diff --git a/compiler/fir/analysis-tests/testData/resolve/diagnostics/conflictingProjection.kt b/compiler/fir/analysis-tests/testData/resolve/diagnostics/conflictingProjection.kt
index 6a8c9c63771..7420d066b10 100644
--- a/compiler/fir/analysis-tests/testData/resolve/diagnostics/conflictingProjection.kt
+++ b/compiler/fir/analysis-tests/testData/resolve/diagnostics/conflictingProjection.kt
@@ -7,12 +7,12 @@ fun a2(value: None<in Int>) {}
 fun a3(value: None<out Int>) {}
 
 fun a4(value: In<Int>) {}
-fun a5(value: In<in Int>) {}
+fun a5(value: In<<!REDUNDANT_PROJECTION!>in<!> Int>) {}
 fun a6(value: In<<!CONFLICTING_PROJECTION!>out<!> Int>) {}
 
 fun a7(value: Out<Int>) {}
 fun a8(value: Out<<!CONFLICTING_PROJECTION!>in<!> Int>) {}
-fun a9(value: Out<out Int>) {}
+fun a9(value: Out<<!REDUNDANT_PROJECTION!>out<!> Int>) {}
 
 typealias A1<K> = None<K>
 typealias A2<K> = None<in K>
@@ -27,28 +27,28 @@ typealias A8<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = None<in K>
 typealias A9<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = None<out K>
 
 typealias A10<K> = In<K>
-typealias A11<K> = In<in K>
+typealias A11<K> = In<<!REDUNDANT_PROJECTION!>in<!> K>
 typealias A12<K> = In<<!CONFLICTING_PROJECTION!>out<!> K>
 
 typealias A13<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = In<K>
-typealias A14<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = In<in K>
+typealias A14<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = In<<!REDUNDANT_PROJECTION!>in<!> K>
 typealias A15<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = In<<!CONFLICTING_PROJECTION!>out<!> K>
 
 typealias A16<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = In<K>
-typealias A17<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = In<in K>
+typealias A17<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = In<<!REDUNDANT_PROJECTION!>in<!> K>
 typealias A18<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = In<<!CONFLICTING_PROJECTION!>out<!> K>
 
 typealias A19<K> = Out<K>
 typealias A20<K> = Out<<!CONFLICTING_PROJECTION!>in<!> K>
-typealias A21<K> = Out<out K>
+typealias A21<K> = Out<<!REDUNDANT_PROJECTION!>out<!> K>
 
 typealias A22<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = Out<K>
 typealias A23<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = Out<<!CONFLICTING_PROJECTION!>in<!> K>
-typealias A24<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = Out<out K>
+typealias A24<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>in<!> K> = Out<<!REDUNDANT_PROJECTION!>out<!> K>
 
 typealias A25<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = Out<K>
 typealias A26<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = Out<<!CONFLICTING_PROJECTION!>in<!> K>
-typealias A27<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = Out<out K>
+typealias A27<<!VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED!>out<!> K> = Out<<!REDUNDANT_PROJECTION!>out<!> K>
 
 class Outer<T> {
     inner class Intermediate<K> {
@@ -82,16 +82,16 @@ class InOuter<in T> {
 
 fun test10(): InOuter<Int>.OutIntermediate<String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 
-fun test11(): InOuter<in Int>.OutIntermediate<String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
+fun test11(): InOuter<<!REDUNDANT_PROJECTION!>in<!> Int>.OutIntermediate<String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 fun test12(): InOuter<<!CONFLICTING_PROJECTION!>out<!> Int>.OutIntermediate<String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 
 fun test13(): InOuter<Int>.OutIntermediate<<!CONFLICTING_PROJECTION!>in<!> String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
-fun test14(): InOuter<Int>.OutIntermediate<out String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
+fun test14(): InOuter<Int>.OutIntermediate<<!REDUNDANT_PROJECTION!>out<!> String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 
-fun test15(): InOuter<Int>.OutIntermediate<String>.InInner<in Char> = InOuter<Int>().OutIntermediate<String>().InInner()
+fun test15(): InOuter<Int>.OutIntermediate<String>.InInner<<!REDUNDANT_PROJECTION!>in<!> Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 fun test16(): InOuter<Int>.OutIntermediate<String>.InInner<<!CONFLICTING_PROJECTION!>out<!> Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 
-fun test17(): InOuter<in Int>.OutIntermediate<out String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
+fun test17(): InOuter<<!REDUNDANT_PROJECTION!>in<!> Int>.OutIntermediate<<!REDUNDANT_PROJECTION!>out<!> String>.InInner<Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 fun test18(): InOuter<Int>.OutIntermediate<<!CONFLICTING_PROJECTION!>in<!> String>.InInner<<!CONFLICTING_PROJECTION!>out<!> Char> = InOuter<Int>().OutIntermediate<String>().InInner()
 
