[FIR] Add pretty rendering of functional types

compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/TypeRenderer.kt

@@ -5,6 +5,10 @@
 
 package org.jetbrains.kotlin.fir.types
 
+import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
 fun ConeKotlinType.render(): String {
     val nullabilitySuffix = if (this !is ConeKotlinErrorType && this !is ConeClassErrorType) nullability.suffix else ""
     return when (this) {
@@ -17,12 +21,7 @@ fun ConeKotlinType.render(): String {
                 append(lookupTag.classId.asString())
                 if (typeArguments.isNotEmpty()) {
                     append(typeArguments.joinToString(prefix = "<", postfix = ">") {
-                        when (it) {
+                        it.render()
-                            ConeStarProjection -> "*"
-                            is ConeKotlinTypeProjectionIn -> "in ${it.type.render()}"
-                            is ConeKotlinTypeProjectionOut -> "out ${it.type.render()}"
-                            is ConeKotlinType -> it.render()
-                        }
                     })
                 }
             }
@@ -49,3 +48,43 @@ fun ConeKotlinType.render(): String {
         is ConeStubType -> "stub type: $variable"
     } + nullabilitySuffix
 }
+
+private fun ConeKotlinTypeProjection.render(): String {
+    return when (this) {
+        ConeStarProjection -> "*"
+        is ConeKotlinTypeProjectionIn -> "in ${type.render()}"
+        is ConeKotlinTypeProjectionOut -> "out ${type.render()}"
+        is ConeKotlinType -> render()
+    }
+}
+
+fun ConeKotlinType.renderFunctionType(kind: FunctionClassDescriptor.Kind?, isExtension: Boolean): String {
+    if (!kind.withPrettyRender()) return render()
+    return buildString {
+        if (kind == FunctionClassDescriptor.Kind.SuspendFunction) {
+            append("suspend ")
+        }
+        val (receiver, otherTypeArguments) = if (isExtension && typeArguments.first() != ConeStarProjection) {
+            typeArguments.first() to typeArguments.drop(1)
+        } else {
+            null to typeArguments.toList()
+        }
+        val arguments = otherTypeArguments.subList(0, otherTypeArguments.size - 1)
+        val returnType = otherTypeArguments.last()
+        if (receiver != null) {
+            append(receiver.render())
+            append(".")
+        }
+        append(arguments.joinToString(", ", "(", ")") { it.render() })
+        append(" -> ")
+        append(returnType.render())
+    }
+}
+
+@UseExperimental(ExperimentalContracts::class)
+fun FunctionClassDescriptor.Kind?.withPrettyRender(): Boolean {
+    contract {
+        returns(true) implies (this@withPrettyRender != null)
+    }
+    return this != null && this != FunctionClassDescriptor.Kind.KSuspendFunction && this != FunctionClassDescriptor.Kind.KFunction
+}

compiler/fir/lightTree/src/org/jetbrains/kotlin/fir/lightTree/converter/DeclarationsConverter.kt

@@ -31,10 +31,7 @@ import org.jetbrains.kotlin.fir.lightTree.fir.modifier.TypeParameterModifier
 import org.jetbrains.kotlin.fir.lightTree.fir.modifier.TypeProjectionModifier
 import org.jetbrains.kotlin.fir.symbols.CallableId
 import org.jetbrains.kotlin.fir.symbols.impl.*
-import org.jetbrains.kotlin.fir.types.FirDelegatedTypeRef
+import org.jetbrains.kotlin.fir.types.*
-import org.jetbrains.kotlin.fir.types.FirTypeProjection
-import org.jetbrains.kotlin.fir.types.FirTypeRef
-import org.jetbrains.kotlin.fir.types.FirUserTypeRef
 import org.jetbrains.kotlin.fir.types.impl.*
 import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.lexer.KtTokens.*
@@ -1463,7 +1460,7 @@ class DeclarationsConverter(
         FirResolvedTypeRefImpl(
             null,
             ConeClassTypeImpl(
-                ConeClassLikeLookupTagImpl(ClassId.fromString("kotlin/ExtensionFunctionType")),
+                ConeClassLikeLookupTagImpl(ClassId.fromString(EXTENSION_FUNCTION_ANNOTATION)),
                 emptyArray(),
                 false
             )

compiler/fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.fir.impl.FirLabelImpl
 import org.jetbrains.kotlin.fir.references.impl.*
 import org.jetbrains.kotlin.fir.symbols.CallableId
 import org.jetbrains.kotlin.fir.symbols.impl.*
+import org.jetbrains.kotlin.fir.types.EXTENSION_FUNCTION_ANNOTATION
 import org.jetbrains.kotlin.fir.types.FirTypeProjection
 import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.types.impl.*
@@ -1376,7 +1377,7 @@ class RawFirBuilder(session: FirSession, val stubMode: Boolean) : BaseFirBuilder
         FirResolvedTypeRefImpl(
             null,
             ConeClassTypeImpl(
-                ConeClassLikeLookupTagImpl(ClassId.fromString("kotlin/ExtensionFunctionType")),
+                ConeClassLikeLookupTagImpl(ClassId.fromString(EXTENSION_FUNCTION_ANNOTATION)),
                 emptyArray(),
                 false
             )

compiler/fir/psi2fir/tests/org/jetbrains/kotlin/fir/builder/AbstractRawFirBuilderTestCase.kt

@@ -172,10 +172,5 @@ abstract class AbstractRawFirBuilderTestCase : KtParsingTestCase(
 
 }
 
-private val FirElement.isExtensionFunctionAnnotationCall: Boolean get() = (this as? FirAnnotationCall)?.let {
+private val FirElement.isExtensionFunctionAnnotationCall: Boolean
-    (it.annotationTypeRef as? FirResolvedTypeRef)?.let {
+    get() = (this as? FirAnnotationCall)?.isExtensionFunctionAnnotationCall == true
-        (it.type as? ConeClassLikeType)?.let {
-            it.lookupTag.classId.asString() == "kotlin/ExtensionFunctionType"
-        }
-    }
-} == true

