From dc9c7b84fd5e1536cff86fb98f2b5c339649dcb4 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Wed, 16 Dec 2020 17:09:41 +0700
Subject: [PATCH] [java-inspections] IDEA-257106 @NotNull Parameters overriding
 non-annotated reports false positives for generic methods

GitOrigin-RevId: fe24523eaaccfef34a3b394ad29337d065f1d786
---
 .../nullable/NullableStuffInspectionBase.java | 19 +++++++++++++++++-
 .../OverrideGenericMethod.java                | 20 +++++++++++++++++++
 .../NullableStuffInspectionTest.java          |  6 ++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/inspection/nullableProblems/OverrideGenericMethod.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/nullable/NullableStuffInspectionBase.java b/java/java-analysis-impl/src/com/intellij/codeInspection/nullable/NullableStuffInspectionBase.java
index b2a8dc1acef3..bca339824bf5 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/nullable/NullableStuffInspectionBase.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/nullable/NullableStuffInspectionBase.java
@@ -30,6 +30,8 @@ import com.intellij.psi.search.searches.OverridingMethodsSearch;
 import com.intellij.psi.util.*;
 import com.intellij.util.ArrayUtilRt;
 import com.intellij.util.containers.ContainerUtil;
+import com.siyeh.ig.psiutils.ClassUtils;
+import com.siyeh.ig.psiutils.TypeUtils;
 import org.jdom.Element;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.Nls;
@@ -854,7 +856,22 @@ public class NullableStuffInspectionBase extends AbstractBaseJavaLocalInspection
     if (!REPORT_NOTNULL_PARAMETERS_OVERRIDES_NOT_ANNOTATED) return false;
     NullabilityAnnotationInfo info = nullableManager.findOwnNullabilityInfo(parameter);
     return info != null && info.getNullability() == Nullability.NOT_NULL && !info.isInferred() &&
-           ContainerUtil.exists(superParameters, sp -> !hasNullability(nullableManager, sp));
+           ContainerUtil.exists(superParameters, sp -> isSuperNotAnnotated(nullableManager, parameter, sp));
+  }
+
+  private static boolean isSuperNotAnnotated(NullableNotNullManager nullableManager, PsiParameter parameter, PsiParameter superParameter) {
+    if (hasNullability(nullableManager, superParameter)) return false;
+    PsiType type = superParameter.getType();
+    if (TypeUtils.isTypeParameter(type)) {
+      PsiClass childClass = ClassUtils.getContainingClass(parameter);
+      PsiClass superClass = ClassUtils.getContainingClass(superParameter);
+      if (superClass != null && childClass != null) {
+        PsiType substituted =
+          TypeConversionUtil.getSuperClassSubstitutor(superClass, childClass, PsiSubstitutor.EMPTY).substitute(type);
+        return DfaPsiUtil.getTypeNullability(substituted) == Nullability.UNKNOWN;
+      }
+    }
+    return true;
   }
 
   private void checkNullLiteralArgumentOfNotNullParameterUsages(PsiMethod method,
diff --git a/java/java-tests/testData/inspection/nullableProblems/OverrideGenericMethod.java b/java/java-tests/testData/inspection/nullableProblems/OverrideGenericMethod.java
new file mode 100644
index 000000000000..c301d419e6e8
--- /dev/null
+++ b/java/java-tests/testData/inspection/nullableProblems/OverrideGenericMethod.java
@@ -0,0 +1,20 @@
+import typeUse.*;
+
+class X {
+  static abstract class Base<T> {
+    abstract void consume(T item);
+  }
+
+  static class Child extends Base<@NotNull String> {
+    @Override
+    void consume(@NotNull String item) {
+      System.out.println(item);
+    }
+  }
+
+  public static void main(String[] args) {
+    Base<@NotNull String> child = new Child();
+    child.consume("this can't be null");
+    child.consume(null);
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/NullableStuffInspectionTest.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/NullableStuffInspectionTest.java
index 4df0ecf7cf25..4be16c533e3e 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/NullableStuffInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/NullableStuffInspectionTest.java
@@ -273,6 +273,12 @@ public class NullableStuffInspectionTest extends LightJavaCodeInsightFixtureTest
     DataFlowInspection8Test.setupTypeUseAnnotations("typeUse", myFixture);
     doTest();
   }
+  
+  public void testOverrideGenericMethod() {
+    myInspection.REPORT_NOTNULL_PARAMETERS_OVERRIDES_NOT_ANNOTATED = true;
+    DataFlowInspection8Test.setupTypeUseAnnotations("typeUse", myFixture);
+    doTest();
+  }
 
   public void testTypeUseNotNullOverriding() {
     myInspection.REPORT_NOTNULL_PARAMETERS_OVERRIDES_NOT_ANNOTATED = true;