Autocomplete support

This outputs your written code alongside a compile error in the case of a build time error, so that you get feedback from Rust Analyzer for autocomplete.

Author: codebycruz

src/lib.rs

@@ -9,23 +9,26 @@ use std::io::Write;
 /// Properly passes an error message to the compiler without crashing macro engines.
 macro_rules! build_error {
 	($($arg:tt)*) => {
-		format!("compile_error!(r#\"{}\"#)", format!($($arg)*))
+		format!("compile_error!(r#\"{}\"#);", format!($($arg)*))
 			.parse::<TokenStream>()
 			.unwrap()
 	};
 }
 
 #[proc_macro]
 #[doc = include_str!("../README.md")]
-pub fn comptime(code: TokenStream) -> TokenStream {
+pub fn comptime(mut code: TokenStream) -> TokenStream {
 	let mut out_dir = None;
 	let mut externs = vec![];
 
 	let mut args = std::env::args();
 	while let Some(arg) = args.next() {
 		// Push deps to rustc so you don't need to explicitly link with 'extern crate'
 		if arg == "--extern" {
-			externs.push(args.next().unwrap());
+			let ext = args.next().unwrap();
+			if !externs.contains(&ext) {
+				externs.push(ext)
+			}
 		} else if arg == "--out-dir" {
 			out_dir = args.next().map(std::path::PathBuf::from);
 		}
@@ -92,7 +95,9 @@ pub fn comptime(code: TokenStream) -> TokenStream {
 		};
 
 		if !output.status.success() {
-			return build_error!("{}", String::from_utf8_lossy(&output.stderr));
+			// Extend the code so that autocompletion works.
+			code.extend(build_error!("{}", String::from_utf8_lossy(&output.stderr)));
+			return code;
 		}
 	}
 

tests/main.rs

@@ -1,7 +1,16 @@
 use constime::comptime;
 
+#[test]
+fn test_const() {
+	const FORMATTED: &str = comptime! { format!("abc{}", 218) };
+	assert_eq!(FORMATTED, "abc218");
+}
+
 #[test]
 fn test_base() {
+	let x: Result<&str, std::env::VarError> = comptime! { std::env::var("CARGO_PKG_NAME") };
+	assert_eq!(x, Ok(env!("CARGO_PKG_NAME")));
+
 	assert_eq!(comptime! { 239 + 259 * 23 }, 239 + 259 * 23);
 	assert_eq!(comptime! { 2 + 259 * 7 }, 2 + 259 * 7);
 	assert_eq!(comptime! { String::from("test") }, "test");