Add better error messages for invalid globs.

This threads the original glob given by end users through all of the
glob parsing errors. This was slightly trickier than it might appear
because the gitignore implementation actually modifies the glob before
compiling it. So in order to get better glob error messages everywhere,
we need to track the original glob both in the glob parser and in the
higher-level abstractions in the `ignore` crate.

Fixes #444

globset/src/glob.rs

@@ -9,7 +9,7 @@ use std::str;
 use regex;
 use regex::bytes::Regex;
 
-use {Candidate, Error, new_regex};
+use {Candidate, Error, ErrorKind, new_regex};
 
 /// Describes a matching strategy for a particular pattern.
 ///
@@ -544,6 +544,7 @@ impl<'a> GlobBuilder<'a> {
     /// Parses and builds the pattern.
     pub fn build(&self) -> Result<Glob, Error> {
         let mut p = Parser {
+            glob: &self.glob,
             stack: vec![Tokens::default()],
             chars: self.glob.chars().peekable(),
             prev: None,
@@ -551,9 +552,15 @@ impl<'a> GlobBuilder<'a> {
         };
         try!(p.parse());
         if p.stack.is_empty() {
-            Err(Error::UnopenedAlternates)
+            Err(Error {
+                glob: Some(self.glob.to_string()),
+                kind: ErrorKind::UnopenedAlternates,
+            })
         } else if p.stack.len() > 1 {
-            Err(Error::UnclosedAlternates)
+            Err(Error {
+                glob: Some(self.glob.to_string()),
+                kind: ErrorKind::UnclosedAlternates,
+            })
         } else {
             let tokens = p.stack.pop().unwrap();
             Ok(Glob {
@@ -698,6 +705,7 @@ fn bytes_to_escaped_literal(bs: &[u8]) -> String {
 }
 
 struct Parser<'a> {
+    glob: &'a str,
     stack: Vec<Tokens>,
     chars: iter::Peekable<str::Chars<'a>>,
     prev: Option<char>,
@@ -705,6 +713,10 @@ struct Parser<'a> {
 }
 
 impl<'a> Parser<'a> {
+    fn error(&self, kind: ErrorKind) -> Error {
+        Error { glob: Some(self.glob.to_string()), kind: kind }
+    }
+
     fn parse(&mut self) -> Result<(), Error> {
         while let Some(c) = self.bump() {
             match c {
@@ -729,7 +741,7 @@ impl<'a> Parser<'a> {
 
     fn push_alternate(&mut self) -> Result<(), Error> {
         if self.stack.len() > 1 {
-            return Err(Error::NestedAlternates);
+            return Err(self.error(ErrorKind::NestedAlternates));
         }
         Ok(self.stack.push(Tokens::default()))
     }
@@ -743,22 +755,22 @@ impl<'a> Parser<'a> {
     }
 
     fn push_token(&mut self, tok: Token) -> Result<(), Error> {
-        match self.stack.last_mut() {
-            None => Err(Error::UnopenedAlternates),
-            Some(ref mut pat) => Ok(pat.push(tok)),
+        if let Some(ref mut pat) = self.stack.last_mut() {
+            return Ok(pat.push(tok));
         }
+        Err(self.error(ErrorKind::UnopenedAlternates))
     }
 
     fn pop_token(&mut self) -> Result<Token, Error> {
-        match self.stack.last_mut() {
-            None => Err(Error::UnopenedAlternates),
-            Some(ref mut pat) => Ok(pat.pop().unwrap()),
+        if let Some(ref mut pat) = self.stack.last_mut() {
+            return Ok(pat.pop().unwrap());
         }
+        Err(self.error(ErrorKind::UnopenedAlternates))
     }
 
     fn have_tokens(&self) -> Result<bool, Error> {
         match self.stack.last() {
-            None => Err(Error::UnopenedAlternates),
+            None => Err(self.error(ErrorKind::UnopenedAlternates)),
             Some(ref pat) => Ok(!pat.is_empty()),
         }
     }
@@ -785,7 +797,7 @@ impl<'a> Parser<'a> {
             try!(self.push_token(Token::RecursivePrefix));
             let next = self.bump();
             if !next.map(is_separator).unwrap_or(true) {
-                return Err(Error::InvalidRecursive);
+                return Err(self.error(ErrorKind::InvalidRecursive));
             }
             return Ok(());
         }
@@ -793,7 +805,7 @@ impl<'a> Parser<'a> {
         if !prev.map(is_separator).unwrap_or(false) {
             if self.stack.len() <= 1
                 || (prev != Some(',') && prev != Some('{')) {
-                return Err(Error::InvalidRecursive);
+                return Err(self.error(ErrorKind::InvalidRecursive));
             }
         }
         match self.chars.peek() {
@@ -808,18 +820,22 @@ impl<'a> Parser<'a> {
                 assert!(self.bump().map(is_separator).unwrap_or(false));
                 self.push_token(Token::RecursiveZeroOrMore)
             }
-            _ => Err(Error::InvalidRecursive),
+            _ => Err(self.error(ErrorKind::InvalidRecursive)),
         }
     }
 