 class TwoParametersOuter<T, in T1> {
diff --git a/compiler/fir/analysis-tests/testData/resolve/fromBuilder/typeParameters.kt b/compiler/fir/analysis-tests/testData/resolve/fromBuilder/typeParameters.kt
index 33ba23f33c2..23f5085fe70 100644
--- a/compiler/fir/analysis-tests/testData/resolve/fromBuilder/typeParameters.kt
+++ b/compiler/fir/analysis-tests/testData/resolve/fromBuilder/typeParameters.kt
@@ -4,7 +4,7 @@ interface List<out T : Any> {
     infix fun concat(other: List<<!TYPE_VARIANCE_CONFLICT!>T<!>>): List<T>
 }
 
-typealias StringList = List<out String>
+typealias StringList = List<<!REDUNDANT_PROJECTION!>out<!> String>
 typealias AnyList = List<*>
 
 abstract class AbstractList<out T : Any> : List<T>
diff --git a/compiler/fir/analysis-tests/testData/resolve/typeAliasWithTypeArguments.kt b/compiler/fir/analysis-tests/testData/resolve/typeAliasWithTypeArguments.kt
index 1e260168afd..3284a8adb33 100644
--- a/compiler/fir/analysis-tests/testData/resolve/typeAliasWithTypeArguments.kt
+++ b/compiler/fir/analysis-tests/testData/resolve/typeAliasWithTypeArguments.kt
@@ -71,13 +71,13 @@ typealias Out1<X> = Out<X>
 typealias Invariant1<X> = Invariant<X>
 
 
-fun test_5(a: A, in1: In1<A>, in2: In1<in A>, in3: In1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>out<!> A>) {
+fun test_5(a: A, in1: In1<A>, in2: In1<<!REDUNDANT_PROJECTION!>in<!> A>, in3: In1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>out<!> A>) {
     in1.take(a)
     in2.take(a)
     in3.<!UNRESOLVED_REFERENCE!>take<!>(a)
 }
 
-fun test_6(a: A, out1: Out1<A>, out2: Out1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>in<!> A>, out3: Out1<out A>) {
+fun test_6(a: A, out1: Out1<A>, out2: Out1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>in<!> A>, out3: Out1<<!REDUNDANT_PROJECTION!>out<!> A>) {
     out1.value().foo()
     out2.<!UNRESOLVED_REFERENCE!>value<!>().foo()
     out3.value().foo()
diff --git a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
index 653bdfb8c1f..271e79df24c 100644
--- a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
+++ b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
@@ -386,6 +386,9 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION by error<KtTypeParameter>(PositioningStrategy.VARIANCE_MODIFIER) {
             parameter<ConeKotlinType>("type")
         }
+        val REDUNDANT_PROJECTION by warning<KtTypeParameter>(PositioningStrategy.VARIANCE_MODIFIER) {
+            parameter<ConeKotlinType>("type")
+        }
         val VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED by error<KtTypeParameter>(PositioningStrategy.VARIANCE_MODIFIER)
 
