Use as_str() method to reference GeneralDnsNameRef contents

The From impl feels a little unidiomatic because the GeneralDnsNameRef is
not consumed. An AsRef impl would unnecessarily constrain the lifetime of
the output value to `&self`, whereas it can live as long as `'a`.

Author: djc

src/end_entity.rs

@@ -217,7 +217,7 @@ mod tests {
         let mut names = cert
             .dns_names()
             .expect("should get all DNS names correctly for end entity cert");
-        assert_eq!(names.next().map(<&str>::from), Some(name));
-        assert_eq!(names.next().map(<&str>::from), None);
+        assert_eq!(names.next().map(|name| name.as_str()), Some(name));
+        assert_eq!(names.next().map(|name| name.as_str()), None);
     }
 }

src/subject_name/dns_name.rs

@@ -28,11 +28,12 @@ pub enum GeneralDnsNameRef<'name> {
     Wildcard(WildcardDnsNameRef<'name>),
 }
 
-impl<'a> From<GeneralDnsNameRef<'a>> for &'a str {
-    fn from(d: GeneralDnsNameRef<'a>) -> Self {
-        match d {
-            GeneralDnsNameRef::DnsName(name) => name.as_str(),
-            GeneralDnsNameRef::Wildcard(name) => name.as_str(),
+impl<'a> GeneralDnsNameRef<'a> {
+    /// Yields the DNS name as a `&str`.
+    pub fn as_str(&self) -> &'a str {
+        match self {
+            Self::DnsName(name) => name.as_str(),
+            Self::Wildcard(name) => name.as_str(),
         }
     }
 }

tests/integration.rs

@@ -351,7 +351,7 @@ fn expect_cert_dns_names(data: &[u8], expected_names: &[&str]) {
     assert_eq!(actual_names.len(), expected_names.len());
 
     let actual_names: std::collections::HashSet<&str> =
-        actual_names.drain(..).map(|name| name.into()).collect();
+        actual_names.drain(..).map(|name| name.as_str()).collect();
 
     assert_eq!(actual_names, expected_names);
 }