From 3abfe59d75f7d2051635b66c39c3b04374d7f76f Mon Sep 17 00:00:00 2001
From: Dmitry Savvinov <dmitry.savvinov@jetbrains.com>
Date: Thu, 17 Oct 2019 14:30:33 +0300
Subject: [PATCH] Deduplicate incompatible actual descriptors

Otherwise, we might get false positive AMBIGUOUS_ACTUALS due to one and
the same descriptor appearing multiple times in a list
---
 .../resolve/checkers/ExpectedActualDeclarationChecker.kt   | 7 ++++++-
 .../top/top.kt                                             | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
index a19621689c0..caac5b873ec 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
@@ -138,7 +138,12 @@ class ExpectedActualDeclarationChecker(
             }
 
         // Several compatible actuals on one path: report AMBIGUIOUS_ACTUALS here
-        val atLeastWeaklyCompatibleActuals = compatibility.filterKeys { it.isCompatibleOrWeakCompatible() }.values.flatten()
+        val atLeastWeaklyCompatibleActuals = compatibility
+            .filterKeys { it.isCompatibleOrWeakCompatible() }
+            .values
+            .flatten()
+            .distinct()
+
         if (atLeastWeaklyCompatibleActuals.size > 1) {
             trace.report(Errors.AMBIGUOUS_ACTUALS.on(
                 reportOn,
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/weaklyIncompatibleActualInIntermediateModule/top/top.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/weaklyIncompatibleActualInIntermediateModule/top/top.kt
index 54bf6400c61..f385c7d7ea1 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/weaklyIncompatibleActualInIntermediateModule/top/top.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/weaklyIncompatibleActualInIntermediateModule/top/top.kt
@@ -1,5 +1,5 @@
 package sample
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "middle, middle")!>A<!> {
+expect class A {
     fun f()
 }
\ No newline at end of file