Make not-null compile-time constants non-flexible

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/structure/impl/JavaPropertyInitializerEvaluatorImpl.java

@@ -18,6 +18,7 @@ package org.jetbrains.jet.lang.resolve.java.structure.impl;
 
 import com.intellij.psi.PsiExpression;
 import com.intellij.psi.impl.JavaConstantExpressionEvaluator;
+import com.intellij.psi.util.PsiUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.PropertyDescriptor;
@@ -43,4 +44,11 @@ public class JavaPropertyInitializerEvaluatorImpl implements JavaPropertyInitial
         }
         return null;
     }
+
+    @Override
+    public boolean isNotNullCompileTimeConstant(@NotNull JavaField field) {
+        // PsiUtil.isCompileTimeConstant returns false for null-initialized fields,
+        // see com.intellij.psi.util.IsConstantExpressionVisitor.visitLiteralExpression()
+        return PsiUtil.isCompileTimeConstant(((JavaFieldImpl) field).getPsi());
+    }
 }

core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/descriptors/LazyJavaMemberScope.kt

@@ -287,10 +287,18 @@ public abstract class LazyJavaMemberScope(
 
     private fun getPropertyType(field: JavaField): JetType {
         // Fields do not have their own generic parameters
-        val propertyType = c.typeResolver.transformJavaType(field.getType(), LazyJavaTypeAttributes(c, field, TypeUsage.MEMBER_SIGNATURE_INVARIANT))
-        if (!PLATFORM_TYPES && field.isFinal() && field.isStatic()) {
+        val finalStatic = field.isFinal() && field.isStatic()
+
+        // simple static constants should not have flexible types:
+        val allowFlexible = PLATFORM_TYPES && !(finalStatic && c.javaPropertyInitializerEvaluator.isNotNullCompileTimeConstant(field))
+        val propertyType = c.typeResolver.transformJavaType(
+                field.getType(),
+                LazyJavaTypeAttributes(c, field, TypeUsage.MEMBER_SIGNATURE_INVARIANT, allowFlexible)
+        )
+        if ((!allowFlexible || !PLATFORM_TYPES) && finalStatic) {
             return TypeUtils.makeNotNullable(propertyType)
         }
+
         return propertyType
     }
 

core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/structure/JavaPropertyInitializerEvaluator.java

@@ -24,4 +24,6 @@ import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
 public interface JavaPropertyInitializerEvaluator {
     @Nullable
     CompileTimeConstant<?> getInitializerConstant(@NotNull JavaField field, @NotNull PropertyDescriptor descriptor);
+
+    boolean isNotNullCompileTimeConstant(@NotNull JavaField field);
 }