patch 9.1.0755: quickfix list does not handle hardlinks well

Problem:  quickfix list does not handle hardlinks well
Solution: store original file name with quickfix entry
          (Austin Chang)

Quickfix list shows entries with duplicate name if the file is opened
with the path of hard links.

The major cause is that qflist assumed that the filename passed into
`qf_add_entry` matches the filename opened with the buffer.

This patch handles this case by introduce a `qf_fname` into `qfline_S`
structure. It stores the filename from `qf_add_entry` for each quickfix
line.

closes: #15687

Signed-off-by: Austin Chang <austin880625@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/quickfix.c

@@ -36,6 +36,7 @@ struct qfline_S
     int		qf_end_col;	// column when the error has range or zero
     int		qf_nr;		// error number
     char_u	*qf_module;	// module name for this error
+    char_u	*qf_fname;	// different filename if there're hard links
     char_u	*qf_pattern;	// search pattern for the error
     char_u	*qf_text;	// description of the error
     char_u	qf_viscol;	// set to TRUE if qf_col and qf_end_col is
@@ -2173,14 +2174,17 @@ qf_add_entry(
     typval_T	*user_data,     // custom user data or NULL
     int		valid)		// valid entry
 {
+    buf_T	*buf;
     qfline_T	*qfp;
     qfline_T	**lastp;	// pointer to qf_last or NULL
+    char_u	*fullname = NULL;
+    char_u	*p = NULL;
 
     if ((qfp = ALLOC_ONE_ID(qfline_T, aid_qf_qfline)) == NULL)
 	return QF_FAIL;
     if (bufnum != 0)
     {
-	buf_T *buf = buflist_findnr(bufnum);
+	buf = buflist_findnr(bufnum);
 
 	qfp->qf_fnum = bufnum;
 	if (buf != NULL)
@@ -2188,7 +2192,24 @@ qf_add_entry(
 		IS_QF_LIST(qfl) ? BUF_HAS_QF_ENTRY : BUF_HAS_LL_ENTRY;
     }
     else
+    {
 	qfp->qf_fnum = qf_get_fnum(qfl, dir, fname);
+	buf = buflist_findnr(qfp->qf_fnum);
+    }
+    if (fname != NULL)
+	fullname = fix_fname(fname);
+    qfp->qf_fname = NULL;
+    if (buf != NULL &&
+	buf->b_ffname != NULL && fullname != NULL)
+    {
+        if (fnamecmp(fullname, buf->b_ffname) != 0)
+        {
+            p = shorten_fname1(fullname);
+            if (p != NULL)
+		qfp->qf_fname = vim_strsave(p);
+        }
+    }
+    vim_free(fullname);
     if ((qfp->qf_text = vim_strsave(mesg)) == NULL)
     {
 	vim_free(qfp);
@@ -3709,7 +3730,10 @@ qf_list_entry(qfline_T *qfp, int qf_idx, int cursel)
 	if (qfp->qf_fnum != 0
 		&& (buf = buflist_findnr(qfp->qf_fnum)) != NULL)
 	{
-	    fname = buf->b_fname;
+	    if (qfp->qf_fname == NULL)
+		fname = buf->b_fname;
+	    else
+		fname = qfp->qf_fname;
 	    if (qfp->qf_type == 1)	// :helpgrep
 		fname = gettail(fname);
 	}
@@ -4034,6 +4058,7 @@ qf_free_items(qf_list_T *qfl)
 	qfpnext = qfp->qf_next;
 	if (!stop)
 	{
+	    vim_free(qfp->qf_fname);
 	    vim_free(qfp->qf_module);
 	    vim_free(qfp->qf_text);
 	    vim_free(qfp->qf_pattern);
@@ -4761,7 +4786,10 @@ qf_buf_add_line(
 			mch_dirname(dirname, MAXPATHL);
 		    shorten_buf_fname(errbuf, dirname, FALSE);
 		}
-		ga_concat(gap, errbuf->b_fname);
+		if (qfp->qf_fname == NULL)
+		    ga_concat(gap, errbuf->b_fname);
+		else
+		    ga_concat(gap, qfp->qf_fname);
 	    }
 	}
 

src/testdir/test_quickfix.vim

@@ -4277,6 +4277,7 @@ endfunc
 
 " The following test used to crash Vim
 func Test_lvimgrep_crash()
+  " this leaves a swapfile .test_quickfix.vim.swp around, why?
   sv Xtest
   augroup QF_Test
     au!
@@ -4370,6 +4371,8 @@ func Test_vimgrep_autocmd()
   autocmd BufRead Xtest2.txt call setloclist(g:save_winid, [], 'f')
   call assert_fails('lvimgrep stars Xtest*.txt', 'E926:')
   au! BufRead Xtest2.txt
+  " cleanup the swap files
+  bw! Xtest2.txt Xtest1.txt
 
   call setqflist([], 'f')
 endfunc
@@ -6578,4 +6581,41 @@ func Test_cbuffer_range()
   call XbufferTests_range('l')
 endfunc
 
+" Test for displaying fname pass from setqflist when the name
+" are hard links to prevent seemly duplicate entries.
+func Xtest_hardlink_fname(cchar)
+  call s:setup_commands(a:cchar)
+  %bwipe
+  " Create a sample source file
+  let lines =<< trim END
+    void sample() {}
+    int main() { sample(); return 0; }
+  END
+  call writefile(lines, 'test_qf_hardlink1.c', 'D')
+  defer delete('test_qf_hardlink1.c')
+  defer delete('test_qf_hardlink2.c')
+  call system('ln test_qf_hardlink1.c test_qf_hardlink2.c')
+  if v:shell_error
+    throw 'Skipped: ln throws error on this platform'
+  endif
+  call g:Xsetlist([], 'f')
+  " Make a qflist that contains the file and it's hard link
+  " like how LSP plugins set response into qflist
+  call g:Xsetlist([{'filename' : 'test_qf_hardlink1.c', 'lnum' : 1},
+        \ {'filename' : 'test_qf_hardlink2.c', 'lnum' : 1}], ' ')
+  Xopen
+  " Ensure that two entries are displayed with different name
+  " so that they aren't seen as duplication.
+  call assert_equal(['test_qf_hardlink1.c|1| ',
+        \ 'test_qf_hardlink2.c|1| '], getline(1, '$'))
+  Xclose
+endfunc
+
+func Test_hardlink_fname()
+  CheckUnix
+  CheckExecutable ln
+  call Xtest_hardlink_fname('c')
+  call Xtest_hardlink_fname('l')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    755,
 /**/
     754,
 /**/