KT-2962 auto completion support for extension functions

#KT-2962 Fixed

idea/testData/completion/basic/ExtensionWithAdditionalTypeParameters.kt

@@ -0,0 +1,14 @@
+open class Base
+
+class Test
+fun <T> Test.extensionEmpty(param: T) = "Test"
+fun <T: Base> Test.extensionBase(param: T) = "Test"
+fun <T: Base, P> Test.extensionTwo(param: T) = "Test"
+
+fun some() {
+    Test().ex<caret>
+}
+
+// EXIST: extensionEmpty
+// EXIST: extensionBase
+// EXIST: extensionTwo

idea/testData/completion/basic/ExtensionWithGenericParamInReceiver.kt

@@ -0,0 +1,14 @@
+open class Base
+open class OtherBase
+
+class Some<T>
+fun <TSome : Base, R : Base> Some<TSome>.extensionBase(param: R) = "Test"
+fun <TSome : OtherBase, R : OtherBase> Some<TSome>.extensionOtherBase(param: R) = "Test"
+fun <TSome> Some<TSome>.extensionExact() = "Test"
+
+fun test() {
+    Some<Base>().ex<caret>
+}
+
+// EXIST: extensionBase, extensionExact
+// ABSENT: extensionOtherBase

idea/testData/completion/basic/ExtensionWithGenericReceiver.kt

@@ -0,0 +1,22 @@
+open class Base
+open class SubBase:Base()
+open class SubSubBase:SubBase()
+open class OtherBase
+
+fun <T: Base> T.extensionSomeBase() = 12
+fun <T: SubBase> T.extensionSomeSubBase() = 12
+fun <T: SubSubBase> T.extensionSomeSubSubBase() = 12
+fun <T: Base> T?.extensionSomeNull() = 12
+fun <T: Base?> T.extensionSomeNullParam() = 12
+fun <T: OtherBase> T.extensionSomeOtherBase() = 12
+
+fun some() {
+    SubBase().extensionSome<caret>
+}
+
+// EXIST: extensionSomeBase
+// EXIST: extensionSomeSubBase
+// EXIST: extensionSomeNull
+// EXIST: extensionSomeNullParam
+// ABSENT: extensionSomeOtherBase
+// ABSENT: extensionSomeSubSubBase

idea/testData/completion/basic/ExtensionWithInternalGenericParameters.kt

@@ -0,0 +1,11 @@
+import java.util.HashSet
+
+open class Base
+
+fun <T: Base> Set<List<T>>.extensionInternal() = 12
+
+fun some() {
+    HashSet<List<Base>>().ex<caret>
+}
+
+// EXIST: extensionInternal

idea/testData/completion/basic/ExtensionWithManyTypeParamsInReceiver.kt

@@ -0,0 +1,18 @@
+open class Base
+
+class ManySome<T, U>
+fun <P1, P2>ManySome<P1, P2>.testExactGeneralGeneral() = "Some"
+fun <P1, P2>ManySome<P1, Int>.testExactGeneralInt() = "Some"
+fun <P1, P2>ManySome<Int, Int>.testExactIntInt() = "Some"
+fun <P1 : Base, P2>ManySome<P1, Int>.testSubBaseIntInt() = "Some"
+fun <P1, P2, P3>ManySome<P1, P2>.testManyGeneralGeneral() = "Some"
+
+fun some() {
+    ManySome<Int, Int>().test<caret>
+}
+
+// EXIST: testExactGeneralGeneral
+// EXIST: testExactGeneralInt
+// EXIST: testExactIntInt
+// EXIST: testManyGeneralGeneral
+// ABSENT: testSubBaseIntInt