lua: Use automatic determining of suffixes only for package.cpath

runtime/doc/if_lua.txt

@@ -13,14 +13,17 @@ Lua Interface to Nvim					*lua* *Lua*
 
 Neovim lua interface automatically adjusts `package.path` and `package.cpath` 
 according to effective &runtimepath value.  Adjustment happens after each time 
-'runtimepath' is changed, `package.path` and `package.cpath` are adjusted by 
-prepending directories from 'runtimepath' each suffixed by `/lua` and 
-`?`-containing suffixes from `package.path` and `package.cpath`. I.e. when 
-'runtimepath' option contains `/foo` and `package.path` contains only 
-`./?.lua;./a?d/j/g.nlua;/bar/?.lua` the resulting `package.path` after 
+'runtimepath' is changed. `package.path` is adjusted by simply appending 
+`/lua/?.lua` and `/lua/?/init.lua` to each directory from 'runtimepath' (`/` 
+is actually a first character from `package.config`).
+
+`package.cpath` is adjusted by prepending directories from 'runtimepath' each 
+suffixed by `/lua` and `?`-containing suffixes from existing `package.cpath`. 
+I.e. when 'runtimepath' option contains `/foo` and `package.cpath` contains 
+only `./?.so;./a?d/j/g.elf;/bar/?.so` the resulting `package.cpath` after 
 adjustments will look like this: >
 
-	/foo/lua/?.lua;/foo/lua/a?d/j/g.nlua;./?.lua;./a?d/j/g.nlua;/bar/?.lua
+	/foo/lua/?.so;/foo/lua/a?d/j/g.elf;./?.so;./a?d/j/g.elf;/bar/?.so
 
 Note that code have taken everything starting from the last path component 
 from existing paths containing a question mark as a `?`-containing suffix, but 
@@ -31,7 +34,8 @@ current values of `package.path` or `package.cpath`. If you happened to delete
 some paths from there you need to reset 'runtimepath' to make them readded.
 
 Note 3: paths from 'runtimepath' which contain semicolons cannot be put into 
-`package.[c]path` and thus are ignored.
+`package.[c]path` for that being a semicolon-separated list and thus are 
+ignored.
 
 ------------------------------------------------------------------------------
 1.1. Example of the plugin which uses lua modules:	*lua-require-example*

src/nvim/lua/vim.lua

@@ -9,7 +9,6 @@ local function _update_package_paths()
   local sep = package.config:sub(1, 1)
   for _, key in ipairs({'path', 'cpath'}) do
     local orig_str = package[key] .. ';'
-    local pathtrails = {}
     local pathtrails_ordered = {}
     local orig = {}
     -- Note: ignores trailing item without trailing `;`. Not using something
@@ -17,15 +16,23 @@ local function _update_package_paths()
     for s in orig_str:gmatch('[^;]*;') do
       s = s:sub(1, -2)  -- Strip trailing semicolon
       orig[#orig + 1] = s
+    end
+    if key == 'path' then
+      -- /?.lua and /?/init.lua
+      pathtrails_ordered = {sep .. '?.lua', sep .. '?' .. sep .. 'init.lua'}
+    else
+      local pathtrails = {}
+      for _, s in ipairs(orig) do
         -- Find out path patterns. pathtrail should contain something like
-      -- /?.so, /?/init.lua, /?.lua. This allows not to bother determining what
-      -- correct suffixes are.
+        -- /?.so, \?.dll. This allows not to bother determining what correct
+        -- suffixes are.
         local pathtrail = s:match('[/\\][^/\\]*%?.*$')
         if pathtrail and not pathtrails[pathtrail] then
           pathtrails[pathtrail] = true
           pathtrails_ordered[#pathtrails_ordered + 1] = pathtrail
         end
       end
+    end
     local new = {}
     for _, rtp in ipairs(rtps) do
       if not rtp:match(';') then

