vim-patch:9.1.0755: quickfix list does not handle hardlinks well (#30637)

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: vim/vim#15687

https://github.com/vim/vim/commit/29822996996550f68a781e85753ebd4d177f22da

Co-authored-by: Austin Chang <austin880625@gmail.com>

2 files changed, 64 insertions, 8 deletions

diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index e7d2da2fc6..ddf2a7247f 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -91,6 +91,7 @@ struct qfline_S {
   int qf_end_col;         ///< column when the error has range or zero
   int qf_nr;              ///< error number
   char *qf_module;        ///< module name for this error
+  char *qf_fname;         ///< different filename if there're hard links
   char *qf_pattern;       ///< search pattern for the error
   char *qf_text;          ///< description of the error
   char qf_viscol;         ///< set to true if qf_col and qf_end_col is screen column
@@ -1866,11 +1867,13 @@ static int qf_add_entry(qf_list_T *qfl, char *dir, char *fname, char *module, in
                         char vis_col, char *pattern, int nr, char type, typval_T *user_data,
                         char valid)
 {
+  buf_T *buf;
   qfline_T *qfp = xmalloc(sizeof(qfline_T));
+  char *fullname = NULL;
+  char *p = NULL;
 
   if (bufnum != 0) {
-    buf_T *buf = buflist_findnr(bufnum);
-
+    buf = buflist_findnr(bufnum);
     qfp->qf_fnum = bufnum;
     if (buf != NULL) {
       buf->b_has_qf_entry |=
@@ -1878,7 +1881,21 @@ static int qf_add_entry(qf_list_T *qfl, char *dir, char *fname, char *module, in
     }
   } 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 (path_fnamecmp(fullname, buf->b_ffname) != 0) {
+      p = path_try_shorten_fname(fullname);
+      if (p != NULL) {
+        qfp->qf_fname = xstrdup(p);
+      }
+    }
+  }
+  xfree(fullname);
   qfp->qf_text = xstrdup(mesg);
   qfp->qf_lnum = lnum;
   qfp->qf_end_lnum = end_lnum;
@@ -3145,7 +3162,7 @@ static void qf_list_entry(qfline_T *qfp, int qf_idx, bool cursel)
     buf_T *buf;
     if (qfp->qf_fnum != 0
         && (buf = buflist_findnr(qfp->qf_fnum)) != NULL) {
-      fname = buf->b_fname;
+      fname = qfp->qf_fname == NULL ? buf->b_fname : qfp->qf_fname;
       if (qfp->qf_type == 1) {  // :helpgrep
         fname = path_tail(fname);
       }
@@ -3431,6 +3448,7 @@ static void qf_free_items(qf_list_T *qfl)
     qfline_T *qfp = qfl->qf_start;
     qfline_T *qfpnext = qfp->qf_next;
     if (!stop) {
+      xfree(qfp->qf_fname);
       xfree(qfp->qf_module);
       xfree(qfp->qf_text);
       xfree(qfp->qf_pattern);
@@ -4059,7 +4077,7 @@ static int qf_buf_add_line(qf_list_T *qfl, buf_T *buf, linenr_T lnum, const qfli
           }
           shorten_buf_fname(errbuf, dirname, false);
         }
-        ga_concat(gap, errbuf->b_fname);
+        ga_concat(gap, qfp->qf_fname == NULL ? errbuf->b_fname : qfp->qf_fname);
       }
     }
 
diff --git a/test/old/testdir/test_quickfix.vim b/test/old/testdir/test_quickfix.vim
index 524e8608f6..753875963b 100644
--- a/test/old/testdir/test_quickfix.vim
+++ b/test/old/testdir/test_quickfix.vim
@@ -4140,6 +4140,7 @@ 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!
@@ -4202,8 +4203,8 @@ endfunc
 " :vimgrep/:lvimgrep commands are running.
 func Test_vimgrep_autocmd()
   call setqflist([], 'f')
-  call writefile(['stars'], 'Xtest1.txt')
-  call writefile(['stars'], 'Xtest2.txt')
+  call writefile(['stars'], 'Xtest1.txt', 'D')
+  call writefile(['stars'], 'Xtest2.txt', 'D')
 
   " Test 1:
   " When searching for a pattern using :vimgrep, if the quickfix list is
@@ -4233,9 +4234,9 @@ 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 delete('Xtest1.txt')
-  call delete('Xtest2.txt')
   call setqflist([], 'f')
 endfunc
 
@@ -6458,4 +6459,41 @@ 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