     fn parse_class(&mut self) -> Result<(), Error> {
         fn add_to_last_range(
+            glob: &str,
             r: &mut (char, char),
             add: char,
         ) -> Result<(), Error> {
             r.1 = add;
             if r.1 < r.0 {
-                Err(Error::InvalidRange(r.0, r.1))
+                Err(Error {
+                    glob: Some(glob.to_string()),
+                    kind: ErrorKind::InvalidRange(r.0, r.1),
+                })
             } else {
                 Ok(())
             }
@@ -837,7 +853,7 @@ impl<'a> Parser<'a> {
                 Some(c) => c,
                 // The only way to successfully break this loop is to observe
                 // a ']'.
-                None => return Err(Error::UnclosedClass),
+                None => return Err(self.error(ErrorKind::UnclosedClass)),
             };
             match c {
                 ']' => {
@@ -854,7 +870,7 @@ impl<'a> Parser<'a> {
                         // invariant: in_range is only set when there is
                         // already at least one character seen.
                         let r = ranges.last_mut().unwrap();
-                        try!(add_to_last_range(r, '-'));
+                        try!(add_to_last_range(&self.glob, r, '-'));
                         in_range = false;
                     } else {
                         assert!(!ranges.is_empty());
@@ -865,7 +881,8 @@ impl<'a> Parser<'a> {
                     if in_range {
                         // invariant: in_range is only set when there is
                         // already at least one character seen.
-                        try!(add_to_last_range(ranges.last_mut().unwrap(), c));
+                        try!(add_to_last_range(
+                            &self.glob, ranges.last_mut().unwrap(), c));
                     } else {
                         ranges.push((c, c));
                     }
@@ -909,7 +926,7 @@ fn ends_with(needle: &[u8], haystack: &[u8]) -> bool {
 mod tests {
     use std::ffi::{OsStr, OsString};
 
-    use {GlobSetBuilder, Error};
+    use {GlobSetBuilder, ErrorKind};
     use super::{Glob, GlobBuilder, Token};
     use super::Token::*;
 
@@ -934,7 +951,7 @@ mod tests {
             #[test]
             fn $name() {
                 let err = Glob::new($pat).unwrap_err();
-                assert_eq!($err, err);
+                assert_eq!(&$err, err.kind());
             }
         }
     }
@@ -1057,19 +1074,19 @@ mod tests {
     syntax!(cls18, "[!0-9a-z]", vec![rclassn(&[('0', '9'), ('a', 'z')])]);
     syntax!(cls19, "[!a-z0-9]", vec![rclassn(&[('a', 'z'), ('0', '9')])]);
 
-    syntaxerr!(err_rseq1, "a**", Error::InvalidRecursive);
-    syntaxerr!(err_rseq2, "**a", Error::InvalidRecursive);
-    syntaxerr!(err_rseq3, "a**b", Error::InvalidRecursive);
-    syntaxerr!(err_rseq4, "***", Error::InvalidRecursive);
-    syntaxerr!(err_rseq5, "/a**", Error::InvalidRecursive);
-    syntaxerr!(err_rseq6, "/**a", Error::InvalidRecursive);
-    syntaxerr!(err_rseq7, "/a**b", Error::InvalidRecursive);
-    syntaxerr!(err_unclosed1, "[", Error::UnclosedClass);
-    syntaxerr!(err_unclosed2, "[]", Error::UnclosedClass);
-    syntaxerr!(err_unclosed3, "[!", Error::UnclosedClass);
-    syntaxerr!(err_unclosed4, "[!]", Error::UnclosedClass);
-    syntaxerr!(err_range1, "[z-a]", Error::InvalidRange('z', 'a'));
-    syntaxerr!(err_range2, "[z--]", Error::InvalidRange('z', '-'));
+    syntaxerr!(err_rseq1, "a**", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq2, "**a", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq3, "a**b", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq4, "***", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq5, "/a**", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq6, "/**a", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_rseq7, "/a**b", ErrorKind::InvalidRecursive);
+    syntaxerr!(err_unclosed1, "[", ErrorKind::UnclosedClass);
+    syntaxerr!(err_unclosed2, "[]", ErrorKind::UnclosedClass);
+    syntaxerr!(err_unclosed3, "[!", ErrorKind::UnclosedClass);
+    syntaxerr!(err_unclosed4, "[!]", ErrorKind::UnclosedClass);
+    syntaxerr!(err_range1, "[z-a]", ErrorKind::InvalidRange('z', 'a'));
+    syntaxerr!(err_range2, "[z--]", ErrorKind::InvalidRange('z', '-'));
 
