Support Tc terminfo flag for 24-bit color support in terminal

* src/term.c (init_tty): Use the Tc flag (bug#44950).

Copyright-paperwork-exempt: yes

1 files changed, 6 insertions, 4 deletions

diff --git a/src/term.c b/src/term.c
index 6f0b827cfc8..d86ae12ba84 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4152,10 +4152,12 @@ use the Bourne shell command 'TERM=...; export TERM' (C-shell:\n\
                could return 32767.  */
             tty->TN_max_colors = 16777216;
           }
-        /* Fall back to xterm+direct (semicolon version) if requested
-           by the COLORTERM environment variable.  */
-        else if ((bg = getenv("COLORTERM")) != NULL
-                 && strcasecmp(bg, "truecolor") == 0)
+        /* Fall back to xterm+direct (semicolon version) if Tc is set
+           (de-facto standard introduced by tmux) or if requested by
+           the COLORTERM environment variable.  */
+        else if (tigetflag("Tc")
+                 || ((bg = getenv("COLORTERM")) != NULL
+                     && strcasecmp(bg, "truecolor") == 0))
           {
             tty->TS_set_foreground = "\033[%?%p1%{8}%<%t3%p1%d%e38;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%d%;m";
             tty->TS_set_background = "\033[%?%p1%{8}%<%t4%p1%d%e48;2;%p1%{65536}%/%d;%p1%{256}%/%{255}%&%d;%p1%{255}%&%d%;m";