pmaports/unity8/mir/0003-Suppress-the-compiler-diagnostic-on-Alpine-Linux-cau.patch

From cc862ef9a703782f7fc8a9a20dbfde882776b9b7 Mon Sep 17 00:00:00 2001
From: Alan Griffiths <alan@octopull.co.uk>
Date: Wed, 9 Jan 2019 10:35:34 +0100
Subject: [PATCH 3/7] Suppress the compiler diagnostic on Alpine Linux caused
 by a mismatch between the signed type of the ioctl() request parameter and
 the unsigned type returned by EVIOCGPROP. (See #692)

---
 src/platforms/evdev/evdev_device_detection.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/platforms/evdev/evdev_device_detection.cpp b/src/platforms/evdev/evdev_device_detection.cpp
index f771f1f234..cf844a7f83 100644
--- a/src/platforms/evdev/evdev_device_detection.cpp
+++ b/src/platforms/evdev/evdev_device_detection.cpp
@@ -48,6 +48,16 @@ struct DeviceInfo
     uint8_t property_bit_mask[(INPUT_PROP_MAX+1)/8];
 };
 
+namespace
+{
+// On Alpine Linux there's a mismatch between the signed type of the ioctl() request parameter and the
+// unsigned type returned by EVIOCGPROP. (See #692)
+// We use a bit of magic to suppress the compiler diagnostic.
+template<typename Param1>
+auto request_param_type(int (*ioctl)(int, Param1, ...)) -> Param1;
+using ioctl_request_t = decltype(request_param_type(&ioctl));
+}
+
 DeviceInfo::DeviceInfo(mir::Fd const& fd)
 {
     auto const get_bitmask = [&](int bit, size_t size, uint8_t* buf) -> void
@@ -62,7 +72,7 @@ DeviceInfo::DeviceInfo(mir::Fd const& fd)
     get_bitmask(EV_ABS, sizeof abs_bit_mask, abs_bit_mask);
     get_bitmask(EV_SW, sizeof sw_bit_mask, sw_bit_mask);
 
-    if (ioctl(fd, EVIOCGPROP(sizeof property_bit_mask), property_bit_mask) < 1)
+    if (ioctl(fd, static_cast<ioctl_request_t>(EVIOCGPROP(sizeof property_bit_mask)), property_bit_mask) < 1)
         BOOST_THROW_EXCEPTION(
             std::system_error(std::error_code(errno, std::system_category()), "Failed to query devices properties"));
 }
-- 
2.20.1