     const CASEI: Options = Options {
         casei: true,

globset/src/lib.rs

@@ -128,7 +128,16 @@ mod pathutil;
 
 /// Represents an error that can occur when parsing a glob pattern.
 #[derive(Clone, Debug, Eq, PartialEq)]
-pub enum Error {
+pub struct Error {
+    /// The original glob provided by the caller.
+    glob: Option<String>,
+    /// The kind of error.
+    kind: ErrorKind,
+}
+
+/// The kind of error that can occur when parsing a glob pattern.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum ErrorKind {
     /// Occurs when a use of `**` is invalid. Namely, `**` can only appear
     /// adjacent to a path separator, or the beginning/end of a glob.
     InvalidRecursive,
@@ -150,45 +159,74 @@ pub enum Error {
 }
 
 impl StdError for Error {
+    fn description(&self) -> &str {
+        self.kind.description()
+    }
+}
+
+impl Error {
+    /// Return the glob that caused this error, if one exists.
+    pub fn glob(&self) -> Option<&str> {
+        self.glob.as_ref().map(|s| &**s)
+    }
+
+    /// Return the kind of this error.
+    pub fn kind(&self) -> &ErrorKind {
+        &self.kind
+    }
+}
+
+impl ErrorKind {
     fn description(&self) -> &str {
         match *self {
-            Error::InvalidRecursive => {
+            ErrorKind::InvalidRecursive => {
                 "invalid use of **; must be one path component"
             }
-            Error::UnclosedClass => {
+            ErrorKind::UnclosedClass => {
                 "unclosed character class; missing ']'"
             }
-            Error::InvalidRange(_, _) => {
+            ErrorKind::InvalidRange(_, _) => {
                 "invalid character range"
             }
-            Error::UnopenedAlternates => {
+            ErrorKind::UnopenedAlternates => {
                 "unopened alternate group; missing '{' \
                 (maybe escape '}' with '[}]'?)"
             }
-            Error::UnclosedAlternates => {
+            ErrorKind::UnclosedAlternates => {
                 "unclosed alternate group; missing '}' \
                 (maybe escape '{' with '[{]'?)"
             }
-            Error::NestedAlternates => {
+            ErrorKind::NestedAlternates => {
                 "nested alternate groups are not allowed"
             }
-            Error::Regex(ref err) => err,
+            ErrorKind::Regex(ref err) => err,
         }
     }
 }
 
 impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.glob {
+            None => self.kind.fmt(f),
+            Some(ref glob) => {
+                write!(f, "error parsing glob '{}': {}", glob, self.kind)
+            }
+        }
+    }
+}
+
+impl fmt::Display for ErrorKind {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            Error::InvalidRecursive
-            | Error::UnclosedClass
-            | Error::UnopenedAlternates
-            | Error::UnclosedAlternates
-            | Error::NestedAlternates
-            | Error::Regex(_) => {
+            ErrorKind::InvalidRecursive
+            | ErrorKind::UnclosedClass
+            | ErrorKind::UnopenedAlternates
+            | ErrorKind::UnclosedAlternates
+            | ErrorKind::NestedAlternates
+            | ErrorKind::Regex(_) => {
                 write!(f, "{}", self.description())
             }
-            Error::InvalidRange(s, e) => {
+            ErrorKind::InvalidRange(s, e) => {
                 write!(f, "invalid range; '{}' > '{}'", s, e)
             }
         }
@@ -201,12 +239,22 @@ fn new_regex(pat: &str) -> Result<Regex, Error> {
         .size_limit(10 * (1 << 20))
         .dfa_size_limit(10 * (1 << 20))
         .build()
-        .map_err(|err| Error::Regex(err.to_string()))
+        .map_err(|err| {
+            Error {
+                glob: Some(pat.to_string()),
+                kind: ErrorKind::Regex(err.to_string()),
+            }
+        })
 }
 
