logging: add new --no-ignore-messages flag

The new --no-ignore-messages flag permits suppressing errors related to
parsing .gitignore or .ignore files. These error messages can be somewhat
annoying since they can surface from repositories that one has no control
over.

Fixes #646

src/app.rs

@@ -544,6 +544,7 @@ pub fn all_args_and_flags() -> Vec<RGArg> {
     flag_mmap(&mut args);
     flag_no_config(&mut args);
     flag_no_ignore(&mut args);
+    flag_no_ignore_messages(&mut args);
     flag_no_ignore_parent(&mut args);
     flag_no_ignore_vcs(&mut args);
     flag_no_messages(&mut args);
@@ -1240,6 +1241,25 @@ This flag can be disabled with the --ignore flag.
     args.push(arg);
 }
 
+fn flag_no_ignore_messages(args: &mut Vec<RGArg>) {
+    const SHORT: &str = "Suppress gitignore parse error messages.";
+    const LONG: &str = long!("\
+Suppresses all error messages related to parsing ignore files such as .ignore
+or .gitignore.
+
+This flag can be disabled with the --ignore-messages flag.
+");
+    let arg = RGArg::switch("no-ignore-messages")
+        .help(SHORT).long_help(LONG)
+        .overrides("ignore-messages");
+    args.push(arg);
+
+    let arg = RGArg::switch("ignore-messages")
+        .hidden()
+        .overrides("no-ignore-messages");
+    args.push(arg);
+}
+
 fn flag_no_ignore_parent(args: &mut Vec<RGArg>) {
     const SHORT: &str = "Don't respect ignore files in parent directories.";
     const LONG: &str = long!("\
@@ -1279,7 +1299,7 @@ This flag can be disabled with the --ignore-vcs flag.
 }
 
 fn flag_no_messages(args: &mut Vec<RGArg>) {
-    const SHORT: &str = "Suppress all error messages.";
+    const SHORT: &str = "Suppress some error messages.";
     const LONG: &str = long!("\
 Suppress all error messages related to opening and reading files. Error
 messages related to the syntax of the pattern given are still shown.

src/args.rs

@@ -63,6 +63,7 @@ pub struct Args {
     maxdepth: Option<usize>,
     mmap: bool,
     no_ignore: bool,
+    no_ignore_messages: bool,
     no_ignore_parent: bool,
     no_ignore_vcs: bool,
     no_messages: bool,
@@ -308,6 +309,12 @@ impl Args {
         self.no_messages
     }
 
+    /// Returns true if error messages associated with parsing .ignore or
+    /// .gitignore files should be suppressed.
+    pub fn no_ignore_messages(&self) -> bool {
+        self.no_ignore_messages
+    }
+
     /// Create a new recursive directory iterator over the paths in argv.
     pub fn walker(&self) -> ignore::Walk {
         self.walker_builder().build()
@@ -327,7 +334,7 @@ impl Args {
         }
         for path in &self.ignore_files {
             if let Some(err) = wd.add_ignore(path) {
-                if !self.no_messages {
+                if !self.no_messages && !self.no_ignore_messages {
                     eprintln!("{}", err);
                 }
             }
@@ -402,6 +409,7 @@ impl<'a> ArgMatches<'a> {
             maxdepth: self.usize_of("maxdepth")?,
             mmap: mmap,
             no_ignore: self.no_ignore(),
+            no_ignore_messages: self.is_present("no-ignore-messages"),
             no_ignore_parent: self.no_ignore_parent(),
             no_ignore_vcs: self.no_ignore_vcs(),
             no_messages: self.is_present("no-messages"),

src/main.rs

@@ -113,6 +113,7 @@ fn run_parallel(args: &Arc<Args>) -> Result<u64> {
                 args.stdout_handle(),
                 args.files(),
                 args.no_messages(),
+                args.no_ignore_messages(),
             ) {
                 None => return Continue,
                 Some(dent) => dent,
@@ -176,6 +177,7 @@ fn run_one_thread(args: &Arc<Args>) -> Result<u64> {
             args.stdout_handle(),
             args.files(),
             args.no_messages(),
+            args.no_ignore_messages(),
         ) {
             None => continue,
             Some(dent) => dent,
@@ -241,6 +243,7 @@ fn run_files_parallel(args: Arc<Args>) -> Result<u64> {
                 args.stdout_handle(),
                 args.files(),
                 args.no_messages(),
+                args.no_ignore_messages(),
             ) {
                 tx.send(dent).unwrap();
             }
@@ -260,6 +263,7 @@ fn run_files_one_thread(args: &Arc<Args>) -> Result<u64> {
             args.stdout_handle(),
             args.files(),
             args.no_messages(),
+            args.no_ignore_messages(),
         ) {
             None => continue,
             Some(dent) => dent,
@@ -288,6 +292,7 @@ fn get_or_log_dir_entry(
     stdout_handle: Option<&same_file::Handle>,
     files_only: bool,
     no_messages: bool,
+    no_ignore_messages: bool,
 ) -> Option<ignore::DirEntry> {
     match result {
         Err(err) => {
@@ -298,7 +303,7 @@ fn get_or_log_dir_entry(
         }
         Ok(dent) => {
             if let Some(err) = dent.error() {
-                if !no_messages {
+                if !no_messages && !no_ignore_messages {
                     eprintln!("{}", err);
                 }
             }