[GR-19220] Range#to_a wasn't working for long ranges (#2198)

PullRequest: truffleruby/2297

Author: eregon

CHANGELOG.md

@@ -5,6 +5,7 @@ New features:
 
 Bug fixes:
 
+* `Range#to_a` wasn't working for `long` ranges (#2198, @tomstuart and @LillianZ).
 
 Compatibility:
 

spec/ruby/core/range/to_a_spec.rb

@@ -16,6 +16,11 @@
     (0xffff...0xfffd).to_a.should == []
   end
 
+  it "works with Ranges of 64-bit integers" do
+    large = 1 << 40
+    (large..large+1).to_a.should == [1099511627776, 1099511627777]
+  end
+
   it "works with Ranges of Symbols" do
     (:A..:z).to_a.size.should == 58
   end

src/main/java/org/truffleruby/core/range/RangeNodes.java

@@ -324,6 +324,9 @@ protected Object stepFallback(VirtualFrame frame, Object range, Object step, Obj
     @CoreMethod(names = "to_a")
     public abstract static class ToANode extends CoreMethodArrayArgumentsNode {
 
+        private final BranchProfile overflow = BranchProfile.create();
+        private final ConditionProfile emptyProfile = ConditionProfile.create();
+
         @Child private DispatchNode toAInternalCall;
 
         @Specialization
@@ -337,7 +340,7 @@ protected RubyArray toA(RubyIntRange range) {
             }
             final int length = result - begin;
 
-            if (length < 0) {
+            if (emptyProfile.profile(length < 0)) {
                 return createEmptyArray();
             } else {
                 final int[] values = new int[length];
@@ -350,6 +353,39 @@ protected RubyArray toA(RubyIntRange range) {
             }
         }
 
+        @Specialization
+        protected RubyArray toA(RubyLongRange range) {
+            final long begin = range.begin;
+            long result;
+            if (range.excludedEnd) {
+                result = range.end;
+            } else {
+                result = range.end + 1;
+            }
+
+            final int length;
+            try {
+                length = Math.toIntExact(result - begin);
+            } catch (ArithmeticException e) {
+                overflow.enter();
+                throw new RaiseException(
+                        getContext(),
+                        coreExceptions().rangeError("long too big to convert into `int'", this));
+            }
+
+            if (emptyProfile.profile(length < 0)) {
+                return createEmptyArray();
+            } else {
+                final long[] values = new long[length];
+
+                for (int n = 0; n < length; n++) {
+                    values[n] = begin + n;
+                }
+
+                return createArray(values);
+            }
+        }
+
         @Specialization(guards = "range.isBounded()")
         protected Object boundedToA(RubyObjectRange range) {
             if (toAInternalCall == null) {