 fn new_regex_set<I, S>(pats: I) -> Result<RegexSet, Error>
         where S: AsRef<str>, I: IntoIterator<Item=S> {
-    RegexSet::new(pats).map_err(|err| Error::Regex(err.to_string()))
+    RegexSet::new(pats).map_err(|err| {
+        Error {
+            glob: None,
+            kind: ErrorKind::Regex(err.to_string()),
+        }
+    })
 }
 
 type Fnv = hash::BuildHasherDefault<fnv::FnvHasher>;

ignore/src/gitignore.rs

@@ -279,7 +279,12 @@ impl GitignoreBuilder {
         let nignore = self.globs.iter().filter(|g| !g.is_whitelist()).count();
         let nwhite = self.globs.iter().filter(|g| g.is_whitelist()).count();
         let set = try!(
-            self.builder.build().map_err(|err| Error::Glob(err.to_string())));
+            self.builder.build().map_err(|err| {
+                Error::Glob {
+                    glob: None,
+                    err: err.to_string(),
+                }
+            }));
         Ok(Gitignore {
             set: set,
             root: self.root.clone(),
@@ -420,7 +425,12 @@ impl GitignoreBuilder {
             GlobBuilder::new(&glob.actual)
                 .literal_separator(literal_separator)
                 .build()
-                .map_err(|err| Error::Glob(err.to_string())));
+                .map_err(|err| {
+                    Error::Glob {
+                        glob: Some(glob.original.clone()),
+                        err: err.kind().to_string(),
+                    }
+                }));
         self.builder.add(parsed);
         self.globs.push(glob);
         Ok(self)

ignore/src/lib.rs

@@ -112,7 +112,17 @@ pub enum Error {
     /// An error that occurs when doing I/O, such as reading an ignore file.
     Io(io::Error),
     /// An error that occurs when trying to parse a glob.
-    Glob(String),
+    Glob {
+        /// The original glob that caused this error. This glob, when
+        /// available, always corresponds to the glob provided by an end user.
+        /// e.g., It is the glob as writtein in a `.gitignore` file.
+        ///
+        /// (This glob may be distinct from the glob that is actually
+        /// compiled, after accounting for `gitignore` semantics.)
+        glob: Option<String>,
+        /// The underlying glob error as a string.
+        err: String,
+    },
     /// A type selection for a file type that is not defined.
     UnrecognizedFileType(String),
     /// A user specified file type definition could not be parsed.
@@ -144,7 +154,7 @@ impl Error {
             Error::WithDepth { ref err, .. } => err.is_io(),
             Error::Loop { .. } => false,
             Error::Io(_) => true,
-            Error::Glob(_) => false,
+            Error::Glob { .. } => false,
             Error::UnrecognizedFileType(_) => false,
             Error::InvalidDefinition => false,
         }
@@ -199,7 +209,7 @@ impl error::Error for Error {
             Error::WithDepth { ref err, .. } => err.description(),
             Error::Loop { .. } => "file system loop found",
             Error::Io(ref err) => err.description(),
-            Error::Glob(ref msg) => msg,
+            Error::Glob { ref err, .. } => err,
             Error::UnrecognizedFileType(_) => "unrecognized file type",
             Error::InvalidDefinition => "invalid definition",
         }
@@ -227,7 +237,10 @@ impl fmt::Display for Error {
                           child.display(), ancestor.display())
             }
             Error::Io(ref err) => err.fmt(f),
-            Error::Glob(ref msg) => write!(f, "{}", msg),
+            Error::Glob { glob: None, ref err } => write!(f, "{}", err),
+            Error::Glob { glob: Some(ref glob), ref err } => {
+                write!(f, "error parsing glob '{}': {}", glob, err)
+            }
             Error::UnrecognizedFileType(ref ty) => {
                 write!(f, "unrecognized file type: {}", ty)
             }

ignore/src/types.rs

@@ -448,13 +448,18 @@ impl TypesBuilder {
                     GlobBuilder::new(glob)
                         .literal_separator(true)
                         .build()
-                        .map_err(|err| Error::Glob(err.to_string()))));
+                        .map_err(|err| {
+                            Error::Glob {
+                                glob: Some(glob.to_string()),
+                                err: err.kind().to_string(),
+                            }
+                        })));
                 glob_to_selection.push((isel, iglob));
             }
             selections.push(selection.clone().map(move |_| def));
         }
         let set = try!(build_set.build().map_err(|err| {
-            Error::Glob(err.to_string())
+            Error::Glob { glob: None, err: err.to_string() }
         }));
         Ok(Types {
             defs: defs,