getcmdline_prompt: Temporarily disable msg_silent so prompt is displayed

vim-patch:7.4.1636
Closes #7378

src/nvim/ex_getln.c

@@ -1863,9 +1863,13 @@ char *getcmdline_prompt(const char firstc, const char *const prompt,
   ccline.input_fn = (firstc == '@');
   ccline.highlight_callback = highlight_callback;
 
+  int msg_silent_saved = msg_silent;
+  msg_silent = 0;
+
   char *const ret = (char *)getcmdline(firstc, 1L, 0);
 
   restore_cmdline(&save_ccline);
+  msg_silent = msg_silent_saved;
   // Restore msg_col, the prompt from input() may have changed it.
   // But only if called recursively and the commandline is therefore being
   // restored to an old one; if not, the input() prompt stays on the screen,

test/functional/eval/input_spec.lua

@@ -239,6 +239,25 @@ describe('input()', function()
       {RBP1:(}{RBP2:()}{RBP1:)}^                     |
     ]])
   end)
+  it('is not hidden by :silent', function()
+    feed([[:silent call input('Foo: ')<CR>]])
+    screen:expect([[
+      {EOB:~                        }|
+      {EOB:~                        }|
+      {EOB:~                        }|
+      Foo: ^                    |
+                               |
+    ]])
+    feed('Bar')
+    screen:expect([[
+      {EOB:~                        }|
+      {EOB:~                        }|
+      {EOB:~                        }|
+      Foo: Bar^                 |
+                               |
+    ]])
+    feed('<CR>')
+  end)
 end)
 describe('inputdialog()', function()
   it('works with multiline prompts', function()