Implement FFI::Pointer#clear

Author: eregon

CHANGELOG.md

@@ -11,6 +11,7 @@ Bug fixes:
 * Calling `Kernel#raise` with a raised exception will no longer set the cause of the exception to itself (#1682).
 * Return a `FFI::Function` correctly for functions returning a callback.
 * Convert to intuitive Ruby exceptions when INVOKE fails (#1690).
+* Implemented `FFI::Pointer#clear` (#1687).
 
 Compatibility
 

src/main/ruby/core/truffle/ffi/pointer.rb

@@ -86,6 +86,11 @@ def initialize_copy(from)
       self
     end
 
+    def clear
+      raise RuntimeError, 'cannot clear unbounded memory area' unless @total
+      Truffle.invoke_primitive :pointer_clear, self, @total
+    end
+
     def inspect
       # Don't have this print the data at the location. It can crash everything.
       addr = address()