clean up CmdString

use From/Into trait to simplify code

Author: tao-guo

macros/src/lexer.rs

@@ -14,7 +14,7 @@ use std::iter::Peekable;
 pub fn scan_str_lit(lit: &Literal) -> TokenStream {
     let s = lit.to_string();
     if !s.starts_with('\"') {
-        return quote!(::cmd_lib::CmdString::default().append(&#lit));
+        return quote!(::cmd_lib::CmdString::from(&#lit));
     }
     let mut iter = s[1..s.len() - 1] // To trim outside ""
         .chars()

src/process.rs

@@ -541,7 +541,7 @@ pub trait AsOsStr {
 
 impl<T: ToString> AsOsStr for T {
     fn as_os_str(&self) -> OsString {
-        OsString::from(self.to_string())
+        self.to_string().into()
     }
 }
 
@@ -559,9 +559,16 @@ impl CmdString {
     }
 
     pub fn into_path_buf(self) -> PathBuf {
-        PathBuf::from(self.0)
+        self.0.into()
     }
 }
+
+impl<T: ?Sized + AsRef<OsStr>> From<&T> for CmdString {
+    fn from(s: &T) -> Self {
+        Self(s.as_ref().into())
+    }
+}
+
 impl fmt::Display for CmdString {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(&self.0.to_string_lossy())