Reporting unnecessary safe calls on Java's @NotNull values

compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmCheckerProvider.kt

@@ -201,11 +201,12 @@ public class JavaNullabilityWarningsChecker : AdditionalTypeChecker {
             safeAccess: Boolean,
             c: CallResolutionContext<*>
     ) {
+        val dataFlowValue = DataFlowValueFactory.createDataFlowValue(receiverArgument, c.trace.getBindingContext())
         if (!safeAccess) {
             doCheckType(
                     receiverArgument.getType(),
                     receiverParameter.getType(),
-                    DataFlowValueFactory.createDataFlowValue(receiverArgument, c.trace.getBindingContext()),
+                    dataFlowValue,
                     c.dataFlowInfo
             ) {
                 expectedMustNotBeNull,
@@ -222,5 +223,12 @@ public class JavaNullabilityWarningsChecker : AdditionalTypeChecker {
 
             }
         }
+        else {
+            if (c.dataFlowInfo.getNullability(dataFlowValue).canBeNull()
+                && receiverArgument.getType().mustNotBeNull() == NullabilityInformationSource.JAVA) {
+                c.trace.report(Errors.UNNECESSARY_SAFE_CALL.on(c.call.getCallOperationNode().getPsi(), receiverArgument.getType()))
+
+            }
+        }
     }
 }

compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.kt

@@ -0,0 +1,44 @@
+// FILE: p/J.java
+package p;
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+
+    public void foo() {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    platformN?.foo()
+    platformJ?.foo()
+
+    if (platformNN != null) {
+        platformNN<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    }
+
+    if (platformN != null) {
+        platformN<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    }
+
+    if (platformJ != null) {
+        platformJ<!UNNECESSARY_SAFE_CALL!>?.<!>foo()
+    }
+}
+

compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun test(): kotlin.Unit

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -8640,6 +8640,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("safeCall.kt")
+                public void testSafeCall() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("throw.kt")
                 public void testThrow() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/throw.kt");