Use strict function prototypes #945

`-Wstrict-prototypes` warn if a function is declared or defined without
specifying the argument types.

This warning disallow function prototypes with empty parameter list.
In C, a function declared with an empty parameter list accepts an
arbitrary number of arguments when being called. This is for historic
reasons; originally, C functions didn't have prototypes, as C evolved
from B, a typeless language. When prototypes were added, the original
typeless declarations were left in the language for backwards
compatibility.
Instead we should provide `void` in argument list to state
that function doesn't have arguments.

Also this warning disallow declaring type of the parameters after the
parentheses because Neovim header generator produce no declarations for
old-stlyle prototypes: it expects to find `{` after prototype.

9 files changed, 24 insertions, 24 deletions

diff --git a/src/nvim/os/channel.c b/src/nvim/os/channel.c
index 14293d71e5..504c1ca05b 100644
--- a/src/nvim/os/channel.c
+++ b/src/nvim/os/channel.c
@@ -56,7 +56,7 @@ static msgpack_sbuffer out_buffer;
 #endif
 
 /// Initializes the module
-void channel_init()
+void channel_init(void)
 {
   channels = pmap_new(uint64_t)();
   event_strings = pmap_new(cstr_t)();
@@ -64,7 +64,7 @@ void channel_init()
 }
 
 /// Teardown the module
-void channel_teardown()
+void channel_teardown(void)
 {
   if (!channels) {
     return;
@@ -470,7 +470,7 @@ static void close_cb(uv_handle_t *handle)
   free(handle);
 }
 
-static Channel *register_channel()
+static Channel *register_channel(void)
 {
   Channel *rv = xmalloc(sizeof(Channel));
   rv->enabled = true;
diff --git a/src/nvim/os/dl.c b/src/nvim/os/dl.c
index e7a957a3aa..b4a35e203e 100644
--- a/src/nvim/os/dl.c
+++ b/src/nvim/os/dl.c
@@ -13,7 +13,7 @@
 /// int -> string
 /// string -> string
 /// string -> int
-typedef void (*gen_fn)();
+typedef void (*gen_fn)(void);
 typedef const char *(*str_str_fn)(const char *str);
 typedef int64_t (*str_int_fn)(const char *str);
 typedef const char *(*int_str_fn)(int64_t i);
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 3e66a019b3..3aefbc39d1 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -55,7 +55,7 @@ char *os_getenvname_at_index(size_t index)
 /// Get the process ID of the Neovim process.
 ///
 /// @return the process ID.
-int64_t os_get_pid()
+int64_t os_get_pid(void)
 {
 #ifdef _WIN32
   return (int64_t)GetCurrentProcessId();
diff --git a/src/nvim/os/event.c b/src/nvim/os/event.c
index a9e97c9190..4e091716b2 100644
--- a/src/nvim/os/event.c
+++ b/src/nvim/os/event.c
@@ -33,7 +33,7 @@ typedef struct {
 #endif
 static klist_t(Event) *deferred_events, *immediate_events;
 
-void event_init()
+void event_init(void)
 {
   // Initialize the event queues
   deferred_events = kl_init(Event);
@@ -52,7 +52,7 @@ void event_init()
   server_init();
 }
 
-void event_teardown()
+void event_teardown(void)
 {
   channel_teardown();
   job_teardown();
@@ -122,7 +122,7 @@ bool event_poll(int32_t ms)
   return !timer_data.timed_out && (events_processed || event_has_deferred());
 }
 
-bool event_has_deferred()
+bool event_has_deferred(void)
 {
   return !kl_empty(get_queue(true));
 }
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index 504aeafbc1..58bdf0cf52 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -32,20 +32,20 @@ static bool eof = false, started_reading = false;
 // Helper function used to push bytes from the 'event' key sequence partially
 // between calls to os_inchar when maxlen < 3
 
-void input_init()
+void input_init(void)
 {
   read_stream = rstream_new(read_cb, READ_BUFFER_SIZE, NULL, false);
   rstream_set_file(read_stream, read_cmd_fd);
 }
 
 // Listen for input
-void input_start()
+void input_start(void)
 {
   rstream_start(read_stream);
 }
 
