vim-patch:8.1.0351: 'incsearch' for :/foo/s//<Esc> changes last search pattern

Problem:    'incsearch' for :/foo/s//<Esc> changes last search pattern.
Solution:   Save the last search pattern earlier.
198cb66d65

src/nvim/ex_docmd.c

@@ -2301,6 +2301,7 @@ static void free_cmdmod(void)
 
 
 // Parse the address range, if any, in "eap".
+// May set the last search pattern.
 // Return FAIL and set "errormsg" or return OK.
 int parse_cmd_address(exarg_T *eap, char_u **errormsg)
   FUNC_ATTR_NONNULL_ALL
@@ -3683,14 +3684,13 @@ char_u *skip_range(
   return (char_u *)cmd;
 }
 
-/*
- * get a single EX address
- *
- * Set ptr to the next character after the part that was interpreted.
- * Set ptr to NULL when an error is encountered.
- *
- * Return MAXLNUM when no Ex address was found.
- */
+// Get a single EX address
+//
+// Set ptr to the next character after the part that was interpreted.
+// Set ptr to NULL when an error is encountered.
+// This may set the last used search pattern.
+//
+// Return MAXLNUM when no Ex address was found.
 static linenr_T get_address(exarg_T *eap,
                             char_u **ptr,
                             int addr_type,  // flag: one of ADDR_LINES, ...

src/nvim/ex_getln.c

@@ -422,13 +422,18 @@ static void may_do_incsearch_highlighting(int firstc, long count,
   char_u next_char;
   char_u use_last_pat;
 
+  // Parsing range may already set the last search pattern.
+  save_last_search_pattern();
+
   if (!do_incsearch_highlighting(firstc, s, &skiplen, &patlen)) {
+    restore_last_search_pattern();
     finish_incsearch_highlighting(false, s, true);
     return;
   }
 
   // if there is a character waiting, search and redraw later
   if (char_avail()) {
+    restore_last_search_pattern();
     s->incsearch_postponed = true;
     return;
   }
@@ -442,7 +447,6 @@ static void may_do_incsearch_highlighting(int firstc, long count,
     curwin->w_cursor.lnum = search_first_line;
     curwin->w_cursor.col = 0;
   }
-  save_last_search_pattern();
   int i;
 
   // Use the previous pattern for ":s//".
@@ -556,8 +560,13 @@ static void may_do_incsearch_highlighting(int firstc, long count,
 static int may_add_char_to_search(int firstc, int *c, incsearch_state_T *s)
 {
   int skiplen, patlen;
+
+  // Parsing range may already set the last search pattern.
+  save_last_search_pattern();
+
   // Add a character from under the cursor for 'incsearch'
   if (!do_incsearch_highlighting(firstc, s, &skiplen, &patlen)) {
+    restore_last_search_pattern();
     return FAIL;
   }
 
@@ -1431,10 +1440,16 @@ static int may_do_command_line_next_incsearch(int firstc, long count,
                                               bool next_match)
 {
   int skiplen, patlen;
+
+  // Parsing range may already set the last search pattern.
+  save_last_search_pattern();
+
   if (!do_incsearch_highlighting(firstc, s, &skiplen, &patlen)) {
+    restore_last_search_pattern();
     return OK;
   }
   if (patlen == 0 && ccline.cmdbuff[skiplen] == NUL) {
+    restore_last_search_pattern();
     return FAIL;
   }
 
@@ -1455,8 +1470,6 @@ static int may_do_command_line_next_incsearch(int firstc, long count,
     pat = ccline.cmdbuff + skiplen;
   }
 
-  save_last_search_pattern();
-
   if (next_match) {
     t = s->match_end;
     if (lt(s->match_start, s->match_end)) {

src/nvim/testdir/test_search.vim

@@ -783,6 +783,24 @@ func Test_incsearch_vimgrep_dump()
   call delete('Xis_vimgrep_script')
 endfunc
 
+func Test_keep_last_search_pattern()
+  throw 'skipped: Nvim does not support test_override()'
+  if !exists('+incsearch')
+    return
+  endif
+  new
+  call setline(1, ['foo', 'foo', 'foo'])
+  set incsearch
+  call test_override("char_avail", 1)
+  let @/ = 'bar'
+  call feedkeys(":/foo/s//\<Esc>", 'ntx')
+  call assert_equal('bar', @/)
+
+  bwipe!
+  call test_override("ALL", 0)
+  set noincsearch
+endfunc
+
 func Test_incsearch_with_change()
   if !has('timers') || !exists('+incsearch') || !CanRunVimInTerminal()
     throw 'Skipped: cannot make screendumps and/or timers feature and/or incsearch option missing'