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/PostponedArguments.kt

@@ -21,14 +21,6 @@ import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystem
 import org.jetbrains.kotlin.resolve.calls.model.PostponedResolvedAtomMarker
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
-fun FirTypeRef.isExtensionFunctionType(): Boolean {
-    return annotations.any {
-        (it.annotationTypeRef as? FirResolvedTypeRef)?.let {
-            it.type.toString() == "kotlin/ExtensionFunctionType"
-        } == true
-    }
-}
-
 fun Candidate.preprocessLambdaArgument(
     csBuilder: ConstraintSystemBuilder,
     argument: FirAnonymousFunction,
@@ -88,18 +80,12 @@ private val ConeKotlinType.isSuspendFunctionType: Boolean
     }
 
 private fun ConeKotlinType.receiverType(expectedTypeRef: FirTypeRef): ConeKotlinType? {
-    if (isFunctionalTypeWithReceiver(expectedTypeRef)) {
+    if (expectedTypeRef.isExtensionFunctionType()) {
         return (this.typeArguments.first() as ConeTypedProjection).type
     }
     return null
 }
 
-private fun isFunctionalTypeWithReceiver(typeRef: FirTypeRef) =
-    typeRef.annotations.any {
-        val coneTypeSafe = it.annotationTypeRef.coneTypeSafe<ConeClassType>() ?: return@any false
-        coneTypeSafe.lookupTag.classId.asString() == "kotlin/ExtensionFunctionType"
-    }
-
 val ConeKotlinType.returnType: ConeKotlinType?
     get() {
         require(this is ConeClassType)

compiler/fir/resolve/testData/resolve/arguments/lambda.txt

@@ -1,9 +1,9 @@
 FILE: lambda.kt
-    public final fun foo(f: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun foo(f: R|() -> kotlin/Unit|): R|kotlin/Unit| {
     }
-    public final fun bar(x: R|kotlin/Int|, f: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun bar(x: R|kotlin/Int|, f: R|() -> kotlin/Unit|): R|kotlin/Unit| {
     }
-    public final fun baz(f: R|kotlin/Function0<kotlin/Unit>|, other: R|kotlin/Boolean| = Boolean(true)): R|kotlin/Unit| {
+    public final fun baz(f: R|() -> kotlin/Unit|, other: R|kotlin/Boolean| = Boolean(true)): R|kotlin/Unit| {
     }
     public final fun test(): R|kotlin/Unit| {
         R|/foo|(<L> = foo@fun <anonymous>(): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/arguments/overloadWithDefault.txt

@@ -2,7 +2,7 @@ FILE: overloadWithDefault.kt
     public abstract interface A : R|kotlin/Any| {
         public abstract fun foo(b: R|kotlin/Boolean| = Boolean(false)): R|A|
 
-        public abstract fun foo(block: R|kotlin/Function0<kotlin/Boolean>|): R|A|
+        public abstract fun foo(block: R|() -> kotlin/Boolean|): R|A|
 
     }
     public final fun test(a: R|A|): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/cast.txt

@@ -3,23 +3,23 @@ FILE: cast.kt
         public get(): R|kotlin/Int|
     public final val y: R|kotlin/Any| = (Int(2) as R|kotlin/Any|)
         public get(): R|kotlin/Any|
-    public final val f: R|kotlin/Function0<kotlin/Any>| = fun <anonymous>(): R|kotlin/Any| {
+    public final val f: R|() -> kotlin/Any| = fun <anonymous>(): R|kotlin/Any| {
         ^ (Int(3) as R|kotlin/Any|)
     }
 
-        public get(): R|kotlin/Function0<kotlin/Any>|
+        public get(): R|() -> kotlin/Any|
-    public final val g: R|kotlin/Function0<kotlin/Unit>| = fun <anonymous>(): R|kotlin/Unit| {
+    public final val g: R|() -> kotlin/Unit| = fun <anonymous>(): R|kotlin/Unit| {
         Unit
     }
 
-        public get(): R|kotlin/Function0<kotlin/Unit>|
+        public get(): R|() -> kotlin/Unit|
-    public final val h: R|kotlin/Function1<kotlin/String, kotlin/Boolean>| = fun <anonymous>(_: R|kotlin/String|): R|kotlin/Boolean| {
+    public final val h: R|(kotlin/String) -> kotlin/Boolean| = fun <anonymous>(_: R|kotlin/String|): R|kotlin/Boolean| {
         Boolean(false)
     }
 
-        public get(): R|kotlin/Function1<kotlin/String, kotlin/Boolean>|
+        public get(): R|(kotlin/String) -> kotlin/Boolean|
-    public final val hError: R|kotlin/Function1<class error: No type for parameter, kotlin/Boolean>| = fun <anonymous>(_: R|class error: No type for parameter|): R|kotlin/Boolean| {
+    public final val hError: R|(class error: No type for parameter) -> kotlin/Boolean| = fun <anonymous>(_: R|class error: No type for parameter|): R|kotlin/Boolean| {
         Boolean(true)
     }
 
-        public get(): R|kotlin/Function1<class error: No type for parameter, kotlin/Boolean>|
+        public get(): R|(class error: No type for parameter) -> kotlin/Boolean|

compiler/fir/resolve/testData/resolve/cfg/jumps.txt

@@ -50,7 +50,7 @@ FILE: jumps.kt
         }
 
     }
-    public final inline fun run(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final inline fun run(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
     public final fun test_6(): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/cfg/lambdas.dot

