FIR/UAST: resolve implicit lambda parameter

^KTIJ-18800 Fixed

plugins/kotlin/uast/uast-kotlin-base/test/org/jetbrains/uast/test/common/kotlin/UastResolveApiFixtureTestBase.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.idea.test.KotlinLightCodeInsightFixtureTestCaseBase
 import org.jetbrains.kotlin.idea.test.KotlinLightCodeInsightFixtureTestCaseBase.assertContainsElements
 import org.jetbrains.kotlin.idea.test.KotlinLightCodeInsightFixtureTestCaseBase.assertDoesntContain
 import org.jetbrains.kotlin.psi.KtConstructor
+import org.jetbrains.kotlin.psi.KtParameter
 import org.jetbrains.kotlin.utils.addToStdlib.cast
 import org.jetbrains.uast.*
 import org.jetbrains.uast.kotlin.KotlinUFunctionCallExpression
@@ -380,6 +381,52 @@ interface UastResolveApiFixtureTestBase : UastPluginSelection {
         TestCase.assertEquals("message", resolved.name)
     }
 
+    fun checkResolveExplicitLambdaParameter(myFixture: JavaCodeInsightTestFixture) {
+        myFixture.configureByText(
+            "main.kt", """
+                inline fun <T, R> T.use(block: (T) -> R): R {
+                  return block(this)
+                }
+                
+                fun foo() {
+                  42.use { it ->
+                    i<caret>t.toString()
+                  }
+                }
+            """.trimIndent()
+        )
+
+        val uCallExpression = myFixture.file.findElementAt(myFixture.caretOffset).toUElement().getUCallExpression()
+            .orFail("cant convert to UCallExpression")
+        TestCase.assertEquals("it", (uCallExpression.receiver as? USimpleNameReferenceExpression)?.identifier)
+        // Expect to be resolved to source KtParameter
+        val resolved = (uCallExpression.receiver?.tryResolve() as? KtParameter)
+            .orFail("cant resolve explicit lambda parameter")
+        TestCase.assertEquals("it", resolved.name)
+    }
+
+    fun checkResolveImplicitLambdaParameter(myFixture: JavaCodeInsightTestFixture) {
+        myFixture.configureByText(
+            "main.kt", """
+                inline fun <T, R> T.use(block: (T) -> R): R {
+                  return block(this)
+                }
+                
+                fun foo() {
+                  42.use { i<caret>t.toString() }
+                }
+            """.trimIndent()
+        )
+
+        val uCallExpression = myFixture.file.findElementAt(myFixture.caretOffset).toUElement().getUCallExpression()
+            .orFail("cant convert to UCallExpression")
+        TestCase.assertEquals("it", (uCallExpression.receiver as? USimpleNameReferenceExpression)?.identifier)
+        // No source for implicit lambda parameter. Expect to be resolved to fake PsiParameter used inside ULambdaExpression
+        val resolved = (uCallExpression.receiver?.tryResolve() as? PsiParameter)
+            .orFail("cant resolve implicit lambda parameter")
+        TestCase.assertEquals("it", resolved.name)
+    }
+
     fun checkResolveSyntheticMethod(myFixture: JavaCodeInsightTestFixture) {
         myFixture.configureByText(
             "MyClass.kt", """

plugins/kotlin/uast/uast-kotlin-fir/src/org/jetbrains/uast/kotlin/FirKotlinUastResolveProviderService.kt

@@ -358,6 +358,15 @@ interface FirKotlinUastResolveProviderService : BaseKotlinUastResolveProviderSer
                     )?.let { return it }
                 }
             }
+            is KtFunctionLiteral -> {
+                // Implicit lambda parameter `it`
+                if ((resolvedTargetSymbol as? KtValueParameterSymbol)?.isImplicitLambdaParameter == true) {
+                    // From its containing lambda (of function literal), build ULambdaExpression
+                    val lambda = resolvedTargetElement.toUElementOfType<ULambdaExpression>()
+                    // and return javaPsi of the corresponding lambda implicit parameter
+                    lambda?.valueParameters?.singleOrNull()?.javaPsi?.let { return it }
+                }
+            }
         }
 
