Handle file extension conflicts in --list-languages

src/assets.rs

@@ -170,6 +170,21 @@ impl HighlightingAssets {
         self.theme_set.themes.keys().map(|s| s.as_ref())
     }
 
+    pub fn syntax_for_file_name(
+        &self,
+        file_name: impl AsRef<Path>,
+        mapping: &SyntaxMapping,
+    ) -> Option<&SyntaxReference> {
+        let file_name = file_name.as_ref();
+        match mapping.get_syntax_for(file_name) {
+            Some(MappingTarget::MapToUnknown) => None,
+            Some(MappingTarget::MapTo(syntax_name)) => {
+                self.syntax_set.find_syntax_by_name(syntax_name)
+            }
+            None => self.get_extension_syntax(file_name.as_os_str()),
+        }
+    }
+
     pub(crate) fn get_theme(&self, theme: &str) -> &Theme {
         match self.theme_set.themes.get(theme) {
             Some(theme) => theme,

src/bin/bat/main.rs

@@ -86,6 +86,29 @@ pub fn list_languages(config: &Config) -> Result<()> {
         .filter(|syntax| !syntax.hidden && !syntax.file_extensions.is_empty())
         .cloned()
         .collect::<Vec<_>>();
+
+    // Handling of file-extension conflicts, see issue #1076
+    for lang in languages.iter_mut() {
+        let lang_name = lang.name.clone();
+        lang.file_extensions.retain(|extension| {
+            // The 'extension' variable is not certainly a real extension.
+            // 
+            // Skip if 'extension' starts with '.', likely a hidden file like '.vimrc'
+            // Also skip if the 'extension' contains another real extension, likely 
+            // that is a full match file name like 'CMakeLists.txt' and 'Cargo.lock'
+            if extension.starts_with('.') || Path::new(extension).extension().is_some() {
+                true
+            } else {
+                let test_file = Path::new("test").with_extension(extension);
+                if let Some(syntax) = assets.syntax_for_file_name(test_file, &config.syntax_mapping) {
+                    syntax.name == lang_name
+                } else {
+                    false
+                }
+            }
+        });
+    }
+
     languages.sort_by_key(|lang| lang.name.to_uppercase());
 
     let configured_languages = get_syntax_mapping_to_paths(config.syntax_mapping.mappings());