fish_tab_title: fix tab title accidentally including window title

Also use the correct OSC number.

Note that this only works on few terminals (such as iTerm2).  Not sure
if it's worth for us to have this feature but I guess multiple users
have requested it.

doc_src/terminal-compatibility.rst

@@ -221,7 +221,7 @@ Optional Commands
      - Set terminal window title (OSC 0). Used in :doc:`fish_title <cmds/fish_title>`.
    * - ``\e]2; Pt \x07``
      - ts
-     - Set terminal tab title (OSC 2). Used in :doc:`fish_tab_title <cmds/fish_tab_title>`.
+     - Set terminal tab title (OSC 1). Used in :doc:`fish_tab_title <cmds/fish_tab_title>`.
    * - ``\e]7;file:// Pt / Pt \x07``
      -
      - Report working directory (OSC 7).

src/reader/reader.rs

@@ -129,7 +129,7 @@
 use crate::terminal::Outputter;
 use crate::terminal::TerminalCommand::{
     self, ClearScreen, DecrstAlternateScreenBuffer, DecsetAlternateScreenBuffer, DecsetShowCursor,
-    Osc0WindowTitle, Osc2TabTitle, Osc133CommandFinished, Osc133CommandStart, QueryCursorPosition,
+    Osc0WindowTitle, Osc1TabTitle, Osc133CommandFinished, Osc133CommandStart, QueryCursorPosition,
     QueryKittyKeyboardProgressiveEnhancements, QueryPrimaryDeviceAttribute, QueryXtgettcap,
     QueryXtversion,
 };
@@ -4647,14 +4647,13 @@ pub fn reader_write_title(
     parser: &Parser,
     reset_cursor_position: bool, /* = true */
 ) {
-    fn write_title<'a>(
+    fn write_title(
         parser: &Parser,
         out: &mut BufferedOutputter,
         cmd: &wstr,
-        osc: fn(&'a [WString]) -> TerminalCommand<'a>,
+        osc: fn(&[WString]) -> TerminalCommand<'_>,
         function_name: &wstr,
         fallback_title: Option<&wstr>,
-        title_buffer: &'a mut Vec<WString>,
     ) -> bool {
         let mut title_function_call;
         let mut title_command = fallback_title;
@@ -4672,15 +4671,16 @@ fn write_title<'a>(
         let Some(title_command) = title_command else {
             return false;
         };
+        let mut title_buffer = vec![];
         let _ = exec_subshell(
             title_command,
             parser,
-            Some(title_buffer),
+            Some(&mut title_buffer),
             /*apply_exit_status=*/ false,
         );
 
         if !title_buffer.is_empty() {
-            out.write_command(osc(&*title_buffer));
+            out.write_command(osc(&title_buffer));
             return true;
         }
         false
@@ -4693,24 +4693,21 @@ fn write_title<'a>(
 
     let mut out = BufferedOutputter::new(Outputter::stdoutput());
     let mut written = false;
-    let mut lst = vec![];
     written |= write_title(
         parser,
         &mut out,
         cmd,
-        Osc0WindowTitle,
+        |title_buffer| Osc0WindowTitle(title_buffer),
         L!("fish_title"),
         Some(DEFAULT_TITLE),
-        &mut lst,
     );
     written |= write_title(
         parser,
         &mut out,
         cmd,
-        Osc2TabTitle,
+        |title_buffer| Osc1TabTitle(title_buffer),
         L!("fish_tab_title"),
         /*default_title=*/ None,
-        &mut lst,
     );
 
     out.reset_text_face();

src/terminal.rs

@@ -102,7 +102,7 @@ pub(crate) enum TerminalCommand<'a> {
     // Note that OSC 7 and OSC 52 are written from fish script, and OSC 8 is written in our
     // man pages (via "man_show_urls").
     Osc0WindowTitle(&'a [WString]),
-    Osc2TabTitle(&'a [WString]),
+    Osc1TabTitle(&'a [WString]),
     Osc133CommandStart(&'a wstr),
     Osc133PromptStart,
     Osc133CommandFinished(libc::c_int),
@@ -176,8 +176,8 @@ fn write(out: &mut impl Output, sequence: &'static [u8]) -> bool {
             ModifyOtherKeysDisable => write(self, b"\x1b[>4;0m"),
             ApplicationKeypadModeEnable => write(self, b"\x1b="),
             ApplicationKeypadModeDisable => write(self, b"\x1b>"),
-            Osc0WindowTitle(title) => osc_0_or_2_terminal_title(self, false, title),
-            Osc2TabTitle(title) => osc_0_or_2_terminal_title(self, true, title),
+            Osc0WindowTitle(title) => osc_0_or_1_terminal_title(self, false, title),
+            Osc1TabTitle(title) => osc_0_or_1_terminal_title(self, true, title),
             Osc133PromptStart => osc_133_prompt_start(self),
             Osc133CommandStart(command) => osc_133_command_start(self, command),
             Osc133CommandFinished(s) => osc_133_command_finished(self, s),
@@ -371,8 +371,8 @@ fn query_kitty_progressive_enhancements(out: &mut impl Output) -> bool {
     true
 }
 
-fn osc_0_or_2_terminal_title(out: &mut impl Output, is_2: bool, title: &[WString]) -> bool {
-    out.write_bytes(if is_2 { b"\x1b]2;" } else { b"\x1b]0;" });
+fn osc_0_or_1_terminal_title(out: &mut impl Output, is_1: bool, title: &[WString]) -> bool {
+    out.write_bytes(if is_1 { b"\x1b]1;" } else { b"\x1b]0;" });
     for title_line in title {
         out.write_bytes(&wcs2bytes(title_line));
     }