         // TODO: need to handle resolved target to library source

plugins/kotlin/uast/uast-kotlin-fir/test/org/jetbrains/kotlin/idea/fir/uast/FirUastResolveApiFixtureTest.kt

@@ -117,6 +117,14 @@ class FirUastResolveApiFixtureTest : KotlinLightCodeInsightFixtureTestCase(), Ua
         doCheck("ResolveCompiledAnnotation", ::checkResolveCompiledAnnotation)
     }
 
+    fun testResolveExplicitLambdaParameter() {
+        doCheck("ResolveExplicitLambdaParameter", ::checkResolveExplicitLambdaParameter)
+    }
+
+    fun testResolveImplicitLambdaParameter() {
+        doCheck("ResolveImplicitLambdaParameter", ::checkResolveImplicitLambdaParameter)
+    }
+
     fun testResolveSyntheticMethod() {
         doCheck("ResolveSyntheticMethod", ::checkResolveSyntheticMethod)
     }

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaExpressionFunctionalInterfaceType.resolved.fe10.txt

@@ -10,5 +10,5 @@ UBlockExpression -> UQualifiedReferenceExpression -> Decompiled_Method: map
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 2))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = of) -> Decompiled_Method: of
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = map) -> Decompiled_Method: map
         UReturnExpression -> UQualifiedReferenceExpression -> Decompiled_Method: toString
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = toString) -> Decompiled_Method: toString

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaExpressionFunctionalInterfaceType.resolved.fir.txt

@@ -10,5 +10,5 @@ UBlockExpression -> UQualifiedReferenceExpression -> Decompiled_Method: map
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 2))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = of) -> Decompiled_Method: of
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = map) -> Decompiled_Method: map
         UReturnExpression -> UQualifiedReferenceExpression -> null: null
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = toString) -> FUN: toString

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaParameters.resolved.fe10.txt

@@ -2,4 +2,4 @@ UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolve
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = append) -> Decompiled_Method: append
     UBlockExpression -> UQualifiedReferenceExpression -> Decompiled_Method: let
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = let) -> Decompiled_Method: let
-        UReturnExpression -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UReturnExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaParameters.resolved.fir.txt

@@ -2,4 +2,4 @@ UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolve
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = append) -> Decompiled_Method: append
     UBlockExpression -> UQualifiedReferenceExpression -> null: null
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to null) -> USimpleNameReferenceExpression (identifier = let) -> FUN: let
-        UReturnExpression -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UReturnExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaReturn.resolved.fe10.txt

@@ -34,9 +34,9 @@ UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = ko
     UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = +) -> Kotlin_Light_Method: plus
     UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = a) -> VALUE_PARAMETER: a
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Kotlin_Light_Method) -> USimpleNameReferenceExpression (identifier = bar) -> Kotlin_Light_Method: bar
-        UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = >) -> null: null
-        UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = +) -> null: null
         UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = b) -> Kotlin_Light_Variable: b
     UTypeReferenceExpression (name = kotlin.Unit) -> USimpleNameReferenceExpression (identifier = Unit) -> Decompiled_Class: Unit

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/LambdaReturn.resolved.fir.txt

@@ -34,9 +34,9 @@ UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = ko
     UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = +) -> FUN: plus
     UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = a) -> VALUE_PARAMETER: a
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Kotlin_Light_Method) -> USimpleNameReferenceExpression (identifier = bar) -> Kotlin_Light_Method: bar
-        UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UBinaryExpression (operator = >) -> USimpleNameReferenceExpression (identifier = >) -> FUN: compareTo
-        UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = +) -> FUN: plus
         UBinaryExpression (operator = +) -> USimpleNameReferenceExpression (identifier = b) -> Kotlin_Light_Variable: b
     UTypeReferenceExpression (name = kotlin.Unit) -> USimpleNameReferenceExpression (identifier = Unit) -> Decompiled_Class: Unit

