From 3297703b932007051decb2f1353b93a1a2d4157c Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 26 Oct 2016 21:33:21 +0300
Subject: [PATCH] Be smarter about detecting backport extensions

Sometimes a more recent and completely unrelated extension reuses some
tokens with their core names, causing them to seem like backport
extensions to the script.
---
 extensions/arb_texture_cube_map.glext         |  1 +
 extensions/arb_texture_float.glext            |  1 +
 extensions/arb_vertex_buffer_object.glext     |  1 +
 extensions/arb_vertex_shader.glext            |  1 +
 extensions/ext_bgra.glext                     |  1 +
 extensions/ext_blend_minmax.glext             |  1 +
 extensions/ext_blend_subtract.glext           |  1 +
 extensions/ext_framebuffer_blit.glext         |  1 +
 extensions/ext_framebuffer_multisample.glext  |  1 +
 extensions/ext_geometry_shader4.glext         |  1 +
 extensions/ext_texture3d.glext                |  1 +
 .../ext_texture_filter_anisotropic.glext      |  1 +
 scripts/extgen.py                             | 31 +++++++++++++++++--
 13 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/extensions/arb_texture_cube_map.glext b/extensions/arb_texture_cube_map.glext
index 88745307..3dd14981 100644
--- a/extensions/arb_texture_cube_map.glext
+++ b/extensions/arb_texture_cube_map.glext
@@ -1,2 +1,3 @@
 extension ARB_texture_cube_map
 core_version gl 1.3
+backport none
diff --git a/extensions/arb_texture_float.glext b/extensions/arb_texture_float.glext
index 24f42c2f..55aa32d1 100644
--- a/extensions/arb_texture_float.glext
+++ b/extensions/arb_texture_float.glext
@@ -1,2 +1,3 @@
 extension ARB_texture_float
 core_version gl 3.0
+backport none
diff --git a/extensions/arb_vertex_buffer_object.glext b/extensions/arb_vertex_buffer_object.glext
index 0eadd25f..e8962591 100644
--- a/extensions/arb_vertex_buffer_object.glext
+++ b/extensions/arb_vertex_buffer_object.glext
@@ -1 +1,2 @@
 extension ARB_vertex_buffer_object
+backport none
diff --git a/extensions/arb_vertex_shader.glext b/extensions/arb_vertex_shader.glext
index 73d559b4..951fbaae 100644
--- a/extensions/arb_vertex_shader.glext
+++ b/extensions/arb_vertex_shader.glext
@@ -1,2 +1,3 @@
 extension ARB_vertex_shader
 secondary ARB_vertex_program
+backport none
diff --git a/extensions/ext_bgra.glext b/extensions/ext_bgra.glext
index 2ba56750..d8522175 100644
--- a/extensions/ext_bgra.glext
+++ b/extensions/ext_bgra.glext
@@ -1,2 +1,3 @@
 extension EXT_bgra
 core_version gl 1.2
+backport none
diff --git a/extensions/ext_blend_minmax.glext b/extensions/ext_blend_minmax.glext
index 5b2174d5..62606988 100644
--- a/extensions/ext_blend_minmax.glext
+++ b/extensions/ext_blend_minmax.glext
@@ -1 +1,2 @@
 extension EXT_blend_minmax
+backport none
diff --git a/extensions/ext_blend_subtract.glext b/extensions/ext_blend_subtract.glext
index 0e89f4d2..cbd8b416 100644
--- a/extensions/ext_blend_subtract.glext
+++ b/extensions/ext_blend_subtract.glext
@@ -1,2 +1,3 @@
 extension EXT_blend_subtract
 core_version gl 1.2
+backport none
diff --git a/extensions/ext_framebuffer_blit.glext b/extensions/ext_framebuffer_blit.glext
index 4c78ba51..cdc1801b 100644
--- a/extensions/ext_framebuffer_blit.glext
+++ b/extensions/ext_framebuffer_blit.glext
@@ -1 +1,2 @@
 extension EXT_framebuffer_blit
+backport ARB_framebuffer_object
diff --git a/extensions/ext_framebuffer_multisample.glext b/extensions/ext_framebuffer_multisample.glext
index 91f26a7f..272ca3ae 100644
--- a/extensions/ext_framebuffer_multisample.glext
+++ b/extensions/ext_framebuffer_multisample.glext
@@ -1 +1,2 @@
 extension EXT_framebuffer_multisample
+backport ARB_framebuffer_object
diff --git a/extensions/ext_geometry_shader4.glext b/extensions/ext_geometry_shader4.glext
index 0bc0f85d..210b9bdb 100644
--- a/extensions/ext_geometry_shader4.glext
+++ b/extensions/ext_geometry_shader4.glext
@@ -1 +1,2 @@
 extension EXT_geometry_shader4
+backport none
diff --git a/extensions/ext_texture3d.glext b/extensions/ext_texture3d.glext
index e9bc90bb..c1516184 100644
--- a/extensions/ext_texture3d.glext
+++ b/extensions/ext_texture3d.glext
@@ -1 +1,2 @@
 extension EXT_texture3D
+backport none
diff --git a/extensions/ext_texture_filter_anisotropic.glext b/extensions/ext_texture_filter_anisotropic.glext
index 6d7c6c11..0f611bf4 100644
--- a/extensions/ext_texture_filter_anisotropic.glext
+++ b/extensions/ext_texture_filter_anisotropic.glext
@@ -1 +1,2 @@
 extension EXT_texture_filter_anisotropic
+backport none
diff --git a/scripts/extgen.py b/scripts/extgen.py
index ec57e2ef..7083e13a 100755
--- a/scripts/extgen.py
+++ b/scripts/extgen.py
@@ -31,6 +31,7 @@ if sys.argv[i].startswith("gl"):
 	i += 1
 
