[java-inspections] IDEA-381019 Invalid local variable type inference in JSpecify mode with generic functions

GitOrigin-RevId: 4a99f16a371b9ad909500aadc14031ebcf547149

java/java-analysis-impl/src/com/intellij/codeInspection/nullable/NullableStuffInspectionBase.java

@@ -266,7 +266,7 @@ public class NullableStuffInspectionBase extends AbstractBaseJavaLocalInspection
         }
         else if (type != null) {
           PsiElement context = type instanceof PsiClassType classType ? classType.getPsiContext() : annotation;
-          if (context != null) {
+          if (context != null && !(PsiUtil.isJavaToken(context, JavaTokenType.VAR_KEYWORD))) {
             checkRedundantInContainerScope(annotation, manager.findDefaultTypeUseNullability(context), nullability);
           }
         }

java/java-psi-api/src/com/intellij/psi/PsiClassType.java

@@ -255,6 +255,7 @@ public abstract class PsiClassType extends PsiType implements JvmReferenceType {
 
   /**
    * If class-type is created from the explicit reference in the code returns that reference.
+   * If type is created from `var` keyword, return this keyword
    * @return reference which the type is created from. Returns null if not applicable.
    */
   @ApiStatus.Experimental

java/java-psi-api/src/com/intellij/util/JavaTypeNullabilityUtil.java

@@ -71,7 +71,8 @@ public final class JavaTypeNullabilityUtil {
   
   private static boolean isLocal(PsiClassType classType) {
     PsiElement context = classType.getPsiContext();
-    return context instanceof PsiJavaCodeReferenceElement &&
+    //PsiKeyword is used for `var` case
+    return (context instanceof PsiJavaCodeReferenceElement || PsiUtil.isJavaToken(context, JavaTokenType.VAR_KEYWORD)) &&
            context.getParent() instanceof PsiTypeElement &&
            context.getParent().getParent() instanceof PsiLocalVariable;
   }

java/java-psi-impl/src/com/intellij/psi/impl/source/PsiTypeElementImpl.java

@@ -89,6 +89,15 @@ public class PsiTypeElementImpl extends CompositePsiElement implements PsiTypeEl
       else if (PsiUtil.isJavaToken(child, JavaTokenType.VAR_KEYWORD)) {
         assert type == null : this;
         type = inferVarType(parent);
+        if (type instanceof PsiClassType) {
+          PsiClassType psiClassType = (PsiClassType)type;
+          PsiClassType.ClassResolveResult result = psiClassType.resolveGenerics();
+          PsiClass element = result.getElement();
+          if (element != null) {
+            type = new PsiImmediateClassType(element, result.getSubstitutor(), psiClassType.getLanguageLevel(),
+                                             psiClassType.getAnnotationProvider(), child);
+          }
+        }
       }
       else if (child instanceof PsiJavaCodeReferenceElement) {
         assert type == null : this;

java/java-tests/testData/inspection/dataFlow/fixture/JSpecifyLocalWithGenericsWithVar.java

@@ -0,0 +1,59 @@
+import org.jspecify.annotations.*;
+
+import java.util.List;
+
+@NullMarked
+class Scratch {
+  void exact(ExactFactory factory) {
+    var created = factory.create();
+    System.out.println("Created: " + created);
+    System.out.println("Created: " + created.<warning descr="Method invocation 'hashCode' may produce 'NullPointerException'">hashCode</warning>());
+  }
+
+  <T> void exact(GenericFactory<T> factory) {
+    var created = factory.create();
+    System.out.println("Created: " + created);
+    System.out.println("Created: " + created.<warning descr="Method invocation 'hashCode' may produce 'NullPointerException'">hashCode</warning>());
+  }
+
+  <T> void exact(GenericFactoryList<T> factory) {
+    for (var o : factory.createList()) {
+      if (o.<warning descr="Method invocation 'hashCode' may produce 'NullPointerException'">hashCode</warning>() == 1) {
+        System.out.println("null");
+      }
+      System.out.println("Created: " + o);
+    }
+  }
+
+  <T> void polyNullNotNull(PolyNullGenericFactory<T> factory) {
+    var created = factory.create();
+    System.out.println("Created: " + created);
+    System.out.println("Created: " + created.hashCode());
+  }
+
+  <T extends @Nullable Object> void polyNullNullable(PolyNullGenericFactory<T> factory) {
+    var created = factory.create();
+    System.out.println("Created: " + created);
+    System.out.println("Created: " + created.<warning descr="Method invocation 'hashCode' may produce 'NullPointerException'">hashCode</warning>());
+  }
+
+  @FunctionalInterface
+  interface ExactFactory {
+    @Nullable String create();
+  }
+
+  @FunctionalInterface
+  interface GenericFactory<T> {
+    @Nullable T create();
+  }
+
+  @FunctionalInterface
+  interface GenericFactoryList<T> {
+    List<@Nullable T> createList();
+  }
+
+  @FunctionalInterface
+  interface PolyNullGenericFactory<T extends @Nullable Object> {
+    T create();
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java

@@ -163,6 +163,12 @@ public class DataFlowInspection21Test extends DataFlowInspectionTestCase {
     doTest();
   }
 
+  public void testJSpecifyLocalWithGenericsWithVar() {
+    addJSpecifyNullMarked(myFixture);
+    setupTypeUseAnnotations("org.jspecify.annotations", myFixture);
+    doTest();
+  }
+
   public void testJSpecifyCallExplicitTypeParameters() {
     addJSpecifyNullMarked(myFixture);
     setupTypeUseAnnotations("org.jspecify.annotations", myFixture);