@@ -110,7 +110,7 @@ digraph lambdas_kt {
         subgraph cluster_13 {
           color=blue
           36 [label="Enter block"];
-          37 [label="Variable declaration: lval lambda: R|kotlin/Function0<kotlin/Int>|"];
+          37 [label="Variable declaration: lval lambda: R|() -> kotlin/Int|"];
           38 [label="Exit block"];
         }
         39 [label="Exit when branch result"];

compiler/fir/resolve/testData/resolve/cfg/lambdas.txt

@@ -1,5 +1,5 @@
 FILE: lambdas.kt
-    public final inline fun run(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final inline fun run(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
     public final fun test_1(x: R|kotlin/Any?|): R|kotlin/Unit| {
@@ -16,7 +16,7 @@ FILE: lambdas.kt
     public final fun test_2(x: R|kotlin/Any?|): R|kotlin/Unit| {
         when () {
             (R|<local>/x| is R|kotlin/Int|) ->  {
-                lval lambda: R|kotlin/Function0<kotlin/Int>| = fun <anonymous>(): R|kotlin/Int| {
+                lval lambda: R|() -> kotlin/Int| = fun <anonymous>(): R|kotlin/Int| {
                     R|<local>/x|.R|kotlin/Int.inc|()
                 }
 
@@ -24,7 +24,7 @@ FILE: lambdas.kt
         }
 
     }
-    public final inline fun getInt(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Int| {
+    public final inline fun getInt(block: R|() -> kotlin/Unit|): R|kotlin/Int| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
         ^getInt Int(1)
     }

compiler/fir/resolve/testData/resolve/cfg/propertiesAndInitBlocks.txt

@@ -1,5 +1,5 @@
 FILE: propertiesAndInitBlocks.kt
-    public final inline fun run(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final inline fun run(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
     public final val x1: R|kotlin/Int| = Int(1)

compiler/fir/resolve/testData/resolve/expresssions/extensionPropertyInLambda.txt

@@ -16,7 +16,7 @@ FILE: extensionPropertyInLambda.kt
         public set(v: R|T|): R|kotlin/Unit| {
             this@R|/C|.R|/C.x| = R|<local>/v|
         }
-    public final fun use(f: R|kotlin/Function0<kotlin/String>|): R|kotlin/Unit| {
+    public final fun use(f: R|() -> kotlin/String|): R|kotlin/Unit| {
     }
     public final fun test1(): R|kotlin/Unit| {
         R|/use|(<L> = use@fun <anonymous>(): R|kotlin/String| {

compiler/fir/resolve/testData/resolve/expresssions/invoke/propertyFromParameter.txt

@@ -1,6 +1,6 @@
 FILE: propertyFromParameter.kt
     public final class Bar : R|kotlin/Any| {
-        public constructor(name: R|kotlin/Function0<kotlin/String>|): R|Bar| {
+        public constructor(name: R|() -> kotlin/String|): R|Bar| {
             super<R|kotlin/Any|>()
         }
 

compiler/fir/resolve/testData/resolve/expresssions/lambda.txt

@@ -1,11 +1,11 @@
 FILE: lambda.kt
-    public final fun foo(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun foo(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
     }
-    public final fun bar(block: R|kotlin/Function0<kotlin/String>|): R|kotlin/Unit| {
+    public final fun bar(block: R|() -> kotlin/String|): R|kotlin/Unit| {
     }
-    public final fun itIs(block: R|kotlin/Function1<kotlin/String, kotlin/String>|): R|kotlin/Unit| {
+    public final fun itIs(block: R|(kotlin/String) -> kotlin/String|): R|kotlin/Unit| {
     }
-    public final fun multipleArgs(block: R|kotlin/Function2<kotlin/String, kotlin/String, kotlin/String>|): R|kotlin/Unit| {
+    public final fun multipleArgs(block: R|(kotlin/String, kotlin/String) -> kotlin/String|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo|(<L> = foo@fun <anonymous>(): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/expresssions/lambdaWithReceiver.txt

@@ -3,13 +3,13 @@ FILE: lambdaWithReceiver.kt
         public abstract fun foo(): R|kotlin/Unit|
 
     }
-    public final fun <T> myWith(receiver: R|T|, block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> myWith(receiver: R|T|, block: R|T.() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/receiver|.<Unresolved name: block>#()
     }
-    public final fun <T> R|T|.myApply(block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> R|T|.myApply(block: R|T.() -> kotlin/Unit|): R|kotlin/Unit| {
         this@R|/myApply|.<Unresolved name: block>#()
     }
-    public final fun withA(block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<A, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun withA(block: R|A.() -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun test_1(): R|kotlin/Unit| {
         R|/withA|(<L> = withA@fun R|A|.<anonymous>(): R|kotlin/Unit| {
@@ -29,7 +29,7 @@ FILE: lambdaWithReceiver.kt
         }
         )
     }
-    public final fun complexLambda(block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function2<kotlin/Int, kotlin/String, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun complexLambda(block: R|kotlin/Int.(kotlin/String) -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun test_4(): R|kotlin/Unit| {
         R|/complexLambda|(<L> = complexLambda@fun R|kotlin/Int|.<anonymous>(it: R|kotlin/String|): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/ft.txt

