Lower priority for extensions on own type parameters

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/CompletionUtils.kt

@@ -135,6 +135,7 @@ enum class CallableWeight {
     thisTypeExtension,
     baseTypeExtension,
     globalOrStatic, // global non-extension
+    typeParameterExtension,
     receiverCastRequired
 }
 

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/LookupElementFactory.kt

@@ -334,12 +334,19 @@ public class LookupElementFactory(
 
         val receiverParameter = descriptor.extensionReceiverParameter ?: descriptor.dispatchReceiverParameter
         if (receiverParameter != null) {
-            return if (receiverTypes.any { TypeUtils.equalTypes(it, receiverParameter.type) })
-                if (descriptor.isExtension) CallableWeight.thisTypeExtension else CallableWeight.thisClassMember
-            else if (receiverTypes.any { it.isSubtypeOf(receiverParameter.type) })
+            return if (receiverTypes.any { TypeUtils.equalTypes(it, receiverParameter.type) }) {
+                when {
+                    descriptor.isExtensionForTypeParameter() -> CallableWeight.typeParameterExtension
+                    descriptor.isExtension -> CallableWeight.thisTypeExtension
+                    else -> CallableWeight.thisClassMember
+                }
+            }
+            else if (receiverTypes.any { it.isSubtypeOf(receiverParameter.type) }) {
                 if (descriptor.isExtension) CallableWeight.baseTypeExtension else CallableWeight.baseClassMember
-            else
+            }
+            else {
                 CallableWeight.receiverCastRequired
+            }
         }
 
         return when (descriptor.containingDeclaration) {
@@ -348,6 +355,12 @@ public class LookupElementFactory(
         }
     }
 
+    private fun CallableDescriptor.isExtensionForTypeParameter(): Boolean {
+        val receiverParameter = original.extensionReceiverParameter ?: return false
+        val typeParameter = receiverParameter.type.constructor.declarationDescriptor as? TypeParameterDescriptor ?: return false
+        return typeParameter.containingDeclaration == original
+    }
+
     companion object {
         public fun getDefaultInsertHandler(descriptor: DeclarationDescriptor): InsertHandler<LookupElement> {
             return when (descriptor) {

idea/idea-completion/testData/basic/common/NonPredictableSmartCast.kt

@@ -12,4 +12,4 @@ fun f(pair: Pair<out Any, out Any>) {
 // EXIST: { lookupString: "hashCode", attributes: "bold" }
 // EXIST: { lookupString: "forString", attributes: "grayed" }
 // EXIST: { lookupString: "forAny", attributes: "bold" }
-// EXIST: { lookupString: "forT", attributes: "bold" }
+// EXIST: { lookupString: "forT", attributes: "" }

idea/idea-completion/testData/basic/common/immediateMembers/ImmediateExtensionMembersGeneric.kt

@@ -0,0 +1,11 @@
+fun <T> List<T>.forListT(){}
+fun <T> Collection<T>.forCollectionT(){}
+fun <T> T.forT() {}
+
+fun foo(list: List<String>) {
+    list.<caret>
+}
+
+// EXIST: { itemText: "forListT", attributes: "bold" }
+// EXIST: { itemText: "forCollectionT", attributes: "" }
+// EXIST: { itemText: "forT", attributes: "" }

idea/idea-completion/testData/weighers/basic/Callables.kt

@@ -18,12 +18,14 @@ class Derived : Base() {
     }
 }
 
-fun Any.aAnyExtensionFun(){}
+fun Any.aaAnyExtensionFun(){}
 fun Derived.aaExtensionFun(){}
 
-val Any.aAnyExtensionProp: Int get() = 1
+val Any.aaAnyExtensionProp: Int get() = 1
 val Derived.aaExtensionProp: Int get() = 1
 
+fun <T> T.aaTypeParamExt(){}
+
 // ORDER: aaLocalVal
 // ORDER: aaLocalFun
 // ORDER: aaDerivedProp
@@ -32,7 +34,8 @@ val Derived.aaExtensionProp: Int get() = 1
 // ORDER: aaBaseFun
 // ORDER: aaExtensionProp
 // ORDER: aaExtensionFun
-// ORDER: aAnyExtensionProp
-// ORDER: aAnyExtensionFun
+// ORDER: aaAnyExtensionProp
+// ORDER: aaAnyExtensionFun
 // ORDER: aaGlobalProp
 // ORDER: aaGlobalFun
+// ORDER: aaTypeParamExt

idea/idea-completion/testData/weighers/smart/SmartPriority.kt

@@ -16,8 +16,8 @@ class C {
 // ORDER: "pFoo, s"
 // ORDER: this
 // ORDER: local
-// ORDER: apply
 // ORDER: nonNullable
+// ORDER: apply
 // ORDER: nullableX
 // ORDER: nullableX
 // ORDER: C

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JSBasicCompletionTestGenerated.java

@@ -1425,6 +1425,12 @@ public class JSBasicCompletionTestGenerated extends AbstractJSBasicCompletionTes
                 doTest(fileName);
             }
 
+            @TestMetadata("ImmediateExtensionMembersGeneric.kt")
+            public void testImmediateExtensionMembersGeneric() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/immediateMembers/ImmediateExtensionMembersGeneric.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("ImmediateMembers1.kt")
             public void testImmediateMembers1() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/immediateMembers/ImmediateMembers1.kt");

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/JvmBasicCompletionTestGenerated.java

@@ -1425,6 +1425,12 @@ public class JvmBasicCompletionTestGenerated extends AbstractJvmBasicCompletionT
                 doTest(fileName);
             }
 
+            @TestMetadata("ImmediateExtensionMembersGeneric.kt")
+            public void testImmediateExtensionMembersGeneric() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/immediateMembers/ImmediateExtensionMembersGeneric.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("ImmediateMembers1.kt")
             public void testImmediateMembers1() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("idea/idea-completion/testData/basic/common/immediateMembers/ImmediateMembers1.kt");