Postpone conversions from signed constants to unsigned ones

#KT-26071 Fixed

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -911,6 +911,7 @@ public interface Errors {
     DiagnosticFactory1<KtConstantExpression, KotlinType> NULL_FOR_NONNULL_TYPE = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory0<KtEscapeStringTemplateEntry> ILLEGAL_ESCAPE_SEQUENCE = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<KtConstantExpression> UNSIGNED_LITERAL_WITHOUT_DECLARATIONS_ON_CLASSPATH = DiagnosticFactory0.create(ERROR);
+    DiagnosticFactory0<KtExpression> SIGNED_CONSTANT_CONVERTED_TO_UNSIGNED = DiagnosticFactory0.create(ERROR);
 
 
     // Casts and is-checks

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -388,6 +388,7 @@ public class DefaultErrorMessages {
         MAP.put(NOT_A_CLASS, "Not a class");
         MAP.put(ILLEGAL_ESCAPE_SEQUENCE, "Illegal escape sequence");
         MAP.put(UNSIGNED_LITERAL_WITHOUT_DECLARATIONS_ON_CLASSPATH, "Type of the constant expression cannot be resolved. Please make sure you have the required dependencies for unsigned types in the classpath");
+        MAP.put(SIGNED_CONSTANT_CONVERTED_TO_UNSIGNED, "Conversion of signed constants to unsigned ones is prohibited");
 
         MAP.put(RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS, "Left-hand side of callable reference matches expression syntax reserved for future releases");
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CallCompleter.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
+import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.*
 import org.jetbrains.kotlin.resolve.BindingContext.CONSTRAINT_SYSTEM_COMPLETER
@@ -321,10 +322,15 @@ class CallCompleter(
 
         val results = completeCallForArgument(deparenthesized, context)
 
+        val constant = context.trace[BindingContext.COMPILE_TIME_VALUE, deparenthesized]
+        val convertedConst = constant is IntegerValueTypeConstant && constant.convertedFromSigned
+        if (convertedConst) {
+            context.trace.report(Errors.SIGNED_CONSTANT_CONVERTED_TO_UNSIGNED.on(deparenthesized))
+        }
+
         if (results != null && results.isSingleResult) {
             val resolvedCall = results.resultingCall
-            val constant = context.trace[BindingContext.COMPILE_TIME_VALUE, deparenthesized]
-            if (constant !is IntegerValueTypeConstant || !constant.convertedFromSigned) {
+            if (!convertedConst) {
                 updatedType =
                         if (resolvedCall.hasInferredReturnType())
                             resolvedCall.makeNullableTypeIfSafeReceiver(resolvedCall.resultingDescriptor?.returnType, context)