patch 9.1.0131: buffer-completion may not always find all matchesv9.1.0131

Problem:  buffer-completion code too complicated and does not always
          find all matches (irisjae)
Solution: do not try to anchor pattern to beginning of line or
          directory-separator, always return all matches

Note: we are considering the non-fuzzy buffer-matching here.

Currently, the buffer-completion code makes 2 attempts to match a
pattern against the list of available patterns. First try is to match
the pattern and anchor it to either the beginning of the file name or
at a directory-separator (// or \\).

When a match is found, Vim returns the matching buffers and does not try
to find a match anywhere within a buffer name. So if you have opened two
buffers like /tmp/Foobar.c and /tmp/MyFoobar.c using `:b Foo` will only
complete to the first filename, but not the second (the same happens
with `getcompletion('Foo', 'buffer')`).

It may make sense, that completion priorities buffer names at directory
boundaries, but it inconsistent, may cause confusion why a certain
buffer name is not completed when typing `:b Foo<C-D>` which returns
only a single file name and then pressing Enter (to switch to that
buffer), Vim will error with 'E93: More than one match for Foo').
Similar things may happen when wiping the /tmp/Foobar.c pattern and
afterwards the completion starts completing other buffers.

So let's simplify the code and always match the pattern anywhere in the
buffer name, do not try to favor matches at directory boundaries. This
is also simplifies the code a bit, we do not need to run over the list
of buffers several times, but only twice.

fixes #13894
closes: #14082

Signed-off-by: Christian Brabandt <cb@256bit.org>

3 files changed, 120 insertions, 112 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 4a39329c5c..b17ae16521 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -2772,17 +2772,19 @@ ExpandBufnames(
     char_u	***file,
     int		options)
 {
-    int		count = 0;
+    int		count;
     buf_T	*buf;
     int		round;
     char_u	*p;
-    int		attempt;
     char_u	*patc = NULL;
 #ifdef FEAT_VIMINFO
     bufmatch_T	*matches = NULL;
 #endif
     int		fuzzy;
     fuzmatch_str_T  *fuzmatch = NULL;
+    regmatch_T	regmatch;
+    int		score = 0;
+    int		to_free = FALSE;
 
     *num_file = 0;		    // return values in case of FAIL
     *file = NULL;
@@ -2798,151 +2800,138 @@ ExpandBufnames(
     // expression matching)
     if (!fuzzy)
     {
-	if (*pat == '^')
+	if (*pat == '^' && pat[1] != NUL)
 	{
-	    patc = alloc(STRLEN(pat) + 11);
+	    int  len = (int)STRLEN(pat);
+	    patc = alloc(len);
 	    if (patc == NULL)
 		return FAIL;
-	    STRCPY(patc, "\\(^\\|[\\/]\\)");
-	    STRCPY(patc + 11, pat + 1);
+	    STRNCPY(patc, pat + 1, len - 1);
+	    patc[len - 1] = NUL;
+	    to_free = TRUE;
 	}
+	else if (*pat == '^')
+	    patc = (char_u *)"";
 	else
 	    patc = pat;
+	regmatch.regprog = vim_regcomp(patc, RE_MAGIC);
     }
 
-    // attempt == 0: try match with    '\<', match at start of word
-    // attempt == 1: try match without '\<', match anywhere
-    for (attempt = 0; attempt <= (fuzzy ? 0 : 1); ++attempt)
+    // round == 1: Count the matches.
+    // round == 2: Build the array to keep the matches.
+    for (round = 1; round <= 2; ++round)
     {
-	regmatch_T	regmatch;
-	int		score = 0;
-
-	if (!fuzzy)
-	{
-	    if (attempt > 0 && patc == pat)
-		break;	// there was no anchor, no need to try again
-	    regmatch.regprog = vim_regcomp(patc + attempt * 11, RE_MAGIC);
-	}
-
-	// round == 1: Count the matches.
-	// round == 2: Build the array to keep the matches.
-	for (round = 1; round <= 2; ++round)
+	count = 0;
+	FOR_ALL_BUFFERS(buf)
 	{
-	    count = 0;
-	    FOR_ALL_BUFFERS(buf)
-	    {
-		if (!buf->b_p_bl)	// skip unlisted buffers
-		    continue;
+	    if (!buf->b_p_bl)	// skip unlisted buffers
+		continue;
 #ifdef FEAT_DIFF
-		if (options & BUF_DIFF_FILTER)
-		    // Skip buffers not suitable for
-		    // :diffget or :diffput completion.
-		    if (buf == curbuf || !diff_mode_buf(buf))
-			continue;
+	    if (options & BUF_DIFF_FILTER)
+		// Skip buffers not suitable for
+		// :diffget or :diffput completion.
+		if (buf == curbuf || !diff_mode_buf(buf))
+		    continue;
 #endif
 
-		if (!fuzzy)
+	    if (!fuzzy)
+	    {
+		if (regmatch.regprog == NULL)
 		{
-		    if (regmatch.regprog == NULL)
-		    {
-			// invalid pattern, possibly after recompiling
-			if (patc != pat)
-			    vim_free(patc);
-			return FAIL;
-		    }
-		    p = buflist_match(&regmatch, buf, p_wic);
+		    // invalid pattern, possibly after recompiling
+		    if (to_free)
+			vim_free(patc);
+		    return FAIL;
 		}
-		else
+		p = buflist_match(&regmatch, buf, p_wic);
+	    }
+	    else
+	    {
+		p = NULL;
+		// first try matching with the short file name
+		if ((score = fuzzy_match_str(buf->b_sfname, pat)) != 0)
+		    p = buf->b_sfname;
+		if (p == NULL)
 		{
-		    p = NULL;
-		    // first try matching with the short file name
-		    if ((score = fuzzy_match_str(buf->b_sfname, pat)) != 0)
-			p = buf->b_sfname;
-		    if (p == NULL)
-		    {
-			// next try matching with the full path file name
-			if ((score = fuzzy_match_str(buf->b_ffname, pat)) != 0)
-			    p = buf->b_ffname;
-		    }
+		    // next try matching with the full path file name
+		    if ((score = fuzzy_match_str(buf->b_ffname, pat)) != 0)
+			p = buf->b_ffname;
 		}
+	    }
 
