Mark everything [[nodiscard]], fix some comments.

src/options.hpp

@@ -27,7 +27,7 @@ namespace epubgrep::options
 namespace po = boost::program_options;
 
 //! Parse options and return them.
-po::variables_map parse_options(int argc, char *argv[]);
+[[nodiscard]] po::variables_map parse_options(int argc, char *argv[]);
 
 /*!
  *  @brief Returns the path of the config file.
@@ -36,7 +36,7 @@ po::variables_map parse_options(int argc, char *argv[]);
  *  If HOME is set:            ${HOME}/.config/epubgrep.conf
  *  Otherwise:                 epubgrep.conf
  */
-fs::path get_config_path();
+[[nodiscard]] fs::path get_config_path();
 
 } // namespace epubgrep::options
 

src/search.hpp

@@ -47,8 +47,9 @@ struct options
     std::uint64_t context{0};
 };
 
-std::vector<match> search(const fs::path &filepath, std::string_view regex,
+[[nodiscard]] std::vector<match> search(const fs::path &filepath,
-                          const options &opts);
+                                        std::string_view regex,
+                                        const options &opts);
 
 } // namespace epubgrep::search
 

src/zip.hpp

@@ -29,19 +29,20 @@
 namespace epubgrep::zip
 {
 
-//! List the contents of a zip file.
+//! Return the table of contents of a zip file.
-std::vector<std::string> list(const fs::path &filepath);
+[[nodiscard]] std::vector<std::string> list(const fs::path &filepath);
 
-//! Read a file from a zip archive.
+//! Read a file from a zip archive and return its contents.
-std::string read_file(const fs::path &filepath, std::string_view entry_path);
+[[nodiscard]] std::string read_file(const fs::path &filepath,
+                                    std::string_view entry_path);
 
 //! Open zip file and return handle.
-struct archive *open_file(const fs::path &filepath);
+[[nodiscard]] struct archive *open_file(const fs::path &filepath);
 
 //! Close zip file.
 void close_file(struct archive *zipfile, const fs::path &filepath);
 
-// It's std::runtime_error, but with another name.
+//! It's std::runtime_error, but with another name.
 class exception : public std::runtime_error
 {
 public: