feat(git-prompt): add option to show upstream branch (#11336)

plugins/git-prompt/README.md

@@ -45,6 +45,7 @@ The symbols are as follows:
 | ●n     | there are `n` staged files     |
 | ✖n     | there are `n` unmerged files   |
 | ✚n     | there are `n` unstaged files   |
+| -n     | there are `n` deleted files    |
 | ⚑n     | there are `n` stashed changes  |
 | …      | there are some untracked files |
 
@@ -59,6 +60,7 @@ The symbols are as follows:
 ## Customisation
 
 - Set the variable `ZSH_THEME_GIT_PROMPT_CACHE` to any value in order to enable caching.
+- Set the variable `ZSH_THEME_GIT_SHOW_UPSTREAM` to any value to display the upstream branch.
 - You may also change a number of variables (whose name start with `ZSH_THEME_GIT_PROMPT_`)
   to change the appearance of the prompt. Take a look at the bottom of the [plugin file](git-prompt.plugin.zsh)`
   to see what variables are available.

plugins/git-prompt/git-prompt.plugin.zsh

@@ -48,12 +48,18 @@ function update_current_git_vars() {
     GIT_STASHED=$__CURRENT_GIT_STATUS[8]
     GIT_CLEAN=$__CURRENT_GIT_STATUS[9]
     GIT_DELETED=$__CURRENT_GIT_STATUS[10]
+
+    if [ -z ${ZSH_THEME_GIT_SHOW_UPSTREAM+x} ]; then
+        GIT_UPSTREAM=
+    else
+        GIT_UPSTREAM=$(git rev-parse --abbrev-ref --symbolic-full-name "@{upstream}" 2>/dev/null) && GIT_UPSTREAM="${ZSH_THEME_GIT_PROMPT_UPSTREAM_SEPARATOR}${GIT_UPSTREAM}"
+    fi
 }
 
 git_super_status() {
     precmd_update_git_vars
     if [ -n "$__CURRENT_GIT_STATUS" ]; then
-      STATUS="$ZSH_THEME_GIT_PROMPT_PREFIX$ZSH_THEME_GIT_PROMPT_BRANCH$GIT_BRANCH%{${reset_color}%}"
+      STATUS="$ZSH_THEME_GIT_PROMPT_PREFIX$ZSH_THEME_GIT_PROMPT_BRANCH$GIT_BRANCH$GIT_UPSTREAM%{${reset_color}%}"
       if [ "$GIT_BEHIND" -ne "0" ]; then
           STATUS="$STATUS$ZSH_THEME_GIT_PROMPT_BEHIND$GIT_BEHIND%{${reset_color}%}"
       fi
@@ -101,6 +107,7 @@ ZSH_THEME_GIT_PROMPT_AHEAD="%{↑%G%}"
 ZSH_THEME_GIT_PROMPT_UNTRACKED="%{$fg[cyan]%}%{…%G%}"
 ZSH_THEME_GIT_PROMPT_STASHED="%{$fg_bold[blue]%}%{⚑%G%}"
 ZSH_THEME_GIT_PROMPT_CLEAN="%{$fg_bold[green]%}%{✔%G%}"
+ZSH_THEME_GIT_PROMPT_UPSTREAM_SEPARATOR="->"
 
 # Set the prompt.
 RPROMPT='$(git_super_status)'