patch 8.2.0906: when setting 'termguicolors' SpellBad is no longer red
Problem: When setting 'termguicolors' SpellBad is no longer red.
Solution: Only use the RGB guisp color for cterm when using the "underline"
or "undercurl" attributes to avoid the background color to be
cleared. Also make t_8u empty when the termresponse indicates a
real xterm. (closes #6207)
diff --git a/src/term.c b/src/term.c
index c024fce..b4b5c09 100644
--- a/src/term.c
+++ b/src/term.c
@@ -4819,6 +4819,11 @@
if (version < 95)
is_not_xterm = TRUE;
+ // With the real Xterm setting the underline RGB color
+ // clears the background color, disable "t_8u".
+ if (!is_not_xterm && *T_8U != NUL)
+ T_8U = empty_option;
+
// Only request the cursor style if t_SH and t_RS are
// set. Only supported properly by xterm since version
// 279 (otherwise it returns 0x18).