From 98250e9c32c5b9b940da2fb0a32d8139bbc68157 Mon Sep 17 00:00:00 2001
From: Alan Griffiths <alan@octopull.co.uk>
Date: Thu, 31 Aug 2023 12:05:13 +0100
Subject: [PATCH] Fix the signature of drmModeCrtcSetGamma

---
 tests/include/mir/test/doubles/mock_drm.h |  2 +-
 tests/mir_test_doubles/mock_drm.cpp       | 22 ++++++++++++++++++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/tests/include/mir/test/doubles/mock_drm.h b/tests/include/mir/test/doubles/mock_drm.h
index aeba8c7d05d..d3c44f30c20 100644
--- a/tests/include/mir/test/doubles/mock_drm.h
+++ b/tests/include/mir/test/doubles/mock_drm.h
@@ -155,7 +155,7 @@ class MockDRM
     MOCK_METHOD6(drmModeCrtcGetGamma, int(int fd, uint32_t crtc_id, uint32_t size,
                                           uint16_t* red, uint16_t* green, uint16_t* blue));
     MOCK_METHOD6(drmModeCrtcSetGamma, int(int fd, uint32_t crtc_id, uint32_t size,
-                                          uint16_t* red, uint16_t* green, uint16_t* blue));
+                                          uint16_t const* red, uint16_t const* green, uint16_t const* blue));
 
     MOCK_METHOD1(drmGetVersion, drmVersionPtr(int));
     MOCK_METHOD1(drmFreeVersion, void(drmVersionPtr));
diff --git a/tests/mir_test_doubles/mock_drm.cpp b/tests/mir_test_doubles/mock_drm.cpp
index d3d5840b7a0..bd51466cbac 100644
--- a/tests/mir_test_doubles/mock_drm.cpp
+++ b/tests/mir_test_doubles/mock_drm.cpp
@@ -489,6 +489,24 @@ testing::Matcher<int> mtd::IsFdOfDevice(char const* device)
     return ::testing::MakeMatcher(new mtd::MockDRM::IsFdOfDeviceMatcher(device));
 }
 
+// The signature of drmModeCrtcSetGamma() changes from passing the gamma as `uint16_t*` to `uint16_t const*`
+// We need to provide a definition that matches
+namespace
+{
+template<typename Any>
+struct Decode_drmModeCrtcSetGamma_signature;
+
+template<typename Arg>
+struct Decode_drmModeCrtcSetGamma_signature<int(int fd, uint32_t crtc_id, uint32_t size, Arg red, Arg gree, Arg blue)>
+{
+    using gamma_t = Arg;
+};
+using gamma_t = Decode_drmModeCrtcSetGamma_signature<decltype(drmModeCrtcSetGamma)>::gamma_t;
+}
+
+// Ensure we get a compile error if the definition doesn't match the declaration (instead of providing an overload)
+extern "C"
+{
 int drmOpen(const char *name, const char *busid)
 {
     return global_mock->drmOpen(name, busid);
@@ -548,8 +566,7 @@ int drmModeCrtcGetGamma(int fd, uint32_t crtc_id, uint32_t size,
     return global_mock->drmModeCrtcGetGamma(fd, crtc_id, size, red, green, blue);
 }
 
-int drmModeCrtcSetGamma(int fd, uint32_t crtc_id, uint32_t size,
-                        uint16_t* red, uint16_t* green, uint16_t* blue)
+int drmModeCrtcSetGamma(int fd, uint32_t crtc_id, uint32_t size, gamma_t red, gamma_t green, gamma_t blue)
 {
     return global_mock->drmModeCrtcSetGamma(fd, crtc_id, size, red, green, blue);
 }
@@ -751,3 +768,4 @@ int drmCheckModesettingSupported(char const* busid)
 {
     return global_mock->drmCheckModesettingSupported(busid);
 }
+}