ripgrep: add --ignore-file-case-insensitive

The --ignore-file-case-insensitive flag causes all
.gitignore/.rgignore/.ignore files to have their globs matched without
regard for case. Because this introduces a potentially significant
performance regression, this is always disabled by default. Users that
need case insensitive matching can enable it on a case by case basis.

Closes #1164, Closes #1170

10 files changed, 156 insertions, 21 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 53c21cc2..e7792a3d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,13 @@
+0.11.0 (TBD)
+============
+TODO.
+
+Feature enhancements:
+
+* [FEATURE #1170](https://github.com/BurntSushi/ripgrep/pull/1170):
+  Add `--ignore-file-case-insensitive` for case insensitive .ignore globs.
+
+
 0.10.0 (2018-09-07)
 ===================
 This is a new minor version release of ripgrep that contains some major new
diff --git a/GUIDE.md b/GUIDE.md
index ffcbff9f..8523b6a5 100644
--- a/GUIDE.md
+++ b/GUIDE.md
@@ -235,6 +235,11 @@ Like `.gitignore`, a `.ignore` file can be placed in any directory. Its rules
 will be processed with respect to the directory it resides in, just like
 `.gitignore`.
 
+To process `.gitignore` and `.ignore` files case insensitively, use the flag
+`--ignore-file-case-insensitive`. This is especially useful on case insensitive
+file systems like those on Windows and macOS. Note though that this can come
+with a significant performance penalty, and is therefore disabled by default.
+
 For a more in depth description of how glob patterns in a `.gitignore` file
 are interpreted, please see `man gitignore`.
 
diff --git a/complete/_rg b/complete/_rg
index 6f7b0ef8..f48c0998 100644
--- a/complete/_rg
+++ b/complete/_rg
@@ -115,6 +115,10 @@ _rg() {
     "(--no-ignore-global --no-ignore-parent --no-ignore-vcs)--no-ignore[don't respect ignore files]"
     $no'(--ignore-global --ignore-parent --ignore-vcs)--ignore[respect ignore files]'
 
+    + '(ignore-file-case-insensitive)' # Ignore-file case sensitivity options
+    '--ignore-file-case-insensitive[process ignore files case insensitively]'
+    $no'--no-ignore-file-case-insensitive[process ignore files case sensitively]'
+
     + '(ignore-global)' # Global ignore-file options
     "--no-ignore-global[don't respect global ignore files]"
     $no'--ignore-global[respect global ignore files]'
diff --git a/ignore/src/dir.rs b/ignore/src/dir.rs
index 66b18635..30f4cb87 100644
--- a/ignore/src/dir.rs
+++ b/ignore/src/dir.rs
@@ -73,6 +73,8 @@ struct IgnoreOptions {
     git_ignore: bool,
     /// Whether to read .git/info/exclude files.
     git_exclude: bool,
+    /// Whether to ignore files case insensitively
+    ignore_case_insensitive: bool,
 }
 
 /// Ignore is a matcher useful for recursively walking one or more directories.
@@ -225,7 +227,11 @@ impl Ignore {
                 Gitignore::empty()
             } else {
                 let (m, err) =
-                    create_gitignore(&dir, &self.0.custom_ignore_filenames);
+                    create_gitignore(
+                        &dir,
+                        &self.0.custom_ignore_filenames,
+                        self.0.opts.ignore_case_insensitive,
+                    );
                 errs.maybe_push(err);
                 m
             };
@@ -233,7 +239,12 @@ impl Ignore {
             if !self.0.opts.ignore {
                 Gitignore::empty()
             } else {
-                let (m, err) = create_gitignore(&dir, &[".ignore"]);
+                let (m, err) =
+                    create_gitignore(
+                        &dir,
+                        &[".ignore"],
+                        self.0.opts.ignore_case_insensitive,
+                    );
                 errs.maybe_push(err);
                 m
             };
@@ -241,7 +252,12 @@ impl Ignore {
             if !self.0.opts.git_ignore {
                 Gitignore::empty()
             } else {
-                let (m, err) = create_gitignore(&dir, &[".gitignore"]);
+                let (m, err) =
+                    create_gitignore(
+                        &dir,
+                        &[".gitignore"],
+                        self.0.opts.ignore_case_insensitive,
+                    );
                 errs.maybe_push(err);
                 m
             };
@@ -249,7 +265,12 @@ impl Ignore {
             if !self.0.opts.git_exclude {
                 Gitignore::empty()
             } else {
-                let (m, err) = create_gitignore(&dir, &[".git/info/exclude"]);
+                let (m, err) =
+                    create_gitignore(
+                        &dir,
+                        &[".git/info/exclude"],
+                        self.0.opts.ignore_case_insensitive,
+                    );
                 errs.maybe_push(err);
                 m
             };
@@ -483,6 +504,7 @@ impl IgnoreBuilder {
                 git_global: true,
                 git_ignore: true,
                 git_exclude: true,
+                ignore_case_insensitive: false,
             },
         }
     }
@@ -496,7 +518,11 @@ impl IgnoreBuilder {
             if !self.opts.git_global {
                 Gitignore::empty()
             } else {
-                let (gi, err) = Gitignore::global();
+                let mut builder = GitignoreBuilder::new("");
+                builder
+                    .case_insensitive(self.opts.ignore_case_insensitive)
+                    .unwrap();
+                let (gi, err) = builder.build_global();
                 if let Some(err) = err {
                     debug!("{}", err);
                 }
@@ -627,6 +653,17 @@ impl IgnoreBuilder {
         self.opts.git_exclude = yes;
         self
     }
+
+    /// Process ignore files case insensitively
+    ///
+    /// This is disabled by default.
+    pub fn ignore_case_insensitive(
+        &mut self,
+        yes: bool,
+    ) -> &mut IgnoreBuilder {
+        self.opts.ignore_case_insensitive = yes;
+        self
+    }
 }
 