test/functional/lua/overrides_spec.lua

@@ -183,9 +183,10 @@ describe('package.path/package.cpath', function()
   local function get_new_paths(sufs, runtimepaths)
     runtimepaths = runtimepaths or meths.list_runtime_paths()
     local new_paths = {}
+    local sep = package.config:sub(1, 1)
     for _, v in ipairs(runtimepaths) do
       for _, suf in ipairs(sufs) do
-        new_paths[#new_paths + 1] = v .. suf:sub(1, 1) .. 'lua' .. suf
+        new_paths[#new_paths + 1] = v .. sep .. 'lua' .. suf
       end
     end
     return new_paths
@@ -225,23 +226,23 @@ describe('package.path/package.cpath', function()
     eq(new_paths_str, eval_lua('package.path'):sub(1, #new_paths_str))
   end)
   it('understands uncommon suffixes', function()
-    set_path('path', './?/foo/bar/baz/x.nlua')
+    set_path('cpath', './?/foo/bar/baz/x.nlua')
     meths.set_option('runtimepath', 'a')
     local new_paths = get_new_paths({'/?/foo/bar/baz/x.nlua'}, {'a'})
     local new_paths_str = table.concat(new_paths, ';')
-    eq(new_paths_str, eval_lua('package.path'):sub(1, #new_paths_str))
+    eq(new_paths_str, eval_lua('package.cpath'):sub(1, #new_paths_str))
 
-    set_path('path', './yyy?zzz/x')
+    set_path('cpath', './yyy?zzz/x')
     meths.set_option('runtimepath', 'b')
     new_paths = get_new_paths({'/yyy?zzz/x'}, {'b'})
     new_paths_str = table.concat(new_paths, ';')
-    eq(new_paths_str, eval_lua('package.path'):sub(1, #new_paths_str))
+    eq(new_paths_str, eval_lua('package.cpath'):sub(1, #new_paths_str))
 
-    set_path('path', './yyy?zzz/123?ghi/x')
+    set_path('cpath', './yyy?zzz/123?ghi/x')
     meths.set_option('runtimepath', 'b')
     new_paths = get_new_paths({'/yyy?zzz/123?ghi/x'}, {'b'})
     new_paths_str = table.concat(new_paths, ';')
-    eq(new_paths_str, eval_lua('package.path'):sub(1, #new_paths_str))
+    eq(new_paths_str, eval_lua('package.cpath'):sub(1, #new_paths_str))
   end)
   it('preserves empty items', function()
     local many_empty_path = ';;;;;;'
@@ -249,17 +250,19 @@ describe('package.path/package.cpath', function()
     set_path('path', many_empty_path)
     set_path('cpath', many_empty_cpath)
     meths.set_option('runtimepath', 'a')
-    -- No suffixes known, so can’t add anything
-    eq(many_empty_path, eval_lua('package.path'))
-    local new_paths = get_new_paths({'/?.luaso'}, {'a'})
+    local new_paths = get_new_paths(sl{'/?.lua', '/?/init.lua'}, {'a'})
     local new_paths_str = table.concat(new_paths, ';')
-    eq(new_paths_str .. ';' .. many_empty_cpath, eval_lua('package.cpath'))
+    eq(new_paths_str .. ';' .. many_empty_path, eval_lua('package.path'))
+    local new_cpaths = get_new_paths({'/?.luaso'}, {'a'})
+    local new_cpaths_str = table.concat(new_cpaths, ';')
+    eq(new_cpaths_str .. ';' .. many_empty_cpath, eval_lua('package.cpath'))
   end)
   it('preserves empty value', function()
     set_path('path', '')
     meths.set_option('runtimepath', 'a')
-    -- No suffixes known, so can’t add anything
-    eq('', eval_lua('package.path'))
+    local new_paths = get_new_paths(sl{'/?.lua', '/?/init.lua'}, {'a'})
+    local new_paths_str = table.concat(new_paths, ';')
+    eq(new_paths_str .. ';', eval_lua('package.path'))
   end)
   it('purges out all additions if runtimepath is set to empty', function()
     local new_paths = get_new_paths(sl{'/?.lua', '/?/init.lua'})