[GR-18163] Pointer#read_pointer should return a pointer with #type_size 1

PullRequest: truffleruby/4528

Author: eregon

CHANGELOG.md

@@ -20,6 +20,7 @@ Compatibility:
 * Joni has been updated from 2.2.1 to 2.2.6 (@andrykonchin).
 * Fix numeric coercing when `#coerce` method is not public (#3848, @andrykonchin).
 * Fix `Kernel#raise` and don't override `cause` at exception re-raising (#3831, @andrykonchin).
+* Return a pointer with `#type_size` of 1 for `Pointer#read_pointer` (@eregon).
 
 Performance:
 

spec/ffi/pointer_spec.rb

@@ -84,6 +84,16 @@ def to_ptr
       expect(memory.read_pointer.address).to eq(0xdeadbeef)
     end
 
+    it "#read_pointer returns a pointer with #type_size 1" do
+      memory = FFI::MemoryPointer.new :pointer
+      expect(memory.read_pointer.type_size).to eq(1)
+    end
+
+    it "#get_pointer returns a pointer with #type_size 1" do
+      memory = FFI::MemoryPointer.new :pointer
+      expect(memory.get_pointer(0).type_size).to eq(1)
+    end
+
     it "#write_pointer" do
       memory = FFI::MemoryPointer.new :pointer
       memory.write_pointer(PointerTestLib.ptr_from_address(0xdeadbeef))
@@ -106,6 +116,7 @@ def to_ptr
       array = memory.read_array_of_pointer(values.size)
       values.each_with_index do |address, j|
         expect(array[j].address).to eq(address)
+        expect(array[j].type_size).to eq(1)
       end
     end
 

src/main/java/org/truffleruby/extra/ffi/PointerNodes.java

@@ -47,6 +47,7 @@
 import com.oracle.truffle.api.dsl.ImportStatic;
 import com.oracle.truffle.api.dsl.Specialization;
 import org.truffleruby.language.objects.AllocationTracing;
+import org.truffleruby.language.objects.WriteObjectFieldNode;
 
 @CoreModule(value = "Truffle::FFI::Pointer", isClass = true)
 public abstract class PointerNodes {
@@ -503,7 +504,8 @@ public abstract static class PointerReadPointerNode extends PrimitiveArrayArgume
 
         @Specialization
         RubyPointer readPointer(long address,
-                @Cached CheckNullPointerNode checkNullPointerNode) {
+                @Cached CheckNullPointerNode checkNullPointerNode,
+                @Cached WriteObjectFieldNode writeTypeSize) {
             final Pointer ptr = new Pointer(getContext(), address);
             checkNullPointerNode.execute(this, ptr);
             final Pointer readPointer = ptr.readPointer(getContext(), 0);
@@ -512,6 +514,10 @@ RubyPointer readPointer(long address,
                     getLanguage().truffleFFIPointerShape,
                     readPointer);
             AllocationTracing.trace(instance, this);
+
+            // We don't call Truffle::FFI::Pointer#initialize so we manually set it instead
+            writeTypeSize.execute(this, instance, "@type_size", 1);
+
             return instance;
         }