Allow to turn off the matches recording introduced in #1469.

src/lib.rs

@@ -509,6 +509,10 @@ impl Builder {
             );
         }
 
+        if !self.options.record_matches {
+            output_vector.push("--no-record-matches".into());
+        }
+
         if !self.options.rustfmt_bindings {
             output_vector.push("--no-rustfmt-bindings".into());
         }
@@ -1137,6 +1141,12 @@ impl Builder {
         self
     }
 
+    /// Set whether we should record matched items in our regex sets.
+    pub fn record_matches(mut self, doit: bool) -> Self {
+        self.options.record_matches = doit;
+        self
+    }
+
     /// Set the absolute path to the rustfmt configuration file, if None, the standard rustfmt
     /// options are used.
     pub fn rustfmt_configuration_file(mut self, path: Option<PathBuf>) -> Self {
@@ -1486,6 +1496,12 @@ struct BindgenOptions {
     /// Features to enable, derived from `rust_target`
     rust_features: RustFeatures,
 
+    /// Whether we should record which items in the regex sets ever matched.
+    ///
+    /// This may be a bit slower, but will enable reporting of unused whitelist
+    /// items via the `error!` log.
+    record_matches: bool,
+
     /// Whether rustfmt should format the generated bindings.
     rustfmt_bindings: bool,
 
@@ -1511,20 +1527,26 @@ impl ::std::panic::UnwindSafe for BindgenOptions {}
 
 impl BindgenOptions {
     fn build(&mut self) {
-        self.whitelisted_vars.build();
-        self.whitelisted_types.build();
-        self.whitelisted_functions.build();
-        self.blacklisted_types.build();
-        self.blacklisted_functions.build();
-        self.blacklisted_items.build();
-        self.opaque_types.build();
-        self.bitfield_enums.build();
-        self.constified_enums.build();
-        self.constified_enum_modules.build();
-        self.rustified_enums.build();
-        self.no_partialeq_types.build();
-        self.no_copy_types.build();
-        self.no_hash_types.build();
+        let mut regex_sets = [
+            &mut self.whitelisted_vars,
+            &mut self.whitelisted_types,
+            &mut self.whitelisted_functions,
+            &mut self.blacklisted_types,
+            &mut self.blacklisted_functions,
+            &mut self.blacklisted_items,
+            &mut self.opaque_types,
+            &mut self.bitfield_enums,
+            &mut self.constified_enums,
+            &mut self.constified_enum_modules,
+            &mut self.rustified_enums,
+            &mut self.no_partialeq_types,
+            &mut self.no_copy_types,
+            &mut self.no_hash_types,
+        ];
+        let record_matches = self.record_matches;
+        for regex_set in &mut regex_sets {
+            regex_set.build(record_matches);
+        }
     }
 
     /// Update rust target version
@@ -1601,6 +1623,7 @@ impl Default for BindgenOptions {
             enable_mangling: true,
             prepend_enum_name: true,
             time_phases: false,
+            record_matches: true,
             rustfmt_bindings: true,
             rustfmt_configuration_file: None,
             no_partialeq_types: Default::default(),

src/options.rs

@@ -277,6 +277,10 @@ where
                        Useful when debugging bindgen, using C-Reduce, or when \
                        filing issues. The resulting file will be named \
                        something like `__bindgen.i` or `__bindgen.ii`."),
+            Arg::with_name("no-record-matches")
+                .long("no-record-matches")
+                .help("Do not record matching items in the regex sets. \
+                      This disables reporting of unused items."),
             Arg::with_name("no-rustfmt-bindings")
                 .long("no-rustfmt-bindings")
                 .help("Do not format the generated bindings with rustfmt."),
@@ -591,6 +595,10 @@ where
         builder.dump_preprocessed_input()?;
     }
 
+    if matches.is_present("no-record-matches") {
+        builder = builder.record_matches(false);
+    }
+
     let no_rustfmt_bindings = matches.is_present("no-rustfmt-bindings");
     if no_rustfmt_bindings {
         builder = builder.rustfmt_bindings(false);

src/regex_set.rs

@@ -4,11 +4,15 @@ use regex::RegexSet as RxSet;
 use std::cell::Cell;
 
 /// A dynamic set of regular expressions.
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct RegexSet {
     items: Vec<String>,
+    /// Whether any of the items in the set was ever matched. The length of this
+    /// vector is exactly the length of `items`.
     matched: Vec<Cell<bool>>,
     set: Option<RxSet>,
+    /// Whether we should record matching items in the `matched` vector or not.
+    record_matches: bool,
 }
 
 impl RegexSet {
@@ -32,23 +36,25 @@ impl RegexSet {
         &self.items[..]
     }
 
-    /// Returns regexes in the set which didn't match any strings yet
-    pub fn unmatched_items(&self) -> Vec<String> {
-        let mut items = vec![];
-        for (i, item) in self.items.iter().enumerate() {
-            if !self.matched[i].get() {
-                items.push(item.clone());
+    /// Returns an iterator over regexes in the set which didn't match any
+    /// strings yet.
+    pub fn unmatched_items(&self) -> impl Iterator<Item = &String> {
+        self.items.iter().enumerate().filter_map(move |(i, item)| {
+            if !self.record_matches || self.matched[i].get() {
+                return None;
             }
-        }
-        items
+
+            Some(item)
+        })
     }
 
     /// Construct a RegexSet from the set of entries we've accumulated.
     ///
     /// Must be called before calling `matches()`, or it will always return
     /// false.
-    pub fn build(&mut self) {
+    pub fn build(&mut self, record_matches: bool) {
         let items = self.items.iter().map(|item| format!("^{}$", item));
+        self.record_matches = record_matches;
         self.set = match RxSet::new(items) {
             Ok(x) => Some(x),
             Err(e) => {
@@ -64,25 +70,23 @@ impl RegexSet {
         S: AsRef<str>,
     {
         let s = string.as_ref();
-        if let Some(set) = self.set.as_ref() {
-            let matches = set.matches(s);
-            if matches.matched_any() {
-                for i in matches.iter() {
-                    self.matched[i].set(true);
-                }
-                return true;
-            }
+        let set = match self.set {
+            Some(ref set) => set,
+            None => return false,
+        };
+
+        if !self.record_matches {
+            return set.is_match(s);
         }
-        false
-    }
-}
 
-impl Default for RegexSet {
-    fn default() -> Self {
-        RegexSet {
-            items: vec![],
-            matched: vec![],
-            set: None,
+        let matches = set.matches(s);
+        if !matches.matched_any() {
+            return false;
         }
+        for i in matches.iter() {
+            self.matched[i].set(true);
+        }
+
+        true
     }
 }