check option names conflict on debug build

src/lib.rs

@@ -178,8 +178,7 @@ impl Options {
         hasarg: HasArg,
         occur: Occur,
     ) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: hint.to_string(),
@@ -207,8 +206,7 @@ impl Options {
     /// assert!(matches.opt_present("h"));
     /// ```
     pub fn optflag(&mut self, short_name: &str, long_name: &str, desc: &str) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: "".to_string(),
@@ -237,8 +235,7 @@ impl Options {
     /// assert_eq!(2, matches.opt_count("v"));
     /// ```
     pub fn optflagmulti(&mut self, short_name: &str, long_name: &str, desc: &str) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: "".to_string(),
@@ -277,8 +274,7 @@ impl Options {
         desc: &str,
         hint: &str,
     ) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: hint.to_string(),
@@ -319,8 +315,7 @@ impl Options {
         desc: &str,
         hint: &str,
     ) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: hint.to_string(),
@@ -360,8 +355,7 @@ impl Options {
         desc: &str,
         hint: &str,
     ) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: hint.to_string(),
@@ -403,8 +397,7 @@ impl Options {
         desc: &str,
         hint: &str,
     ) -> &mut Options {
-        validate_names(short_name, long_name);
-        self.grps.push(OptGroup {
+        self.push_group(OptGroup {
             short_name: short_name.to_string(),
             long_name: long_name.to_string(),
             hint: hint.to_string(),
@@ -680,21 +673,39 @@ impl Options {
 
         Box::new(rows)
     }
-}
 
-fn validate_names(short_name: &str, long_name: &str) {
-    let len = short_name.len();
-    assert!(
-        len == 1 || len == 0,
-        "the short_name (first argument) should be a single character, \
-         or an empty string for none"
-    );
-    let len = long_name.len();
-    assert!(
-        len == 0 || len > 1,
-        "the long_name (second argument) should be longer than a single \
-         character, or an empty string for none"
-    );
+    fn push_group(&mut self, group: OptGroup) {
+        self.validate_names(&group);
+        self.grps.push(group);
+    }
+
+    fn validate_names(&self, group: &OptGroup) {
+        let len = group.short_name.len();
+        assert!(
+            len == 1 || len == 0,
+            "the short_name (first argument) should be a single character, \
+            or an empty string for none"
+        );
+        let len = group.long_name.len();
+        assert!(
+            len == 0 || len > 1,
+            "the long_name (second argument) should be longer than a single \
+            character, or an empty string for none"
+        );
+
+        debug_assert!(
+            group.short_name.is_empty()
+                || self.grps.iter().all(|g| g.short_name != group.short_name),
+            "the short option name -{} caused conflict among multiple options",
+            group.short_name,
+        );
+        debug_assert!(
+            group.long_name.is_empty()
+                || self.grps.iter().all(|g| g.long_name != group.long_name),
+            "the long option name --{} caused conflict among multiple options",
+            group.long_name,
+        );
+    }
 }
 
 /// What parsing style to use when parsing arguments.

src/tests/mod.rs

@@ -1319,3 +1319,31 @@ fn test_opt_strs_pos() {
         ]
     );
 }
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic(expected = "the short option name -s caused conflict among multiple options")]
+fn test_check_conflicts_in_short_name() {
+    let mut opts = Options::new();
+    opts.optflag("s", "long", "");
+    opts.optflag("s", "other", "");
+}
+
+#[cfg(debug_assertions)]
+#[test]
+#[should_panic(expected = "the long option name --long caused conflict among multiple options")]
+fn test_check_conflicts_in_long_name() {
+    let mut opts = Options::new();
+    opts.optflag("a", "long", "");
+    opts.optflag("b", "long", "");
+}
+
+#[cfg(debug_assertions)]
+#[test]
+fn test_empty_names_should_not_cause_conflict() {
+    let mut opts = Options::new();
+    opts.optflag("", "long1", "");
+    opts.optflag("", "long2", "");
+    opts.optflag("a", "", "");
+    opts.optflag("b", "", "");
+}