[FIR] Implement SAM candidates discrimination

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt

@@ -110,7 +110,9 @@ class FirCallResolver(
         return resultFunctionCall
     }
 
-    private data class ResolutionResult(val info: CallInfo, val applicability: CandidateApplicability, val candidates: Collection<Candidate>)
+    private data class ResolutionResult(
+        val info: CallInfo, val applicability: CandidateApplicability, val candidates: Collection<Candidate>
+    )
 
     private fun collectCandidates(functionCall: FirFunctionCall): ResolutionResult {
         val explicitReceiver = functionCall.explicitReceiver
@@ -289,7 +291,7 @@ class FirCallResolver(
         symbol: FirClassSymbol<*>,
         typeArguments: List<FirTypeProjection>
     ): FirDelegatedConstructorCall? {
-        val scope = symbol.fir.unsubstitutedScope(session, scopeSession) ?: return null
+        val scope = symbol.fir.unsubstitutedScope(session, scopeSession)
         val className = symbol.classId.shortClassName
         val callInfo = CallInfo(
             CallKind.Function,
@@ -313,7 +315,9 @@ class FirCallResolver(
         return callResolver.selectCandidateFromGivenCandidates(delegatedConstructorCall, className, candidates)
     }
 
-    fun <T> selectCandidateFromGivenCandidates(call: T, name: Name, candidates: Collection<Candidate>): T where T : FirResolvable, T : FirCall {
+    private fun <T> selectCandidateFromGivenCandidates(
+        call: T, name: Name, candidates: Collection<Candidate>
+    ): T where T : FirResolvable, T : FirCall {
         val result = CandidateCollector(this, resolutionStageRunner)
         candidates.forEach { result.consumeCandidate(TowerGroup.Start, it) }
         val bestCandidates = result.bestCandidates()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Arguments.kt

@@ -306,7 +306,9 @@ private fun Candidate.getExpectedTypeWithSAMConversion(
 
     // TODO: resolvedCall.registerArgumentWithSamConversion(argument, SamConversionDescription(convertedTypeByOriginal, convertedTypeByCandidate!!))
 
-    return samResolver.getFunctionTypeForPossibleSamType(candidateExpectedType) ?: return null
+    return samResolver.getFunctionTypeForPossibleSamType(candidateExpectedType).apply {
+        usesSAM = true
+    } ?: return null
 }
 
 internal fun FirExpression.getExpectedType(

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Candidate.kt

@@ -104,6 +104,7 @@ class Candidate(
     lateinit var freshVariables: List<ConeTypeVariable>
     var resultingTypeForCallableReference: ConeKotlinType? = null
     var outerConstraintBuilderEffect: (ConstraintSystemOperation.() -> Unit)? = null
+    var usesSAM: Boolean = false
 
     var argumentMapping: Map<FirExpression, FirValueParameter>? = null
     val postponedAtoms = mutableListOf<PostponedResolvedAtomMarker>()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ConeOverloadConflictResolver.kt

@@ -28,6 +28,14 @@ class ConeOverloadConflictResolver(
     override fun chooseMaximallySpecificCandidates(
         candidates: Set<Candidate>,
         discriminateGenerics: Boolean
+    ): Set<Candidate> {
+        return chooseMaximallySpecificCandidates(candidates, discriminateGenerics, discriminateSAMs = true)
+    }
+
+    private fun chooseMaximallySpecificCandidates(
+        candidates: Set<Candidate>,
+        discriminateGenerics: Boolean,
+        discriminateSAMs: Boolean
     ): Set<Candidate> {
         findMaximallySpecificCall(candidates, false)?.let { return setOf(it) }
 
@@ -35,6 +43,16 @@ class ConeOverloadConflictResolver(
             findMaximallySpecificCall(candidates, true)?.let { return setOf(it) }
         }
 
+        if (discriminateSAMs) {
+            val filtered = candidates.filterTo(mutableSetOf()) { !it.usesSAM }
+            when (filtered.size) {
+                1 -> return filtered
+                0, candidates.size -> {
+                }
+                else -> return chooseMaximallySpecificCandidates(filtered, discriminateGenerics, discriminateSAMs = false)
+            }
+        }
+
         return candidates
     }
 

compiler/fir/resolve/testData/resolve/stdlib/problems/inapplicableRemoveAll.kt

@@ -1,5 +1,5 @@
 fun test(list: MutableList<String>) {
-    list.<!AMBIGUITY!>removeAll<!> {
+    list.removeAll {
-        <!UNRESOLVED_REFERENCE!>it<!>.<!AMBIGUITY!>isEmpty<!>()
+        it.isEmpty()
     }
 }

compiler/fir/resolve/testData/resolve/stdlib/problems/inapplicableRemoveAll.txt

@@ -1,7 +1,7 @@
 FILE: inapplicableRemoveAll.kt
     public final fun test(list: R|kotlin/collections/MutableList<kotlin/String>|): R|kotlin/Unit| {
-        R|<local>/list|.<Ambiguity: removeAll, [kotlin/collections/removeAll, kotlin/collections/removeAll, kotlin/collections/removeAll, kotlin/collections/removeAll]>#(<L> = removeAll@fun <anonymous>(): R|ERROR CLASS: Ambiguity: isEmpty, [kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/text/isEmpty]| {
+        R|<local>/list|.R|kotlin/collections/removeAll|<R|kotlin/String|>(<L> = removeAll@fun <anonymous>(it: R|kotlin/String|): R|kotlin/Boolean| {
-            <Unresolved name: it>#.<Ambiguity: isEmpty, [kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/collections/isEmpty, kotlin/text/isEmpty]>#()
+            R|<local>/it|.R|kotlin/text/isEmpty|()
         }
         )
     }

compiler/testData/diagnostics/tests/platformTypes/methodCall/kt27565.fir.kt

@@ -11,8 +11,8 @@ public interface Runnable {
 // FILE: k.kt
 
 fun fail() {
-    <!AMBIGUITY!>foo<!>({ }, { })
+    foo({ }, { })
-    <!AMBIGUITY!>foo<!>(::bar, { })
+    foo(::bar, { })
 }
 
 fun foo(f: Runnable, selector: () -> Unit) {}

compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.fir.kt

@@ -7,4 +7,4 @@ object X2
 fun <T1> foo(x: T1, f: (T1) -> T1) = X1
 fun <T2> foo(xf: () -> T2, f: (T2) -> T2) = X2
 
-val test: X2 = <!AMBIGUITY!>foo<!>({ 0 }, { it -> it + 1 })
+val test: X2 = foo({ 0 }, { it -> it + 1 })

compiler/testData/diagnostics/tests/samConversions/sameCandidatesFromKotlinAndJavaInOneScope.fir.kt

@@ -21,6 +21,6 @@ interface B {
 interface C : B, Other
 
 fun test(c: C) {
-    c.<!AMBIGUITY!>pluginManagement<!> {
+    c.pluginManagement {
     }
 }