vim patches 7.4.955/974/975/989. #3919

Helped by @Shougo.

vim-patch:7.4.955
vim-patch:7.4.974
vim-patch:7.4.975
vim-patch:7.4.989

Port upstream vim patches 955, 974, 975 and 989. Mark patches
964, 968, 970, and 971, and 982 as NA. Update patch list to 1022.

patch 7.4.955
Problem:    Vim doesn't recognize .pl6 and .pod6 files.
Solution:   Recognize them as perl6 and pod6. (Mike Eve)

patch 7.4.974
Problem:    When using :diffsplit the cursor jumps to the first line.
Solution:   Put the cursor on the line related to where the cursor was before
            the split.

patch 7.4.975
Problem:    Using ":sort" on a very big file sometimes causes text to be
            corrupted. (John Beckett)
Solution:   Copy the line into a buffer before calling ml_append().

patch 7.4.989
Problem:    Leaking memory when hash_add() fails. Coverity error 99126.
Solution:   When hash_add() fails free the memory.

778 marked as not NA as it will be needed once vim patch 754 is merged

Marked as NA:
964 test 87 was deleted
968 tests 86/87 were deleted
970 guarded by: `# if defined(FEAT_GUI_GTK) || defined(PROTO`
    and is inside a function that no longer exists
971 function table already sorted correctly
982 marked as NA because Neovim tests are only specified in exactly one location

runtime/filetype.vim

@@ -1393,7 +1393,7 @@ else
   au BufNewFile,BufRead *.pl			call s:FTpl()
 endif
 au BufNewFile,BufRead *.plx,*.al		setf perl
-au BufNewFile,BufRead *.p6,*.pm6		setf perl6
+au BufNewFile,BufRead *.p6,*.pm6,*.pl6	setf perl6
 
 func! s:FTpl()
   if exists("g:filetype_pl")
@@ -1422,6 +1422,7 @@ au BufNewFile,BufRead *.pm
 
 " Perl POD
 au BufNewFile,BufRead *.pod			setf pod
+au BufNewFile,BufRead *.pod6		setf pod6
 
 " Php, php3, php4, etc.
 " Also Phtml (was used for PHP 2 in the past)

src/nvim/diff.c

@@ -1007,6 +1007,7 @@ theend:
 void ex_diffsplit(exarg_T *eap)
 {
   win_T *old_curwin = curwin;
+  buf_T *old_curbuf = curbuf;
 
   // don't use a new tab page, each tab page has its own diffs
   cmdmod.tab = 0;
@@ -1020,8 +1021,19 @@ void ex_diffsplit(exarg_T *eap)
     // split must have worked
     if (curwin != old_curwin) {
       // Set 'diff', 'scrollbind' on and 'wrap' off.
-      diff_win_options(curwin, TRUE);
-      diff_win_options(old_curwin, TRUE);
+      diff_win_options(curwin, true);
+      if (win_valid(old_curwin)) {
+        diff_win_options(old_curwin, true);
+
+        if (buf_valid(old_curbuf)) {
+          // Move the cursor position to that of the old window.
+          curwin->w_cursor.lnum = diff_get_corresponding_line(
+              old_curbuf,
+              old_curwin->w_cursor.lnum,
+              curbuf,
+              curwin->w_cursor.lnum);
+        }
+      }
     }
   }
 }

src/nvim/eval.c

@@ -19793,7 +19793,10 @@ void ex_function(exarg_T *eap)
 
     /* insert the new function in the function list */
     STRCPY(fp->uf_name, name);
-    hash_add(&func_hashtab, UF2HIKEY(fp));
+    if (hash_add(&func_hashtab, UF2HIKEY(fp)) == FAIL) {
+        xfree(fp);
+        goto erret;
+    }
   }
   fp->uf_refcount = 1;
   fp->uf_args = newargs;

src/nvim/ex_cmds.c

@@ -495,10 +495,12 @@ void ex_sort(exarg_T *eap)
     s = ml_get(nrs[eap->forceit ? count - i - 1 : i].lnum);
     if (!unique || i == 0
         || (sort_ic ? STRICMP(s, sortbuf1) : STRCMP(s, sortbuf1)) != 0) {
-      if (ml_append(lnum++, s, (colnr_T)0, FALSE) == FAIL)
-        break;
-      if (unique)
+      // Copy the line into a buffer, it may become invalid in
+      // ml_append(). And it's needed for "unique".
       STRCPY(sortbuf1, s);
+      if (ml_append(lnum++, sortbuf1, (colnr_T)0, false) == FAIL) {
+        break;
+      }
     }
     fast_breakcheck();
     if (got_int)

src/nvim/version.c

@@ -135,32 +135,32 @@ static int included_patches[] = {
   // 992 NA
   // 991,
   // 990 NA
-  // 989,
+  989,
   // 988 NA
   // 987 NA
   // 986 NA
   // 985 NA
   // 984,
   // 983,
-  // 982,
+  // 982 NA
   // 981,
   // 980,
   // 979 NA
   // 978,
   // 977,
   // 976 NA
-  // 975,
+  975,
   // 974,
   // 973,
-  // 972,
-  // 971,
-  // 970,
+  972,
+  // 971 NA
+  // 970 NA
   // 969,
-  // 968,
+  // 968 NA
   // 967 NA
   // 966 NA
   // 965 NA
-  // 964,
+  // 964 NA
   // 963,
   // 962 NA
   // 961,
@@ -169,7 +169,7 @@ static int included_patches[] = {
   // 958,
   // 957,
   // 956,
-  // 955,
+  955,
   // 954 NA
   953,
   // 952,
@@ -346,7 +346,7 @@ static int included_patches[] = {
   781,
   // 780 NA
   // 779,
-  // 778 NA
+  // 778,
   // 777 NA
   776,
   775,