From 38ed6d1569354ad5b6b027bb357798dcde90f7ec Mon Sep 17 00:00:00 2001
From: Elias Naur <mail@eliasnaur.com>
Date: Mon, 23 Mar 2020 11:27:07 +0100
Subject: [PATCH] app/internal: use pkg-config for finding system headers and
 libraries

I've resisted relying on pkg-config in the hope that hard-coded include and
library paths would suffice. However, apart from having to work around some
distro-specific differences, building with hardcoded include paths fails when
building on a buildroot:

	x86_64-buildroot-linux-gnu-gcc: ERROR: unsafe header/library path used in cross-compilation: '-I/usr/include/wayland'

(see #91)

Andri mentions a workaround (prefixing paths with "="), but that doesn't seem
to work on the BSDs.

Let's see how pkg-config fares. It's an extra dependency, but it promises to keep
us isolated from the varying paths on Linux distrobutions.

Updates #91

Signed-off-by: Elias Naur <mail@eliasnaur.com>
---
 app/internal/egl/egl_unix.go       | 5 ++---
 app/internal/glimpl/gl.go          | 3 ++-
 app/internal/window/egl_wayland.go | 5 +++--
 app/internal/window/os_wayland.go  | 3 ++-
 app/internal/window/os_x11.go      | 4 +++-
 app/internal/xkb/xkb_unix.go       | 4 ++--
 6 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/app/internal/egl/egl_unix.go b/app/internal/egl/egl_unix.go
index e23660ff..4a0cac22 100644
--- a/app/internal/egl/egl_unix.go
+++ b/app/internal/egl/egl_unix.go
@@ -5,7 +5,8 @@
 package egl
 
 /*
-#cgo LDFLAGS: -lEGL
+#cgo linux pkg-config: egl
+#cgo freebsd openbsd LDFLAGS: -lEGL
 #cgo freebsd CFLAGS: -I/usr/local/include
 #cgo freebsd LDFLAGS: -L/usr/local/lib
 #cgo openbsd CFLAGS: -I/usr/X11R6/include
@@ -14,8 +15,6 @@ package egl
 
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
-#include <GLES2/gl2.h>
-#include <GLES3/gl3.h>
 */
 import "C"
 
diff --git a/app/internal/glimpl/gl.go b/app/internal/glimpl/gl.go
index 17bac1f7..0f8272c1 100644
--- a/app/internal/glimpl/gl.go
+++ b/app/internal/glimpl/gl.go
@@ -14,8 +14,9 @@ import (
 
 /*
 #cgo CFLAGS: -Werror
-#cgo linux freebsd openbsd LDFLAGS: -lGLESv2
+#cgo linux pkg-config: glesv2
 #cgo linux freebsd LDFLAGS: -ldl
+#cgo freebsd openbsd LDFLAGS: -lGLESv2
 #cgo freebsd CFLAGS: -I/usr/local/include
 #cgo freebsd LDFLAGS: -L/usr/local/lib
 #cgo openbsd CFLAGS: -I/usr/X11R6/include
diff --git a/app/internal/window/egl_wayland.go b/app/internal/window/egl_wayland.go
index c4115fb5..b4878b4c 100644
--- a/app/internal/window/egl_wayland.go
+++ b/app/internal/window/egl_wayland.go
@@ -12,8 +12,9 @@ import (
 )
 
 /*
-#cgo LDFLAGS: -lwayland-egl
-#cgo CFLAGS: -I/usr/include/wayland -DMESA_EGL_NO_X11_HEADERS
+#cgo linux pkg-config: egl wayland-egl
+#cgo freebsd openbsd LDFLAGS: -lwayland-egl
+#cgo CFLAGS: -DMESA_EGL_NO_X11_HEADERS
 
 #include <EGL/egl.h>
 #include <wayland-client.h>
diff --git a/app/internal/window/os_wayland.go b/app/internal/window/os_wayland.go
index 700c307f..95a75bbf 100644
--- a/app/internal/window/os_wayland.go
+++ b/app/internal/window/os_wayland.go
@@ -40,7 +40,8 @@ import (
 //go:generate sed -i "1s;^;// +build linux,!android,!nowayland freebsd\\n\\n;" wayland_text_input.c
 
 /*
-#cgo LDFLAGS: -lwayland-client -lwayland-cursor
+#cgo linux pkg-config: wayland-client wayland-cursor
+#cgo freebsd openbsd LDFLAGS: -lwayland-client -lwayland-cursor
 #cgo freebsd CFLAGS: -I/usr/local/include
 #cgo freebsd LDFLAGS: -L/usr/local/lib
 
diff --git a/app/internal/window/os_x11.go b/app/internal/window/os_x11.go
index fa6f7a31..7189d042 100644
--- a/app/internal/window/os_x11.go
+++ b/app/internal/window/os_x11.go
@@ -7,7 +7,9 @@ package window
 /*
 #cgo openbsd CFLAGS: -I/usr/X11R6/include -I/usr/local/include
 #cgo openbsd LDFLAGS: -L/usr/X11R6/lib -L/usr/local/lib
-#cgo LDFLAGS: -lX11 -lxkbcommon -lxkbcommon-x11 -lX11-xcb
+#cgo freebsd openbsd LDFLAGS: -lX11 -lxkbcommon -lxkbcommon-x11 -lX11-xcb
+#cgo linux pkg-config: x11 xkbcommon xkbcommon-x11 x11-xcb
+
 #include <stdlib.h>
 #include <locale.h>
 #include <X11/Xlib.h>
diff --git a/app/internal/xkb/xkb_unix.go b/app/internal/xkb/xkb_unix.go
index 026b2e69..89cd6495 100644
--- a/app/internal/xkb/xkb_unix.go
+++ b/app/internal/xkb/xkb_unix.go
@@ -19,9 +19,9 @@ import (
 )
 
 /*
-#cgo LDFLAGS: -lxkbcommon
+#cgo linux pkg-config: xkbcommon
 #cgo freebsd openbsd CFLAGS: -I/usr/local/include
-#cgo freebsd openbsd LDFLAGS: -L/usr/local/lib
+#cgo freebsd openbsd LDFLAGS: -L/usr/local/lib -lxkbcommon
 
 #include <stdlib.h>
 #include <xkbcommon/xkbcommon.h>