@@ -1,5 +1,5 @@
 FILE: ft.kt
     public abstract interface KMutableProperty1<T> : R|KProperty1<T>| {
     }
-    public abstract interface KProperty1<T> : R|kotlin/Function1<T, kotlin/Int>| {
+    public abstract interface KProperty1<T> : R|(T) -> kotlin/Int| {
     }

compiler/fir/resolve/testData/resolve/functionTypes.txt

@@ -1,15 +1,15 @@
 FILE: functionTypes.kt
-    public final fun <T> simpleRun(f: R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> simpleRun(f: R|(T) -> kotlin/Unit|): R|kotlin/Unit| {
         ^simpleRun R|<local>/f|.R|FakeOverride<kotlin/Function1.invoke: R|kotlin/Unit|>|(^simpleRun Unit)
     }
-    public final fun <T, R> R|kotlin/collections/List<T>|.simpleMap(f: R|kotlin/Function1<T, R>|): R|R| {
+    public final fun <T, R> R|kotlin/collections/List<T>|.simpleMap(f: R|(T) -> R|): R|R| {
     }
-    public final fun <T> simpleWith(t: R|T|, f: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> simpleWith(t: R|T|, f: R|T.() -> kotlin/Unit|): R|kotlin/Unit| {
         ^simpleWith R|<local>/t|.<Unresolved name: f>#()
     }
     public abstract interface KMutableProperty1<T, R> : R|KProperty1<T, R>|, R|KMutableProperty<R>| {
     }
-    public abstract interface KProperty1<T, out R> : R|KProperty<R>|, R|kotlin/Function1<T, R>| {
+    public abstract interface KProperty1<T, out R> : R|KProperty<R>|, R|(T) -> R| {
     }
     public abstract interface KProperty<out R> : R|kotlin/Any| {
     }

compiler/fir/resolve/testData/resolve/localObject.txt

@@ -1,5 +1,5 @@
 FILE: localObject.kt
-    public final fun <T> run(block: R|kotlin/Function0<T>|): R|T| {
+    public final fun <T> run(block: R|() -> T|): R|T| {
         ^run R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|T|>|()
     }
     public abstract interface Foo : R|kotlin/Any| {

compiler/fir/resolve/testData/resolve/samConstructors/kotlinSam.txt

@@ -14,7 +14,7 @@ FILE: kotlinSam.kt
             >(R|<local>/it|, Int(1))
         }
         ))
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConstructors/realConstructorFunction.txt

@@ -1,7 +1,7 @@
 FILE: main.kt
     public final fun foo(m: R|MyRunnable|): R|kotlin/Unit| {
     }
-    public final fun MyRunnable(x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>|): R|kotlin/Int| {
+    public final fun MyRunnable(x: R|(kotlin/Int) -> kotlin/Boolean|): R|kotlin/Int| {
         ^MyRunnable Int(1)
     }
     public final fun main(): R|kotlin/Unit| {
@@ -13,7 +13,7 @@ FILE: main.kt
             >(R|<local>/it|, Int(1))
         }
         ))
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConstructors/simple.txt

@@ -10,7 +10,7 @@ FILE: main.kt
             >(R|<local>/it|, Int(1))
         }
         ))
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConversions/kotlinSam.txt

@@ -29,7 +29,7 @@ FILE: kotlinSam.kt
     public final fun foo4(m: R|Derived|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
-        lval f: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(t: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval f: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(t: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/t|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConversions/notSamBecauseOfSupertype.txt

@@ -10,7 +10,7 @@ FILE: main.kt
             >(<Unresolved name: it>#, Int(1))
         }
         )
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConversions/samSupertype.txt

@@ -10,7 +10,7 @@ FILE: main.kt
             >(R|<local>/it|, Int(1))
         }
         )
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConversions/samSupertypeWithOverride.txt

@@ -10,7 +10,7 @@ FILE: main.kt
             >(R|<local>/it|, Int(1))
         }
         )
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/samConversions/simple.txt

@@ -10,7 +10,7 @@ FILE: main.kt
             >(R|<local>/it|, Int(1))
         }
         )
-        lval x: R|kotlin/Function1<kotlin/Int, kotlin/Boolean>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
+        lval x: R|(kotlin/Int) -> kotlin/Boolean| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/Boolean| {
             >(R|<local>/x|, Int(1))
         }
 

compiler/fir/resolve/testData/resolve/smartcasts/implicitReceivers.txt

@@ -8,7 +8,7 @@ FILE: implicitReceivers.kt
         }
 
     }
-    public final fun <T> R|T|.with(block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> R|T|.with(block: R|T.() -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun R|kotlin/Any?|.test_1(): R|kotlin/Unit| {
         when () {

compiler/fir/resolve/testData/resolve/smartcasts/inPlaceLambdas.txt

@@ -7,7 +7,7 @@ FILE: inPlaceLambdas.kt
         public abstract fun bar(): R|kotlin/Unit|
 
     }
-    public final inline fun run(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final inline fun run(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
     public final fun test_1(x: R|kotlin/Any?|): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/beyoundCalls.txt

@@ -12,9 +12,9 @@ FILE: beyoundCalls.kt
         ^foobaz R|kotlin/TODO|()
     }
     public final fun foo(): R|kotlin/Unit| {
-        lval x: R|kotlin/Function1<kotlin/String, kotlin/Int>| = ::R|/bar|
+        lval x: R|(kotlin/String) -> kotlin/Int| = ::R|/bar|
         lval y: <ERROR TYPE REF: No result type for initializer> = ::<Unresolved reference: bar>#
         lval z: R|kotlin/reflect/KFunction1<kotlin/String, kotlin/Int>| = ::R|/baz|
-        lval w: R|kotlin/Function1<kotlin/String, kotlin/Int>| = ::R|/foobaz<kotlin/String, kotlin/Int>|
+        lval w: R|(kotlin/String) -> kotlin/Int| = ::R|/foobaz<kotlin/String, kotlin/Int>|
         ::R|/baz|
     }

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/companions.txt

@@ -41,13 +41,13 @@ FILE: main.kt
         }
 
     }
-    public final fun foo1(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo1(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo2(x: R|kotlin/Function2<KotlinClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo2(x: R|(KotlinClass, kotlin/CharSequence) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo3(x: R|kotlin/Function2<KotlinClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo3(x: R|(KotlinClass, kotlin/CharSequence) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo3(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo3(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo1|(Q|KotlinClass|::R|/KotlinClass.Companion.baz|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/constructors.txt

