build: Rework the build rules for generated files in Meson

Instead of using a generator and having to deal with tweaking the
inclusion paths, we can use a custom target rule, which will do the
right thing and put the generate files where we expect them to be.

Due to how Meson and Ninja work we need to be a bit more careful as to
how we deal with dependencies and generated files, especially since
Epoxy is built on the assumption that the only inclusion path for the
headers lies under the 'include' sub-directory.

First of all, we need to split the dispatch table generation into two
separate steps, one for the headers and one for the source files.

Additionally, we need to munge the paths of the non-generated headers
so that we reference them by their correct path.

These changes are necessary to ensure that Epoxy can be built on a
system without Epoxy installed already; the previous Meson-based build
system relied on the headers being installed in a system directory.

2 files changed, 101 insertions, 47 deletions

diff --git a/src/gen_dispatch.py b/src/gen_dispatch.py
index 283d965..71c3bc1 100755
--- a/src/gen_dispatch.py
+++ b/src/gen_dispatch.py
@@ -836,23 +836,36 @@ class Generator(object):
 
 argparser = argparse.ArgumentParser(description='Generate GL dispatch wrappers.')
 argparser.add_argument('files', metavar='file.xml', nargs='+', help='GL API XML files to be parsed')
-argparser.add_argument('--srcdir', metavar='srcdir', required=False, help='Destination directory for source files')
-argparser.add_argument('--includedir', metavar='incdir', required=False, help='Destination director for header files')
-argparser.add_argument('--dir', metavar='dir', required=False, help='Destination directory')
+argparser.add_argument('--outputdir', metavar='dir', required=False, help='Destination directory for files (default to current dir)')
+argparser.add_argument('--includedir', metavar='dir', required=False, help='Destination directory for headers')
+argparser.add_argument('--srcdir', metavar='dir', required=False, help='Destination directory for source')
+argparser.add_argument('--source', dest='source', action='store_true', required=False, help='Generate the source file')
+argparser.add_argument('--no-source', dest='source', action='store_false', required=False, help='Do not generate the source file')
+argparser.add_argument('--header', dest='header', action='store_true', required=False, help='Generate the header file')
+argparser.add_argument('--no-header', dest='header', action='store_false', required=False, help='Do not generate the header file')
 args = argparser.parse_args()
 
-if args.dir:
-    srcdir = args.dir
-    incdir = args.dir
+if args.outputdir:
+    outputdir = args.outputdir
 else:
+    outputdir = os.getcwd()
+
+if args.includedir:
+    includedir = args.includedir
+else:
+    includedir = outputdir
+
+if args.srcdir:
     srcdir = args.srcdir
-    incdir = args.includedir
+else:
+    srcdir = outputdir
 
-if not srcdir:
-    srcdir = os.getcwd()
+build_source = args.source
+build_header = args.header
 
-if not incdir:
-    incdir = os.getcwd()
+if not build_source and not build_header:
+    build_source = True
+    build_header = True
 
 for file in args.files:
     name = os.path.basename(file).split('.xml')[0]
@@ -881,5 +894,7 @@ for file in args.files:
 
     generator.prepare_provider_enum()
 
-    generator.write_header(os.path.join(incdir, name + '_generated.h'))
-    generator.write_source(os.path.join(srcdir, name + '_generated_dispatch.c'))
+    if build_header:
+        generator.write_header(os.path.join(includedir, name + '_generated.h'))
+    if build_source:
+        generator.write_source(os.path.join(srcdir, name + '_generated_dispatch.c'))
diff --git a/src/meson.build b/src/meson.build
index 1ca4117..c47a674 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -6,45 +6,87 @@ common_sources = [
 # Configuration file
 configure_file(output: 'config.h', configuration: conf)
 
-# Generate the dispatch tables
-gen_dispatch_py = find_program('gen_dispatch.py')
+gl_generated = custom_target('gl_generated_dispatch.c',
+                             input: gl_registry,
+                             output: [
+                               'gl_generated_dispatch.c',
+                             ],
+                             command: [
+                               python,
+                               gen_dispatch_py,
+                               '--source',
+                               '--no-header',
+                               '--outputdir=' + meson.current_build_dir(),
+                               '@INPUT@',
+                             ])
 
-gen_dispatch = generator(gen_dispatch_py,
-			 output: [ '@BASENAME@_generated.h', '@BASENAME@_generated_dispatch.c', ],
-                         arguments: [ '--dir=@BUILD_DIR@', '@INPUT@' ])
+gen_sources = [ gl_generated ]
+sources = common_sources 
 
