[FIR] Approximate exotic return types for public declarations

compiler/fir/analysis-tests/testData/resolve/intersectionTypes.txt

@@ -16,12 +16,12 @@ FILE: intersectionTypes.kt
 
     }
     public final fun <K> select(x: R|K|, y: R|K|): R|K|
-    public final fun test(): R|it(A & B)| {
+    public final fun test(): R|kotlin/Any| {
         ^test R|/select|<R|it(A & B)|>(R|/Clazz1.Clazz1|(), R|/Clazz2.Clazz2|())
     }
     public final fun <T> makeNull(x: R|T|): R|T?| {
         ^makeNull Null(null)
     }
-    public final fun testNull(): R|it(A? & B?)| {
+    public final fun testNull(): R|kotlin/Any?| {
         ^testNull R|/makeNull|<R|it(A & B)|>(R|/select|<R|it(A & B)|>(R|/Clazz1.Clazz1|(), R|/Clazz2.Clazz2|()))
     }

compiler/fir/analysis-tests/testData/resolve/whenElse.txt

@@ -28,7 +28,7 @@ FILE: whenElse.kt
             public get(): R|B|
 
     }
-    public final fun get(f: R|kotlin/Boolean|): R|it(kotlin/Comparable<it(A & kotlin/String)> & java/io/Serializable)| {
+    public final fun get(f: R|kotlin/Boolean|): R|kotlin/Any| {
         ^get when () {
             R|<local>/f| ->  {
                 Q|A|.R|/A.A1|

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirDeclarationsResolveTransformer.kt

@@ -7,6 +7,10 @@ package org.jetbrains.kotlin.fir.resolve.transformers.body.resolve
 
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fir.*
+import org.jetbrains.kotlin.fir.Visibilities.Internal
+import org.jetbrains.kotlin.fir.Visibilities.Private
+import org.jetbrains.kotlin.fir.Visibilities.Protected
+import org.jetbrains.kotlin.fir.Visibilities.Public
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.builder.buildValueParameter
 import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertyAccessor
@@ -28,6 +32,7 @@ import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.transformers.*
 import org.jetbrains.kotlin.fir.scopes.impl.FirLocalScope
 import org.jetbrains.kotlin.fir.scopes.impl.FirMemberTypeParameterScope
+import org.jetbrains.kotlin.fir.scopes.impl.withReplacedConeType
 import org.jetbrains.kotlin.fir.symbols.constructStarProjectedType
 import org.jetbrains.kotlin.fir.symbols.impl.ConeClassLookupTagWithFixedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirVariableSymbol
@@ -37,6 +42,7 @@ import org.jetbrains.kotlin.fir.types.builder.buildImplicitTypeRef
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.visitors.*
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransformer) : FirPartialBodyResolveTransformer(transformer) {
@@ -503,7 +509,7 @@ open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransfor
                 result.transformReturnTypeRef(
                     transformer,
                     withExpectedType(
-                        body.resultType.hideLocalTypeIfNeeded(simpleFunction?.visibility, simpleFunction?.isInline == true)
+                        body.resultType.approximateTypeIfNeeded(simpleFunction?.visibility, simpleFunction?.isInline == true)
                     )
                 )
             } else {
@@ -911,7 +917,7 @@ open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransfor
                     }
                     variable.transformReturnTypeRef(
                         transformer,
-                        withExpectedType(expectedType.hideLocalTypeIfNeeded((variable as? FirProperty)?.visibility))
+                        withExpectedType(expectedType.approximateTypeIfNeeded((variable as? FirProperty)?.visibility))
                     )
                 }
                 variable.getter != null && variable.getter !is FirDefaultPropertyAccessor -> {
@@ -933,7 +939,7 @@ open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransfor
                     }
                     variable.transformReturnTypeRef(
                         transformer,
-                        withExpectedType(expectedType?.hideLocalTypeIfNeeded((variable as? FirProperty)?.visibility))
+                        withExpectedType(expectedType?.approximateTypeIfNeeded((variable as? FirProperty)?.visibility))
                     )
                 }
                 else -> {
@@ -956,6 +962,34 @@ open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransfor
         }
     }
 
+    private fun FirTypeRef.approximateTypeIfNeeded(
+        containingCallableVisibility: Visibility?,
+        isInlineFunction: Boolean = false
+    ): FirTypeRef {
+        val approximatedType = if (this is FirResolvedTypeRef &&
+            (containingCallableVisibility == Public || containingCallableVisibility == Protected)
+        ) {
+            when (this.type) {
+                is ConeIntegerLiteralType,
+                is ConeCapturedType,
+                is ConeDefinitelyNotNullType,
+                is ConeIntersectionType -> {
+                    this.withReplacedConeType(
+                        inferenceComponents.approximator.approximateToSuperType(
+                            this.type, TypeApproximatorConfiguration.PublicDeclaration
+                        ) as ConeKotlinType
+                    )
+                }
+                else -> {
+                    this
+                }
+            }
+        } else {
+            this
+        }
+        return approximatedType.hideLocalTypeIfNeeded(containingCallableVisibility, isInlineFunction)
+    }
+
     /*
      * Suppose a function without an explicit return type just returns an anonymous object:
      *
@@ -976,10 +1010,10 @@ open class FirDeclarationsResolveTransformer(transformer: FirBodyResolveTransfor
         }
         // Approximate types for non-private (all but package private or private) members.
         // Also private inline functions, as per KT-33917.
-        if (containingCallableVisibility == Visibilities.Public ||
+        if (containingCallableVisibility == Public ||
-            containingCallableVisibility == Visibilities.Protected ||
+            containingCallableVisibility == Protected ||
-            containingCallableVisibility == Visibilities.Internal ||
+            containingCallableVisibility == Internal ||
-            (containingCallableVisibility == Visibilities.Private && isInlineFunction)
+            (containingCallableVisibility == Private && isInlineFunction)
         ) {
             val firClass =
                 (((this as? FirResolvedTypeRef)