 target_ext = sys.argv[i]
+backport_ext = None
 out_base = None
 if target_ext.endswith(".glext"):
 	fn = target_ext
@@ -46,6 +47,8 @@ if target_ext.endswith(".glext"):
 				core_version = parts[2]
 		elif parts[0]=="secondary":
 			secondary.append(parts[1])
+		elif parts[0]=="backport":
+			backport_ext = parts[1]
 	if i+1<len(sys.argv):
 		out_base = os.path.splitext(sys.argv[i+1])[0]
 else:
@@ -55,7 +58,6 @@ else:
 		core_version = secondary.pop(0)
 
 ext_type = target_ext.split('_')[0]
-backport_ext = None
 
 if core_version:
 	core_version = map(int, core_version.split('.'))
@@ -95,7 +97,9 @@ class Extension:
 	def __init__(self, name):
 		self.name = name
 		self.supported_apis = []
-		self.ext_type = name[0:name.find('_')]
+		underscore = name.find('_')
+		self.ext_type = name[0:underscore]
+		self.base_name = name[underscore+1:]
 
 extensions = {}
 things = {}
@@ -315,6 +319,7 @@ enums = filter(is_relevant, enums)
 enums.sort(key=(lambda e: e.value))
 
 # Some final preparations for creating the files
+backport_ext_candidates = []
 for t in itertools.chain(funcs, enums):
 	if target_api in t.supported_apis and t.supported_apis[target_api]!="ext":
 		t.version = t.supported_apis[target_api]
@@ -323,7 +328,27 @@ for t in itertools.chain(funcs, enums):
 
 	# Things in backport extensions don't acquire an extension suffix
 	if t.extension and not t.name.endswith(ext_type) and target_api in t.supported_apis:
-		backport_ext = t.extension
+		if t.extension not in backport_ext_candidates:
+			backport_ext_candidates.append(t.extension)
+
+if backport_ext:
+	if backport_ext=="none":
+		backport_ext = None
+	else:
+		backport_ext = extensions[backport_ext]
+
+		if backport_ext not in backport_ext_candidates:
+			print "Warning: explicitly specified backport extension %s does not look like a backport extension"
+elif backport_ext_candidates:
+	if len(backport_ext_candidates)>1:
+		print "Warning: multiple backport extension candidates: %s"%(" ".join(e.name for e in backport_ext_candidates))
+
+	for e in backport_ext_candidates:
+		if e.base_name==target_ext.base_name:
+			backport_ext = e
+
+	if not backport_ext and len(backport_ext_candidates)==1:
+		print "Warning: potential backport extension has mismatched name: %s"%backport_ext_candidates[0].name
 
 for f in funcs:
 	f.typedef = "FPtr_%s"%f.name
-- 
2.43.0