         val CATCH_PARAMETER_WITH_DEFAULT_VALUE by error<PsiElement>()
diff --git a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
index f0b0043b757..ca038204b85 100644
--- a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
+++ b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
@@ -276,6 +276,7 @@ object FirErrors {
     val TYPE_PARAMETERS_IN_ENUM by error0<PsiElement>()
     val CONFLICTING_PROJECTION by error1<KtTypeParameter, ConeKotlinType>(SourceElementPositioningStrategies.VARIANCE_MODIFIER)
     val CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION by error1<KtTypeParameter, ConeKotlinType>(SourceElementPositioningStrategies.VARIANCE_MODIFIER)
+    val REDUNDANT_PROJECTION by warning1<KtTypeParameter, ConeKotlinType>(SourceElementPositioningStrategies.VARIANCE_MODIFIER)
     val VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED by error0<KtTypeParameter>(SourceElementPositioningStrategies.VARIANCE_MODIFIER)
     val CATCH_PARAMETER_WITH_DEFAULT_VALUE by error0<PsiElement>()
     val REIFIED_TYPE_IN_CATCH_CLAUSE by error0<PsiElement>()
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
index 7010cc4feac..190563c7f88 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
@@ -15,14 +15,13 @@ import org.jetbrains.kotlin.fir.analysis.checkers.syntax.FirDelegationInInterfac
 import org.jetbrains.kotlin.fir.analysis.checkers.syntax.FirFunctionTypeParametersSyntaxChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.syntax.FirTypeParameterSyntaxChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.expression.FirReservedUnderscoreDeclarationChecker
-import org.jetbrains.kotlin.fir.declarations.FirClass
 
 object CommonDeclarationCheckers : DeclarationCheckers() {
     override val basicDeclarationCheckers: Set<FirBasicDeclarationChecker>
         get() = setOf(
             FirModifierChecker,
             FirConflictsChecker,
-            FirConflictingProjectionChecker,
+            FirProjectionRelationChecker,
             FirTypeConstraintsChecker,
             FirReservedUnderscoreDeclarationChecker
         )
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirConflictingProjectionChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirProjectionRelationChecker.kt
similarity index 59%
rename from compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirConflictingProjectionChecker.kt
rename to compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirProjectionRelationChecker.kt
index 8dd79479ced..6b25a52743e 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirConflictingProjectionChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirProjectionRelationChecker.kt
@@ -6,8 +6,8 @@
 package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
 import org.jetbrains.kotlin.fir.FirFakeSourceElementKind
-import org.jetbrains.kotlin.fir.FirSourceElement
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.extractTypeRefAndSourceFromTypeArgument
 import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
@@ -17,7 +17,7 @@ import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
-object FirConflictingProjectionChecker : FirBasicDeclarationChecker() {
+object FirProjectionRelationChecker : FirBasicDeclarationChecker() {
     override fun check(declaration: FirDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
         if (declaration is FirPropertyAccessor) {
             return
@@ -62,16 +62,28 @@ object FirConflictingProjectionChecker : FirBasicDeclarationChecker() {
                 ?.symbol?.fir
                 ?.variance
 
-            if (
-                (fullyExpandedProjection is ConeKotlinTypeConflictingProjection ||
-                        actual is ConeKotlinTypeProjectionIn && protoVariance == Variance.OUT_VARIANCE ||
-                        actual is ConeKotlinTypeProjectionOut && protoVariance == Variance.IN_VARIANCE) &&
-                typeRef.source?.kind !is FirFakeSourceElementKind
+            val projectionRelation = if (fullyExpandedProjection is ConeKotlinTypeConflictingProjection ||
+                actual is ConeKotlinTypeProjectionIn && protoVariance == Variance.OUT_VARIANCE ||
+                actual is ConeKotlinTypeProjectionOut && protoVariance == Variance.IN_VARIANCE
             ) {
-                val typeArgSource = extractTypeArgumentSource(typeRef, it)
+                ProjectionRelation.Conflicting
+            } else if (actual is ConeKotlinTypeProjectionIn && protoVariance == Variance.IN_VARIANCE ||
+                actual is ConeKotlinTypeProjectionOut && protoVariance == Variance.OUT_VARIANCE
+            ) {
+                ProjectionRelation.Redundant
+            } else {
+                ProjectionRelation.None
+            }
+
+            val (typeArgTypeRef, typeArgSource) = extractTypeRefAndSourceFromTypeArgument(typeRef, it) ?: continue
+
+            if (projectionRelation != ProjectionRelation.None && typeRef.source?.kind !is FirFakeSourceElementKind) {
                 reporter.reportOn(
-                    typeArgSource ?: typeRef.source,
-                    if (type != fullyExpandedType) FirErrors.CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION else FirErrors.CONFLICTING_PROJECTION,
+                    typeArgSource ?: typeArgTypeRef.source,
+                    if (projectionRelation == ProjectionRelation.Conflicting)
+                        if (type != fullyExpandedType) FirErrors.CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION else FirErrors.CONFLICTING_PROJECTION
+                    else
+                        FirErrors.REDUNDANT_PROJECTION,
                     fullyExpandedType,
                     context
                 )
@@ -79,31 +91,9 @@ object FirConflictingProjectionChecker : FirBasicDeclarationChecker() {
         }
     }
 