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/Lambdas.resolved.fe10.txt

@@ -12,7 +12,7 @@ UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = St
     UTypeReferenceExpression (name = java.lang.String) -> USimpleNameReferenceExpression (identifier = String) -> Decompiled_Class: String
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = filter) -> Decompiled_Method: filter
         UReturnExpression -> UQualifiedReferenceExpression -> Decompiled_Method: isEmpty
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = isEmpty) -> Decompiled_Method: isEmpty
 UTypeReferenceExpression (name = kotlin.Unit) -> USimpleNameReferenceExpression (identifier = Unit) -> Decompiled_Class: Unit
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = selectItemFunction) -> Kotlin_Light_Value_Parameter: selectItemFunction

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/Lambdas.resolved.fir.txt

@@ -12,7 +12,7 @@ UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = St
     UTypeReferenceExpression (name = java.lang.String) -> USimpleNameReferenceExpression (identifier = String) -> null: null
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = filter) -> Decompiled_Method: filter
         UReturnExpression -> UQualifiedReferenceExpression -> null: null
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = isEmpty) -> FUN: isEmpty
 UTypeReferenceExpression (name = kotlin.Unit) -> USimpleNameReferenceExpression (identifier = Unit) -> Decompiled_Class: Unit
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = selectItemFunction) -> Kotlin_Light_Value_Parameter: selectItemFunction

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/Resolve.resolved.fe10.txt

@@ -24,7 +24,7 @@ UBlockExpression -> UQualifiedReferenceExpression -> Kotlin_Light_Method: foo
 }: A
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = forEach) -> Decompiled_Method: forEach
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = println) -> Decompiled_Method: println
-        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
     UBlockExpression -> UQualifiedReferenceExpression -> Decompiled_Method: joinToString
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = listOf) -> Decompiled_Method: listOf
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = joinToString) -> Decompiled_Method: joinToString

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/Resolve.resolved.fir.txt

@@ -24,7 +24,7 @@ UBlockExpression -> UQualifiedReferenceExpression -> Kotlin_Light_Method: foo
 }: A
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to null) -> USimpleNameReferenceExpression (identifier = forEach) -> FUN: forEach
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = println) -> Decompiled_Method: println
-        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
     UBlockExpression -> UQualifiedReferenceExpression -> null: null
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to null) -> USimpleNameReferenceExpression (identifier = listOf) -> FUN: listOf
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = joinToString) -> FUN: joinToString

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/TypeReferences.resolved.fe10.txt

@@ -23,7 +23,7 @@ UTypeReferenceExpression (name = T) -> USimpleNameReferenceExpression (identifie
     UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = tl) -> Kotlin_Light_Variable: tl
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to Decompiled_Method) -> USimpleNameReferenceExpression (identifier = map) -> Decompiled_Method: map
         UReturnExpression -> UQualifiedReferenceExpression -> null: null
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = toString) -> null: null
     UTypeReferenceExpression (name = java.util.List<? extends java.util.List<? extends java.lang.String>>) -> USimpleNameReferenceExpression (identifier = List) -> Decompiled_Class: List
     UTypeReferenceExpression (name = java.util.List<? extends java.lang.String>) -> USimpleNameReferenceExpression (identifier = List) -> Decompiled_Class: List

plugins/kotlin/uast/uast-kotlin-fir/testData/legacyResolved/TypeReferences.resolved.fir.txt

