From c9ad2b3bf991b985297ce56fe57328b1d70bc291 Mon Sep 17 00:00:00 2001
From: Ivan Kochurkin <ivan.kochurkin@jetbrains.com>
Date: Wed, 27 Oct 2021 18:20:28 +0300
Subject: [PATCH] [FIR] Ignore visited super types during bypass in
 FirInconsistentTypeParameterHelpers

Get rid of potential exponential complexity
---
 .../checkers/FirInconsistentTypeParameterHelpers.kt       | 8 ++++++--
 .../tests/generics/InconsistentTypeParameterBounds.fir.kt | 7 +++++++
 .../tests/generics/InconsistentTypeParameterBounds.kt     | 1 -
 3 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt

diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirInconsistentTypeParameterHelpers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirInconsistentTypeParameterHelpers.kt
index d04b8985dda..8a6437e9343 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirInconsistentTypeParameterHelpers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirInconsistentTypeParameterHelpers.kt
@@ -58,6 +58,7 @@ private fun buildDeepSubstitutionMultimap(
 ): Map<FirTypeParameterSymbol, ClassSymbolAndProjections> {
     val result = mutableMapOf<FirTypeParameterSymbol, ClassSymbolAndProjections>()
     val substitution = mutableMapOf<FirTypeParameterSymbol, ConeKotlinType>()
+    val visitedSupertypes = mutableSetOf<ConeKotlinType>()
     val session = context.session
     val typeContext = session.typeContext
 
@@ -94,9 +95,12 @@ private fun buildDeepSubstitutionMultimap(
         }
 
         for (superTypeRef in classSymbol.resolvedSuperTypeRefs) {
+            val fullyExpandedType = superTypeRef.coneType.fullyExpandedType(session)
+            if (!visitedSupertypes.add(fullyExpandedType))
+                return
+
+            val superClassSymbol = fullyExpandedType.toRegularClassSymbol(session)
             withSuppressedDiagnostics(superTypeRef, context) {
-                val fullyExpandedType = superTypeRef.coneType.fullyExpandedType(session)
-                val superClassSymbol = fullyExpandedType.toRegularClassSymbol(session)
                 if (!fullyExpandedType.isEnum && superClassSymbol != null) {
                     fillInDeepSubstitutor(fullyExpandedType.typeArguments, superClassSymbol)
                 }
diff --git a/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt
new file mode 100644
index 00000000000..df51cf022ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt
@@ -0,0 +1,7 @@
+interface A
+interface B : A
+
+interface ListA : List<A>
+interface ListB : List<B>
+
+interface Z<<!INCONSISTENT_TYPE_PARAMETER_BOUNDS!>T<!>> where T : ListA, T : ListB
diff --git a/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.kt b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.kt
index 74e687e8307..71dc57aa668 100644
--- a/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.kt
+++ b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.kt
@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 interface A
 interface B : A