 /// Creates a new gitignore matcher for the directory given.
@@ -638,9 +675,11 @@ impl IgnoreBuilder {
 pub fn create_gitignore<T: AsRef<OsStr>>(
     dir: &Path,
     names: &[T],
+    case_insensitive: bool,
 ) -> (Gitignore, Option<Error>) {
     let mut builder = GitignoreBuilder::new(dir);
     let mut errs = PartialErrorBuilder::default();
+    builder.case_insensitive(case_insensitive).unwrap();
     for name in names {
         let gipath = dir.join(name.as_ref());
         errs.maybe_push_ignore_io(builder.add(gipath));
diff --git a/ignore/src/gitignore.rs b/ignore/src/gitignore.rs
index a151e2de..66f98dfe 100644
--- a/ignore/src/gitignore.rs
+++ b/ignore/src/gitignore.rs
@@ -127,16 +127,7 @@ impl Gitignore {
     /// `$XDG_CONFIG_HOME/git/ignore` is read. If `$XDG_CONFIG_HOME` is not
     /// set or is empty, then `$HOME/.config/git/ignore` is used instead.
     pub fn global() -> (Gitignore, Option<Error>) {
-        match gitconfig_excludes_path() {
-            None => (Gitignore::empty(), None),
-            Some(path) => {
-                if !path.is_file() {
-                    (Gitignore::empty(), None)
-                } else {
-                    Gitignore::new(path)
-                }
-            }
-        }
+        GitignoreBuilder::new("").build_global()
     }
 
     /// Creates a new empty gitignore matcher that never matches anything.
@@ -359,6 +350,36 @@ impl GitignoreBuilder {
         })
     }
 
+    /// Build a global gitignore matcher using the configuration in this
+    /// builder.
+    ///
+    /// This consumes ownership of the builder unlike `build` because it
+    /// must mutate the builder to add the global gitignore globs.
+    ///
+    /// Note that this ignores the path given to this builder's constructor
+    /// and instead derives the path automatically from git's global
+    /// configuration.
+    pub fn build_global(mut self) -> (Gitignore, Option<Error>) {
+        match gitconfig_excludes_path() {
+            None => (Gitignore::empty(), None),
+            Some(path) => {
+                if !path.is_file() {
+                    (Gitignore::empty(), None)
+                } else {
+                    let mut errs = PartialErrorBuilder::default();
+                    errs.maybe_push_ignore_io(self.add(path));
+                    match self.build() {
+                        Ok(gi) => (gi, errs.into_error_option()),
+                        Err(err) => {
+                            errs.push(err);
+                            (Gitignore::empty(), errs.into_error_option())
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     /// Add each glob from the file path given.
     ///
     /// The file given should be formatted as a `gitignore` file.
@@ -505,12 +526,16 @@ impl GitignoreBuilder {
 
     /// Toggle whether the globs should be matched case insensitively or not.
     ///
-    /// When this option is changed, only globs added after the change will be affected.
+    /// When this option is changed, only globs added after the change will be
+    /// affected.
     ///
     /// This is disabled by default.
     pub fn case_insensitive(
-        &mut self, yes: bool
+        &mut self,
+        yes: bool,
     ) -> Result<&mut GitignoreBuilder, Error> {
+        // TODO: This should not return a `Result`. Fix this in the next semver
+        // release.
         self.case_insensitive = yes;
         Ok(self)
     }
diff --git a/ignore/src/overrides.rs b/ignore/src/overrides.rs
index c63532af..08dbdac2 100644
--- a/ignore/src/overrides.rs
+++ b/ignore/src/overrides.rs
@@ -139,13 +139,16 @@ impl OverrideBuilder {
     }
 