@@ -9,7 +9,7 @@ FILE: constructors.kt
         }
 
     }
-    public final fun user(f: R|kotlin/Function1<kotlin/Int, Klass>|): R|kotlin/Unit| {
+    public final fun user(f: R|(kotlin/Int) -> Klass|): R|kotlin/Unit| {
     }
     public final fun fn(): R|kotlin/Unit| {
         R|/user|(::R|/Klass.Klass|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/differentLevels.txt

@@ -1,5 +1,5 @@
 FILE: differentLevels.kt
-    public final fun foo(x: R|kotlin/Function0<kotlin/Int>|, y: R|kotlin/Int|): R|kotlin/Unit| {
+    public final fun foo(x: R|() -> kotlin/Int|, y: R|kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(x: R|kotlin/String|): R|kotlin/Int| {
         ^bar Int(1)
@@ -9,7 +9,7 @@ FILE: differentLevels.kt
             ^bar Int(1)
         }
 
-        local final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|, y: R|kotlin/String|): R|kotlin/Unit| {
+        local final fun foo(x: R|(kotlin/String) -> kotlin/Int|, y: R|kotlin/String|): R|kotlin/Unit| {
         }
 
         R|/foo|(::R|<local>/bar|, Int(1))

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/extensionReceiverInference.txt

@@ -12,7 +12,7 @@ FILE: extensionReceiverInference.kt
     public final fun <X> R|X|.baz(): R|kotlin/Int| {
         ^baz Int(1)
     }
-    public final fun foo(x: R|kotlin/Function1<A, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(A) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo|(Q|A|::R|/prop<A>|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/ambiguityWhenNoApplicableCallableReferenceCandidate.txt

@@ -3,7 +3,7 @@ FILE: ambiguityWhenNoApplicableCallableReferenceCandidate.kt
     }
     public final fun foo(y: R|kotlin/String|): R|kotlin/Unit| {
     }
-    public final fun <T> bar(f: R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> bar(f: R|(T) -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun test(): R|kotlin/Unit| {
         R|/bar|<R|kotlin/Any?|>(::<Unresolved reference: foo>#)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/applicableCallableReferenceFromDistantScope.txt

@@ -12,7 +12,7 @@ FILE: applicableCallableReferenceFromDistantScope.kt
         public final fun foo(b: R|kotlin/Boolean|): R|kotlin/Unit| {
         }
 
-        public final fun <T> bar(f: R|kotlin/Function1<T, kotlin/Unit>|): R|T| {
+        public final fun <T> bar(f: R|(T) -> kotlin/Unit|): R|T| {
             ^bar R|kotlin/TODO|()
         }
 

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/chooseCallableReferenceDependingOnInferredReceiver.txt

@@ -26,7 +26,7 @@ FILE: chooseCallableReferenceDependingOnInferredReceiver.kt
         }
 
     }
-    public final fun <T> bar(f: R|kotlin/Function1<T, kotlin/Unit>|): R|T| {
+    public final fun <T> bar(f: R|(T) -> kotlin/Unit|): R|T| {
         ^bar R|kotlin/TODO|()
     }
     public final fun test(): R|kotlin/Unit| {
@@ -43,6 +43,6 @@ FILE: chooseCallableReferenceDependingOnInferredReceiver.kt
         }
         )
     }
-    public final inline fun <T, R> myWith(receiver: R|T|, block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, R>|): R|R| {
+    public final inline fun <T, R> myWith(receiver: R|T|, block: R|T.() -> R|): R|R| {
         ^myWith R|kotlin/TODO|()
     }

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/eagerAndPostponedCallableReferences.txt

@@ -11,7 +11,7 @@ FILE: eagerAndPostponedCallableReferences.kt
     }
     public final fun singleB(a: R|B|): R|kotlin/Unit| {
     }
-    public final fun <T> foo(f: R|kotlin/Function1<T, kotlin/Unit>|, g: R|kotlin/Function1<T, kotlin/Unit>|): R|T| {
+    public final fun <T> foo(f: R|(T) -> kotlin/Unit|, g: R|(T) -> kotlin/Unit|): R|T| {
         ^foo R|kotlin/TODO|()
     }
     public final fun test(): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/eagerResolveOfSingleCallableReference.txt

@@ -26,6 +26,6 @@ FILE: eagerResolveOfSingleCallableReference.kt
     public final fun test(ls: R|Out<B>|): R|kotlin/Unit| {
         R|<local>/ls|.R|/reduce|<R|A|, R|B|>(::R|/Or.Or|)
     }
-    public final fun <S, T : R|S|> R|Out<T>|.reduce(operation: R|kotlin/Function2<S, T, S>|): R|S| {
+    public final fun <S, T : R|S|> R|Out<T>|.reduce(operation: R|(S, T) -> S|): R|S| {
         ^reduce R|kotlin/TODO|()
     }

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/multipleOutersAndMultipleCallableReferences.txt

@@ -13,9 +13,9 @@ FILE: multipleOutersAndMultipleCallableReferences.kt
     public final fun foo(y: R|kotlin/String|): R|Inv<kotlin/String>| {
         ^foo R|kotlin/TODO|()
     }
-    public final fun <T, R : R|kotlin/Number|> bar(f: R|kotlin/Function1<T, Inv<R>>|, p: R|kotlin/String| = String()): R|kotlin/Unit| {
+    public final fun <T, R : R|kotlin/Number|> bar(f: R|(T) -> Inv<R>|, p: R|kotlin/String| = String()): R|kotlin/Unit| {
     }
-    public final fun <T, R : R|Base|> bar(f: R|kotlin/Function1<T, Inv<R>>|, p: R|kotlin/Int| = Int(4)): R|kotlin/Unit| {
+    public final fun <T, R : R|Base|> bar(f: R|(T) -> Inv<R>|, p: R|kotlin/Int| = Int(4)): R|kotlin/Unit| {
     }
     public final fun test(): R|kotlin/Unit| {
         R|/bar|<R|kotlin/Int|, R|kotlin/Int|>(::R|/foo|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/overloadsBound.txt