@@ -23,7 +23,7 @@ UTypeReferenceExpression (name = T) -> USimpleNameReferenceExpression (identifie
     UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = tl) -> Kotlin_Light_Variable: tl
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to null) -> USimpleNameReferenceExpression (identifier = map) -> FUN: map
         UReturnExpression -> UQualifiedReferenceExpression -> null: null
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> FUNCTION_LITERAL: <anonymous>
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Kotlin_Light_Value_Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = toString) -> FUN: toString
     UTypeReferenceExpression (name = java.util.List<? extends java.util.List<? extends java.lang.String>>) -> USimpleNameReferenceExpression (identifier = List) -> Decompiled_Class: List
     UTypeReferenceExpression (name = java.util.List<? extends java.lang.String>) -> USimpleNameReferenceExpression (identifier = List) -> Decompiled_Class: List

plugins/kotlin/uast/uast-kotlin/src/org/jetbrains/uast/kotlin/internal/kotlinInternalUastUtils.kt

@@ -14,16 +14,17 @@ import com.intellij.psi.impl.compiled.StubBuildingVisitor
 import com.intellij.psi.util.PsiTypesUtil
 import com.intellij.util.SmartList
 import org.jetbrains.kotlin.asJava.*
-import org.jetbrains.kotlin.backend.jvm.serialization.DisabledDescriptorMangler.signatureString
 import org.jetbrains.kotlin.builtins.isBuiltinFunctionalTypeOrSubtype
 import org.jetbrains.kotlin.codegen.signature.BothSignatureWriter
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationArgumentVisitor
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
+import org.jetbrains.kotlin.descriptors.impl.AnonymousFunctionDescriptor
 import org.jetbrains.kotlin.descriptors.impl.EnumEntrySyntheticClassDescriptor
 import org.jetbrains.kotlin.descriptors.impl.TypeAliasConstructorDescriptor
 import org.jetbrains.kotlin.descriptors.synthetic.SyntheticMemberDescriptor
 import org.jetbrains.kotlin.idea.KotlinLanguage
+import org.jetbrains.kotlin.js.resolve.diagnostics.findPsi
 import org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaPackageFragment
 import org.jetbrains.kotlin.load.java.sam.SamAdapterDescriptor
 import org.jetbrains.kotlin.load.kotlin.KotlinJvmBinaryPackageSourceElement
@@ -45,7 +46,6 @@ import org.jetbrains.kotlin.resolve.calls.inference.model.TypeVariableTypeConstr
 import org.jetbrains.kotlin.resolve.calls.model.ArgumentMatch
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.resolve.calls.tower.NewResolvedCallImpl
-import org.jetbrains.kotlin.resolve.calls.util.isFakePsiElement
 import org.jetbrains.kotlin.resolve.constants.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.resolve.references.ReferenceAccess
@@ -384,6 +384,13 @@ fun resolveToDeclarationImpl(sourcePsi: KtExpression, declarationDescriptor: Dec
         if (parentDeclaration is PsiClass && parentDeclaration.isAnnotationType) {
             parentDeclaration.findMethodsByName(declarationDescriptor.name.asString(), false).firstOrNull()?.let { return it }
         }
+        // Implicit lambda parameter `it`
+        if (declarationDescriptor.isImplicitLambdaParameter(sourcePsi)) {
+            // From its containing lambda (of function literal), build ULambdaExpression
+            val lambda = declarationDescriptor.containingDeclaration.findPsi().toUElementOfType<ULambdaExpression>()
+            // and return javaPsi of the corresponding lambda implicit parameter
+            return lambda?.valueParameters?.singleOrNull()?.javaPsi
+        }
     }
 
     if (declarationDescriptor is CallableMemberDescriptor && declarationDescriptor.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE) {
@@ -398,6 +405,15 @@ fun resolveToDeclarationImpl(sourcePsi: KtExpression, declarationDescriptor: Dec
     return null
 }
 
