Improve error on wildcard after another comparator

Author: dtolnay

src/error.rs

@@ -10,7 +10,7 @@ pub(crate) enum ErrorKind {
     Overflow(Position),
     EmptySegment(Position),
     IllegalCharacter(Position),
-    CommaAfterWildcard(char),
+    WildcardNotTheOnlyComparator(char),
     UnexpectedAfterWildcard,
     ExcessiveComparators,
 }
@@ -59,7 +59,7 @@ impl Display for Error {
             ErrorKind::IllegalCharacter(pos) => {
                 write!(formatter, "unexpected character in {}", pos)
             }
-            ErrorKind::CommaAfterWildcard(ch) => {
+            ErrorKind::WildcardNotTheOnlyComparator(ch) => {
                 write!(
                     formatter,
                     "wildcard req ({}) must be the only comparator in the version req",

src/parse.rs

@@ -92,7 +92,7 @@ impl FromStr for VersionReq {
                     comparators: Vec::new(),
                 });
             } else if rest.starts_with(',') {
-                return Err(Error::new(ErrorKind::CommaAfterWildcard(ch)));
+                return Err(Error::new(ErrorKind::WildcardNotTheOnlyComparator(ch)));
             } else {
                 return Err(Error::new(ErrorKind::UnexpectedAfterWildcard));
             }
@@ -365,7 +365,18 @@ fn comparator(input: &str) -> Result<(Comparator, Position, &str), Error> {
 }
 
 fn version_req(input: &str, out: &mut Vec<Comparator>, depth: usize) -> Result<usize, Error> {
-    let (comparator, pos, text) = comparator(input)?;
+    let (comparator, pos, text) = match comparator(input) {
+        Ok(success) => success,
+        Err(mut error) => {
+            if let Some((ch, mut rest)) = wildcard(input) {
+                rest = rest.trim_start_matches(' ');
+                if rest.is_empty() || rest.starts_with(',') {
+                    error.kind = ErrorKind::WildcardNotTheOnlyComparator(ch);
+                }
+            }
+            return Err(error);
+        }
+    };
 
     if text.is_empty() {
         out.reserve_exact(depth + 1);

tests/test_version_req.rs

@@ -425,6 +425,12 @@ fn test_wildcard_and_another() {
     let err = req_err("0.20.0-any, *");
     assert_to_string(
         err,
-        "unexpected character '*' while parsing major version number",
+        "wildcard req (*) must be the only comparator in the version req",
+    );
+
+    let err = req_err("0.20.0-any, *, 1.0");
+    assert_to_string(
+        err,
+        "wildcard req (*) must be the only comparator in the version req",
     );
 }