From 48cea4b80000f0d11bb5579af59f365ef7b2f428 Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <mikhail.glukhikh@jetbrains.com>
Date: Mon, 17 Jun 2019 19:14:09 +0300
Subject: [PATCH] FIR: take expected type into account during inference

NB: this commit provokes some inference problems,
which are fixed by next commit about type inference for assignments
---
 .../fir/resolve/transformers/FirBodyResolveTransformer.kt    | 5 +++++
 compiler/fir/resolve/testData/resolve/stdlib/hashSet.txt     | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirBodyResolveTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirBodyResolveTransformer.kt
index dc533f06c5c..ff1dcc54324 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirBodyResolveTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirBodyResolveTransformer.kt
@@ -39,6 +39,7 @@ import org.jetbrains.kotlin.resolve.calls.NewCommonSuperTypeCalculator
 import org.jetbrains.kotlin.resolve.calls.components.InferenceSession
 import org.jetbrains.kotlin.resolve.calls.inference.buildAbstractResultingSubstitutor
 import org.jetbrains.kotlin.resolve.calls.inference.components.KotlinConstraintSystemCompleter
+import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystemConstraintPosition
 import org.jetbrains.kotlin.resolve.calls.results.TypeSpecificityComparator
 import org.jetbrains.kotlin.types.model.*
 import org.jetbrains.kotlin.utils.addIfNotNull
@@ -602,6 +603,10 @@ open class FirBodyResolveTransformer(val session: FirSession, val implicitTypeOn
 
         val initialType = initialSubstitutor.substituteOrSelf(typeRef.type)
 
+        if (expectedTypeRef is FirResolvedTypeRef) {
+            candidate.system.addSubtypeConstraint(initialType, expectedTypeRef.type, SimpleConstraintSystemConstraintPosition)
+        }
+
         val completionMode = candidate.computeCompletionMode(inferenceComponents, expectedTypeRef, initialType)
         val completer = ConstraintSystemCompleter(inferenceComponents)
         val replacements = mutableMapOf<FirExpression, FirExpression>()
diff --git a/compiler/fir/resolve/testData/resolve/stdlib/hashSet.txt b/compiler/fir/resolve/testData/resolve/stdlib/hashSet.txt
index ca80d3e7ee9..f6a513b7b8e 100644
--- a/compiler/fir/resolve/testData/resolve/stdlib/hashSet.txt
+++ b/compiler/fir/resolve/testData/resolve/stdlib/hashSet.txt
@@ -1,5 +1,5 @@
 FILE: hashSet.kt
-    public final val a: R|kotlin/collections/MutableSet<kotlin/String>|? = R|java/util/HashSet.HashSet|<R|kotlin/Any|?>()
+    public final val a: R|kotlin/collections/MutableSet<kotlin/String>|? = R|java/util/HashSet.HashSet|<R|kotlin/String|>()
         public get(): R|kotlin/collections/MutableSet<kotlin/String>|?
     public final var b: R|kotlin/collections/MutableSet<kotlin/String>|? = Null(null)
         public get(): R|kotlin/collections/MutableSet<kotlin/String>|?