build: Check for included system headersebassi/header-check

The generated dispatch headers for EGL and GLX include system headers.
We do a pkg-config check for those, but the dependency is not required,
in order to support builds on systems that do not use pkg-config.

If the dependency is not found, we need to check for the headers we
include, otherwise building Epoxy will fail. If the support for EGL or
GLX was explicitly enabled, fail the configuration step; otherwise,
disable the EGL or GLX support.

1 files changed, 57 insertions, 35 deletions

diff --git a/meson.build b/meson.build
index ca37e80..6b5a942 100644
--- a/meson.build
+++ b/meson.build
@@ -69,6 +69,63 @@ else
   has_znow = true
 endif
 
+# Dependencies
+dl_dep = cc.find_library('dl', required: false)
+gl_dep = dependency('gl', required: false)
+
+egl_dep = dependency('egl', required: false)
+if not egl_dep.found()
+  # The generated EGL dispatch table includes eglplatform.h, so we need
+  # this header to build Epoxy itself
+  if not cc.has_header('EGL/eglplatform.h')
+    if get_option('egl') == 'yes'
+      error('EGL required, but EGL/eglplatform.h could not be found')
+    else
+      build_egl = false
+    endif
+  endif
+endif
+
+x11_dep = dependency('x11', required: false)
+if not x11_dep.found()
+  # The generated GLX dispatch table includes Xlib.h, so we need this
+  # header to build Epoxy itself
+  if not cc.has_header('X11/Xlib.h')
+    if get_option('glx') == 'yes'
+      error('GLX required, but X11/Xlib.h cound not be found')
+    else
+      build_glx = false
+    endif
+  endif
+endif
+
+# GLES v2 and v1 may have pkg-config files, courtesy of downstream
+# packagers; let's check those first, and fall back to find_library()
+# if we fail
+gles2_dep = dependency('glesv2', required: false)
+if not gles2_dep.found()
+  gles2_dep = cc.find_library('libGLESv2', required: false)
+endif
+
+gles1_dep = dependency('glesv1_cm', required: false)
+if not gles1_dep.found()
+  gles1_dep = cc.find_library('libGLESv1_CM', required: false)
+endif
+
+# On windows, the DLL has to have all of its functions
+# resolved at link time, so we have to link directly against
+# opengl32.  But that's the only GL provider, anyway.
+if host_system == 'windows'
+  opengl32_dep = cc.find_library('opengl32', required: true)
+
+  # When building against static libraries, we need to control
+  # the order of the dependencies, and gdi32 provides symbols
+  # needed when using opengl32, like SetPixelFormat and
+  # ChoosePixelFormat. This is mostly a workaround for older
+  # versions of Meson.
+  gdi32_dep = cc.find_library('gdi32', required: true)
+endif
+
 conf.set10('ENABLE_GLX', build_glx)
 conf.set10('ENABLE_EGL', build_egl)
 conf.set10('ENABLE_X11', enable_x11)
@@ -161,41 +218,6 @@ if host_system == 'windows'
   endif
 endif
 
-# Dependencies
-dl_dep = cc.find_library('dl', required: false)
-gl_dep = dependency('gl', required: false)
-egl_dep = dependency('egl', required: false)
-
-# Optional dependencies for tests
-x11_dep = dependency('x11', required: false)
-
-# GLES v2 and v1 may have pkg-config files, courtesy of downstream
-# packagers; let's check those first, and fall back to find_library()
-# if we fail
-gles2_dep = dependency('glesv2', required: false)
-if not gles2_dep.found()
-  gles2_dep = cc.find_library('libGLESv2', required: false)
-endif
-
-gles1_dep = dependency('glesv1_cm', required: false)
-if not gles1_dep.found()
-  gles1_dep = cc.find_library('libGLESv1_CM', required: false)
-endif
-
-# On windows, the DLL has to have all of its functions
-# resolved at link time, so we have to link directly against
-# opengl32.  But that's the only GL provider, anyway.
-if host_system == 'windows'
-  opengl32_dep = cc.find_library('opengl32', required: true)
-
-  # When building against static libraries, we need to control
-  # the order of the dependencies, and gdi32 provides symbols
-  # needed when using opengl32, like SetPixelFormat and
-  # ChoosePixelFormat. This is mostly a workaround for older
-  # versions of Meson.
-  gdi32_dep = cc.find_library('gdi32', required: true)
-endif
-
 # Generates the dispatch tables
 gen_dispatch_py = find_program('src/gen_dispatch.py')