-    private fun extractTypeArgumentSource(typeRef: FirTypeRef, index: Int): FirSourceElement? {
-        if (typeRef is FirResolvedTypeRef) {
-            val delegatedTypeRef = typeRef.delegatedTypeRef
-            if (delegatedTypeRef is FirUserTypeRef) {
-                var currentTypeArguments: List<FirTypeProjection>? = null
-                var currentIndex = index
-                val qualifier = delegatedTypeRef.qualifier
-
-                for (i in qualifier.size - 1 downTo 0) {
-                    val typeArguments = qualifier[i].typeArgumentList.typeArguments
-                    if (currentIndex < typeArguments.size) {
-                        currentTypeArguments = typeArguments
-                        break
-                    } else {
-                        currentIndex -= typeArguments.size
-                    }
-                }
-
-                val typeArgument = currentTypeArguments?.elementAtOrNull(currentIndex)
-                if (typeArgument is FirTypeProjectionWithVariance) {
-                    return typeArgument.source
-                }
-            }
-        }
-
-        return null
+    private enum class ProjectionRelation {
+        Conflicting,
+        Redundant,
+        None
     }
 }
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
index 6f3863f0e6a..db846fa1a37 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt
@@ -254,6 +254,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_EXPLICI
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_MODALITY_MODIFIER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_MODIFIER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_OPEN_IN_INTERFACE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_PROJECTION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_RETURN_UNIT_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_SETTER_PARAMETER_TYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_SINGLE_EXPRESSION_STRING_TEMPLATE
@@ -616,6 +617,11 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
                 "Conflicting projection in type alias expansion in intermediate type '{0}'",
                 RENDER_TYPE
             )
+            map.put(
+                REDUNDANT_PROJECTION,
+                "Projection is redundant: the corresponding type parameter of {0} has the same variance",
+                RENDER_TYPE
+            )
             map.put(
                 VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED,
                 "Variance annotations are only allowed for type parameters of classes and interfaces"
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt
deleted file mode 100644
index 107683a2e03..00000000000
--- a/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-class In<in T>
-class Out<out T>
-class Inv<T>
-class X
-
-fun f1(p: In<in X>) {}
-fun f2(p: In<<!CONFLICTING_PROJECTION!>out<!> X>) {}
-fun f3(p: In<X>) {}
-
-fun f4(p: Out<out X>) {}
-fun f5(p: Out<<!CONFLICTING_PROJECTION!>in<!> X>) {}
-fun f6(p: Out<X>) {}
-
-fun f6(p: Inv<X>) {}
-fun f7(p: Inv<in X>) {}
-fun f8(p: Inv<out X>) {}
-
-fun f9(p: In<*>) {}
-fun f10(p: Out<*>) {}
-fun f11(p: Inv<*>) {}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.kt b/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.kt
index 746da40db8c..e08fb9e1e20 100644
--- a/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.kt
+++ b/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.kt
@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 class In<in T>
 class Out<out T>
 class Inv<T>
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypesSubstitutionIntoAbbreviation.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypesSubstitutionIntoAbbreviation.fir.kt
index 32741c4edf6..d7561d83ff1 100644
--- a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypesSubstitutionIntoAbbreviation.fir.kt
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypesSubstitutionIntoAbbreviation.fir.kt
@@ -2,11 +2,11 @@ typealias Action<K> = (@UnsafeVariance K) -> Unit
 typealias Action2<K> = (@UnsafeVariance K) -> K
 