compiler/testData/codegen/box/javaInterop/notNullAssertions/enhancedNullability/inFunctionWithExpressionBodyWithJavaGeneric.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // !LANGUAGE: +StrictJavaNullabilityAssertions
 // TARGET_BACKEND: JVM
 // SKIP_JDK6

compiler/testData/codegen/box/lazyCodegen/ifElse.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 class A (val p: String, p1: String, p2: String) {
 
     var cond1 :String = ""

compiler/testData/diagnostics/tests/inference/publicApproximation/chainedLambdas.fir.kt

@@ -29,6 +29,6 @@ fun chained2(arg: First) = run {
 }
 
 fun test(arg: First) {
-    chained1(arg).first()
+    chained1(arg).<!UNRESOLVED_REFERENCE!>first<!>()
-    chained2(arg).first()
+    chained2(arg).<!UNRESOLVED_REFERENCE!>first<!>()
 }

compiler/testData/diagnostics/tests/inference/publicApproximation/intersectionAfterSmartCastInLambdaReturn.fir.kt

@@ -33,6 +33,6 @@ fun intersectArgWithSmartCastFromLambda(arg: One, arg2: Base) = argOrFn(arg) {
 }
 
 fun test() {
-    intersectAfterSmartCast(O1, O2).base()
+    intersectAfterSmartCast(O1, O2).<!UNRESOLVED_REFERENCE!>base<!>()
-    intersectArgWithSmartCastFromLambda(O1, O2).base()
+    intersectArgWithSmartCastFromLambda(O1, O2).<!UNRESOLVED_REFERENCE!>base<!>()
 }

compiler/testData/diagnostics/tests/inference/publicApproximation/smartCastInLambdaReturnAfterIntersection.fir.kt

@@ -18,5 +18,5 @@ fun smartCastAfterIntersection(a: One, b: Two) = run {
 }
 
 fun test(one: One, two: Two) {
-    smartCastAfterIntersection(one, two)?.base()
+    smartCastAfterIntersection(one, two)?.<!UNRESOLVED_REFERENCE!>base<!>()
 }

compiler/testData/diagnostics/tests/inference/publicApproximation/twoIntersections.fir.kt

@@ -21,5 +21,5 @@ fun <S> intersectNoBound(vararg elements: S): S = TODO()
 fun some(a: One, b: Two, c: Three) = intersectNoBound(intersect(a, b), c)
 
 fun test(arg: Base, arg2: Base) {
-    some(O1, O2, O3).base()
+    some(O1, O2, O3).<!UNRESOLVED_REFERENCE!>base<!>()
 }

compiler/testData/ir/irText/types/intersectionType2_NI.fir.txt

@@ -75,9 +75,9 @@ FILE fqName:<root> fileName:/intersectionType2_NI.kt
       RETURN type=kotlin.Nothing from='public final fun run <T> (fn: kotlin.Function0<T of <root>.run>): T of <root>.run declared in <root>'
         CALL 'public abstract fun invoke (): R of kotlin.Function0 [operator] declared in kotlin.Function0' type=T of <root>.run origin=INVOKE
           $this: GET_VAR 'fn: kotlin.Function0<T of <root>.run> declared in <root>.run' type=kotlin.Function0<T of <root>.run> origin=null
-  FUN name:foo visibility:public modality:FINAL <> () returnType:<root>.Foo
+  FUN name:foo visibility:public modality:FINAL <> () returnType:kotlin.Any
     BLOCK_BODY
-      RETURN type=kotlin.Nothing from='public final fun foo (): <root>.Foo declared in <root>'
+      RETURN type=kotlin.Nothing from='public final fun foo (): kotlin.Any declared in <root>'
         CALL 'public final fun run <T> (fn: kotlin.Function0<T of <root>.run>): T of <root>.run declared in <root>' type=<root>.Foo origin=null
           <T>: <root>.Foo
           fn: FUN_EXPR type=kotlin.Function0<<root>.Foo> origin=LAMBDA

compiler/testData/ir/irText/types/intersectionType2_OI.fir.txt

@@ -75,9 +75,9 @@ FILE fqName:<root> fileName:/intersectionType2_OI.kt
       RETURN type=kotlin.Nothing from='public final fun run <T> (fn: kotlin.Function0<T of <root>.run>): T of <root>.run declared in <root>'
         CALL 'public abstract fun invoke (): R of kotlin.Function0 [operator] declared in kotlin.Function0' type=T of <root>.run origin=INVOKE
           $this: GET_VAR 'fn: kotlin.Function0<T of <root>.run> declared in <root>.run' type=kotlin.Function0<T of <root>.run> origin=null
-  FUN name:foo visibility:public modality:FINAL <> () returnType:<root>.Foo
+  FUN name:foo visibility:public modality:FINAL <> () returnType:kotlin.Any
     BLOCK_BODY
-      RETURN type=kotlin.Nothing from='public final fun foo (): <root>.Foo declared in <root>'
+      RETURN type=kotlin.Nothing from='public final fun foo (): kotlin.Any declared in <root>'
         CALL 'public final fun run <T> (fn: kotlin.Function0<T of <root>.run>): T of <root>.run declared in <root>' type=<root>.Foo origin=null
           <T>: <root>.Foo
           fn: FUN_EXPR type=kotlin.Function0<<root>.Foo> origin=LAMBDA