-		if (p == NULL)
-		    continue;
+	    if (p == NULL)
+		continue;
 
-		if (round == 1)
-		{
-		    ++count;
-		    continue;
-		}
+	    if (round == 1)
+	    {
+		++count;
+		continue;
+	    }
 
-		if (options & WILD_HOME_REPLACE)
-		    p = home_replace_save(buf, p);
-		else
-		    p = vim_strsave(p);
+	    if (options & WILD_HOME_REPLACE)
+		p = home_replace_save(buf, p);
+	    else
+		p = vim_strsave(p);
 
-		if (!fuzzy)
-		{
+	    if (!fuzzy)
+	    {
 #ifdef FEAT_VIMINFO
-		    if (matches != NULL)
-		    {
-			matches[count].buf = buf;
-			matches[count].match = p;
-			count++;
-		    }
-		    else
-#endif
-			(*file)[count++] = p;
-		}
-		else
+		if (matches != NULL)
 		{
-		    fuzmatch[count].idx = count;
-		    fuzmatch[count].str = p;
-		    fuzmatch[count].score = score;
+		    matches[count].buf = buf;
+		    matches[count].match = p;
 		    count++;
 		}
+		else
+#endif
+		    (*file)[count++] = p;
 	    }
-	    if (count == 0)	// no match found, break here
-		break;
-	    if (round == 1)
+	    else
 	    {
-		if (!fuzzy)
+		fuzmatch[count].idx = count;
+		fuzmatch[count].str = p;
+		fuzmatch[count].score = score;
+		count++;
+	    }
+	}
+	if (count == 0)	// no match found, break here
+	    break;
+	if (round == 1)
+	{
+	    if (!fuzzy)
+	    {
+		*file = ALLOC_MULT(char_u *, count);
+		if (*file == NULL)
 		{
-		    *file = ALLOC_MULT(char_u *, count);
-		    if (*file == NULL)
-		    {
-			vim_regfree(regmatch.regprog);
-			if (patc != pat)
-			    vim_free(patc);
-			return FAIL;
-		    }
+		    vim_regfree(regmatch.regprog);
+		    if (to_free)
+			vim_free(patc);
+		    return FAIL;
+		}
 #ifdef FEAT_VIMINFO
-		    if (options & WILD_BUFLASTUSED)
-			matches = ALLOC_MULT(bufmatch_T, count);
+		if (options & WILD_BUFLASTUSED)
+		    matches = ALLOC_MULT(bufmatch_T, count);
 #endif
-		}
-		else
+	    }
+	    else
+	    {
+		fuzmatch = ALLOC_MULT(fuzmatch_str_T, count);
+		if (fuzmatch == NULL)
 		{
-		    fuzmatch = ALLOC_MULT(fuzmatch_str_T, count);
-		    if (fuzmatch == NULL)
-		    {
-			*num_file = 0;
-			*file = NULL;
-			return FAIL;
-		    }
+		    *num_file = 0;
+		    *file = NULL;
+		    return FAIL;
 		}
 	    }
 	}
-
-	if (!fuzzy)
-	{
-	    vim_regfree(regmatch.regprog);
-	    if (count)		// match(es) found, break here
-		break;
-	}
     }
 
-    if (!fuzzy && patc != pat)
-	vim_free(patc);
+    if (!fuzzy)
+    {
+	vim_regfree(regmatch.regprog);
+	if (to_free)
+	    vim_free(patc);
+    }
 
 #ifdef FEAT_VIMINFO
     if (!fuzzy)
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index ea95cbfce5..c0d01fb967 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -691,7 +691,7 @@ func Test_getcompletion()
     bw Xtest\
   endif
 
-  call assert_fails("call getcompletion('\\\\@!\\\\@=', 'buffer')", 'E871:')
+  call assert_fails("call getcompletion('\\\\@!\\\\@=', 'buffer')", 'E866:')
   call assert_fails('call getcompletion("", "burp")', 'E475:')
   call assert_fails('call getcompletion("abc", [])', 'E1174:')
 endfunc
@@ -3755,4 +3755,21 @@ func Test_window_size_stays_same_after_changing_cmdheight()
   call assert_equal(expected, winheight(0))
 endfunc
 
+" verify that buffer-completion finds all buffer names matching a pattern
+func Test_buffer_completion()
+  " should return empty list
+  call assert_equal([], getcompletion('', 'buffer'))
+
+  call mkdir('Xbuf_complete', 'R')
+  e Xbuf_complete/Foobar.c
+  e Xbuf_complete/MyFoobar.c
+  e AFoobar.h
+  let expected = ["Xbuf_complete/Foobar.c", "Xbuf_complete/MyFoobar.c", "AFoobar.h"]
+
+  call assert_equal(3, len(getcompletion('Foo', 'buffer')))
+  call assert_equal(expected, getcompletion('Foo', 'buffer'))
+  call feedkeys(":b Foo\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"b Xbuf_complete/Foobar.c Xbuf_complete/MyFoobar.c AFoobar.h", @:)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index b6e25e665a..a80f2a87b5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    131,
+/**/
     130,
 /**/
     129,