 data class Tag<L>(val action: Action<L>)
-data class Tag2<L>(val action: Action<in L>)
+data class Tag2<L>(val action: Action<<!REDUNDANT_PROJECTION!>in<!> L>)
 data class Tag3<in L>(val action: Action<L>)
-data class Tag4<in L>(val action: Action<in L>)
+data class Tag4<in L>(val action: Action<<!REDUNDANT_PROJECTION!>in<!> L>)
 data class Tag5<L>(val action: Action2<L>)
-data class Tag6<out L>(val action: Action<in L>)
+data class Tag6<out L>(val action: Action<<!REDUNDANT_PROJECTION!>in<!> L>)
 data class Tag7<out L>(val action: Action<L>)
 data class Tag8<out L>(val action: Action2<L>)
 
diff --git a/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt b/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt
index 7f0fb514060..f645dbbd820 100644
--- a/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt
+++ b/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt
@@ -13,7 +13,7 @@ fun foo() : G<Point> {
 
 class Out<out T>() {}
 
-fun <T> fout(expression : T) : Out<out T> = Out<T>()
+fun <T> fout(expression : T) : Out<<!REDUNDANT_PROJECTION!>out<!> T> = Out<T>()
 
 fun fooout() : Out<Point> {
   val p = Point();
diff --git a/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt b/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt
index 13c04c13877..a66ba100b71 100644
--- a/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt
+++ b/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt
@@ -5,13 +5,13 @@ class Out<out T>
 class Inv<T>
 
 typealias In1<T> = In<T>
-typealias In2<T> = In<in T>
+typealias In2<T> = In<<!REDUNDANT_PROJECTION!>in<!> T>
 typealias In3<T> = In<<!CONFLICTING_PROJECTION!>out<!> T>
 typealias In4<T> = In<*>
 
 typealias Out1<T> = Out<T>
 typealias Out2<T> = Out<<!CONFLICTING_PROJECTION!>in<!> T>
-typealias Out3<T> = Out<out T>
+typealias Out3<T> = Out<<!REDUNDANT_PROJECTION!>out<!> T>
 typealias Out4<T> = Out<*>
 
 typealias Inv1<T> = Inv<T>
@@ -22,12 +22,12 @@ typealias Inv4<T> = Inv<*>
 val inv1: Inv1<Int> = Inv<Int>()
 
 fun inInv_Inv(x: In1<Int>) = x
-fun inInv_In(x: In1<in Int>) = x
+fun inInv_In(x: In1<<!REDUNDANT_PROJECTION!>in<!> Int>) = x
 fun inInv_Out(x: In1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>out<!> Int>) = x
 fun inInv_Star(x: In1<*>) = x
 
 fun inIn_Inv(x: In2<Int>) = x
-fun inIn_In(x: In2<in Int>) = x
+fun inIn_In(x: In2<<!REDUNDANT_PROJECTION!>in<!> Int>) = x
 fun inIn_Out(x: In2<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>out<!> Int>) = x
 fun inIn_Star(x: In2<*>) = x
 
@@ -38,7 +38,7 @@ fun inOut_Star(x: In3<*>) = x
 
 fun outInv_Inv(x: Out1<Int>) = x
 fun outInv_In(x: Out1<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>in<!> Int>) = x
-fun outInv_Out(x: Out1<out Int>) = x
+fun outInv_Out(x: Out1<<!REDUNDANT_PROJECTION!>out<!> Int>) = x
 fun outInv_Star(x: Out1<*>) = x
 
 fun outIn_Inv(x: Out2<Int>) = x
@@ -48,7 +48,7 @@ fun outIn_Star(x: Out2<*>) = x
 
 fun outOut_Inv(x: Out3<Int>) = x
 fun outOut_In(x: Out3<<!CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION!>in<!> Int>) = x
-fun outOut_Out(x: Out3<out Int>) = x
+fun outOut_Out(x: Out3<<!REDUNDANT_PROJECTION!>out<!> Int>) = x
 fun outOut_Star(x: Out3<*>) = x
 
 fun invInv_Inv(x: Inv1<Int>) = x
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt
index 34d52277449..95c4d4badec 100644
--- a/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt
@@ -8,11 +8,11 @@ typealias InvOut = Inv<out Int>
 typealias InvT<T> = Inv<T>
 
