ObviousNullCheck: defer resolve; isVoidContext

java/java-impl/src/com/intellij/codeInspection/ObviousNullCheckInspection.java

@@ -30,10 +30,13 @@ public class ObviousNullCheckInspection extends AbstractBaseJavaLocalInspectionT
     return new JavaElementVisitor() {
       @Override
       public void visitMethodCallExpression(PsiMethodCallExpression call) {
+        PsiExpression[] args = call.getArgumentList().getExpressions();
+        // Avoid method resolve if no argument is a candidate for obvious non-null warning
+        // (checking this is easier than resolving and calls without arguments are excluded at all)
+        if (!ContainerUtil.exists(args, arg -> getObviouslyNonNullExplanation(PsiUtil.skipParenthesizedExprDown(arg)) != null)) return;
         NullCheckParameter nullCheckParameter = NullCheckParameter.fromCall(call);
         if (nullCheckParameter == null) return;
-        if (!(call.getParent() instanceof PsiExpressionStatement || nullCheckParameter.myReturnsParameter)) return;
-        PsiExpression[] args = call.getArgumentList().getExpressions();
+        if (!ExpressionUtils.isVoidContext(call) && !nullCheckParameter.myReturnsParameter) return;
         if (args.length <= nullCheckParameter.myIndex) return;
         PsiExpression nullArg = PsiUtil.skipParenthesizedExprDown(args[nullCheckParameter.myIndex]);
         String explanation = getObviouslyNonNullExplanation(nullArg);

java/java-tests/testData/inspection/obviousNotNull/ObviousNullCheck.java

@@ -24,6 +24,16 @@ abstract class ObviousNullCheck {
     System.out.println(inferred(<warning descr="Redundant null-check: literal is never null">"foo"</warning>));
   }
 
+  static String concat(String s, String m) {
+    if(s == null) throw new NullPointerException();
+    return s+m;
+  }
+
+  void testStrings(List<String> list) {
+    list.forEach(s -> concat(<warning descr="Redundant null-check: literal is never null">"Not null!"</warning>, s));
+    list.stream().map(s -> concat("Not null!", s)).forEach(System.out::println);
+  }
+
   @Contract(value="null -> fail", pure=true)
   String trim(String s) {
     return s.trim();