Do not try to read member on proc because of the [] method

Author: pitr-ch

CHANGELOG.md

@@ -9,6 +9,7 @@ Bug fixes:
 * Fixed `Addrinfo.new(String)` to reliably find the address family (#1702).
 * Fixed argument checks in `BasicSocket#setsockopt` (#1460).
 * Fixed `ObjectSpace.trace_object_allocations` (#1456).
+* `Truffle::Interop.read(a_proc, key)` will no longer call the proc.
 
 Compatibility:
 

doc/contributor/interop.md

@@ -165,8 +165,8 @@ If the receiver is a Ruby `Array` or `Hash`, call `receiver[name/index]`.
 
 Otherwise if the name starts with an `@` it is read as an instance variable.
 
-Otherwise, if there is a method `[]` defined on the receiver, call
-`receiver[name/index]`.
+Otherwise, if there is a method `[]` defined on the receiver and the receiver 
+is not a Proc, call `receiver[name/index]`.
 
 Otherwise, if there is a method defined on the object with the same name, return
 it as a (bound) `Method`.

spec/truffle/interop/read_spec.rb

@@ -99,4 +99,15 @@
 
   end
 
+  describe "with a Proc" do
+
+    it "does not call the proc" do
+      proc = -> { raise 'called' }
+      -> { Truffle::Interop.read(proc, :key) }.should raise_error NameError
+      Truffle::Interop.read(proc, :@var).should be_nil
+      Truffle::Interop.read(proc, 'call').should == proc.method(:call)
+    end
+
+  end
+
 end

src/main/java/org/truffleruby/interop/ForeignReadStringCachedHelperNode.java

@@ -55,7 +55,7 @@ public Object readInstanceVariable(
     }
 
     @Specialization(guards = {
-            "!isRubyArray(receiver)", "!isRubyHash(receiver)", "!isIVar",
+            "!isRubyArray(receiver)", "!isRubyHash(receiver)", "!isIVar", "!isRubyProc(receiver)",
             "methodDefined(frame, receiver, INDEX_METHOD_NAME, getIndexDefinedNode())"
     })
     public Object callIndex(
@@ -70,7 +70,7 @@ public Object callIndex(
 
     @Specialization(guards = {
             "!isRubyArray(receiver)", "!isRubyHash(receiver)", "!isIVar",
-            "!methodDefined(frame, receiver, INDEX_METHOD_NAME, getIndexDefinedNode())",
+            "!methodDefined(frame, receiver, INDEX_METHOD_NAME, getIndexDefinedNode()) || isRubyProc(receiver)",
             "methodDefined(frame, receiver, stringName, getDefinedNode())"
     })
     public Object getBoundMethod(
@@ -85,7 +85,7 @@ public Object getBoundMethod(
 
     @Specialization(guards = {
             "!isRubyArray(receiver)", "!isRubyHash(receiver)", "!isIVar",
-            "!methodDefined(frame, receiver, INDEX_METHOD_NAME, getIndexDefinedNode())",
+            "!methodDefined(frame, receiver, INDEX_METHOD_NAME, getIndexDefinedNode()) || isRubyProc(receiver)",
             "!methodDefined(frame, receiver, stringName, getDefinedNode())"
     })
     public Object unknownIdentifier(