 typealias OutStar = Out<*>
-typealias OutOut = Out<out Int>
+typealias OutOut = Out<<!REDUNDANT_PROJECTION!>out<!> Int>
 typealias OutT<T> = Out<T>
 
 typealias InStar = In<*>
-typealias InIn = In<in Int>
+typealias InIn = In<<!REDUNDANT_PROJECTION!>in<!> Int>
 typealias InT<T> = In<T>
 
 class Test1 : InvStar
@@ -24,9 +24,9 @@ class Test5 : InvT<InvT<*>>
 class Test6 : OutStar
 class Test7 : OutOut
 class Test8 : OutT<Int>
-class Test9 : OutT<out Int>
+class Test9 : OutT<<!REDUNDANT_PROJECTION!>out<!> Int>
 
 class Test10 : InStar
 class Test11 : InIn
 class Test12 : InT<Int>
-class Test13 : InT<in Int>
\ No newline at end of file
+class Test13 : InT<<!REDUNDANT_PROJECTION!>in<!> Int>
diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/13.fir.kt b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/13.fir.kt
index 484f872b425..4060ccbd849 100644
--- a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/13.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/13.fir.kt
@@ -2525,7 +2525,7 @@ fun <T> case_37(x: Map<in T, *>?) {
 }
 
 // TESTCASE NUMBER: 38
-fun <T> case_38(x: Map<*, out T>?) {
+fun <T> case_38(x: Map<*, <!REDUNDANT_PROJECTION!>out<!> T>?) {
     if (x != null) {
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<*, out T>? & kotlin.collections.Map<*, out T>")!>x<!>
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<*, out T>? & kotlin.collections.Map<*, out T>")!>x<!>.equals(null)
@@ -2731,7 +2731,7 @@ fun <T> case_40(x: InterfaceWithTwoTypeParameters<in T, in T>?) {
 }
 
 // TESTCASE NUMBER: 41
-fun <T> case_41(x: Map<out T, out T>?) {
+fun <T> case_41(x: Map<out T, <!REDUNDANT_PROJECTION!>out<!> T>?) {
     if (x != null) {
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<out T, out T>? & kotlin.collections.Map<out T, out T>")!>x<!>
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<out T, out T>? & kotlin.collections.Map<out T, out T>")!>x<!>.equals(null)
@@ -2803,7 +2803,7 @@ fun <T> case_41(x: Map<out T, out T>?) {
 }
 
 // TESTCASE NUMBER: 42
-fun <T> case_42(x: Map<T, out T>?) {
+fun <T> case_42(x: Map<T, <!REDUNDANT_PROJECTION!>out<!> T>?) {
     if (x != null) {
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<T, out T>? & kotlin.collections.Map<T, out T>")!>x<!>
         <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.collections.Map<T, out T>? & kotlin.collections.Map<T, out T>")!>x<!>.equals(null)
diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/9.fir.kt b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/9.fir.kt
index f6479804ae3..a2b6f12e658 100644
--- a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/9.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/9.fir.kt
@@ -3,7 +3,7 @@
 // SKIP_TXT
 
 // TESTCASE NUMBER: 1
-fun case_1(x: Out<out Int?>?) {
+fun case_1(x: Out<<!REDUNDANT_PROJECTION!>out<!> Int?>?) {
     if (x != null) {
         <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int?>? & Out<out kotlin.Int?>")!>x<!>
         <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int?>? & Out<out kotlin.Int?>")!>x<!>.equals(null)
@@ -23,7 +23,7 @@ fun case_1(x: Out<out Int?>?) {
  * UNEXPECTED BEHAVIOUR
  * ISSUES: KT-28598
  */
-fun case_2(a: Out<out Out<out Out<out Out<out Out<out Out<out Int?>?>?>?>?>?>?) {
+fun case_2(a: Out<<!REDUNDANT_PROJECTION!>out<!> Out<out Out<out Out<out Out<out Out<out Int?>?>?>?>?>?>?) {
     if (a != null) {
         val b = <!DEBUG_INFO_EXPRESSION_TYPE("Out<out Out<out Out<out Out<out Out<out Out<out kotlin.Int?>?>?>?>?>?>? & Out<out Out<out Out<out Out<out Out<out Out<out kotlin.Int?>?>?>?>?>?>")!>a<!>.get()
         if (b != null) {
@@ -75,7 +75,7 @@ fun case_3(a: Inv<out Int>?) {
 }
 
