fix parsing issues with vk 1.3.278

This change introduced len/optional attributes for
arrays. Previously, we assumed that these would only
occur on pointers, but now, this information is also
available for arrays.

This adapts the registery and parsing code to also
parse these properly. No modifications are made to the
rendering part as of yet, since these partially filled
arrays cannot be cleanly represented in Zig.

generator/vulkan/registry.zig

@@ -123,8 +123,10 @@ pub const Command = struct {
 pub const Pointer = struct {
     pub const PointerSize = union(enum) {
         one,
-        many, // The length is given by some complex expression, possibly involving another field
-        other_field: []const u8, // The length is given by some other field or parameter
+        /// The length is given by some complex expression, possibly involving another field
+        many,
+        /// The length is given by some other field or parameter
+        other_field: []const u8,
         zero_terminated,
     };
 
@@ -140,7 +142,26 @@ pub const Array = struct {
         alias: []const u8, // Field size is given by an api constant
     };
 
+    pub const ArrayValidSize = union(enum) {
+        /// All elements are valid.
+        all,
+        /// The length is given by some complex expression, possibly involving another field
+        many,
+        /// The length is given by some complex expression, possibly involving another field
+        other_field: []const u8,
+        /// The valid elements are terminated by a 0, or by the bounds of the array.
+        zero_terminated,
+    };
+
+    /// This is the total size of the array
     size: ArraySize,
+    /// The number of items that are actually filled with valid values
+    valid_size: ArrayValidSize,
+    /// Some members may indicate than an array is optional. This happens with
+    /// VkPhysicalDeviceHostImageCopyPropertiesEXT::optimalTilingLayoutUUID for example.
+    /// The spec is not entirely clear about what this means, but presumably it should
+    /// be filled with all zeroes.
+    is_optional: bool,
     child: *TypeInfo,
 };