KT-16436 Incorrect primitive constants handling

Expression '1.unaryMinus()' is resolved as Int::unaryMinus call with Int receiver.
However, this expression is implicitly coerced to a different integral type (Byte, Short, Long)
based on results of constant evaluation.

Introduce IMPLICIT_INTEGER_COERCION type operator to handle such cases.

TODO: should we use it for simple constant expressions like '1' and '-1'?

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/transformations/InsertImplicitCasts.kt

@@ -93,7 +93,7 @@ class InsertImplicitCasts(val builtIns: KotlinBuiltIns): IrElementTransformerVoi
     override fun visitReturn(expression: IrReturn): IrExpression {
         expression.transformChildrenVoid(this)
 
-        expression.value = expression.value?.cast(expression.returnTarget.returnType)
+        expression.value = expression.value.cast(expression.returnTarget.returnType)
 
         return expression
     }
@@ -186,27 +186,29 @@ class InsertImplicitCasts(val builtIns: KotlinBuiltIns): IrElementTransformerVoi
 
     private fun IrExpression.cast(expectedType: KotlinType?): IrExpression {
         if (expectedType == null) return this
-
         if (expectedType.isError) return this
 
-        if (KotlinBuiltIns.isUnit(expectedType)) return coerceToUnit()
-
         val valueType = this.type
 
-        if (valueType.isNullabilityFlexible() && valueType.containsNull() && !expectedType.containsNull()) {
-            val nonNullValueType = valueType.upperIfFlexible().makeNotNullable()
-            return IrTypeOperatorCallImpl(
-                    this.startOffset, this.endOffset, nonNullValueType,
-                    IrTypeOperator.IMPLICIT_NOTNULL, nonNullValueType, this
-            ).cast(expectedType)
+        return when {
+            KotlinBuiltIns.isUnit(expectedType) ->
+                coerceToUnit()
+            valueType.isNullabilityFlexible() && valueType.containsNull() && !expectedType.containsNull() -> {
+                val nonNullValueType = valueType.upperIfFlexible().makeNotNullable()
+                IrTypeOperatorCallImpl(
+                        this.startOffset, this.endOffset, nonNullValueType,
+                        IrTypeOperator.IMPLICIT_NOTNULL, nonNullValueType, this
+                ).cast(expectedType)
+            }
+            KotlinTypeChecker.DEFAULT.isSubtypeOf(valueType.makeNotNullable(), expectedType) ->
+                this
+            KotlinBuiltIns.isInt(valueType) ->
+                IrTypeOperatorCallImpl(this.startOffset, this.endOffset, expectedType,
+                                       IrTypeOperator.IMPLICIT_INTEGER_COERCION, expectedType.makeNotNullable(), this)
+            else ->
+                IrTypeOperatorCallImpl(this.startOffset, this.endOffset, expectedType,
+                                       IrTypeOperator.IMPLICIT_CAST, expectedType, this)
         }
-
-        if (!KotlinTypeChecker.DEFAULT.isSubtypeOf(valueType.makeNotNullable(), expectedType)) {
-            return IrTypeOperatorCallImpl(this.startOffset, this.endOffset, expectedType,
-                                          IrTypeOperator.IMPLICIT_CAST, expectedType, this)
-        }
-
-        return this
     }
 
     private fun IrExpression.coerceToUnit(): IrExpression {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrTypeOperatorCall.kt

@@ -23,6 +23,7 @@ enum class IrTypeOperator {
     IMPLICIT_CAST,
     IMPLICIT_NOTNULL,
     IMPLICIT_COERCION_TO_UNIT,
+    IMPLICIT_INTEGER_COERCION,
     SAFE_CAST,
     INSTANCEOF,
     NOT_INSTANCEOF;

compiler/testData/ir/irText/expressions/primitivesImplicitConversions.kt

@@ -0,0 +1,9 @@
+fun test() {
+    val test1: Int? = 42
+    val test2: Long = 42
+    val test3: Long? = 42
+    val test4: Long? = -1
+    val test5: Long? = 1.unaryMinus()
+    val test6: Short? = 1.unaryMinus()
+    val test7: Byte? = 1.unaryMinus()
+}

compiler/testData/ir/irText/expressions/primitivesImplicitConversions.txt

@@ -0,0 +1,23 @@
+FILE /primitivesImplicitConversions.kt
+  FUN public fun test(): kotlin.Unit
+    BLOCK_BODY
+      VAR val test1: kotlin.Int? = 42
+        CONST Int type=kotlin.Int value='42'
+      VAR val test2: kotlin.Long = 42.toLong()
+        CONST Long type=kotlin.Long value='42'
+      VAR val test3: kotlin.Long? = 42.toLong()
+        CONST Long type=kotlin.Long value='42'
+      VAR val test4: kotlin.Long? = -1.toLong()
+        CONST Long type=kotlin.Long value='-1'
+      VAR val test5: kotlin.Long? = -1.toLong()
+        TYPE_OP origin=IMPLICIT_INTEGER_COERCION typeOperand=kotlin.Long
+          CALL 'unaryMinus(): Int' type=kotlin.Int origin=null
+            $this: CONST Int type=kotlin.Int value='1'
+      VAR val test6: kotlin.Short? = -1.toShort()
+        TYPE_OP origin=IMPLICIT_INTEGER_COERCION typeOperand=kotlin.Short
+          CALL 'unaryMinus(): Int' type=kotlin.Int origin=null
+            $this: CONST Int type=kotlin.Int value='1'
+      VAR val test7: kotlin.Byte? = -1.toByte()
+        TYPE_OP origin=IMPLICIT_INTEGER_COERCION typeOperand=kotlin.Byte
+          CALL 'unaryMinus(): Int' type=kotlin.Int origin=null
+            $this: CONST Int type=kotlin.Int value='1'

compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java

@@ -545,6 +545,12 @@ public class IrTextTestCaseGenerated extends AbstractIrTextTestCase {
             doTest(fileName);
         }
 
+        @TestMetadata("primitivesImplicitConversions.kt")
+        public void testPrimitivesImplicitConversions() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/primitivesImplicitConversions.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("references.kt")
         public void testReferences() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irText/expressions/references.kt");