IDEA-97643 don't highlight methods of @Category annotated class with 'Method may be static'

plugins/groovy/src/META-INF/plugin.xml

@@ -346,6 +346,8 @@
                            order="last"/>
     <completion.contributor language="Groovy" implementationClass="org.jetbrains.plugins.groovy.geb.GebPageFieldNameCompletionContributor"/>
 
+    <cantBeStatic implementation="org.jetbrains.plugins.groovy.codeInspection.declaration.GrCategoryMethodsCantBeStaticExtension" />
+
     <psi.referenceContributor  language="Properties" implementation="org.jetbrains.plugins.groovy.dgm.DGMReferenceContributor"/>
 
     <weigher key="completion" implementationClass="org.jetbrains.plugins.groovy.lang.completion.weighers.GrWithWeigher"

plugins/groovy/src/org/jetbrains/plugins/groovy/codeInspection/declaration/GrCategoryMethodsCantBeStaticExtension.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2000-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jetbrains.plugins.groovy.codeInspection.declaration;
+
+import com.intellij.openapi.util.Condition;
+import com.intellij.psi.PsiClass;
+import com.intellij.psi.PsiElement;
+import org.jetbrains.plugins.groovy.lang.psi.api.statements.typedef.members.GrMethod;
+import org.jetbrains.plugins.groovy.lang.psi.util.GdkMethodUtil;
+
+public class GrCategoryMethodsCantBeStaticExtension implements Condition<PsiElement> {
+  @Override
+  public boolean value(PsiElement t) {
+    if (t instanceof GrMethod) {
+      final PsiClass clazz = ((GrMethod)t).getContainingClass();
+      if (clazz != null && GdkMethodUtil.getCategoryType(clazz) != null) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+}

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/highlighting/GrInspectionTest.groovy

@@ -21,6 +21,7 @@ import org.jetbrains.plugins.groovy.codeInspection.confusing.*
 import org.jetbrains.plugins.groovy.codeInspection.control.GroovyTrivialConditionalInspection
 import org.jetbrains.plugins.groovy.codeInspection.control.GroovyTrivialIfInspection
 import org.jetbrains.plugins.groovy.codeInspection.control.GroovyUnnecessaryReturnInspection
+import org.jetbrains.plugins.groovy.codeInspection.declaration.GrMethodMayBeStaticInspection
 import org.jetbrains.plugins.groovy.codeInspection.metrics.GroovyOverlyLongMethodInspection
 import org.jetbrains.plugins.groovy.codeInspection.noReturnMethod.MissingReturnInspection
 import org.jetbrains.plugins.groovy.codeInspection.untypedUnresolvedAccess.GrUnresolvedAccessInspection
@@ -184,4 +185,20 @@ print foo+<warning descr="Access to 'bar' exceeds its access rights">bar</warnin
 
   public void testUntypedAccess() { doTest(new GroovyUntypedAccessInspection()) }
 
+  public void testMethodMayBeStaticForCategoryClasses() {
+    testHighlighting('''\
+class Cat{
+  def <warning descr="Method may be static">foo</warning>() {
+      print 2
+  }
+}
+
+@groovy.lang.Category(Cat)
+class I{
+    def foo() {
+      print 2
+    }
+}
+''', GrMethodMayBeStaticInspection)
+  }
 }