templates: colorize description_placeholder

Also, see https://github.com/martinvonz/jj/pull/2100.

cli/src/config/colors.toml

@@ -32,6 +32,8 @@
 "divergent change_id"="red"
 "conflict" = "red"
 "empty" = "green"
+"description placeholder" = "yellow"
+"empty description placeholder" = "green"
 "separator" = "bright black"
 "root" = "green"
 
@@ -51,6 +53,8 @@
 "working_copy divergent change_id" = "bright red"
 "working_copy conflict" = "bright red"
 "working_copy empty" = "bright green"
+"working_copy description placeholder" = "yellow"
+"working_copy empty description placeholder" = "bright green"
 "diff header" = "yellow"
 "diff empty" = "cyan"
 "diff file_header" = { bold = true }

cli/src/config/templates.toml

@@ -121,7 +121,8 @@ separate(" ",
 )
 '''
 
-description_placeholder = 'label("description placeholder", "(no description set)")'
+description_placeholder = '''
+  label(if(empty, "empty ") ++ "description placeholder", "(no description set)")'''
 commit_summary_separator = 'label("separator", " | ")'
 
 # Hook points for users to customize the default templates:

cli/tests/test_commit_template.rs

@@ -266,9 +266,9 @@ fn test_log_obslog_divergence() {
     @  qpvuntsm?? test.user@example.com 2001-02-03 04:05:08.000 +07:00 7a17d52e
     │  description 1
     ◉  qpvuntsm?? hidden test.user@example.com 2001-02-03 04:05:08.000 +07:00 3b68ce25
-    │  (no description set)
+    │  (no description set)
     ◉  qpvuntsm?? hidden test.user@example.com 2001-02-03 04:05:07.000 +07:00 230dd059
-       (empty) (no description set)
+       (empty) (no description set)
     "###);
 }
 
@@ -286,7 +286,7 @@ fn test_log_git_head() {
     @  rlvkpnrz test.user@example.com 2001-02-03 04:05:09.000 +07:00 50aaf475
     │  initial
     ◉  qpvuntsm test.user@example.com 2001-02-03 04:05:07.000 +07:00 master HEAD@git 230dd059
-    │  (empty) (no description set)
+    │  (empty) (no description set)
     ◉  zzzzzzzz root 00000000
     "###);
 }