 // Stop listening for input
-void input_stop()
+void input_stop(void)
 {
   rstream_stop(read_stream);
 }
@@ -105,14 +105,14 @@ int os_inchar(uint8_t *buf, int maxlen, int32_t ms, int tb_change_cnt)
 }
 
 // Check if a character is available for reading
-bool os_char_avail()
+bool os_char_avail(void)
 {
   return inbuf_poll(0) == kInputAvail;
 }
 
 // Check for CTRL-C typed by reading all available characters.
 // In cooked mode we should get SIGINT, no need to check.
-void os_breakcheck()
+void os_breakcheck(void)
 {
   if (curr_tmode == TMODE_RAW && input_poll(0))
     fill_input_buf(false);
@@ -148,7 +148,7 @@ static InbufPollResult inbuf_poll(int32_t ms)
   return kInputNone;
 }
 
-static void stderr_switch()
+static void stderr_switch(void)
 {
   int mode = cur_tmode;
   // We probably set the wrong file descriptor to raw mode. Switch back to
@@ -198,7 +198,7 @@ static int push_event_key(uint8_t *buf, int maxlen)
 }
 
 // Check if there's pending input
-bool input_ready()
+bool input_ready(void)
 {
   return rstream_available(read_stream) > 0 || eof;
 }
diff --git a/src/nvim/os/job.c b/src/nvim/os/job.c
index dcf50243a9..d2f9c10981 100644
--- a/src/nvim/os/job.c
+++ b/src/nvim/os/job.c
@@ -65,14 +65,14 @@ static uv_prepare_t job_prepare;
 // Callbacks for libuv
 
 /// Initializes job control resources
-void job_init()
+void job_init(void)
 {
   uv_disable_stdio_inheritance();
   uv_prepare_init(uv_default_loop(), &job_prepare);
 }
 
 /// Releases job control resources and terminates running jobs
-void job_teardown()
+void job_teardown(void)
 {
   // 20 tries will give processes about 1 sec to exit cleanly
   uint32_t remaining_tries = 20;
diff --git a/src/nvim/os/server.c b/src/nvim/os/server.c
index 9adc867cd0..23f9393122 100644
--- a/src/nvim/os/server.c
+++ b/src/nvim/os/server.c
@@ -47,7 +47,7 @@ static PMap(cstr_t) *servers = NULL;
 #endif
 
 /// Initializes the module
-void server_init()
+void server_init(void)
 {
   servers = pmap_new(cstr_t)();
 
@@ -61,7 +61,7 @@ void server_init()
 }
 
 /// Teardown the server module
-void server_teardown()
+void server_teardown(void)
 {
   if (!servers) {
     return;
diff --git a/src/nvim/os/signal.c b/src/nvim/os/signal.c
index c7b4f86d6f..65657fda9c 100644
--- a/src/nvim/os/signal.c
+++ b/src/nvim/os/signal.c
@@ -26,7 +26,7 @@ static bool rejecting_deadly;
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/signal.c.generated.h"
 #endif
-void signal_init()
+void signal_init(void)
 {
   uv_signal_init(uv_default_loop(), &sint);
   uv_signal_init(uv_default_loop(), &spipe);
@@ -46,7 +46,7 @@ void signal_init()
 #endif
 }
 
-void signal_stop()
+void signal_stop(void)
 {
   uv_signal_stop(&sint);
   uv_signal_stop(&spipe);
@@ -59,12 +59,12 @@ void signal_stop()
 #endif
 }
 
-void signal_reject_deadly()
+void signal_reject_deadly(void)
 {
   rejecting_deadly = true;
 }
 
-void signal_accept_deadly()
+void signal_accept_deadly(void)
 {
   rejecting_deadly = false;
 }
diff --git a/src/nvim/os/time.c b/src/nvim/os/time.c
index 977a4f19c4..90a17aa513 100644
--- a/src/nvim/os/time.c
+++ b/src/nvim/os/time.c
@@ -16,7 +16,7 @@ static uv_cond_t delay_cond;
 # include "os/time.c.generated.h"
 #endif
 /// Initializes the time module
-void time_init()
+void time_init(void)
 {
   uv_mutex_init(&delay_mutex);
   uv_cond_init(&delay_cond);