path::{Path, PathBuf};
 
+/// Parse all target description files in the input directory and create
+/// a single output file with the Rust source code
+/// for all targets.
 pub fn run(input_dir: impl AsRef<Path>, output_file: impl AsRef<Path>) {
     // Determine all config files to parse.
     let mut files = vec![];
@@ -375,15 +378,20 @@ fn extract_chip_family(
 
 /// Extracts the jep code token stream from a yaml value.
 fn extract_manufacturer(chip: &serde_yaml::Value) -> Option<proc_macro2::TokenStream> {
-    chip.get("manufacturer").map(|manufacturer| {
+    chip.get("manufacturer").and_then(|manufacturer| {
         let cc = manufacturer.get("cc").map(|v| v.as_u64().unwrap() as u8);
         let id = manufacturer.get("id").map(|v| v.as_u64().unwrap() as u8);
 
-        quote::quote! {
-            JEP106Code {
-                cc: #cc,
-                id: #id,
-            }
+        // For a valid JEP106 Code we need both cc and id
+        if cc.is_some() && id.is_some() {
+            Some(quote::quote! {
+                JEP106Code {
+                    cc: #cc,
+                    id: #id,
+                }
+            })
+        } else {
+            None
         }
     })
 }

probe-rs/build.rs

@@ -16,7 +16,16 @@ fn main() {
 
     let mut rustfmt = Command::new("rustfmt");
 
-    rustfmt.arg("--emit").arg("files").arg(dest_path);
+    rustfmt.arg("--emit").arg("files").arg(&dest_path);
 
-    rustfmt.status().expect("Failed to run rustfmt");
+    let fmt_result = rustfmt.status().expect("Failed to run rustfmt");
+
+    if !fmt_result.success() {
+        println!("cargo:warning=Failed to formated generated target file.",);
+        println!(
+            "cargo:warning='rustfmt --emit files {}' failed with {}",
+            dest_path.display(),
+            fmt_result
+        );
+    }
 }