 // TESTCASE NUMBER: 4
-fun case_4(a: Out<out Int>?, b: Out<out Int> = if (a != null) <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>? & Out<out kotlin.Int>")!>a<!> else Out<Int>()) {
+fun case_4(a: Out<<!REDUNDANT_PROJECTION!>out<!> Int>?, b: Out<<!REDUNDANT_PROJECTION!>out<!> Int> = if (a != null) <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>? & Out<out kotlin.Int>")!>a<!> else Out<Int>()) {
     <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>?")!>a<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>")!>b<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>")!>b<!>.equals(null)
@@ -90,7 +90,7 @@ fun case_4(a: Out<out Int>?, b: Out<out Int> = if (a != null) <!DEBUG_INFO_EXPRE
 }
 
 // TESTCASE NUMBER: 5
-val x: Out<out Int>? = null
+val x: Out<<!REDUNDANT_PROJECTION!>out<!> Int>? = null
 
 fun case_5() {
     if (x != null) {
@@ -127,7 +127,7 @@ fun case_6() {
 
 // TESTCASE NUMBER: 7
 fun case_7() {
-    var x: Out<out Int>? = null
+    var x: Out<<!REDUNDANT_PROJECTION!>out<!> Int>? = null
 
     if (x != null) {
         <!DEBUG_INFO_EXPRESSION_TYPE("Out<out kotlin.Int>? & Out<out kotlin.Int>")!>x<!>
@@ -469,7 +469,7 @@ fun case_20(a: Inv<out Any?>) {
  * UNEXPECTED BEHAVIOUR
  * ISSUES: KT-28785
  */
-fun case_21(a: Out<out Int?>) {
+fun case_21(a: Out<<!REDUNDANT_PROJECTION!>out<!> Int?>) {
     if (a.x != null) {
         a.x
         a.x.equals(null)
@@ -489,7 +489,7 @@ fun case_21(a: Out<out Int?>) {
  * UNEXPECTED BEHAVIOUR
  * ISSUES: KT-28785
  */
-fun case_22(a: Out<out Nothing?>) {
+fun case_22(a: Out<<!REDUNDANT_PROJECTION!>out<!> Nothing?>) {
     if (a.x != null) {
         a.x
         a.x.hashCode()
@@ -501,7 +501,7 @@ fun case_22(a: Out<out Nothing?>) {
  * UNEXPECTED BEHAVIOUR
  * ISSUES: KT-28785
  */
-fun case_23(a: Out<out Any?>) {
+fun case_23(a: Out<<!REDUNDANT_PROJECTION!>out<!> Any?>) {
     if (a.x != null) {
         a.x
         a.x.equals(null)
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
index 5f3f1c00693..5f364455b75 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt
@@ -1200,6 +1200,13 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.REDUNDANT_PROJECTION) { firDiagnostic ->
+        RedundantProjectionImpl(
+            firSymbolBuilder.typeBuilder.buildKtType(firDiagnostic.a),
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.VARIANCE_ON_TYPE_PARAMETER_NOT_ALLOWED) { firDiagnostic ->
         VarianceOnTypeParameterNotAllowedImpl(
             firDiagnostic as FirPsiDiagnostic<*>,
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
index 2b46411aa10..6d9366f470f 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt
@@ -850,6 +850,11 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         abstract val type: KtType
     }
 
+    abstract class RedundantProjection : KtFirDiagnostic<KtTypeParameter>() {
+        override val diagnosticClass get() = RedundantProjection::class
+        abstract val type: KtType
+    }
+
     abstract class VarianceOnTypeParameterNotAllowed : KtFirDiagnostic<KtTypeParameter>() {
         override val diagnosticClass get() = VarianceOnTypeParameterNotAllowed::class
     }
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
index ecdec42eb22..72527ea5471 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
@@ -1370,6 +1370,14 @@ internal class ConflictingProjectionInTypealiasExpansionImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class RedundantProjectionImpl(
+    override val type: KtType,
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.RedundantProjection(), KtAbstractFirDiagnostic<KtTypeParameter> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class VarianceOnTypeParameterNotAllowedImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,