Additional fixes of clang-tidy's performance warnings

src/filesystem.cc

@@ -187,7 +187,7 @@ boost::filesystem::path filesystem::get_executable(const boost::filesystem::path
         return executable_name;
     }
     
-    auto executable_name_str = executable_name.string();
+    auto &executable_name_str = executable_name.string();
     for(auto &path: bin_paths) {
       boost::filesystem::path executable;
       for(boost::filesystem::directory_iterator it(path), end; it != end; ++it) {

src/git.cc

@@ -98,8 +98,7 @@ Git::Repository::Repository(const boost::filesystem::path &path) {
   {
     Error error;
     std::lock_guard<std::mutex> lock(mutex);
-    auto path_str=path.generic_string();
+    error.code = git_repository_open_ext(&repository_ptr, path.generic_string().c_str(), 0, nullptr);
-    error.code = git_repository_open_ext(&repository_ptr, path_str.c_str(), 0, nullptr);
     if(error)
       throw std::runtime_error(error.message());
   }
@@ -229,8 +228,7 @@ boost::filesystem::path Git::Repository::get_root_path(const boost::filesystem::
   {
     Error error;
     std::lock_guard<std::mutex> lock(mutex);
-    auto path_str=path.generic_string();
+    error.code = git_repository_discover(&root, path.generic_string().c_str(), 0, nullptr);
-    error.code = git_repository_discover(&root, path_str.c_str(), 0, nullptr);
     if(error)
       throw std::runtime_error(error.message());
   }

src/source_spellcheck.cc

@@ -66,12 +66,11 @@ Source::SpellCheckView::SpellCheckView(const boost::filesystem::path &file_path,
         if(!iter.starts_line() && !iter.ends_line() && is_word_iter(iter) &&
            previous_iter.backward_char() && !previous_iter.starts_line() && !is_word_iter(previous_iter)) {
           auto first=previous_iter;
-          auto second=iter;
           if(first.backward_char()) {
-            get_buffer()->remove_tag(spellcheck_error_tag, first, second);
+            get_buffer()->remove_tag(spellcheck_error_tag, first, iter);
             auto word=get_word(first);
             spellcheck_word(word.first, word.second);
-            word=get_word(second);
+            word=get_word(iter);
             spellcheck_word(word.first, word.second);
           }
         }