vim-patch:8.2.4465: fuzzy completion does not order matches properly

Problem:    Fuzzy completion does not order matches properly.
Solution:   Do not use regular expression match. (Yegappan Lakshmanan,
            closes vim/vim#9843)

https://github.com/vim/vim/commit/5ec633b9b0400519db60253cb5846e50394218b4

Nvim's ExpandGeneric() was refactored to eliminate looping for "round",
so the patch has been adapted.

fuzzy_match_str() change was already applied earlier.

In Test_wildoptions_fuzzy(), test for NvimParenthesis over MatchParen
for :syntax list, as the fuzzy matching algorithm prefers the former
(even in Vim).

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

2 files changed, 61 insertions, 25 deletions

diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index f18869bb1c..566a17b82b 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -2765,8 +2765,14 @@ static void ExpandGeneric(expand_T *xp, regmatch_T *regmatch, char ***matches, i
     if (*str == NUL) {  // skip empty strings
       continue;
     }
-    if (vim_regexec(regmatch, str, (colnr_T)0)
-        || (fuzzy && fuzzy_match_str(str, fuzzystr) != 0)) {
+
+    bool match;
+    if (!fuzzy) {
+      match = vim_regexec(regmatch, str, (colnr_T)0);
+    } else {
+      match = fuzzy_match_str(str, fuzzystr) != 0;
+    }
+    if (match) {
       count++;
     }
   }
@@ -2792,28 +2798,37 @@ static void ExpandGeneric(expand_T *xp, regmatch_T *regmatch, char ***matches, i
     if (*str == NUL) {  // Skip empty strings.
       continue;
     }
-    int score;
-    if (vim_regexec(regmatch, str, (colnr_T)0)
-        || (fuzzy && ((score = fuzzy_match_str(str, fuzzystr)) != 0))) {
-      if (escaped) {
-        str = vim_strsave_escaped(str, " \t\\.");
-      } else {
-        str = xstrdup(str);
-      }
-      if (fuzzy) {
-        fuzmatch[count].idx = (int)count;
-        fuzmatch[count].str = str;
-        fuzmatch[count].score = score;
-      } else {
-        (*matches)[count] = str;
-      }
-      count++;
-      if (func == get_menu_names) {
-        // Test for separator added by get_menu_names().
-        str += strlen(str) - 1;
-        if (*str == '\001') {
-          *str = '.';
-        }
+
+    bool match;
+    int score = 0;
+    if (!fuzzy) {
+      match = vim_regexec(regmatch, str, (colnr_T)0);
+    } else {
+      score = fuzzy_match_str(str, fuzzystr);
+      match = (score != 0);
+    }
+    if (!match) {
+      continue;
+    }
+
+    if (escaped) {
+      str = vim_strsave_escaped(str, " \t\\.");
+    } else {
+      str = xstrdup(str);
+    }
+    if (fuzzy) {
+      fuzmatch[count].idx = (int)count;
+      fuzmatch[count].str = str;
+      fuzmatch[count].score = score;
+    } else {
+      (*matches)[count] = str;
+    }
+    count++;
+    if (func == get_menu_names) {
+      // Test for separator added by get_menu_names().
+      str += strlen(str) - 1;
+      if (*str == '\001') {
+        *str = '.';
       }
     }
   }
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index e068685164..f5726c093b 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -2941,7 +2941,9 @@ func Test_wildoptions_fuzzy()
   call assert_equal('"syntax list mpar', @:)
   set wildoptions=fuzzy
   call feedkeys(":syntax list mpar\<Tab>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"syntax list MatchParen', @:)
+  " Fuzzy match favours NvimParenthesis over MatchParen
+  " call assert_equal('"syntax list MatchParen', @:)
+  call assert_equal('"syntax list NvimParenthesis', @:)
 
   " :syntime suboptions fuzzy completion
   if has('profile')
@@ -2968,6 +2970,25 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":let SVar\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"let SomeVariable', @:)
 
+  " Test for sorting the results by the best match
+  %bw!
+  command T123format :
+  command T123goformat :
+  command T123TestFOrmat :
+  command T123fendoff :
+  command T123state :
+  command T123FendingOff :
+  set wildoptions=fuzzy
+  call feedkeys(":T123fo\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"T123format T123TestFOrmat T123FendingOff T123goformat T123fendoff', @:)
+  delcommand T123format
+  delcommand T123goformat
+  delcommand T123TestFOrmat
+  delcommand T123fendoff
+  delcommand T123state
+  delcommand T123FendingOff
+  %bw
+
   set wildoptions&
   %bw!
 endfunc