From 898bd798e823e7708e4dbeb07955ae2ee17f925a Mon Sep 17 00:00:00 2001 From: Jan Engelhardt Date: Tue, 12 Jul 2022 17:10:18 +0200 Subject: [PATCH] Drop wayland-client.h include Upstream: not sent References: https://build.opensuse.org/package/show/X11:Wayland/vulkan-loader comment from 2022-07-12 wayland-client may be located outside the default search paths of the compiler toolchain. In other words, *any* user of wayland-client must use `pkg-config wayland-client --cflags` for compilation, and, later, `pkg-config wayland-client --libs` for linking. A Vulkan program that defines -DVK_USE_PLATFORM_WAYLAND_KHR would, in the general case, also call at least some Wayland functions. The build scripts for that program would have to employ `pkg-config wayland-client --cflags --libs` in any case, based simply on the use of said Wayland functions. Now, there is a corner case wherein the program defines VK_USE_PLATFORM_*, but does not make use of Wayland functions directly: echo "#define VK_USE_PLATFORM_WAYLAND_KHR #include int main() {return 0;}" | gcc -x c - "Should `pkg-config` be required for this?" One opinion is that the use of -DVK_USE_PLATFORM_WAYLAND_KHR is so explicitly willful that `pkg-config` is required. Another stance is that, since no Wayland header and no Wayland functions were directly used by the program, the program itself should not have to use `pkg-config`; responsibility to satisfy the "#include " in vulkan.h would then fall to vulkan.pc, which would have to pull in wayland-client.pc. That on the other hand would pull in wayland for everyone, which is bad. Either way, I found the following option: Delete the include for which you would need wayland's -I flags. This works because we can just add forward declaration like "struct wl_display;" to vulkan_wayland.h. But we don't even need that. C (and C++) seem to be fine with undeclared names, e.g. //no "struct T;" struct S { struct T *t; } void f(struct T *t) {} so I guess it's the solution, for now. Keep in mind that, as soon as a program uses Wayland functions (directly; not indirectly through vulkan), it needs to #include anyway on its own, and then the pkg-config case from the first paragraph applies. --- include/vulkan/vulkan.h | 1 - 1 file changed, 1 deletion(-) diff --git a/include/vulkan/vulkan.h b/include/vulkan/vulkan.h index 004fa70..3510ac9 100644 --- a/include/vulkan/vulkan.h +++ b/include/vulkan/vulkan.h @@ -38,7 +38,6 @@ #ifdef VK_USE_PLATFORM_WAYLAND_KHR -#include #include "vulkan_wayland.h" #endif -- 2.36.1