Can place skulls inside when creativeNoClip. Fixes #775

src/main/java/carpet/mixins/WallStandingBlockItem_creativeNoClipMixin.java

@@ -0,0 +1,38 @@
+package carpet.mixins;
+
+import carpet.CarpetSettings;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.ShapeContext;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.ItemPlacementContext;
+import net.minecraft.item.WallStandingBlockItem;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.shape.VoxelShape;
+import net.minecraft.world.WorldView;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+@Mixin(WallStandingBlockItem.class)
+public class WallStandingBlockItem_creativeNoClipMixin
+{
+    @Redirect(method = "getPlacementState", at = @At(
+                value = "INVOKE",
+                target = "Lnet/minecraft/world/WorldView;canPlace(Lnet/minecraft/block/BlockState;Lnet/minecraft/util/math/BlockPos;Lnet/minecraft/block/ShapeContext;)Z"
+    ))
+    private boolean canCreativePlayerPlace(
+            WorldView worldView, BlockState state, BlockPos pos, ShapeContext context,
+            ItemPlacementContext itemcontext
+    )
+    {
+        PlayerEntity player = itemcontext.getPlayer();
+        if (CarpetSettings.creativeNoClip && player != null && player.isCreative() && player.abilities.flying)
+        {
+            // copy from canPlace
+            VoxelShape voxelShape = state.getCollisionShape(worldView, pos, context);
+            return voxelShape.isEmpty() || worldView.intersectsEntities(player, voxelShape.offset(pos.getX(), pos.getY(), pos.getZ()));
+
+        }
+        return worldView.canPlace(state, pos, context);
+    }
+}

src/main/resources/carpet.mixins.json

@@ -194,6 +194,7 @@
     "PlayerEntity_creativeNoClipMixin",
     "PistonBlockEntity_playerHandlingMixin",
     "BlockItem_creativeNoClipMixin",
+    "WallStandingBlockItem_creativeNoClipMixin",
     "LivingEntity_creativeFlyMixin"
 
   ],