vim-patch:8.2.4504: when there is a partially matching map full map may not work

Problem:    When there is a partially matching map and modifyOtherKeys is
            active a full map may not work.
Solution:   Only simplify modifiers when there is no matching mapping.
            (closes vim/vim#8792)
https://github.com/vim/vim/commit/196c3850dbe95247f7aa1b0000a5cae625a99ef2

Omit test as it sends terminal codes. Use a Lua test instead.

2 files changed, 13 insertions, 2 deletions

diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 42044f6378..555eadb5d4 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -1972,7 +1972,7 @@ static int handle_mapping(int *keylenp, bool *timedout, int *mapdepth)
     }
 
     // If no partly match found, use the longest full match.
-    if (keylen != KEYLEN_PART_MAP) {
+    if (keylen != KEYLEN_PART_MAP && mp_match != NULL) {
       mp = mp_match;
       keylen = mp_match_len;
     }
@@ -2011,7 +2011,7 @@ static int handle_mapping(int *keylenp, bool *timedout, int *mapdepth)
     }
   }
 
-  if ((mp == NULL || max_mlen >= mp_match_len) && keylen != KEYLEN_PART_MAP) {
+  if ((mp == NULL || max_mlen > mp_match_len) && keylen != KEYLEN_PART_MAP) {
     // When no matching mapping found or found a non-matching mapping that
     // matches at least what the matching mapping matched:
     // Try to include the modifier into the key, when:
diff --git a/test/functional/ui/input_spec.lua b/test/functional/ui/input_spec.lua
index d137049d55..25fc9cdcd1 100644
--- a/test/functional/ui/input_spec.lua
+++ b/test/functional/ui/input_spec.lua
@@ -275,6 +275,17 @@ it('mixing simplified and unsimplified keys can trigger mapping vim-patch:8.2.09
   expect('c-a')
 end)
 
+it('unsimplified mapping works when there was a partial match vim-patch:8.2.4504', function()
+  command('set timeoutlen=10')
+  command('nnoremap <C-J> a')
+  command('nnoremap <NL> x')
+  command('nnoremap <C-J>x <Nop>')
+  funcs.setline(1, 'x')
+  -- CTRL-J b should have trigger the <C-J> mapping and then insert "b"
+  feed('<C-J>b<Esc>')
+  expect('xb')
+end)
+
 describe('input non-printable chars', function()
   after_each(function()
     os.remove('Xtest-overwrite')