partially roll back 4def4452 and work around bugs in some terminals that draw an extra ruler sometimes under load

powerlevel9k.zsh-theme

@@ -394,10 +394,8 @@ prompt_background_jobs() {
   $1_prompt_segment $0 $2 "$DEFAULT_COLOR" cyan BACKGROUND_JOBS_ICON 1 '${${(%):-%j}:#0}' "$msg"
 }
 
-typeset -g _P9K_XY
+typeset -g _P9K_XY _P9K_ALIGNED_RPROMPT
-typeset -gi _P9K_X _P9K_Y _P9K_M
+typeset -gi _P9K_X _P9K_Y _P9K_M _P9K_RPROMPT_DONE _P9K_IND
-typeset -gi _P9K_RPROMPT_DONE
-typeset -g _P9K_ALIGNED_RPROMPT
 
 # Returns 1 if the cursor is at the very end of the screen.
 function _p9k_left_prompt_end_line() {
@@ -2315,6 +2313,22 @@ _p9k_init_timer() {
   fi
 }
 
+# Does ZSH have a certain off-by-one bug that triggers when PROMPT overflows to a new line?
+#
+# Bug: https://github.com/zsh-users/zsh/commit/d8d9fee137a5aa2cf9bf8314b06895bfc2a05518.
+# ZSH_PATCHLEVEL=zsh-5.4.2-159-gd8d9fee13. Released in 5.5.
+#
+# Fix: https://github.com/zsh-users/zsh/commit/64d13738357c9b9c212adbe17f271716abbcf6ea.
+# ZSH_PATCHLEVEL=zsh-5.7.1-50-g64d137383.
+#
+# Test: PROMPT="${(pl:$((COLUMNS))::-:)}<%1(l.%2(l.FAIL.PASS).FAIL)> " zsh -dfis <<<exit
+# Workaround: PROMPT="${(pl:$((COLUMNS))::-:)}%{%G%}<%1(l.%2(l.FAIL.PASS).FAIL)> " zsh -dfis <<<exit
+function _p9k_prompt_overflow_bug() {
+  [[ $ZSH_PATCHLEVEL =~ '^zsh-5\.4\.2-([0-9]+)-' ]] && return $(( match[1] < 159 ))
+  [[ $ZSH_PATCHLEVEL =~ '^zsh-5\.7\.1-([0-9]+)-' ]] && return $(( match[1] >= 50 ))
+  is-at-least 5.5 && ! is-at-least 5.7.2
+}
+
 # Some people write POWERLEVEL9K_DIR_PATH_SEPARATOR='\uNNNN' instead of
 # POWERLEVEL9K_DIR_PATH_SEPARATOR=$'\uNNNN'. There is no good reason for it and if we were
 # starting from scratch we wouldn't perform automatic conversion from the former to the latter.
@@ -2431,7 +2445,7 @@ _p9k_init() {
     _P9K_ALIGNED_RPROMPT+='${_P9K_X::=${_P9K_XY%;*}}'
     _P9K_ALIGNED_RPROMPT+='${_P9K_Y::=${_P9K_XY#*;}}'
   done
-  _P9K_ALIGNED_RPROMPT+='${_P9K_X::=$((_P9K_X+2+${${ZLE_RPROMPT_INDENT:-1}/#-*/0}))}'
+  _P9K_ALIGNED_RPROMPT+='${_P9K_X::=$((_P9K_X+2+_P9K_IND))}'
   _P9K_ALIGNED_RPROMPT+='${_P9K_Y::=$((_P9K_X+31))}}+}'
 
   repeat 32; do
@@ -2441,7 +2455,9 @@ _p9k_init() {
     _P9K_ALIGNED_RPROMPT+='%-$_P9K_X(l. .)'
   done
   _P9K_ALIGNED_RPROMPT+=' $_P9K_RPROMPT'
-  _P9K_ALIGNED_RPROMPT+=$'\n'
+  _P9K_ALIGNED_RPROMPT+='$_P9K_T[$((3+!_P9K_IND))]'
+
+  _P9K_LEFT_PREFIX+='${${_P9K_IND::=${${ZLE_RPROMPT_INDENT:-1}/#-*/0}}+}'
 
   if [[ $POWERLEVEL9K_PROMPT_ADD_NEWLINE == true ]]; then
     repeat ${POWERLEVEL9K_PROMPT_ADD_NEWLINE_COUNT:-1} _P9K_LEFT_PREFIX+=$'\n'
@@ -2459,10 +2475,9 @@ _p9k_init() {
       _p9k_foreground $_P9K_RETVAL
       _P9K_LEFT_PREFIX+=$_P9K_RETVAL
       [[ $ruler_char == '.' ]] && local sep=',' || local sep='.'
-      local indent='${${ZLE_RPROMPT_INDENT:-1}/#-*/0}'
+      local ruler_len='${$((COLUMNS-_P9K_IND))/#-*/0}'
-      local ruler_len="\${\$((COLUMNS-$indent))/#-*/0}"
       _P9K_LEFT_PREFIX+="%b\${(pl$sep$ruler_len$sep$sep${(q)ruler_char}$sep)}%k%f"
-      _P9K_LEFT_PREFIX+=$'\n'
+      _P9K_LEFT_PREFIX+='$_P9K_T[$((3+!_P9K_IND))]'
     else
       print -P "%F{red}WARNING!%f %BPOWERLEVEL9K_RULER_CHAR%b is not one character long. Ruler won't be rendered."
       print -P "Either change the value of %BPOWERLEVEL9K_RULER_CHAR%b or set %BPOWERLEVEL9K_SHOW_RULER=false%b to"
@@ -2478,7 +2493,8 @@ _p9k_init() {
   _P9K_RIGHT_PREFIX+='${${_P9K_BG::=NONE}+}${${_P9K_I::=0}+}'
 
   _p9k_get_icon LEFT_SEGMENT_SEPARATOR
-  _P9K_T=("%f$_P9K_RETVAL" "")
+  _P9K_T=("%f$_P9K_RETVAL" "" $'\n')
+  _p9k_prompt_overflow_bug && _P9K_T+='%{%G%}' || _P9K_T+=''
 
   _P9K_RIGHT_SUFFIX+='%f%b%k'
   _P9K_RIGHT_PREFIX+='%f%b%k'