     /// Toggle whether the globs should be matched case insensitively or not.
-    /// 
+    ///
     /// When this option is changed, only globs added after the change will be affected.
     ///
     /// This is disabled by default.
     pub fn case_insensitive(
-        &mut self, yes: bool
+        &mut self,
+        yes: bool,
     ) -> Result<&mut OverrideBuilder, Error> {
+        // TODO: This should not return a `Result`. Fix this in the next semver
+        // release.
         self.builder.case_insensitive(yes)?;
         Ok(self)
     }
diff --git a/ignore/src/walk.rs b/ignore/src/walk.rs
index aee7a881..ae1f58ba 100644
--- a/ignore/src/walk.rs
+++ b/ignore/src/walk.rs
@@ -764,6 +764,14 @@ impl WalkBuilder {
         self
     }
 
+    /// Process ignore files case insensitively
+    ///
+    /// This is disabled by default.
+    pub fn ignore_case_insensitive(&mut self, yes: bool) -> &mut WalkBuilder {
+        self.ig_builder.ignore_case_insensitive(yes);
+        self
+    }
+
     /// Set a function for sorting directory entries by their path.
     ///
     /// If a compare function is set, the resulting iterator will return all
diff --git a/src/app.rs b/src/app.rs
index 5b25b72f..037feec3 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -571,6 +571,7 @@ pub fn all_args_and_flags() -> Vec<RGArg> {
     flag_iglob(&mut args);
     flag_ignore_case(&mut args);
     flag_ignore_file(&mut args);
+    flag_ignore_file_case_insensitive(&mut args);
     flag_invert_match(&mut args);
     flag_json(&mut args);
     flag_line_buffered(&mut args);
@@ -1209,6 +1210,27 @@ directly on the command line, then used -g instead.
     args.push(arg);
 }
 
+fn flag_ignore_file_case_insensitive(args: &mut Vec<RGArg>) {
+    const SHORT: &str =
+        "Process ignore files (.gitignore, .ignore, etc.) case insensitively.";
+    const LONG: &str = long!("\
+Process ignore files (.gitignore, .ignore, etc.) case insensitively. Note that
+this comes with a performance penalty and is most useful on case insensitive
+file systems (such as Windows).
+
+This flag can be disabled with the --no-ignore-file-case-insensitive flag.
+");
+    let arg = RGArg::switch("ignore-file-case-insensitive")
+        .help(SHORT).long_help(LONG)
+        .overrides("no-ignore-file-case-insensitive");
+    args.push(arg);
+
+    let arg = RGArg::switch("no-ignore-file-case-insensitive")
+        .hidden()
+        .overrides("ignore-file-case-insensitive");
+    args.push(arg);
+}
+
 fn flag_invert_match(args: &mut Vec<RGArg>) {
     const SHORT: &str = "Invert matching.";
     const LONG: &str = long!("\
diff --git a/src/args.rs b/src/args.rs
index 70af9df1..df55df25 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -797,7 +797,8 @@ impl ArgMatches {
                 && !self.no_ignore_vcs()
                 && !self.no_ignore_global())
             .git_ignore(!self.no_ignore() && !self.no_ignore_vcs())
-            .git_exclude(!self.no_ignore() && !self.no_ignore_vcs());
+            .git_exclude(!self.no_ignore() && !self.no_ignore_vcs())
+            .ignore_case_insensitive(self.ignore_file_case_insensitive());
         if !self.no_ignore() {
             builder.add_custom_ignore_filename(".rgignore");
         }
@@ -1003,6 +1004,11 @@ impl ArgMatches {
         self.is_present("hidden") || self.unrestricted_count() >= 2
     }
 
+    /// Returns true if ignore files should be processed case insensitively.
+    fn ignore_file_case_insensitive(&self) -> bool {
+        self.is_present("ignore-file-case-insensitive")
+    }
+
     /// Return all of the ignore file paths given on the command line.
     fn ignore_paths(&self) -> Vec<PathBuf> {
         let paths = match self.values_of_os("ignore-file") {
@@ -1143,7 +1149,7 @@ impl ArgMatches {
             builder.add(&glob)?;
         }
         // This only enables case insensitivity for subsequent globs.
-        builder.case_insensitive(true)?;
+        builder.case_insensitive(true).unwrap();
         for glob in self.values_of_lossy_vec("iglob") {
             builder.add(&glob)?;
         }
diff --git a/tests/regression.rs b/tests/regression.rs
index 4ee3ab53..90760ec9 100644
--- a/tests/regression.rs
+++ b/tests/regression.rs
@@ -568,3 +568,16 @@ rgtest!(r1064, |dir: Dir, mut cmd: TestCommand| {
     dir.create("input", "abc");
     eqnice!("input:abc\n", cmd.arg("a(.*c)").stdout());
 });
+
+// See: https://github.com/BurntSushi/ripgrep/issues/1164
+rgtest!(r1164, |dir: Dir, mut cmd: TestCommand| {
+    dir.create_dir(".git");
+    dir.create(".gitignore", "myfile");
+    dir.create("MYFILE", "test");
+
+    cmd.arg("--ignore-file-case-insensitive").arg("test").assert_err();
+    eqnice!(
+        "MYFILE:test\n",
+        cmd.arg("--no-ignore-file-case-insensitive").stdout()
+    );
+});