fix: relax sized req on cow (#21)

Author: prestwich

Cargo.toml

@@ -4,7 +4,7 @@ name = "init4-bin-base"
 description = "Internal utilities for binaries produced by the init4 team"
 keywords = ["init4", "bin", "base"]
 
-version = "0.3.1"
+version = "0.3.2"
 edition = "2021"
 rust-version = "1.81"
 authors = ["init4", "James Prestwich"]

src/utils/from_env.rs

@@ -371,7 +371,7 @@ where
 impl<T, U> FromEnv for std::borrow::Cow<'static, U>
 where
     T: FromEnv,
-    U: std::borrow::ToOwned<Owned = T> + core::fmt::Debug,
+    U: std::borrow::ToOwned<Owned = T> + core::fmt::Debug + ?Sized,
 {
     type Error = T::Error;
 
@@ -538,7 +538,7 @@ where
 impl<T, U> FromEnvVar for std::borrow::Cow<'static, U>
 where
     T: FromEnvVar,
-    U: std::borrow::ToOwned<Owned = T> + core::fmt::Debug,
+    U: std::borrow::ToOwned<Owned = T> + core::fmt::Debug + ?Sized,
 {
     type Error = T::Error;
 
@@ -639,13 +639,13 @@ impl FromEnvVar for bool {
 
 #[cfg(test)]
 mod test {
-    use std::time::Duration;
+    use std::{borrow::Cow, time::Duration};
 
     use super::*;
 
     fn set<T>(env: &str, val: &T)
     where
-        T: ToString,
+        T: ToString + ?Sized,
     {
         std::env::set_var(env, val.to_string());
     }
@@ -720,4 +720,12 @@ mod test {
 
         test_expect_err::<u8, _>("U8_", "", FromEnvErr::empty("U8_"));
     }
+
+    #[test]
+    fn is_cow_str_from_env_var() {
+        let s = "hello";
+        set("COW", s);
+        let res: Cow<'static, str> = Cow::from_env_var("COW").unwrap();
+        assert_eq!(res, Cow::<'static, str>::Owned(s.to_owned()));
+    }
 }

tests/macro.rs

@@ -13,6 +13,9 @@ pub struct MyCfg {
     #[from_env(var = "PERFECT", desc = "A bold and neat string", infallible)]
     pub strings_cannot_fail: String,
 
+    #[from_env(var = "COW", desc = "Cow<str>", infallible)]
+    pub cow: std::borrow::Cow<'static, str>,
+
     #[from_env(
         var = "MAYBE_NOT_NEEDED",
         desc = "This is an optional string",
@@ -31,12 +34,12 @@ pub struct MyTupleCfg(
 #[test]
 fn basic_inventory() {
     let inv = MyCfg::inventory();
-    assert_eq!(inv.len(), 4);
+    assert_eq!(inv.len(), 5);
 }
 
 #[test]
 fn nested_inventory() {
     let inv = MyTupleCfg::inventory();
-    assert_eq!(inv.len(), 5);
+    assert_eq!(inv.len(), 6);
     dbg!(inv);
 }