KT-7693 Unused constructor parameter is not detected if class is constructed with named argument

#KT-7693 fixed

compiler/frontend/src/org/jetbrains/kotlin/psi/JetParameter.java

@@ -20,6 +20,7 @@ import com.intellij.lang.ASTNode;
 import com.intellij.navigation.ItemPresentation;
 import com.intellij.navigation.ItemPresentationProviders;
 import com.intellij.psi.PsiElement;
+import com.intellij.psi.search.SearchScope;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.lexer.JetTokens;
@@ -174,4 +175,17 @@ public class JetParameter extends JetNamedDeclarationStub<KotlinParameterStub> i
     public List<JetTypeParameter> getTypeParameters() {
         return Collections.emptyList();
     }
+
+    @NotNull
+    @Override
+    public SearchScope getUseScope() {
+        PsiElement parent = getParent();
+        if (parent != null) {
+            PsiElement grandparent = parent.getParent();
+            if (grandparent instanceof JetNamedFunction) {
+                return grandparent.getUseScope();
+            }
+        }
+        return super.getUseScope();
+    }
 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/findUsages/UsageTypeUtils.kt

@@ -133,6 +133,8 @@ public object UsageTypeUtils {
                 return DELEGATE
             }
 
+            if (refExpr.getParent() is JetValueArgumentName) return NAMED_ARGUMENT
+
             val dotQualifiedExpression = refExpr.getNonStrictParentOfType<JetDotQualifiedExpression>()
 
             if (dotQualifiedExpression != null) {
@@ -258,5 +260,6 @@ enum class UsageTypeEnum {
     TYPE_PARAMETER,
     CLASS_CAST_TO,
     ANNOTATION,
-    CLASS_NEW_OPERATOR
+    CLASS_NEW_OPERATOR,
+    NAMED_ARGUMENT
 }

idea/src/org/jetbrains/kotlin/idea/findUsages/JetUsageTypeProvider.kt

@@ -71,6 +71,7 @@ public object JetUsageTypeProvider : UsageTypeProviderEx {
             CLASS_CAST_TO -> UsageType.CLASS_CAST_TO
             ANNOTATION -> UsageType.ANNOTATION
             CLASS_NEW_OPERATOR -> UsageType.CLASS_NEW_OPERATOR
+            NAMED_ARGUMENT -> JetUsageTypes.NAMED_ARGUMENT
         }
     }
 }
@@ -107,4 +108,5 @@ object JetUsageTypes {
 
     // common usage types
     val CALLABLE_REFERENCE = UsageType(JetBundle.message("usageType.callable.reference"))
+    val NAMED_ARGUMENT = UsageType("Named argument")
 }

idea/src/org/jetbrains/kotlin/idea/inspections/UnusedSymbolInspection.kt

@@ -199,7 +199,7 @@ public class UnusedSymbolInspection : AbstractKotlinInspection() {
         return !query.forEach(Processor {
             assert(it != null, { "Found reference is null, was looking for: " + declaration.getElementTextWithContext() +
                                  " findAll(): " + query.findAll().map { it?.getElement()?.let{ it.getElementTextWithContext() } } })
-            declaration.isAncestor(it.getElement())
+            declaration.isAncestor(it.getElement()) || it.getElement().getParent() is JetValueArgumentName
         })
     }
 

idea/testData/findUsages/kotlin/findParameterUsages/kotlinConstructorParameterUsages.0.kt

@@ -6,4 +6,12 @@ open class A<T>(<caret>foo: T) {
     }
 
     val t: T = foo
+
+    fun usage() {
+        return A(foo = ":)")
+    }
 }
+
+fun usage() {
+    A(foo = ":)")
+}

idea/testData/findUsages/kotlin/findParameterUsages/kotlinConstructorParameterUsages.results.txt

@@ -1,2 +1,4 @@
+Named argument (11: 18) return A(foo = ":)")
+Named argument (16: 7) A(foo = ":)")
 Value read (5: 17) println(foo)
 Value read (8: 16) val t: T = foo

idea/testData/findUsages/kotlin/findParameterUsages/kotlinFunctionParameterUsages.0.kt

@@ -4,3 +4,7 @@ fun foo<T>(<caret>t: T): T {
     println(t)
     return t
 }
+
+fun usage() {
+    foo(t = ":)")
+}

idea/testData/findUsages/kotlin/findParameterUsages/kotlinFunctionParameterUsages.results.txt

@@ -1,2 +1,3 @@
+Named argument (9: 9) foo(t = ":)")
 Value read (4: 13) println(t)
 Value read (5: 12) return t

idea/testData/inspections/unusedSymbol/parameter/inspectionData/expected.xml

@@ -7,4 +7,22 @@
     <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
     <description>Property 'param' is never used</description>
   </problem>
+
+  <problem>
+    <file>paramPropertyUsedOnlyAsNamedArgument.kt</file>
+    <line>1</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/paramPropertyUsedOnlyAsNamedArgument.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
+    <description>Property 'param1' is never used</description>
+  </problem>
+
+  <problem>
+    <file>paramPropertyUsedOnlyAsNamedArgument.kt</file>
+    <line>1</line>
+    <module>light_idea_test_case</module>
+    <entry_point TYPE="file" FQNAME="temp:///src/paramPropertyUsedOnlyAsNamedArgument.kt" />
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Unused Symbol</problem_class>
+    <description>Property 'param2' is never used</description>
+  </problem>
 </problems>

idea/testData/inspections/unusedSymbol/parameter/paramPropertyUsedOnlyAsNamedArgument.kt

@@ -0,0 +1,5 @@
+class C(val param1: Int, val param2: Int)
+
+fun main(args: Array<String>) {
+    C(1, param2 = 1)
+}