From ec4b87b34a5f180b3613abcc7714c6d8ceb36dd3 Mon Sep 17 00:00:00 2001
From: Kévin Le Gouguec <kevin.legouguec@gmail.com>
Date: Fri, 3 Feb 2023 07:56:09 +0100
Subject: Give up on colored PS4
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The first mistake here was to forget to wrap console codes with \[…\];
for some reason though after adding those…

  export PS4=$(echo -en '\[\e[7m\]+ \[\e[0m\]')

… bash no longer repeats the first character (+) according to the
indirection level, or rather, it repeats an entirely unrelated
character:

$ ( PS4='+ ' ; set -x ; echo $(echo $(echo hi | grep hi)) )
+++ echo hi
+++ grep --color=auto hi
++ echo hi
+ echo hi
hi
$ ( PS4=$(echo -en '\[\e[7m\]+ \[\e[0m\]')
    set -x
    echo $(echo $(echo hi | grep hi))
  ) |& hexdump -C
00000000  01 01 01 1b 5b 37 6d 02  2b 20 01 1b 5b 30 6d 02  |....[7m.+ ..[0m.|
          ^^ ^^ ^^ (echo)
00000010  65 63 68 6f 20 68 69 0a  01 01 01 1b 5b 37 6d 02  |echo hi.....[7m.|
                                   ^^ ^^ ^^ (grep)
00000020  2b 20 01 1b 5b 30 6d 02  67 72 65 70 20 2d 2d 63  |+ ..[0m.grep --c|
00000030  6f 6c 6f 72 3d 61 75 74  6f 20 68 69 0a 01 01 1b  |olor=auto hi....|
                                                  ^^ ^^ (echo)
00000040  5b 37 6d 02 2b 20 01 1b  5b 30 6d 02 65 63 68 6f  |[7m.+ ..[0m.echo|
00000050  20 68 69 0a 01 1b 5b 37  6d 02 2b 20 01 1b 5b 30  | hi...[7m.+ ..[0|
                      ^^ (echo)
00000060  6d 02 65 63 68 6f 20 68  69 0a 68 69 0a           |m.echo hi.hi.|
0000006d

No idea where those ^A characters come from.

While at it, wrap PS2 to avoid line-wrapping shenanigans.
---
 .bash_prompt | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

(limited to '.bash_prompt')

diff --git a/.bash_prompt b/.bash_prompt
index 4777251..8b280e5 100644
--- a/.bash_prompt
+++ b/.bash_prompt
@@ -58,11 +58,11 @@ __set-title ()
     echo -ne "\E]2;${title}\a"
 }
 
-# In order to know how much space PS1 takes, Bash needs us to delimit
-# non-printing characters with \[ and \].
+# In order to know how much space a prompt takes, Bash needs us to
+# delimit non-printing characters with \[ and \].
 __start-nonprinting ()
 {
-    if [ ${BUILDING_PS1} ]
+    if [ ${BUILDING_PS} ]
     then
         echo -en '\['
     fi
@@ -70,7 +70,7 @@ __start-nonprinting ()
 
 __end-nonprinting ()
 {
-    if [ ${BUILDING_PS1} ]
+    if [ ${BUILDING_PS} ]
     then
         echo -en '\]'
     fi
@@ -118,11 +118,11 @@ __fontify ()
 
 __set-prompt ()
 {
-    BUILDING_PS1=t
+    BUILDING_PS=t
 
     PS1="$(__write-context)\n$(__fontify '\$' dim) "
 
-    unset BUILDING_PS1
+    unset BUILDING_PS
 }
 
 __current-column ()
@@ -209,9 +209,6 @@ __init-smart ()
 {
     ### Prompts.
 
-    PS2=$(__fontify '… ' dim)
-    export PS4=$(__fontify "${PS4}" reverse)
-
     if __have-gitprompt
     then
         . /usr/lib/git-core/git-sh-prompt
@@ -223,6 +220,11 @@ __init-smart ()
 
     PROMPT_COMMAND=__refresh-terminal
 
+    PS2=$(
+        BUILDING_PS=t
+        __fontify '… ' dim
+    )
+
     ### Bindings.
 
     bind -f ~/.bash_inputrc
-- 
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