charset: change Utf8ToLocale to produce std::string_view

src/FileBrowserPage.cxx

@@ -210,7 +210,7 @@ FileBrowserPage::HandleSave(struct mpdclient &c) noexcept
 
 	if(defaultname)
 		playlist_save(screen, c, nullptr,
-			      Utf8ToLocale(defaultname).c_str());
+			      Utf8ToLocaleZ{defaultname}.c_str());
 	else
 		playlist_save(screen, c, nullptr, nullptr);
 }
@@ -244,7 +244,7 @@ FileBrowserPage::HandleDelete(struct mpdclient &c) noexcept
 		char prompt[256];
 		snprintf(prompt, sizeof(prompt),
 			 _("Delete playlist %s?"),
-			 Utf8ToLocale(GetUriFilename(mpd_playlist_get_path(playlist))).c_str());
+			 Utf8ToLocaleZ{GetUriFilename(mpd_playlist_get_path(playlist))}.c_str());
 		bool confirmed = screen_get_yesno(screen, prompt, false);
 		if (!confirmed) {
 			/* translators: a dialog was aborted by the user */
@@ -288,7 +288,7 @@ FileBrowserPage::GetTitle(std::span<char> buffer) const noexcept
 
 	return FmtTruncate(buffer, "{}: {}",
 			   /* translators: caption of the browser screen */
-			   _("Browse"), Utf8ToLocale(path).c_str());
+			   _("Browse"), (std::string_view)Utf8ToLocale{path});
 }
 
 void

src/FileListPage.cxx

@@ -109,7 +109,7 @@ load_playlist(struct mpdclient *c, const struct mpd_playlist *playlist)
 	if (mpd_run_load(connection, mpd_playlist_get_path(playlist))) {
 		const char *name = GetUriFilename(mpd_playlist_get_path(playlist));
 		screen_status_printf(_("Loading playlist '%s'"),
-				     Utf8ToLocale(name).c_str());
+				     Utf8ToLocaleZ{name}.c_str());
 
 		c->events |= MPD_IDLE_QUEUE;
 	} else
@@ -239,7 +239,7 @@ browser_select_entry(struct mpdclient &c, FileListEntry &entry,
 			return false;
 
 		screen_status_fmt(_("Adding '{}' to queue"),
-				  Utf8ToLocale(mpd_directory_get_path(dir)).c_str());
+				  (std::string_view)Utf8ToLocale{mpd_directory_get_path(dir)});
 		return true;
 	}
 
@@ -472,7 +472,7 @@ FileListPage::OnCommand(struct mpdclient &c, Command cmd)
 
 void
 screen_browser_paint_directory(const Window window, unsigned width,
-			       bool selected, const char *name) noexcept
+			       bool selected, std::string_view name) noexcept
 {
 	row_color(window, Style::DIRECTORY, selected);
 
@@ -502,7 +502,7 @@ FileListPage::PaintListItem(const Window window, unsigned i,
 	const auto &entry = (*filelist)[i];
 	const struct mpd_entity *entity = entry.entity;
 	if (entity == nullptr) {
-		screen_browser_paint_directory(window, width, selected, "..");
+		screen_browser_paint_directory(window, width, selected, ".."sv);
 		return;
 	}
 
@@ -516,8 +516,7 @@ FileListPage::PaintListItem(const Window window, unsigned i,
 	case MPD_ENTITY_TYPE_DIRECTORY: {
 		const auto *directory = mpd_entity_get_directory(entity);
 		const char *name = GetUriFilename(mpd_directory_get_path(directory));
-		screen_browser_paint_directory(window, width, selected,
-					       Utf8ToLocale(name).c_str());
+		screen_browser_paint_directory(window, width, selected, Utf8ToLocale{name});
 		break;
 	}
 
@@ -530,8 +529,7 @@ FileListPage::PaintListItem(const Window window, unsigned i,
 	case MPD_ENTITY_TYPE_PLAYLIST: {
 		const auto *playlist = mpd_entity_get_playlist(entity);
 		const char *name = GetUriFilename(mpd_playlist_get_path(playlist));
-		screen_browser_paint_playlist(window, width, selected,
-					      Utf8ToLocale(name).c_str());
+		screen_browser_paint_playlist(window, width, selected, Utf8ToLocale{name});
 		break;
 	}
 

src/FileListPage.hxx

@@ -95,4 +95,4 @@ screen_browser_sync_highlights(FileList &, const MpdQueue &) noexcept
 
 void
 screen_browser_paint_directory(Window window, unsigned width,
-			       bool selected, const char *name) noexcept;
+			       bool selected, std::string_view name) noexcept;

src/LibraryPage.cxx

@@ -47,7 +47,7 @@ MakePageTitle(std::span<char> buffer, std::string_view prefix,
 		return prefix;
 
 	return FmtTruncate(buffer, "{}: {}"sv, prefix,
-			   Utf8ToLocale{ToString(filter)}.c_str());
+			   (std::string_view)Utf8ToLocale{ToString(filter)});
 }
 
 class SongListPage final : public FileListPage {

src/charset.hxx

@@ -32,7 +32,7 @@ class Utf8ToLocale {
 #ifdef HAVE_ICONV
 	const std::string value;
 #else
-	const char *const value;
+	const std::string_view value;
 #endif
 
 public:
@@ -44,18 +44,21 @@ public:
 	Utf8ToLocale &operator=(const Utf8ToLocale &) = delete;
 #else
 	[[nodiscard]]
-	explicit Utf8ToLocale(const char *src) noexcept
+	explicit Utf8ToLocale(std::string_view src) noexcept
 		:value(src) {}
 #endif
 
+	[[nodiscard]]
+	operator std::string_view() const noexcept {
+			return value;
+	}
+
+#ifdef HAVE_ICONV
 	[[nodiscard]] [[gnu::pure]]
 	const char *c_str() const noexcept {
-#ifdef HAVE_ICONV
 		return value.c_str();
-#else
-		return value;
-#endif
 	}
+#endif
 };
 
 /**
@@ -98,10 +101,32 @@ public:
 
 #ifdef HAVE_ICONV
 
+using Utf8ToLocaleZ = Utf8ToLocale;
 using LocaleToUtf8Z = LocaleToUtf8;
 
 #else
 
+/**
+ * Like #Utf8ToLocaleZ, but return a null-terminated string.
+ */
+class Utf8ToLocaleZ {
+	const char *const value;
+
+public:
+	[[nodiscard]]
+	explicit constexpr Utf8ToLocaleZ(const char *src) noexcept
+		:value(src) {}
+
+	[[nodiscard]]
+	explicit constexpr Utf8ToLocaleZ(const std::string &src) noexcept
+		:Utf8ToLocaleZ(src.c_str()) {}
+
+	[[nodiscard]] [[gnu::pure]]
+	constexpr const char *c_str() const noexcept {
+		return value;
+	}
+};
+
 /**
  * Like #LocaleToUtf8Z, but return a null-terminated string.
  */

src/screen_client.cxx

@@ -29,7 +29,7 @@ screen_database_update(struct mpdclient &c, const char *path)
 
 	if (path != nullptr && *path != 0) {
 		screen_status_printf(_("Database update of %s started"),
-				     Utf8ToLocale(path).c_str());
+				     Utf8ToLocaleZ{path}.c_str());
 	} else
 		screen_status_message(_("Database update started"));
 }