Initial commit

.gitignore

+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
\ No newline at end of file

.vscode/tasks.json

+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "type": "cargo",
+            "label": "cargo build",
+            "command": "cargo",
+            "args": [
+                "build"
+            ],
+            "problemMatcher": [
+                "$rustc"
+            ]
+        },
+        {
+            "type": "shell",
+            "label": "cargo build --example example",
+            "command": "cargo build --example example",
+            "problemMatcher": [
+                "$rustc"
+            ],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        }
+    ]
+}
\ No newline at end of file

Cargo.toml

+[package]
+name = "array-debug"
+version = "0.1.0"
+authors = ["Per Lindgren <per.lindgren@ltu.se>"]
+edition = "2018"
+
+[dependencies]

examples/example.rs

+extern crate array_debug;
+
+use array_debug::ArrayDebug;
+
+#[derive(Debug)]
+struct RegisterBlock {
+    primitive: u32,
+    small: ArrayDebug<[u32; 3], u32>,
+    big: ArrayDebug<[u32; 44], u32>,
+}
+
+fn main() {
+    let t = ArrayDebug::new([1, 2, 3]);
+    println!("<=32 :{:?}", t);
+
+    let t = ArrayDebug::new([1; 33]);
+    println!(">32 :{:?}", t);
+
+    let r = RegisterBlock {
+        primitive: 7,
+        small: ArrayDebug::new([1, 3, 4]),
+        big: ArrayDebug::new([8; 44]),
+    };
+
+    println!("r :{:?}", r);
+
+    println!("here");
+}

src/lib.rs

+#![feature(unsize)]
+
+use core::iter::Iterator;
+use core::{fmt, marker::PhantomData, marker::Unsize};
+
+pub struct ArrayDebug<A, T>(A, PhantomData<T>)
+where
+    A: Unsize<[T]>,
+    T: fmt::Debug;
+
+impl<A, T> ArrayDebug<A, T>
+where
+    A: Unsize<[T]>,
+    T: fmt::Debug,
+{
+    pub fn new(x: A) -> ArrayDebug<A, T> {
+        ArrayDebug(x, PhantomData)
+    }
+}
+
+impl<A, T> fmt::Debug for ArrayDebug<A, T>
+where
+    A: Unsize<[T]>,
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let slice: &[T] = &self.0;
+        let mut slice = slice.iter().peekable();
+        f.write_fmt(format_args!("["))?;
+        while let Some(i) = slice.next() {
+            f.write_fmt(format_args!("{:?}", i))?;
+            if slice.peek().is_some() {
+                f.write_fmt(format_args!(", "))?;
+            }
+        }
+        f.write_fmt(format_args!("]"))
+    }
+}

src/main.rs

+#![feature(unsize)]
+
+use core::iter::Iterator;
+use core::{fmt, marker::PhantomData, marker::Unsize};
+
+struct ArrayDebug<A, T>(A, PhantomData<T>)
+where
+    A: Unsize<[T]>,
+    T: fmt::Debug;
+
+impl<A, T> fmt::Debug for ArrayDebug<A, T>
+where
+    A: Unsize<[T]>,
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let slice: &[T] = &self.0;
+        let mut slice = slice.iter().peekable();
+        f.write_fmt(format_args!("["))?;
+        while let Some(i) = slice.next() {
+            f.write_fmt(format_args!("{:?}", i))?;
+            if slice.peek().is_some() {
+                f.write_fmt(format_args!(", "))?;
+            }
+        }
+        f.write_fmt(format_args!("]"))
+    }
+}
+
+// example
+#[derive(Debug)]
+struct RegisterBlock {
+    primitive: u32,
+    small: ArrayDebug<[u32; 3], u32>,
+    big: ArrayDebug<[u32; 44], u32>,
+}
+
+fn main() {
+    let t = ArrayDebug([1, 2, 3], PhantomData);
+    println!("<=32 :{:?}", t);
+
+    let t = ArrayDebug([1; 33], PhantomData);
+    println!(">32 :{:?}", t);
+
+    let r = RegisterBlock {
+        primitive: 7,
+        small: ArrayDebug([1, 3, 4], PhantomData),
+        big: ArrayDebug([8; 44], PhantomData),
+    };
+
+    println!("r :{:?}", r);
+}