Add special cases for bit packed structs

This commit adds special cases for AccelerationStructureInstanceKHR and
VkAccelerationStructureSRTMotionInstanceNV. These types use bit-packed
fields which are not representable in the current version of the zig
stage 2 compiler. This might change when
https://github.com/ziglang/zig/issues/13009 is resolved.

Fixes #56

generator/vulkan/build_integration.zig

@@ -75,7 +75,25 @@ pub const GenerateStep = struct {
         const spec = try cwd.readFileAlloc(self.builder.allocator, self.spec_path, std.math.maxInt(usize));
 
         var out_buffer = std.ArrayList(u8).init(self.builder.allocator);
-        try generate(self.builder.allocator, spec, out_buffer.writer());
+        generate(self.builder.allocator, spec, out_buffer.writer()) catch |err| switch (err) {
+            error.InvalidXml => {
+                std.log.err("invalid vulkan registry - invalid xml", .{});
+                std.log.err("please check that the correct vk.xml file is passed", .{});
+                return err;
+            },
+            error.InvalidRegistry => {
+                std.log.err("invalid vulkan registry - registry is valid xml but contents are invalid", .{});
+                std.log.err("please check that the correct vk.xml file is passed", .{});
+                return err;
+            },
+            error.UnhandledBitfieldStruct => {
+                std.log.err("unhandled struct with bit fields detected in vk.xml", .{});
+                std.log.err("this is a bug in vulkan-zig", .{});
+                std.log.err("please make a bug report at https://github.com/Snektron/vulkan-zig/issues/", .{});
+                return err;
+            },
+            error.OutOfMemory => return error.OutOfMemory,
+        };
         try out_buffer.append(0);
 
         const src = out_buffer.items[0 .. out_buffer.items.len - 1 :0];

generator/vulkan/generator.zig

@@ -175,13 +175,49 @@ pub const Generator = struct {
 /// internal datastructures - mostly via an ArenaAllocator, but sometimes a hashmap uses this allocator
 /// directly.
 pub fn generate(allocator: Allocator, spec_xml: []const u8, writer: anytype) !void {
-    const spec = try xml.parse(allocator, spec_xml);
+    const spec = xml.parse(allocator, spec_xml) catch |err| switch (err) {
+        error.InvalidDocument,
+        error.UnexpectedEof,
+        error.UnexpectedCharacter,
+        error.IllegalCharacter,
+        error.InvalidEntity,
+        error.InvalidName,
+        error.InvalidStandaloneValue,
+        error.NonMatchingClosingTag,
+        error.UnclosedComment,
+        error.UnclosedValue,
+        => return error.InvalidXml,
+        error.OutOfMemory => return error.OutOfMemory,
+    };
     defer spec.deinit();
 
-    var gen = try Generator.init(allocator, spec.root);
+    var gen = Generator.init(allocator, spec.root) catch |err| switch (err) {
+        error.InvalidXml,
+        error.InvalidCharacter,
+        error.Overflow,
+        error.InvalidFeatureLevel,
+        error.InvalidSyntax,
+        error.InvalidTag,
+        error.MissingTypeIdentifier,
+        error.UnexpectedCharacter,
+        error.UnexpectedEof,
+        error.UnexpectedToken,
+        error.InvalidRegistry,
+        => return error.InvalidRegistry,
+        error.OutOfMemory => return error.OutOfMemory,
+    };
     defer gen.deinit();
 
     try gen.mergeEnumFields();
     try gen.fixupBitFlags();
-    try gen.render(writer);
+    gen.render(writer) catch |err| switch (err) {
+        error.InvalidApiConstant,
+        error.InvalidConstantExpr,
+        error.InvalidRegistry,
+        error.UnexpectedCharacter,
+        error.InvalidCharacter,
+        error.Overflow,
+        => return error.InvalidRegistry,
+        else => |others| return others,
+    };
 }

generator/vulkan/render.zig

@@ -625,15 +625,85 @@ fn Renderer(comptime WriterType: type) type {
             }
         }
 
+        fn renderSpecialContainer(self: *Self, name: []const u8) !bool {
+            const maybe_author = self.id_renderer.getAuthorTag(name);
+            const basename = self.id_renderer.stripAuthorTag(name);
+            if (std.mem.eql(u8, basename, "VkAccelerationStructureInstance")) {
+                try self.writer.print(
+                    \\extern struct {{
+                    \\    transform: TransformMatrix{s},
+                    \\    instance_custom_index_and_mask: packed struct(u32) {{
+                    \\        instance_custom_index: u24,
+                    \\        mask: u8,
+                    \\    }},
+                    \\    instance_shader_binding_table_record_offset_and_flags: packed struct(u32) {{
+                    \\        instance_shader_binding_table_record_offset: u24,
+                    \\        flags: u8, // GeometryInstanceFlagsKHR
+                    \\    }},
+                    \\    acceleration_structure_reference: u64,
+                    \\}};
+                    \\
+                ,
+                    .{maybe_author orelse ""},
+                );
+                return true;
+            } else if (std.mem.eql(u8, basename, "VkAccelerationStructureSRTMotionInstance")) {
+                try self.writer.print(
+                    \\extern struct {{
+                    \\    transform_t0: SRTData{0s},
+                    \\    transform_t1: SRTData{0s},
+                    \\    instance_custom_index_and_mask: packed struct(u32) {{
+                    \\        instance_custom_index: u24,
+                    \\        mask: u8,
+                    \\    }},
+                    \\    instance_shader_binding_table_record_offset_and_flags: packed struct(u32) {{
+                    \\        instance_shader_binding_table_record_offset: u24,
+                    \\        flags: u8, // GeometryInstanceFlagsKHR
+                    \\    }},
+                    \\    acceleration_structure_reference: u64,
+                    \\}};
+                    \\
+                ,
+                    .{maybe_author orelse ""},
+                );
+                return true;
+            } else if (std.mem.eql(u8, basename, "VkAccelerationStructureMatrixMotionInstance")) {
+                try self.writer.print(
+                    \\extern struct {{
+                    \\    transform_t0: TransformMatrix{0s},
+                    \\    transform_t1: TransformMatrix{0s},
+                    \\    instance_custom_index_and_mask: packed struct(u32) {{
+                    \\        instance_custom_index: u24,
+                    \\        mask: u8,
+                    \\    }},
+                    \\    instance_shader_binding_table_record_offset_and_flags: packed struct(u32) {{
+                    \\        instance_shader_binding_table_record_offset: u24,
+                    \\        flags: u8, // GeometryInstanceFlagsKHR
+                    \\    }},
+                    \\    acceleration_structure_reference: u64,
+                    \\}};
+                    \\
+                ,
+                    .{maybe_author orelse ""},
+                );
+                return true;
+            }
+
+            return false;
+        }
+
         fn renderContainer(self: *Self, name: []const u8, container: reg.Container) !void {
             try self.writer.writeAll("pub const ");
             try self.renderName(name);
             try self.writer.writeAll(" = ");
 
+            if (try self.renderSpecialContainer(name)) {
+                return;
+            }
+
             for (container.fields) |field| {
                 if (field.bits != null) {
-                    try self.writer.writeAll("packed ");
-                    break;
+                    return error.UnhandledBitfieldStruct;
                 }
             } else {
                 try self.writer.writeAll("extern ");