@@ -11,7 +11,7 @@ FILE: overloadsBound.kt
         }
 
     }
-    public final fun foo(p: R|kotlin/Function1<kotlin/String, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun foo(p: R|(kotlin/String) -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun bar(c: R|C|): R|kotlin/Unit| {
         R|/foo|(R|<local>/c|::R|/C.xf1|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/postponedResolveOfManyCallableReference.txt

@@ -7,10 +7,10 @@ FILE: postponedResolveOfManyCallableReference.kt
     }
     public final fun foo(b: R|B|): R|kotlin/Unit| {
     }
-    public final fun <T> bar1(f: R|kotlin/Function1<T, kotlin/Unit>|): R|T| {
+    public final fun <T> bar1(f: R|(T) -> kotlin/Unit|): R|T| {
         ^bar1 R|kotlin/TODO|()
     }
-    public final fun <T> bar2(f: R|kotlin/Function1<T, kotlin/Unit>|, e: R|T|): R|kotlin/Unit| {
+    public final fun <T> bar2(f: R|(T) -> kotlin/Unit|, e: R|T|): R|kotlin/Unit| {
     }
     public final fun test(a: R|A|, b: R|B|): R|kotlin/Unit| {
         lval expectedType1: R|A| = R|/bar1|<R|A|>(::R|/foo|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/resolveCallableReferencesAfterAllSimpleArguments.txt

@@ -5,9 +5,9 @@ FILE: resolveCallableReferencesAfterAllSimpleArguments.kt
     }
     public final fun fooB(b: R|B|): R|kotlin/Unit| {
     }
-    public final fun <T> bar(f: R|kotlin/Function1<T, kotlin/Unit>|, e: R|T|): R|kotlin/Unit| {
+    public final fun <T> bar(f: R|(T) -> kotlin/Unit|, e: R|T|): R|kotlin/Unit| {
     }
-    public final fun <T> baz(e: R|T|, f: R|kotlin/Function1<T, kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun <T> baz(e: R|T|, f: R|(T) -> kotlin/Unit|): R|kotlin/Unit| {
     }
     public final fun test(a: R|A|, b: R|B|): R|kotlin/Unit| {
         <Inapplicable(INAPPLICABLE): [/baz]>#(R|<local>/a|, ::R|/fooB|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/fromBasicDiagnosticTests/withGenericFun.txt

@@ -1,5 +1,5 @@
 FILE: withGenericFun.kt
-    public final fun <T, R> apply(x: R|T|, f: R|kotlin/Function1<T, R>|): R|R| {
+    public final fun <T, R> apply(x: R|T|, f: R|(T) -> R|): R|R| {
         ^apply R|<local>/f|.R|FakeOverride<kotlin/Function1.invoke: R|R|>|(R|<local>/x|)
     }
     public final fun foo(i: R|kotlin/Int|): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/implicitTypes.txt

@@ -1,8 +1,8 @@
 FILE: implicitTypes.kt
-    public final fun <T, R> use(x: R|kotlin/Function1<T, R>|): R|kotlin/Function1<T, R>| {
+    public final fun <T, R> use(x: R|(T) -> R|): R|(T) -> R| {
         ^use R|<local>/x|
     }
-    public final fun foo(): R|kotlin/Function1<kotlin/String, kotlin/Int>| {
+    public final fun foo(): R|(kotlin/String) -> kotlin/Int| {
         ^foo R|/use|<R|kotlin/String|, R|kotlin/Int|>(::R|/bar|)
     }
     public final fun bar(x: R|kotlin/String|): R|kotlin/Int| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/inferenceFromCallableReferenceType.txt

@@ -1,7 +1,7 @@
 FILE: inferenceFromCallableReferenceType.kt
-    public final fun <T, E> foo(x: R|kotlin/Function1<T, E>|): R|kotlin/Unit| {
+    public final fun <T, E> foo(x: R|(T) -> E|): R|kotlin/Unit| {
     }
-    public final fun <T, E> foo2(x: R|kotlin/Function2<A, T, E>|): R|kotlin/Unit| {
+    public final fun <T, E> foo2(x: R|(A, T) -> E|): R|kotlin/Unit| {
     }
     public final class A : R|kotlin/Any| {
         public constructor(): R|A| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/inferenceFromExpectedType.txt

@@ -1,7 +1,7 @@
 FILE: inferenceFromExpectedType.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo2(x: R|kotlin/Function2<A, kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo2(x: R|(A, kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final class A : R|kotlin/Any| {
         public constructor(): R|A| {

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/javaStatic.txt

@@ -1,11 +1,11 @@
 FILE: main.kt
-    public final fun foo1(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo1(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo2(x: R|kotlin/Function2<JavaClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo2(x: R|(JavaClass, kotlin/CharSequence) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo3(x: R|kotlin/Function2<JavaClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo3(x: R|(JavaClass, kotlin/CharSequence) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo3(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo3(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo1|(Q|JavaClass|::R|/JavaClass.bar|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/manyCandidatesInference.txt

@@ -1,5 +1,5 @@
 FILE: manyCandidatesInference.kt
-    public final fun <T> foo(x: R|kotlin/Function0<T>|, y: R|kotlin/Int|): R|kotlin/Unit| {
+    public final fun <T> foo(x: R|() -> T|, y: R|kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun <E> bar(x: R|E|): R|kotlin/Int| {
         ^bar Int(1)
@@ -9,7 +9,7 @@ FILE: manyCandidatesInference.kt
             ^bar Int(1)
         }
 
