From 06d9cc734bf0397b365d5d75b1766a4fb245d2f5 Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Tue, 30 Jul 2019 11:37:39 +0200
Subject: [PATCH] exists(): return false for empty env var #10657

Fixes https://github.com/neovim/neovim/issues/3266
close #10657
---
 src/nvim/eval.c                       |  2 +-
 test/functional/eval/environ_spec.lua | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 31a49faaf3..1d221bb600 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -8718,7 +8718,7 @@ static void f_exists(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   const char *p = tv_get_string(&argvars[0]);
   if (*p == '$') {  // Environment variable.
     // First try "normal" environment variables (fast).
-    if (os_getenv(p + 1) != NULL) {
+    if (os_env_exists(p + 1)) {
       n = true;
     } else {
       // Try expanding things like $VIM and ${HOME}.
diff --git a/test/functional/eval/environ_spec.lua b/test/functional/eval/environ_spec.lua
index eb52f9e2da..4c2adcf1bf 100644
--- a/test/functional/eval/environ_spec.lua
+++ b/test/functional/eval/environ_spec.lua
@@ -2,11 +2,17 @@ local helpers = require('test.functional.helpers')(after_each)
 local clear = helpers.clear
 local eq = helpers.eq
 local environ = helpers.funcs.environ
+local exists = helpers.funcs.exists
 
-describe('environ()', function()
-  it('handles empty env variable', function()
+describe('environment variables', function()
+  it('environ() handles empty env variable', function()
     clear({env={EMPTY_VAR=""}})
     eq("", environ()['EMPTY_VAR'])
     eq(nil, environ()['DOES_NOT_EXIST'])
   end)
+  it('exists() handles empty env variable', function()
+    clear({env={EMPTY_VAR=""}})
+    eq(1, exists('$EMPTY_VAR'))
+    eq(0, exists('$DOES_NOT_EXIST'))
+  end)
 end)