chore: comptime sanity type check

Author: twoeths

src/ssz/type/container.zig

@@ -81,6 +81,10 @@ pub fn FixedContainerType(comptime ST: type) type {
         /// Caller owns the memory.
         pub fn clone(value: *const Type, out: anytype) !void {
             const OutType = @TypeOf(out.*);
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out));
+                std.debug.assert(OutInfo == .pointer);
+            }
             if (OutType == Type) {
                 out.* = value.*;
             } else {
@@ -357,6 +361,11 @@ pub fn VariableContainerType(comptime ST: type) type {
             value: *const Type,
             out: anytype,
         ) !void {
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out));
+                std.debug.assert(OutInfo == .pointer);
+            }
+
             inline for (fields) |field| {
                 if (comptime isFixedType(field.type)) {
                     try field.type.clone(&@field(value, field.name), &@field(out, field.name));

src/ssz/type/list.zig

@@ -77,6 +77,11 @@ pub fn FixedListType(comptime ST: type, comptime _limit: comptime_int) type {
         ///
         /// Caller owns the memory.
         pub fn clone(allocator: std.mem.Allocator, value: *const Type, out: anytype) !void {
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out));
+                std.debug.assert(OutInfo == .pointer);
+            }
+
             try out.resize(allocator, value.items.len);
 
             for (value.items, 0..) |v, i| {
@@ -327,6 +332,11 @@ pub fn VariableListType(comptime ST: type, comptime _limit: comptime_int) type {
         /// Clones the underlying `ArrayList`.
         /// Caller owns the memory.
         pub fn clone(allocator: std.mem.Allocator, value: *const Type, out: anytype) !void {
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out));
+                std.debug.assert(OutInfo == .pointer);
+            }
+
             try out.resize(allocator, value.items.len);
             for (0..value.items.len) |i|
                 try Element.clone(allocator, &value.items[i], &out.items[i]);

src/ssz/type/vector.zig

@@ -57,6 +57,12 @@ pub fn FixedVectorType(comptime ST: type, comptime _length: comptime_int) type {
         }
 
         pub fn clone(value: *const Type, out: anytype) !void {
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out.*));
+                std.debug.assert(OutInfo == .array);
+                std.debug.assert(OutInfo.array.len == length);
+            }
+
             const OutType = @TypeOf(out.*);
             if (OutType == Type) {
                 out.* = value.*;
@@ -238,6 +244,12 @@ pub fn VariableVectorType(comptime ST: type, comptime _length: comptime_int) typ
         }
 
         pub fn clone(allocator: std.mem.Allocator, value: *const Type, out: anytype) !void {
+            comptime {
+                const OutInfo = @typeInfo(@TypeOf(out.*));
+                std.debug.assert(OutInfo == .array);
+                std.debug.assert(OutInfo.array.len == length);
+            }
+
             for (value, 0..) |*element, i| {
                 try Element.clone(allocator, element, &out[i]);
             }