From eabec4e9b6590408f92557fd2bdb24408aaf8068 Mon Sep 17 00:00:00 2001
From: "Kenneth Benzie (Benie)" <benie@infektor.net>
Date: Tue, 13 Jul 2021 21:00:48 +0100
Subject: [PATCH] Add build#dir() popup_menu() fallback

When `popup_menu()` is not available, i.e. neovim or old version of vim,
fallback to using `inputlist()` instead.
---
 autoload/build.vim | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/autoload/build.vim b/autoload/build.vim
index a389436..10f5e20 100644
--- a/autoload/build.vim
+++ b/autoload/build.vim
@@ -10,12 +10,25 @@ function! build#dir(...) abort
       let l:dir = s:dirs[0]
       unlet s:dirs
     else
-      " Multiple build directories found, create popup menu to select one.
-      " Set the callback to this function on completion, handled below.
-      call popup_menu(s:dirs, #{
-      \   filter: 'popup_filter_menu',
-      \   callback: 'build#dir',
-      \ })
+      " Multiple build directories found, select one.
+      if exists('*popup_menu')
+        " Create popup menu to select the build directory. Callback to this
+        " function on completion, handled in the else branch below.
+        call popup_menu(s:dirs, #{
+        \   filter: 'popup_filter_menu',
+        \   callback: 'build#dir',
+        \ })
+      else
+        " Fallback to inputlist when popup_menu is not available.
+        let l:choices = []
+        let l:index = 1
+        for l:dir in s:dirs
+          call add(l:choices, string(l:index).': '.l:dir)
+          let l:index += 1
+        endfor
+        let l:index = inputlist(l:choices)
+        let l:dir = s:dirs[l:index - 1]
+      endif
     endif
   else
     if a:0 == 1