-        local final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|, y: R|kotlin/String|): R|kotlin/Unit| {
+        local final fun foo(x: R|(kotlin/String) -> kotlin/Int|, y: R|kotlin/String|): R|kotlin/Unit| {
         }
 
         R|/foo|<R|kotlin/Int|>(::R|<local>/bar|, Int(1))

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/manyInnerCandidates.txt

@@ -1,5 +1,5 @@
 FILE: manyInnerCandidates.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(y: R|kotlin/Any|): R|kotlin/Int| {
         ^bar Int(1)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/manyInnerManyOuterCandidates.txt

@@ -1,7 +1,7 @@
 FILE: manyInnerManyOuterCandidates.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo(x: R|kotlin/Function0<kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|() -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(): R|kotlin/Int| {
         ^bar Int(1)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/manyInnermanyOuterCandidatesAmbiguity.txt

@@ -1,7 +1,7 @@
 FILE: manyInnermanyOuterCandidatesAmbiguity.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo(x: R|kotlin/Function0<kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|() -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(): R|kotlin/Int| {
         ^bar Int(1)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/manyOuterCandidates.txt

@@ -1,7 +1,7 @@
 FILE: manyOuterCandidates.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo(x: R|kotlin/Function0<kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|() -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(): R|kotlin/Int| {
         ^bar Int(1)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/properties.txt

@@ -14,13 +14,13 @@ FILE: properties.kt
         public get(): R|kotlin/Int| {
             ^ Int(1)
         }
-    public final fun foo1(x: R|kotlin/Function0<kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo1(x: R|() -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun foo2(x: R|kotlin/Function1<A, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo2(x: R|(A) -> kotlin/Int|): R|kotlin/Unit| {
     }
-    public final fun <R> foo3(x: R|kotlin/Function0<R>|): R|kotlin/Unit| {
+    public final fun <R> foo3(x: R|() -> R|): R|kotlin/Unit| {
     }
-    public final fun <T, R> foo4(x: R|kotlin/Function1<T, R>|): R|kotlin/Unit| {
+    public final fun <T, R> foo4(x: R|(T) -> R|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo1|(::R|/bar|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/simpleClassReceiver.txt

@@ -8,7 +8,7 @@ FILE: simpleClassReceiver.kt
         }
 
     }
-    public final fun foo(x: R|kotlin/Function2<A, kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(A, kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         R|/foo|(Q|A|::R|/A.bar|)

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/simpleExpressionReceiver.txt

@@ -8,7 +8,7 @@ FILE: simpleExpressionReceiver.kt
         }
 
     }
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun main(): R|kotlin/Unit| {
         lval a: R|A| = R|/A.A|()

compiler/fir/resolve/testData/resolve/stdlib/callableReferences/simpleNoReceiver.txt

@@ -1,5 +1,5 @@
 FILE: simpleNoReceiver.kt
-    public final fun foo(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    public final fun foo(x: R|(kotlin/String) -> kotlin/Int|): R|kotlin/Unit| {
     }
     public final fun bar(x: R|kotlin/String|): R|kotlin/Int| {
     }

compiler/fir/resolve/testData/resolve/stdlib/contracts/callsInPlace.txt

@@ -33,7 +33,7 @@ FILE: callsInPlace.kt
         }
         )
     }
-    public final inline fun myRun(block1: R|kotlin/Function0<kotlin/Unit>|, block2: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final inline fun myRun(block1: R|() -> kotlin/Unit|, block2: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block1|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
         R|<local>/block2|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
@@ -55,7 +55,7 @@ FILE: callsInPlace.kt
         }
         )
     }
-    public final fun myDummyRun(block: R|kotlin/Function0<kotlin/Unit>|): R|kotlin/Unit| {
+    public final fun myDummyRun(block: R|() -> kotlin/Unit|): R|kotlin/Unit| {
         R|<local>/block|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/Unit|>|()
     }
     public final fun test_8(): R|kotlin/Unit| {

compiler/fir/resolve/testData/resolve/stdlib/functionX.txt

@@ -4,12 +4,12 @@ FILE: functionX.kt
     }
 
         public get(): R|kotlin/jvm/functions/Function0<kotlin/Int>|
-    public final val y: R|kotlin/Function1<kotlin/String, kotlin/String>| = fun <anonymous>(it: R|kotlin/String|): R|kotlin/String| {
+    public final val y: R|(kotlin/String) -> kotlin/String| = fun <anonymous>(it: R|kotlin/String|): R|kotlin/String| {
         R|<local>/it|
     }
 
-        public get(): R|kotlin/Function1<kotlin/String, kotlin/String>|
+        public get(): R|(kotlin/String) -> kotlin/String|
-    public final class MyFunction : R|kotlin/Function2<kotlin/Int, kotlin/String, kotlin/Unit>| {
+    public final class MyFunction : R|(kotlin/Int, kotlin/String) -> kotlin/Unit| {
         public constructor(): R|MyFunction| {
             super<R|kotlin/Any|>()
         }

compiler/fir/resolve/testData/resolve/stdlib/j+k/FunctionTypeInJava.txt

@@ -12,7 +12,7 @@ FILE: main.kt
             R|<local>/it|.R|kotlin/Int.plus|(Int(3)).R|kotlin/Any.toString|()
         }
         )
-        lval y: R|kotlin/Function1<kotlin/Int, kotlin/String>| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/String| {
+        lval y: R|(kotlin/Int) -> kotlin/String| = fun <anonymous>(x: R|kotlin/Int|): R|kotlin/String| {
             R|<local>/x|.R|kotlin/Any.toString|()
         }
 

