Add check.

src/lib.rs

@@ -174,8 +174,7 @@ impl<'a> FMBuilder<'a> {
     /// ```
     ///
     /// As this shows, once `$1` has matched "a", all further instances of `$1` must also match
-    /// "a", but `_` can match different values at different points. This is true even if distinct
-    /// name matching (see [Self::distinct_name_matching] is enabled.
+    /// "a", but `_` can match different values at different points.
     pub fn name_matcher_ignore(mut self, ptn_re: Regex, text_re: Regex) -> Self {
         self.options.name_matchers.push((ptn_re, text_re, true));
         self
@@ -256,6 +255,11 @@ impl<'a> FMBuilder<'a> {
 
     /// Turn this `FMBuilder` into a `FMatcher`.
     pub fn build(self) -> Result<FMatcher<'a>, Box<dyn Error>> {
+        if !self.options.name_matching_processors.is_empty()
+            && self.options.name_matchers.is_empty()
+        {
+            return Err("If a name matching processor(s) is/are specified, one or more name matchers must also be specified".into());
+        }
         self.validate()?;
         let (ptn_lines, ptn_lines_off) = line_trimmer(self.options.trim_whitespace, self.ptn);
         Ok(FMatcher {
@@ -1101,6 +1105,18 @@ mod tests {
             .unwrap();
     }
 
+    #[test]
+    #[should_panic(
+        expected = "If a name matching processor(s) is/are specified, one or more name matchers must also be specified"
+    )]
+    fn name_matching_processor_requires_name_matcher() {
+        FMBuilder::new("$1")
+            .unwrap()
+            .name_matching_processor(|_| true)
+            .build()
+            .unwrap();
+    }
+
     #[test]
     fn consecutive_wildcards_disallowed() {
         match FMatcher::new("...\n...") {