KT-944 iterations over empty ranges

compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -536,7 +536,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> {
                 gen(expression.getLoopRange(), loopRangeType);
                 v.dup();
 
-                v.invokevirtual("jet/IntRange", "getStart", "()I");
+                v.invokevirtual("jet/IntRange", "getIteratorStart", "()I");
                 v.store(lookupLocal(parameterDescriptor), Type.INT_TYPE);
                 v.invokevirtual("jet/IntRange", "getEnd", "()I");
                 v.store(myEndVar, Type.INT_TYPE);

compiler/frontend/src/jet/Ranges.jet

@@ -11,6 +11,8 @@ class IntRange(val start : Int, val size : Int) : Range<Int>, IntIterable {
 
     val end : Int
 
+    val iteratorStart : Int
+
     fun minus() : IntRange
 
     fun step(step: Int) : IntIterator
@@ -23,6 +25,8 @@ class LongRange(val start : Long, val size : Long) : Range<Long>, LongIterable {
 
     fun contains (elem: Long) : Boolean
 
+    val iteratorStart : Long
+
     val end : Long
 
     fun minus() : LongRange
@@ -39,6 +43,8 @@ class ByteRange(val start : Byte, val size : Int) : Range<Byte>, ByteIterable {
 
     val end : Byte
 
+    val iteratorStart : Byte
+
     fun minus() : ByteRange
 
     fun step(step: Int) : ByteIterator
@@ -51,6 +57,8 @@ class ShortRange(val start : Short, val size : Int) : Range<Short>, ShortIterabl
 
     fun contains (elem: Byte) : Boolean
 
+    val iteratorStart : Short
+
     val end : Short
 
     fun minus() : ShortRange
@@ -65,6 +73,8 @@ class CharRange(val start : Char, val size : Int) : Range<Char>, CharIterable {
 
     fun contains (elem: Char) : Boolean
 
+    val iteratorStart : Char
+
     val end : Char
 
     fun minus() : CharRange

compiler/testData/codegen/regressions/kt944.kt

@@ -0,0 +1,8 @@
+fun box() : String {
+  for (i in "".indices) {
+      ""[i]
+  }
+  return "OK"
+}
+
+val String?.indices : IntRange get() = IntRange(0, this.sure().length)

compiler/tests/org/jetbrains/jet/codegen/PrimitiveTypesTest.java

@@ -379,4 +379,8 @@ public class PrimitiveTypesTest extends CodegenTestCase {
     public void testKt930 () {
         blackBoxFile("regressions/kt930.kt");
     }
+
+    public void testKt944 () {
+        blackBoxFile("regressions/kt944.kt");
+    }
 }

stdlib/src/jet/ByteRange.java

@@ -30,6 +30,10 @@ public final class ByteRange implements Range<Byte>, ByteIterable, JetObject {
         return start;
     }
 
+    public byte getIteratorStart () {
+        return count == 0 ? 1 : start;
+    }
+
     public byte getEnd() {
         return (byte) (count < 0 ? start + count + 1: count == 0 ? 0 : start+count-1);
     }

stdlib/src/jet/CharRange.java

@@ -30,6 +30,10 @@ public final class CharRange implements Range<Character>, CharIterable, JetObjec
         return start;
     }
 
+    public char getIteratorStart () {
+        return count == 0 ? 1 : start;
+    }
+
     public char getEnd() {
         return (char) (count < 0 ? start + count + 1: count == 0 ? 0 : start+count-1);
     }

stdlib/src/jet/IntRange.java

@@ -33,6 +33,10 @@ public final class IntRange implements Range<Integer>, IntIterable, JetObject {
         return count < 0;
     }
 
+    public int getIteratorStart () {
+        return count == 0 ? 1 : start;
+    }
+    
     public int getStart() {
         return start;
     }

stdlib/src/jet/LongRange.java

@@ -37,6 +37,10 @@ public final class LongRange implements Range<Long>, LongIterable, JetObject {
         return start;
     }
 
+    public long getIteratorStart () {
+        return count == 0 ? 1 : start;
+    }
+
     public long getEnd() {
         return count < 0 ? start + count + 1: count == 0 ? 0 : start+count-1;
     }

stdlib/src/jet/ShortRange.java

@@ -37,6 +37,10 @@ public final class ShortRange implements Range<Short>, ShortIterable, JetObject
         return start;
     }
 
+    public int getIteratorStart () {
+        return count == 0 ? 1 : start;
+    }
+
     public short getEnd() {
         return (short) (count < 0 ? start + count + 1: count == 0 ? 0 : start+count-1);
     }