From 374b59dee31e0c95e3aa1fe379f2874d75c19262 Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <mikhail.glukhikh@jetbrains.com>
Date: Tue, 28 May 2019 20:36:17 +0300
Subject: [PATCH] FIR resolve: add early explicit receiver type check

Before this commit, explicit extension receiver type check was performed
during found candidates analysis (together with arguments type check etc.)
Now we do it just after candidate is found, and filter the candidate
out if explicit receiver type is inappropriate.

This commit slightly changes resolve semantics,
replacing WRONG_RECEIVER with UNRESOLVED_REFERENCE in certain situations.
However, it provides significant performance boost.
---
 .../kotlin/fir/resolve/calls/CallResolver.kt  | 39 ++++++++++++++-----
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallResolver.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallResolver.kt
index 694198df82d..006f18437b5 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallResolver.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CallResolver.kt
@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.expressions.FirResolvedQualifier
 import org.jetbrains.kotlin.fir.resolve.FirSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.ScopeSession
+import org.jetbrains.kotlin.fir.resolve.constructClassType
 import org.jetbrains.kotlin.fir.resolve.scope
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculator
@@ -29,12 +30,15 @@ import org.jetbrains.kotlin.fir.symbols.*
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
+import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystemConstraintPosition
 import org.jetbrains.kotlin.resolve.calls.model.PostponedResolvedAtomMarker
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
+import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.utils.addToStdlib.cast
 import kotlin.coroutines.*
 import kotlin.coroutines.intrinsics.createCoroutineUnintercepted
@@ -544,14 +548,34 @@ class ExplicitReceiverTowerDataConsumer<T : ConeSymbol>(
                             dispatchReceiverValue: ClassDispatchReceiverValue?,
                             implicitExtensionReceiverValue: ImplicitReceiverValue?
                         ): ProcessorAction {
+                            val explicitReceiverType = explicitReceiver.type
+                            if (dispatchReceiverValue == null && explicitReceiverType is ConeClassType) {
+                                val declarationReceiverTypeRef = (symbol as? FirCallableSymbol)?.fir?.receiverTypeRef as? FirResolvedTypeRef
+                                val declarationReceiverType = declarationReceiverTypeRef?.type
+                                if (declarationReceiverType is ConeClassType) {
+                                    if (!AbstractTypeChecker.isSubtypeOf(
+                                            candidateFactory.inferenceComponents.ctx,
+                                            explicitReceiverType,
+                                            declarationReceiverType.lookupTag.constructClassType(
+                                                declarationReceiverType.typeArguments.map { ConeStarProjection }.toTypedArray(),
+                                                isNullable = true
+                                            )
+                                        )
+                                    ) {
+                                        return ProcessorAction.NEXT
+                                    }
+                                }
+                            }
+                            val candidate = candidateFactory.createCandidate(
+                                symbol,
+                                dispatchReceiverValue,
+                                implicitExtensionReceiverValue,
+                                ExplicitReceiverKind.EXTENSION_RECEIVER
+                            )
+
                             resultCollector.consumeCandidate(
                                 group,
-                                candidateFactory.createCandidate(
-                                    symbol,
-                                    dispatchReceiverValue,
-                                    implicitExtensionReceiverValue,
-                                    ExplicitReceiverKind.EXTENSION_RECEIVER
-                                )
+                                candidate
                             )
                             return ProcessorAction.NEXT
                         }
@@ -690,9 +714,6 @@ enum class CandidateApplicability {
     RESOLVED
 }
 
-
-var ID = ""
-
 class CandidateCollector(val callInfo: CallInfo, val components: InferenceComponents) {
 
     val groupNumbers = mutableListOf<Int>()