-gl_generated = gen_dispatch.process(join_paths(meson.source_root(), 'registry/gl.xml'))
-gl_headers = [ join_paths(meson.source_root(), 'include/epoxy/gl.h'), 'gl_generated.h', ]
-gl_sources = gl_generated
-
-egl_headers = []
-egl_sources = []
 if build_egl
-  egl_generated = gen_dispatch.process(join_paths(meson.source_root(), 'registry/egl.xml'))
-  egl_headers += [ join_paths(meson.source_root(), 'include/epoxy/egl.h'), 'egl_generated.h', ]
-  egl_sources += [ egl_generated, 'dispatch_egl.c', ]
+  egl_generated = custom_target('egl_generated_dispatch.c',
+                                input: egl_registry,
+                                output: [
+                                  'egl_generated_dispatch.c',
+                                ],
+                                command: [
+                                  python,
+                                  gen_dispatch_py,
+                                  '--source',
+                                  '--no-header',
+                                  '--outputdir=' + meson.current_build_dir(),
+                                  '@INPUT@',
+                                ])
+  gen_sources += [ egl_generated ]                              
+  sources += [ 'dispatch_egl.c' ]
 endif
 
-glx_headers = []
-glx_sources = []
 if build_glx
-  glx_generated = gen_dispatch.process(join_paths(meson.source_root(), 'registry/glx.xml'))
-  glx_headers += [ join_paths(meson.source_root(), 'include/epoxy/glx.h'), 'glx_generated.h', ]
-  glx_sources += [ glx_generated, 'dispatch_glx.c', ]
+  glx_generated = custom_target('glx_generated_dispatch.c',
+                                input: glx_registry,
+                                output: [
+                                  'glx_generated_dispatch.c',
+                                ],
+                                command: [
+                                  python,
+                                  gen_dispatch_py,
+                                  '--source',
+                                  '--no-header',
+                                  '--outputdir=' + meson.current_build_dir(),
+                                  '@INPUT@',
+                                ])
+  gen_sources += [ glx_generated ]
+  sources += [ 'dispatch_glx.c' ]
 endif
 
-wgl_headers = []
-wgl_sources = []
 if build_wgl
-  wgl_generated = gen_dispatch.process(join_paths(meson.source_root(), 'registry/wgl.xml'))
-  wgl_headers += [ join_paths(meson.source_root(), 'include/epoxy/wgl.h'), 'wgl_generated.h', ]
-  wgl_sources += [ wgl_generated, 'dispatch_wgl.c', ]
+  wgl_generated = custom_target('wgl_generated_dispatch.c',
+                                input: wgl_registry,
+                                output: [
+                                  'wgl_generated_dispatch.c',
+                                ],
+                                command: [
+                                  python,
+                                  gen_dispatch_py,
+                                  '--source',
+                                  '--no-header',
+                                  '--outputdir=' + meson.current_build_dir(),
+                                  '@INPUT@',
+                                ])
+  gen_sources += [ wgl_generated ]
+  sources += [ 'dispatch_wgl.c' ]
 endif
 
-if cc.get_id() == 'msvc'
-  common_ldflags = []
-else
+epoxy_sources = common_sources + sources + gen_sources
+epoxy_headers = gen_headers
+foreach h: headers
+  epoxy_headers += join_paths(meson.source_root(), 'include/epoxy/@0@'.format(h))
+endforeach
+
+if cc.get_id() == 'gcc'
   common_ldflags = [ '-Wl,-Bsymbolic', ]
+else
+  common_ldflags = []
 endif
 
 epoxy_deps = [ dl_dep, ]
@@ -53,14 +95,12 @@ if host_system == 'windows'
   epoxy_deps += [ ogl_dep, ]
 endif
 
-libepoxy_inc = [ epoxy_include, include_directories('.'), ]
-
 # Allow building a static version of epoxy
 libtype = get_option('default_library')
 
 if libtype != 'shared'
   libepoxy_static = static_library('epoxy',
-                                   common_sources + [ gl_sources, egl_sources, glx_sources, wgl_sources ],
+                                   sources: epoxy_sources + epoxy_headers,
                                    install: true,
                                    dependencies: epoxy_deps,
                                    include_directories: libepoxy_inc,
@@ -71,7 +111,7 @@ endif
 
 if libtype != 'static'
   libepoxy_shared = shared_library('epoxy',
-                                   sources: common_sources + [ gl_sources, egl_sources, glx_sources, wgl_sources ],
+                                   sources: epoxy_sources + epoxy_headers,
                                    version: '0.0.0',
                                    install: true,
                                    dependencies: epoxy_deps,
@@ -83,6 +123,5 @@ endif
 
 libepoxy_dep = declare_dependency(link_with: libepoxy,
                                   include_directories: libepoxy_inc,
-                                  dependencies: dl_dep)
-
-install_headers(gl_headers + glx_headers + egl_headers + wgl_headers, subdir: 'epoxy')
+                                  dependencies: epoxy_deps,
+                                  sources: epoxy_headers)