From d4c6e55e0ab6e17ecb7f706193dae5aba57fa395 Mon Sep 17 00:00:00 2001
From: Nikolay Lunyak <nikolay.lunyak@jetbrains.com>
Date: Thu, 6 Jul 2023 09:53:52 +0300
Subject: [PATCH] [FIR] Require equivalent candidates to have the same
 parameters count

---
 .../jvm/ConeEquivalentCallConflictResolver.kt | 20 ++++++++++++++++---
 .../overloadConflicts/varargsMixed.fir.kt     |  2 +-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/compiler/fir/java/src/org/jetbrains/kotlin/fir/resolve/calls/jvm/ConeEquivalentCallConflictResolver.kt b/compiler/fir/java/src/org/jetbrains/kotlin/fir/resolve/calls/jvm/ConeEquivalentCallConflictResolver.kt
index b6f53e60ce9..f9be90c5740 100644
--- a/compiler/fir/java/src/org/jetbrains/kotlin/fir/resolve/calls/jvm/ConeEquivalentCallConflictResolver.kt
+++ b/compiler/fir/java/src/org/jetbrains/kotlin/fir/resolve/calls/jvm/ConeEquivalentCallConflictResolver.kt
@@ -68,7 +68,7 @@ class ConeEquivalentCallConflictResolver(
         if (first is FirVariable != second is FirVariable) {
             return false
         }
-        if (!firstCandidate.orderOfMappedArguments.contentEquals(secondCandidate.orderOfMappedArguments)) {
+        if (!firstCandidate.mappedArgumentsOrderRepresentation.contentEquals(secondCandidate.mappedArgumentsOrderRepresentation)) {
             return false
         }
         val firstSignature = createFlatSignature(firstCandidate, first)
@@ -77,11 +77,25 @@ class ConeEquivalentCallConflictResolver(
                 compareCallsByUsedArguments(secondSignature, firstSignature, discriminateGenerics = false, useOriginalSamTypes = false)
     }
 
-    private val Candidate.orderOfMappedArguments: IntArray?
+    /**
+     * If the candidate is a function, then the arguments
+     * order representation is an array containing the
+     * parameters count and the indices of the parameters
+     * that the call arguments correspond to in the order
+     * the call arguments happen to be.
+     *
+     * Otherwise, null.
+     */
+    private val Candidate.mappedArgumentsOrderRepresentation: IntArray?
         get() {
             val function = symbol.fir as? FirFunction ?: return null
             val parametersToIndices = function.valueParameters.mapIndexed { index, it -> it to index }.toMap()
-            return argumentMapping?.map { parametersToIndices[it.value] ?: error("Unmapped argument in arguments mapping") }?.toIntArray()
+            val mapping = argumentMapping ?: return null
+            val result = IntArray(mapping.size + 1) { function.valueParameters.size }
+            for ((index, parameter) in mapping.values.withIndex()) {
+                result[index + 1] = parametersToIndices[parameter] ?: error("Unmapped argument in arguments mapping")
+            }
+            return result
         }
 
     private fun createFlatSignature(call: Candidate, declaration: FirCallableDeclaration): FlatSignature<Candidate> {
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt
index bbd1b14884b..761e283d389 100644
--- a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt
@@ -7,7 +7,7 @@ object X2
 fun overloadedFun5(vararg ss: String) = X1
 fun overloadedFun5(s: String, vararg ss: String) = X2
 
-val test1 = overloadedFun5("")
+val test1 = <!OVERLOAD_RESOLUTION_AMBIGUITY!>overloadedFun5<!>("")
 val test2 = <!OVERLOAD_RESOLUTION_AMBIGUITY!>overloadedFun5<!>("", "")
 val test3: X2 = overloadedFun5(s = "", ss = <!ARGUMENT_TYPE_MISMATCH, ASSIGNING_SINGLE_ELEMENT_TO_VARARG_IN_NAMED_FORM_FUNCTION_ERROR!>""<!>)
 val test4: X1 = overloadedFun5(ss = <!ARGUMENT_TYPE_MISMATCH, ASSIGNING_SINGLE_ELEMENT_TO_VARARG_IN_NAMED_FORM_FUNCTION_ERROR!>""<!>)