Fix: iMap <Cr> Interfere in completion (alias popup-menu, pum) (Issue: #813)

Problem: When pum opened, the mapping of <CR> is triggered but user
want the default behaviour: to choose a completion item

Solution: Conditional mapping:
inoremap <expr><silent><buffer> <CR> pumvisible() ? '<CR>' : ':<Esc>:VimwikiReturn 1 5<Cr>'
                         The previous mapping  -----------------^

doc/vimwiki.txt

@@ -3717,7 +3717,6 @@ http://code.google.com/p/vimwiki/issues/list. They may be accessible from
 https://github.com/vimwiki-backup/vimwiki/issues.
 
 New:~
-
     * Issue #209: Feature: Markdown: Support SetExt Heading
     * Issue #847 #640: Feature: Markdown anchor
       normalize and unormalize: better follow_link and |VimwikiTOC|
@@ -3744,6 +3743,7 @@ Changed:~
 Removed:~
 
 Fixed:~
+    * Issue #813: iMap <Cr> interfere with completion (pum)
     * Issue #709: Support inline code spans inside emphasis
       Refactoring code, del, eq, sup, sub as regions
     * Issue #847 #640: Refactor: Syntax highlighting typeface: match -> region

ftplugin/vimwiki.vim

@@ -501,17 +501,18 @@ if str2nr(vimwiki#vars#get_global('key_mappings').lists)
   call vimwiki#u#map_key('n', 'o', '<Plug>VimwikiListo')
   call vimwiki#u#map_key('n', 'O', '<Plug>VimwikiListO')
 
-  " handle case of existing VimwikiReturn mappings outside the <Plug> definition
+  " Handle case of existing VimwikiReturn mappings outside the <Plug> definition
+  " Note: Avoid interfering with popup/completion menu if it's active (#813)
   if maparg('<CR>', 'i') !~# '.*VimwikiReturn*.'
     if has('patch-7.3.489')
       " expand iabbrev on enter
-      inoremap <silent><buffer> <CR> <C-]><Esc>:VimwikiReturn 1 5<CR>
+      inoremap <expr><silent><buffer> <CR> pumvisible() ? '<CR>' : '<C-]><Esc>:VimwikiReturn 1 5<CR>'
     else
-      inoremap <silent><buffer> <CR> <Esc>:VimwikiReturn 1 5<CR>
+      inoremap <expr><silent><buffer> <CR> pumvisible() ? '<CR>' : '<Esc>:VimwikiReturn 1 5<CR>'
     endif
   endif
   if  maparg('<S-CR>', 'i') !~# '.*VimwikiReturn*.'
-    inoremap <silent><buffer> <S-CR> <Esc>:VimwikiReturn 2 2<CR>
+    inoremap <expr><silent><buffer> <S-CR> pumvisible() ? '<CR>' : '<Esc>:VimwikiReturn 2 2<CR>'
   endif
 
   " change symbol for bulleted lists

test/independent_runs/map.vader

@@ -114,9 +114,11 @@ Do (,w,m -> open tomorrow [Assert]):
 Execute (===========================================================):
   Log "Checking local map"
 
+
 # 2.1 Heading {{{2
 ##############
 
+
 Do (,wn -> Create new wiki [Assert]):
   ,wn
   new_file1
@@ -293,6 +295,24 @@ Expect (Dec header level):
 # 2.2 List {{{2
 ##############
 
+
+
+Given vimwiki (Completion list #813 {{{3):
+  complete1
+  complete2
+  complete3
+
+Do (Insert a list item and complete):
+  Go
+  * comp\<C-n>\<Down>\<Cr>
+
+Expect (With a completion but no new item):
+  complete1
+  complete2
+  complete3
+  * complete2
+
+
 Given (Number list):
   1. I
     1. Relly