+private fun ValueParameterDescriptor.isImplicitLambdaParameter(sourcePsi: KtExpression): Boolean {
+    return containingDeclaration is AnonymousFunctionDescriptor &&
+            name.identifierOrNullIfSpecial == "it" &&
+            // Implicit lambda parameter doesn't have a source PSI.
+            source.getPsi() == null &&
+            // But, that could be the case for a declaration from Library. Double-check the slice in the binding context
+            sourcePsi.analyze().get(BindingContext.AUTO_CREATED_IT, this) != null
+}
+
 private fun resolveContainingDeserializedClass(context: KtElement, memberDescriptor: DeserializedCallableMemberDescriptor): PsiClass? {
     return when (val containingDeclaration = memberDescriptor.containingDeclaration) {
         is LazyJavaPackageFragment -> {

plugins/kotlin/uast/uast-kotlin/tests/test/org/jetbrains/uast/test/kotlin/comparison/FE1UastResolveApiFixtureTest.kt

@@ -63,6 +63,14 @@ class FE1UastResolveApiFixtureTest : KotlinLightCodeInsightFixtureTestCase(), Ua
         checkResolveCompiledAnnotation(myFixture)
     }
 
+    fun testResolveExplicitLambdaParameter() {
+        checkResolveExplicitLambdaParameter(myFixture)
+    }
+
+    fun testResolveImplicitLambdaParameter() {
+        checkResolveImplicitLambdaParameter(myFixture)
+    }
+
     fun testResolveSyntheticMethod() {
         checkResolveSyntheticMethod(myFixture)
     }
@@ -82,4 +90,4 @@ class FE1UastResolveApiFixtureTest : KotlinLightCodeInsightFixtureTestCase(), Ua
     fun testSyntheticEnumMethods() {
         checkSyntheticEnumMethods(myFixture)
     }
-}
\ No newline at end of file
+}

plugins/kotlin/uast/uast-kotlin/tests/testData/Resolve.resolved.txt

@@ -24,7 +24,7 @@ UBlockExpression -> UQualifiedReferenceExpression -> KtUltraLightMethodForSource
 }: A
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:forEach) -> USimpleNameReferenceExpression (identifier = forEach) -> PsiMethod:forEach: forEach
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:println) -> USimpleNameReferenceExpression (identifier = println) -> PsiMethod:println: println
-        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:println) -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:println) -> USimpleNameReferenceExpression (identifier = it) -> Light Parameter: it
     UBlockExpression -> UQualifiedReferenceExpression -> PsiMethod:joinToString: joinToString
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:listOf) -> USimpleNameReferenceExpression (identifier = listOf) -> PsiMethod:listOf: listOf
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to PsiMethod:joinToString) -> USimpleNameReferenceExpression (identifier = joinToString) -> PsiMethod:joinToString: joinToString

plugins/kotlin/uast/uast-kotlin/tests/testData/TypeReferences.resolved.txt

@@ -23,7 +23,7 @@ UTypeReferenceExpression (name = T) -> USimpleNameReferenceExpression (identifie
     UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = tl) -> LightVariableBuilder:tl: tl
     UCallExpression (kind = UastCallKind(name='method_call'), argCount = 1))(resolves to PsiMethod:map) -> USimpleNameReferenceExpression (identifier = map) -> PsiMethod:map: map
         UReturnExpression -> UQualifiedReferenceExpression -> null: null
-        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> null: null
+        UQualifiedReferenceExpression -> USimpleNameReferenceExpression (identifier = it) -> Light Parameter: it
         UCallExpression (kind = UastCallKind(name='method_call'), argCount = 0))(resolves to null) -> USimpleNameReferenceExpression (identifier = toString) -> null: null
     UTypeReferenceExpression (name = java.util.List<? extends java.util.List<? extends java.lang.String>>) -> USimpleNameReferenceExpression (identifier = List) -> PsiClass:List: List
     UTypeReferenceExpression (name = java.util.List<? extends java.lang.String>) -> USimpleNameReferenceExpression (identifier = List) -> PsiClass:List: List