compiler/fir/resolve/testData/resolve/stdlib/mapList.txt

@@ -11,6 +11,6 @@ FILE: mapList.kt
         }
         )
     }
-    public final inline fun <T> R|T|.applyX(block: @R|kotlin/ExtensionFunctionType|() R|kotlin/Function1<T, kotlin/Unit>|): R|T| {
+    public final inline fun <T> R|T|.applyX(block: R|T.() -> kotlin/Unit|): R|T| {
         R|kotlin/TODO|()
     }

compiler/fir/resolve/testData/resolve/stdlib/recursiveBug.txt

@@ -1,6 +1,6 @@
 FILE: recursiveBug.kt
     public final class Foo : R|kotlin/Any| {
-        public constructor(name: R|kotlin/Function0<kotlin/String>|): R|Foo| {
+        public constructor(name: R|() -> kotlin/String|): R|Foo| {
             super<R|kotlin/Any|>()
         }
 
@@ -14,7 +14,7 @@ FILE: recursiveBug.kt
             public get(): R|kotlin/Int|
 
     }
-    public final fun bar(name: R|kotlin/Function0<kotlin/String>|): R|kotlin/Unit| {
+    public final fun bar(name: R|() -> kotlin/String|): R|kotlin/Unit| {
         lval result: R|kotlin/String| = R|kotlin/run|<R|kotlin/String|>(<L> = run@fun <anonymous>(): R|kotlin/String| <kind=EXACTLY_ONCE>  {
             R|<local>/name|.R|FakeOverride<kotlin/Function0.invoke: R|kotlin/String|>|()
         }

compiler/fir/resolve/testData/resolve/stdlib/typeParameterDerived.txt

@@ -1,5 +1,5 @@
 FILE: typeParameterDerived.kt
-    public final inline fun <K, V, VA : R|V|> R|kotlin/collections/MutableMap<K, V>|.getOrPut(key: R|K|, defaultValue: R|kotlin/Function1<K, VA>|, postCompute: R|kotlin/Function1<VA, kotlin/Unit>|): R|V| {
+    public final inline fun <K, V, VA : R|V|> R|kotlin/collections/MutableMap<K, V>|.getOrPut(key: R|K|, defaultValue: R|(K) -> VA|, postCompute: R|(VA) -> kotlin/Unit|): R|V| {
         lval value: R|V| = this@R|kotlin/collections/Map|.R|FakeOverride<kotlin/collections/Map.get: R|V|>|(R|<local>/key|)
         ^getOrPut when () {
             ==(R|<local>/value|, Null(null)) ->  {

compiler/fir/resolve/testData/resolve/whenAsReceiver.txt

@@ -1,5 +1,5 @@
 FILE: whenAsReceiver.kt
-    public final fun <T, R> R|T|.also(block: R|kotlin/Function0<R>|): R|R| {
+    public final fun <T, R> R|T|.also(block: R|() -> R|): R|R| {
         ^also when (lval <bangbang>: R|kotlin/Nothing?| = Null(null)) {
             ==($subj$, Null(null)) ->  {
                 throw <Unresolved name: KotlinNullPointerException>#()

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.fir
 
+import org.jetbrains.kotlin.builtins.functions.BuiltInFictitiousFunctionClassFactory
+import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationUseSiteTarget
@@ -736,13 +738,27 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
     }
 
     override fun visitResolvedTypeRef(resolvedTypeRef: FirResolvedTypeRef) {
-        resolvedTypeRef.annotations.renderAnnotations()
+        val kind = resolvedTypeRef.functionTypeKind
+        val annotations = if (kind.withPrettyRender()) {
+            resolvedTypeRef.annotations.dropExtensionFunctionAnnotation()
+        } else {
+            resolvedTypeRef.annotations
+        }
+        annotations.renderAnnotations()
         print("R|")
         val coneType = resolvedTypeRef.type
-        print(coneType.render())
+        print(coneType.renderFunctionType(kind, resolvedTypeRef.isExtensionFunctionType()))
         print("|")
     }
 
+    private val FirResolvedTypeRef.functionTypeKind: FunctionClassDescriptor.Kind?
+        get() {
+            val classId = (type as? ConeClassLikeType)?.lookupTag?.classId ?: return null
+            return BuiltInFictitiousFunctionClassFactory.getFunctionalClassKind(
+                classId.shortClassName.asString(), classId.packageFqName
+            )
+        }
+
     override fun visitUserTypeRef(userTypeRef: FirUserTypeRef) {
         userTypeRef.annotations.renderAnnotations()
         for ((index, qualifier) in userTypeRef.qualifier.withIndex()) {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/FirTypeUtils.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.fir.types
 
+import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.name.ClassId
@@ -33,3 +35,25 @@ val FirFunctionTypeRef.parametersCount: Int
         valueParameters.size + 1
     else
         valueParameters.size
+
+const val EXTENSION_FUNCTION_ANNOTATION = "kotlin/ExtensionFunctionType"
+
+fun FirTypeRef.isExtensionFunctionType(): Boolean {
+    return annotations.any {
+        it.isExtensionFunctionAnnotationCall
+    }
+}
+
+val FirAnnotationCall.isExtensionFunctionAnnotationCall: Boolean
+    get() = (this as? FirAnnotationCall)?.let {
+        (it.annotationTypeRef as? FirResolvedTypeRef)?.let {
+            (it.type as? ConeClassLikeType)?.let {
+                it.lookupTag.classId.asString() == EXTENSION_FUNCTION_ANNOTATION
+            }
+        }
+    } == true
+
+
+fun List<FirAnnotationCall>.dropExtensionFunctionAnnotation(): List<FirAnnotationCall> {
+    return filterNot { it.isExtensionFunctionAnnotationCall }
+}