vim-patch:8.2.0272: ":helptags ALL" gives error for some directories

Problem:    ":helptags ALL" gives error for directories without write
            permission. (Matěj Cepl)
Solution:   Ignore errors for ":helptags ALL". (Ken Takata, closes vim/vim#5026,
            closes vim/vim#5652)
414b796627

Cherry-pick Test_helptag_cmd() from patch v8.2.0203.

src/nvim/ex_cmds.c

@@ -5248,8 +5248,10 @@ void ex_viusage(exarg_T *eap)
 /// @param tagname  Name of the tags file ("tags" for English, "tags-fr" for
 ///                 French)
 /// @param add_help_tags  Whether to add the "help-tags" tag
-static void helptags_one(char_u *const dir, const char_u *const ext,
+/// @param ignore_writeerr  ignore write error
-                         const char_u *const tagfname, const bool add_help_tags)
+static void helptags_one(char_u *dir, const char_u *ext, const char_u *tagfname,
+                         bool add_help_tags, bool ignore_writeerr)
+  FUNC_ATTR_NONNULL_ALL
 {
   garray_T ga;
   int filecount;
@@ -5293,7 +5295,9 @@ static void helptags_one(char_u *const dir, const char_u *const ext,
 
   FILE *const fd_tags = os_fopen((char *)NameBuff, "w");
   if (fd_tags == NULL) {
+    if (!ignore_writeerr) {
       EMSG2(_("E152: Cannot open %s for writing"), NameBuff);
+    }
     FreeWild(filecount, files);
     return;
   }
@@ -5441,7 +5445,9 @@ static void helptags_one(char_u *const dir, const char_u *const ext,
 }
 
 /// Generate tags in one help directory, taking care of translations.
-static void do_helptags(char_u *dirname, bool add_help_tags)
+static void do_helptags(char_u *dirname, bool add_help_tags,
+                        bool ignore_writeerr)
+  FUNC_ATTR_NONNULL_ALL
 {
   int len;
   garray_T ga;
@@ -5523,17 +5529,17 @@ static void do_helptags(char_u *dirname, bool add_help_tags)
       ext[1] = fname[5];
       ext[2] = fname[6];
     }
-    helptags_one(dirname, ext, fname, add_help_tags);
+    helptags_one(dirname, ext, fname, add_help_tags, ignore_writeerr);
   }
 
   ga_clear(&ga);
   FreeWild(filecount, files);
 }
 
-    static void
+static void helptags_cb(char_u *fname, void *cookie)
-helptags_cb(char_u *fname, void *cookie)
+  FUNC_ATTR_NONNULL_ALL
 {
-    do_helptags(fname, *(bool *)cookie);
+    do_helptags(fname, *(bool *)cookie, true);
 }
 
 /*
@@ -5562,7 +5568,7 @@ void ex_helptags(exarg_T *eap)
     if (dirname == NULL || !os_isdir(dirname)) {
       EMSG2(_("E150: Not a directory: %s"), eap->arg);
     } else {
-      do_helptags(dirname, add_help_tags);
+      do_helptags(dirname, add_help_tags, false);
     }
     xfree(dirname);
   }

src/nvim/testdir/test_help.vim

@@ -56,3 +56,49 @@ func Test_help_local_additions()
   call delete('Xruntime', 'rf')
   let &rtp = rtp_save
 endfunc
+
+" Test for the :helptags command
+func Test_helptag_cmd()
+  call mkdir('Xdir/a/doc', 'p')
+
+  " No help file to process in the directory
+  call assert_fails('helptags Xdir', 'E151:')
+
+  call writefile([], 'Xdir/a/doc/sample.txt')
+
+  " Test for ++t argument
+  helptags ++t Xdir
+  call assert_equal(["help-tags\ttags\t1"], readfile('Xdir/tags'))
+  call delete('Xdir/tags')
+
+  " The following tests fail on FreeBSD for some reason
+  if has('unix') && !has('bsd')
+    " Read-only tags file
+    call mkdir('Xdir/doc', 'p')
+    call writefile([''], 'Xdir/doc/tags')
+    call writefile([], 'Xdir/doc/sample.txt')
+    call setfperm('Xdir/doc/tags', 'r-xr--r--')
+    call assert_fails('helptags Xdir/doc', 'E152:', getfperm('Xdir/doc/tags'))
+
+    let rtp = &rtp
+    let &rtp = 'Xdir'
+    helptags ALL
+    let &rtp = rtp
+
+    call delete('Xdir/doc/tags')
+
+    " No permission to read the help file
+    call setfperm('Xdir/a/doc/sample.txt', '-w-------')
+    call assert_fails('helptags Xdir', 'E153:', getfperm('Xdir/a/doc/sample.txt'))
+    call delete('Xdir/a/doc/sample.txt')
+    call delete('Xdir/tags')
+  endif
+
+  " Duplicate tags in the help file
+  call writefile(['*tag1*', '*tag1*', '*tag2*'], 'Xdir/a/doc/sample.txt')
+  call assert_fails('helptags Xdir', 'E154:')
+
+  call delete('Xdir', 'rf')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab