Send SYN_REPORT with shift modifying keys to make libinput happy

notes.txt

@@ -0,0 +1,40 @@
+After all these years of this technique working perfectly, libinput goes and breaks it (along with apparantly many other things):
+
+https://bugs.freedesktop.org/show_bug.cgi?id=104030
+
+A normal USB keyboard pressing shift+3:
+
+E: 0.000001 0004 0004 458977    # EV_MSC / MSC_SCAN             458977
+E: 0.000001 0001 002a 0001      # EV_KEY / KEY_LEFTSHIFT        1
+E: 0.000001 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +0ms
+E: 0.151990 0004 0004 458784    # EV_MSC / MSC_SCAN             458784
+E: 0.151990 0001 0004 0001      # EV_KEY / KEY_3                1
+E: 0.151990 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +151ms
+#E: 0.327930 0004 0004 458784   # EV_MSC / MSC_SCAN             458784
+E: 0.327930 0001 0004 0000      # EV_KEY / KEY_3                0
+E: 0.327930 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +176ms
+E: 0.400020 0004 0004 458977    # EV_MSC / MSC_SCAN             458977
+E: 0.400020 0001 002a 0000      # EV_KEY / KEY_LEFTSHIFT        0
+E: 0.400020 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +73ms
+
+rusty-keys pre SYN_REPORT fix:
+
+E: 0.000001 0001 002a 0001      # EV_KEY / KEY_LEFTSHIFT        1
+E: 0.000001 0001 001a 0001      # EV_KEY / KEY_LEFTBRACE        1
+E: 0.000001 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +0ms
+{E: 0.031945 0001 001a 0000     # EV_KEY / KEY_LEFTBRACE        0
+E: 0.031945 0001 002a 0000      # EV_KEY / KEY_LEFTSHIFT        0
+E: 0.031945 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +31ms
+
+rusty-keys post SYN_REPORT fix:
+
+E: 0.000001 0001 002a 0001      # EV_KEY / KEY_LEFTSHIFT        1
+E: 0.000001 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +0ms
+E: 0.000032 0001 001a 0001      # EV_KEY / KEY_LEFTBRACE        1
+E: 0.000032 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +0ms
+{E: 0.096031 0001 001a 0000     # EV_KEY / KEY_LEFTBRACE        0
+E: 0.096031 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +96ms
+E: 0.096091 0001 002a 0000      # EV_KEY / KEY_LEFTSHIFT        0
+E: 0.096091 0000 0000 0000      # ------------ SYN_REPORT (0) ---------- +0ms
+
+Seems to be good enough for now...

src/device/device.rs

@@ -18,7 +18,7 @@ impl Device {
 	}
 
 	#[doc(hidden)]
-	pub fn write(&mut self, kind: c_int, code: c_int, value: c_int) -> Res<()> {
+	pub fn write(&self, kind: c_int, code: c_int, value: c_int) -> Res<()> {
 		let mut event = input_event {
 			time:  timeval { tv_sec: 0, tv_usec: 0 },
 			type_:  kind as u16,
@@ -44,27 +44,27 @@ impl Device {
 	}
 
 	/// Synchronize the device.
-	pub fn synchronize(&mut self) -> Res<()> {
+	pub fn synchronize(&self) -> Res<()> {
 		self.write(EV_SYN, SYN_REPORT, 0)
 	}
 
 	/// Send an event.
-	pub fn send(&mut self, kind: c_int, code: c_int, value: i32) -> Res<()> {
+	pub fn send(&self, kind: c_int, code: c_int, value: i32) -> Res<()> {
 		self.write(kind, code, value)
 	}
 
 	/// Send a press event.
-	pub fn press(&mut self, kind: c_int, code: c_int) -> Res<()> {
+	pub fn press(&self, kind: c_int, code: c_int) -> Res<()> {
 		self.write(kind, code, 1)
 	}
 
 	/// Send a release event.
-	pub fn release(&mut self, kind: c_int, code: c_int) -> Res<()> {
+	pub fn release(&self, kind: c_int, code: c_int) -> Res<()> {
 		self.write(kind, code, 0)
 	}
 
 	/// Send a press and release event.
-	pub fn click(&mut self, kind: c_int, code: c_int) -> Res<()> {
+	pub fn click(&self, kind: c_int, code: c_int) -> Res<()> {
 		try!(self.press(kind, code));
 		try!(self.release(kind, code));
 
@@ -72,7 +72,7 @@ impl Device {
 	}
 
 	/// Send a relative or absolute positioning event.
-	pub fn position(&mut self, kind: c_int, code: c_int, value: i32) -> Res<()> {
+	pub fn position(&self, kind: c_int, code: c_int, value: i32) -> Res<()> {
 		self.write(kind, code, value)
 	}
 }

src/keymapper.rs

@@ -321,6 +321,8 @@ impl HalfInvertedKey {
                 }
                 //event.code.send_event(key_state, event, device);
                 device.write_event(event)?;
+                // SYN_REPORT after, then key, then key's SYN_REPORT
+                device.synchronize()?;
                 event.code = code; // not needed since u16 does it
                 event.value = value;
             }
@@ -342,6 +344,8 @@ impl HalfInvertedKey {
                     event.value = UP;
                 }
                 //event.code.send_event(key_state, event, device);
+                // SYN_REPORT first after key, then shift, then key's SYN_REPORT which will be used for shift's
+                device.synchronize()?;
                 device.write_event(event)?;
                 // neither of these are needed now...
                 event.code = code; // not needed since u16 does it