vim-patch:8.2.1978: making a mapping work in all modes is complicated

Problem:    Making a mapping work in all modes is complicated.
Solution:   Add the <Cmd> special key. (Yegappan Lakshmanan, closes vim/vim#7282,
            closes 4784, based on patch by Bjorn Linse)

https://github.com/vim/vim/commit/957cf67d50516ba98716f59c9e1cb6412ec1535d

Change docs to match Vim if it's wording is better.
Change error numbers to match Vim.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

3 files changed, 13 insertions, 10 deletions

diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 2078fc4251..c544daee08 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -876,7 +876,7 @@ static int insert_handle_key(InsertState *s)
     state_handle_k_event();
     goto check_pum;
 
-  case K_COMMAND:       // some command
+  case K_COMMAND:     // <Cmd>command<CR>
     do_cmdline(NULL, getcmdkeycmd, NULL, 0);
     goto check_pum;
 
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index a0e8350287..31817676e1 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -134,6 +134,10 @@ static size_t last_recorded_len = 0;      // number of last recorded chars
 #endif
 
 static const char e_recursive_mapping[] = N_("E223: Recursive mapping");
+static const char e_cmd_mapping_must_end_with_cr[]
+  = N_("E1135: <Cmd> mapping must end with <CR>");
+static const char e_cmd_mapping_must_end_with_cr_before_second_cmd[]
+  = N_("E1136: <Cmd> mapping must end with <CR> before second <Cmd>");
 
 // Free and clear a buffer.
 void free_buff(buffheader_T *buf)
@@ -2884,7 +2888,8 @@ int fix_input_buffer(uint8_t *buf, int len)
   return len;
 }
 
-/// Get command argument for <Cmd> key
+/// Function passed to do_cmdline() to get the command after a <Cmd> key from
+/// typeahead.
 char *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
 {
   garray_T line_ga;
@@ -2894,6 +2899,7 @@ char *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
 
   ga_init(&line_ga, 1, 32);
 
+  // no mapping for these characters
   no_mapping++;
 
   got_int = false;
@@ -2903,16 +2909,17 @@ char *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
     if (vgetorpeek(false) == NUL) {
       // incomplete <Cmd> is an error, because there is not much the user
       // could do in this state.
-      emsg(e_cmdmap_err);
+      emsg(_(e_cmd_mapping_must_end_with_cr));
       aborted = true;
       break;
     }
 
     // Get one character at a time.
     c1 = vgetorpeek(true);
+
     // Get two extra bytes for special keys
     if (c1 == K_SPECIAL) {
-      c1 = vgetorpeek(true);          // no mapping for these chars
+      c1 = vgetorpeek(true);
       c2 = vgetorpeek(true);
       if (c1 == KS_MODIFIER) {
         cmod = c2;
@@ -2928,8 +2935,8 @@ char *getcmdkeycmd(int promptc, void *cookie, int indent, bool do_concat)
     } else if (c1 == ESC) {
       aborted = true;
     } else if (c1 == K_COMMAND) {
-      // special case to give nicer error message
-      emsg(e_cmdmap_repeated);
+      // give a nicer error message for this special case
+      emsg(_(e_cmd_mapping_must_end_with_cr_before_second_cmd));
       aborted = true;
     } else if (c1 == K_SNR) {
       ga_concat(&line_ga, "<SNR>");
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 698f4a98c7..6eae2f7589 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1003,10 +1003,6 @@ EXTERN const char e_cannot_edit_other_buf[] INIT(= N_("E788: Not allowed to edit
 EXTERN const char e_using_number_as_bool_nr[] INIT(= N_("E1023: Using a Number as a Bool: %d"));
 EXTERN const char e_not_callable_type_str[] INIT(= N_("E1085: Not a callable type: %s"));
 
-EXTERN const char e_cmdmap_err[] INIT(= N_("E5520: <Cmd> mapping must end with <CR>"));
-EXTERN const char e_cmdmap_repeated[]
-INIT(= N_("E5521: <Cmd> mapping must end with <CR> before second <Cmd>"));
-
 EXTERN const char e_api_error[] INIT(= N_("E5555: API call: %s"));
 
 EXTERN const char e_luv_api_disabled[] INIT(= N_("E5560: %s must not be called in a lua loop callback"));