Merge pull request #12352 from jamessan/fix/hang-headless-mode

src/nvim/message.c

@@ -2570,10 +2570,15 @@ static int do_more_prompt(int typed_char)
   msgchunk_T  *mp;
   int i;
 
+  // If headless mode is enabled and no input is required, this variable
+  // will be true. However If server mode is enabled, the message "--more--"
+  // should be displayed.
+  bool no_need_more = headless_mode && !embedded_mode;
+
   // We get called recursively when a timer callback outputs a message. In
   // that case don't show another prompt. Also when at the hit-Enter prompt
   // and nothing was typed.
-  if (entered || (State == HITRETURN && typed_char == 0)) {
+  if (no_need_more || entered || (State == HITRETURN && typed_char == 0)) {
     return false;
   }
   entered = true;

test/functional/core/startup_spec.lua

@@ -277,6 +277,24 @@ describe('startup', function()
         [4] = {bold = true, foreground = Screen.colors.Blue1},
     }})
   end)
+
+  it('fixed hang issue with --headless (#11386)', function()
+    local expected = ''
+    local period = 100
+    for i = 1, period - 1 do
+      expected = expected .. i .. '\r\n'
+    end
+    expected = expected .. period
+    eq(
+      expected,
+      -- FIXME(codehex): We should really set a timeout for the system function.
+      -- If this test fails, there will be a waiting input state.
+      funcs.system({nvim_prog, '-u', 'NONE', '-c',
+        'for i in range(1, 100) | echo i | endfor | quit',
+        '--headless'
+      })
+    )
+  end)
 end)
 
 describe('sysinit', function()