From b10bb327f3909a215d65bc30b10cef3aaed5459b Mon Sep 17 00:00:00 2001
From: Charly Delay <0xcharly@users.noreply.github.com>
Date: Sat, 30 Oct 2021 19:05:20 +0900
Subject: [PATCH] misc.merge: ensure that `misc.none` is never returned (#441)
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Before this change:

1. `misc.merge({a = misc.none}, {a = nil})` returned `{a = misc.none}`
2. `misc.merge({a = nil}, {a = misc.none})` returned `{a = misc.none}`

(1) can cause error if a non-existing mapping is set to `config.disable`
(which is an alias for `misc.none`).

(2) does not cause any issue to date, but is inconsistent with the
expected behavior of `misc.merge(…)`.

After this change:

1. `misc.merge({a = misc.none}, {a = nil})` returns `{a = nil}`
2. `misc.merge({a = nil}, {a = misc.none})` returns `{a = nil}`

Fixes #440.
---
 lua/cmp/utils/misc.lua      |  8 ++++++--
 lua/cmp/utils/misc_spec.lua | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/lua/cmp/utils/misc.lua b/lua/cmp/utils/misc.lua
index 90d07cf..8ce41d4 100644
--- a/lua/cmp/utils/misc.lua
+++ b/lua/cmp/utils/misc.lua
@@ -46,7 +46,7 @@ misc.merge = function(v1, v2)
       new_tbl[k] = misc.merge(v1[k], v)
     end
     for k, v in pairs(v1) do
-      if v2[k] == nil then
+      if v2[k] == nil and v ~= misc.none then
         new_tbl[k] = v
       end
     end
@@ -56,7 +56,11 @@ misc.merge = function(v1, v2)
     return nil
   end
   if v1 == nil then
-    return v2
+    if v2 == misc.none then
+      return nil
+    else
+      return v2
+    end
   end
   if v1 == true then
     if merge2 then
diff --git a/lua/cmp/utils/misc_spec.lua b/lua/cmp/utils/misc_spec.lua
index d7cec0b..4e705ef 100644
--- a/lua/cmp/utils/misc_spec.lua
+++ b/lua/cmp/utils/misc_spec.lua
@@ -33,5 +33,19 @@ describe('misc', function()
       },
     })
     assert.are.equal(merged.a, nil)
+
+    merged = misc.merge({
+      a = misc.none,
+    }, {
+      a = nil,
+    })
+    assert.are.equal(merged.a, nil)
+
+    merged = misc.merge({
+      a = nil,
+    }, {
+      a = misc.none,
+    })
+    assert.are.equal(merged.a, nil)
   end)
 end)