vim-patch:9.1.0605: internal error with fuzzy completion

Problem:  internal error with fuzzy completion
          (techntools)
Solution: only fuzzy complete the pattern after directory separator
          (glepnir)

fixes: vim/vim#15287
closes: vim/vim#15291

https://github.com/vim/vim/commit/0be03e14b9a2899f5e96720e3b21935bd9d2d34e

Co-authored-by: glepnir <glephunter@gmail.com>

3 files changed, 38 insertions, 11 deletions

diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 7a123898a5..a02d7a62d2 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -3315,12 +3315,31 @@ static void get_next_filename_completion(void)
   char **matches;
   int num_matches;
   char *leader = ins_compl_leader();
-  size_t leader_len = strlen(leader);
+  size_t leader_len = ins_compl_leader_len();
   bool in_fuzzy = ((get_cot_flags() & kOptCotFlagFuzzy) != 0 && leader_len > 0);
 
   if (in_fuzzy) {
-    API_CLEAR_STRING(compl_pattern);
-    compl_pattern = cbuf_to_string("*", 1);
+    char *last_sep = strrchr(leader, PATHSEP);
+    if (last_sep == NULL) {
+      // No path separator or separator is the last character,
+      // fuzzy match the whole leader
+      API_CLEAR_STRING(compl_pattern);
+      compl_pattern = cbuf_to_string("*", 1);
+    } else if (*(last_sep + 1) == NUL) {
+      in_fuzzy = false;
+    } else {
+      // Split leader into path and file parts
+      size_t path_len = (size_t)(last_sep - leader) + 1;
+      char *path_with_wildcard = xmalloc(path_len + 2);
+      vim_snprintf(path_with_wildcard, path_len + 2, "%*.*s*",
+                   (int)path_len, (int)path_len, leader);
+      API_CLEAR_STRING(compl_pattern);
+      compl_pattern.data = path_with_wildcard;
+      compl_pattern.size = path_len + 1;
+
+      // Move leader to the file part
+      leader = last_sep + 1;
+    }
   }
 
   if (expand_wildcards(1, &compl_pattern.data, &num_matches, &matches,
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 30653cbe63..756a4c5255 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -3689,15 +3689,15 @@ bool search_for_fuzzy_match(buf_T *buf, pos_T *pos, char *pattern, int dir, pos_
     current_pos.lnum += dir;
   }
 
-  while (true) {
-    if (buf == curbuf) {
-      circly_end = *start_pos;
-    } else {
-      circly_end.lnum = buf->b_ml.ml_line_count;
-      circly_end.col = 0;
-      circly_end.coladd = 0;
-    }
+  if (buf == curbuf) {
+    circly_end = *start_pos;
+  } else {
+    circly_end.lnum = buf->b_ml.ml_line_count;
+    circly_end.col = 0;
+    circly_end.coladd = 0;
+  }
 
+  while (true) {
     // Check if looped around and back to start position
     if (looped_around && equalpos(current_pos, circly_end)) {
       break;
@@ -3717,6 +3717,8 @@ bool search_for_fuzzy_match(buf_T *buf, pos_T *pos, char *pattern, int dir, pos_
           if (found_new_match) {
             *pos = current_pos;
             break;
+          } else if (looped_around && current_pos.lnum == circly_end.lnum) {
+            break;
           }
         } else {
           if (fuzzy_match_str(*ptr, pattern) > 0) {
diff --git a/test/old/testdir/test_ins_complete.vim b/test/old/testdir/test_ins_complete.vim
index 9b123a65b6..381a69dd41 100644
--- a/test/old/testdir/test_ins_complete.vim
+++ b/test/old/testdir/test_ins_complete.vim
@@ -2871,6 +2871,10 @@ func Test_complete_fuzzy_match()
   call assert_equal('fobar', getline('.'))
   call feedkeys("Sfob\<C-X>\<C-f>\<C-N>\<Esc>0", 'tx!')
   call assert_equal('foobar', getline('.'))
+  call feedkeys("S../\<C-X>\<C-f>\<Esc>0", 'tx!')
+  call assert_match('../*', getline('.'))
+  call feedkeys("S../td\<C-X>\<C-f>\<Esc>0", 'tx!')
+  call assert_match('../testdir', getline('.'))
 
   " can get completion from other buffer
   set completeopt=fuzzy,menu,menuone
@@ -2885,6 +2889,8 @@ func Test_complete_fuzzy_match()
   call assert_equal('Omnipotent', getline('.'))
   call feedkeys("Somp\<C-P>\<C-P>\<Esc>0", 'tx!')
   call assert_equal('Composite', getline('.'))
+  call feedkeys("S omp\<C-N>\<Esc>0", 'tx!')
+  call assert_equal(' completeness', getline('.'))
 
   " fuzzy on whole line completion
   call setline(1, ["world is on fire", "no one can save me but you", 'user can execute', ''])