From e65d0e53b1234f9173831a8a34c4e64d5542b0cb Mon Sep 17 00:00:00 2001
From: smolck <46855713+smolck@users.noreply.github.com>
Date: Wed, 3 Feb 2021 18:13:04 -0600
Subject: [PATCH 1/5] vim.fn: throw error when trying to use API function

---
 src/nvim/lua/vim.lua | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index dbf4f6014c..e154404836 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -253,9 +253,17 @@ end
 -- vim.fn.{func}(...)
 vim.fn = setmetatable({}, {
   __index = function(t, key)
-    local function _fn(...)
-      return vim.call(key, ...)
+    local _fn
+    if vim.api[key] ~= nil then
+      _fn = function(...)
+        error(string.format("Tried to call API function with vim.fn: use vim.api.%s() instead", key))
+      end
+    else
+      _fn = function(...)
+        return vim.call(key, ...)
+      end
     end
+
     t[key] = _fn
     return _fn
   end

From 2d06538b5eb8513ad58a7d34eed8e38664627cd8 Mon Sep 17 00:00:00 2001
From: smolck <46855713+smolck@users.noreply.github.com>
Date: Thu, 4 Feb 2021 08:27:38 -0600
Subject: [PATCH 2/5] remove extra line, remove () in error

---
 src/nvim/lua/vim.lua | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index e154404836..da6c2c4678 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -256,14 +256,13 @@ vim.fn = setmetatable({}, {
     local _fn
     if vim.api[key] ~= nil then
       _fn = function(...)
-        error(string.format("Tried to call API function with vim.fn: use vim.api.%s() instead", key))
+        error(string.format("Tried to call API function with vim.fn: use vim.api.%s instead", key))
       end
     else
       _fn = function(...)
         return vim.call(key, ...)
       end
     end
-
     t[key] = _fn
     return _fn
   end

From ad1a437835dd78d668c2255892ee4dc3bfcebcfc Mon Sep 17 00:00:00 2001
From: smolck <46855713+smolck@users.noreply.github.com>
Date: Thu, 4 Feb 2021 09:22:27 -0600
Subject: [PATCH 3/5] vim.fn: add test for error

---
 test/functional/lua/vim_spec.lua | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index e253db5297..301dc503df 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -715,6 +715,11 @@ describe('lua stdlib', function()
     eq({false, 'Vim:E714: List required'}, exec_lua([[return {pcall(vim.fn.add, "aa", "bb")}]]))
   end)
 
+  it('vim.fn should error when calling API function', function()
+      eq({false, 'vim.lua:259: Tried to call API function with vim.fn: use vim.api.nvim_get_current_line instead'},
+          exec_lua([[return {pcall(vim.fn.nvim_get_current_line)}]]))
+  end)
+
   it('vim.rpcrequest and vim.rpcnotify', function()
     exec_lua([[
       chan = vim.fn.jobstart({'cat'}, {rpc=true})

From 4526294848e5289a1f67cdb6c7e6fe5327f340fb Mon Sep 17 00:00:00 2001
From: smolck <46855713+smolck@users.noreply.github.com>
Date: Sat, 6 Feb 2021 11:06:33 -0600
Subject: [PATCH 4/5] Fix unused vararg

---
 src/nvim/lua/vim.lua | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index da6c2c4678..fd53bffe94 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -255,7 +255,7 @@ vim.fn = setmetatable({}, {
   __index = function(t, key)
     local _fn
     if vim.api[key] ~= nil then
-      _fn = function(...)
+      _fn = function()
         error(string.format("Tried to call API function with vim.fn: use vim.api.%s instead", key))
       end
     else

From d1899bb5f40d9f6f0e4426b6e87a44b69e38b29f Mon Sep 17 00:00:00 2001
From: smolck <46855713+smolck@users.noreply.github.com>
Date: Tue, 9 Mar 2021 15:23:42 -0600
Subject: [PATCH 5/5] use pcall_err

---
 test/functional/lua/vim_spec.lua | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/functional/lua/vim_spec.lua b/test/functional/lua/vim_spec.lua
index 301dc503df..9bf00b594b 100644
--- a/test/functional/lua/vim_spec.lua
+++ b/test/functional/lua/vim_spec.lua
@@ -716,8 +716,8 @@ describe('lua stdlib', function()
   end)
 
   it('vim.fn should error when calling API function', function()
-      eq({false, 'vim.lua:259: Tried to call API function with vim.fn: use vim.api.nvim_get_current_line instead'},
-          exec_lua([[return {pcall(vim.fn.nvim_get_current_line)}]]))
+      eq('Error executing lua: vim.lua:0: Tried to call API function with vim.fn: use vim.api.nvim_get_current_line instead',
+          pcall_err(exec_lua, "vim.fn.nvim_get_current_line()"))
   end)
 
   it('vim.rpcrequest and vim.rpcnotify', function()