FIR: Temporary support FE 1.0 behavior for SAM vs. generic ambiguity

^KT-48300 Relates
^KT-48938 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -25249,6 +25249,18 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/samConversions/samConversionsWithSmartCasts.kt");
             }
 
+            @Test
+            @TestMetadata("samPriorityVsGeneric.kt")
+            public void testSamPriorityVsGeneric() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGeneric.kt");
+            }
+
+            @Test
+            @TestMetadata("samPriorityVsGenericCompatibilityDisabled.kt")
+            public void testSamPriorityVsGenericCompatibilityDisabled() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGenericCompatibilityDisabled.kt");
+            }
+
             @Test
             @TestMetadata("sameCandidatesFromKotlinAndJavaInOneScope.kt")
             public void testSameCandidatesFromKotlinAndJavaInOneScope() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -25249,6 +25249,18 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/samConversions/samConversionsWithSmartCasts.kt");
             }
 
+            @Test
+            @TestMetadata("samPriorityVsGeneric.kt")
+            public void testSamPriorityVsGeneric() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGeneric.kt");
+            }
+
+            @Test
+            @TestMetadata("samPriorityVsGenericCompatibilityDisabled.kt")
+            public void testSamPriorityVsGenericCompatibilityDisabled() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGenericCompatibilityDisabled.kt");
+            }
+
             @Test
             @TestMetadata("sameCandidatesFromKotlinAndJavaInOneScope.kt")
             public void testSameCandidatesFromKotlinAndJavaInOneScope() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -25249,6 +25249,18 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/samConversions/samConversionsWithSmartCasts.kt");
             }
 
+            @Test
+            @TestMetadata("samPriorityVsGeneric.kt")
+            public void testSamPriorityVsGeneric() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGeneric.kt");
+            }
+
+            @Test
+            @TestMetadata("samPriorityVsGenericCompatibilityDisabled.kt")
+            public void testSamPriorityVsGenericCompatibilityDisabled() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGenericCompatibilityDisabled.kt");
+            }
+
             @Test
             @TestMetadata("sameCandidatesFromKotlinAndJavaInOneScope.kt")
             public void testSameCandidatesFromKotlinAndJavaInOneScope() throws Exception {

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

@@ -5,26 +5,27 @@
 
 package org.jetbrains.kotlin.fir.resolve.calls
 
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.fir.FirVisibilityChecker
+import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.expressions.*
-import org.jetbrains.kotlin.fir.matchingParameterFunctionType
 import org.jetbrains.kotlin.fir.references.FirSuperReference
 import org.jetbrains.kotlin.fir.resolve.directExpansionType
 import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
 import org.jetbrains.kotlin.fir.resolve.inference.*
 import org.jetbrains.kotlin.fir.resolve.isTypeMismatchDueToNullability
 import org.jetbrains.kotlin.fir.resolve.toSymbol
+import org.jetbrains.kotlin.fir.scopes.FirTypeScope
 import org.jetbrains.kotlin.fir.scopes.FirUnstableSmartcastTypeScope
+import org.jetbrains.kotlin.fir.scopes.ProcessorAction
+import org.jetbrains.kotlin.fir.scopes.processOverriddenFunctions
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.SyntheticSymbol
 import org.jetbrains.kotlin.fir.symbols.ensureResolved
 import org.jetbrains.kotlin.fir.symbols.impl.*
-import org.jetbrains.kotlin.fir.typeContext
 import org.jetbrains.kotlin.fir.types.*
-import org.jetbrains.kotlin.fir.visibilityChecker
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -351,12 +352,42 @@ internal object CheckArguments : CheckerStage() {
                 context = context
             )
         }
-        if (candidate.system.hasContradiction && callInfo.arguments.isNotEmpty()) {
-            sink.yieldDiagnostic(InapplicableCandidate)
+
+        when {
+            candidate.system.hasContradiction && callInfo.arguments.isNotEmpty() -> {
+                sink.yieldDiagnostic(InapplicableCandidate)
+            }
+            candidate.usesSAM && !candidate.isJavaApplicableCandidate() -> {
+                sink.markCandidateForCompatibilityResolve(context)
+            }
         }
     }
 }
 
+private fun Candidate.isJavaApplicableCandidate(): Boolean {
+    val symbol = symbol as? FirNamedFunctionSymbol ?: return false
+    if (symbol.origin == FirDeclarationOrigin.Enhancement) return true
+    if (originScope !is FirTypeScope) return false
+
+    var result = false
+
+    originScope.processOverriddenFunctions(symbol) {
+        if (it.origin == FirDeclarationOrigin.Enhancement) {
+            result = true
+            ProcessorAction.STOP
+        } else {
+            ProcessorAction.NEXT
+        }
+    }
+
+    return result
+}
+
+private fun CheckerSink.markCandidateForCompatibilityResolve(context: ResolutionContext) {
+    if (context.session.languageVersionSettings.supportsFeature(LanguageFeature.DisableCompatibilityModeForNewInference)) return
+    reportDiagnostic(LowerPriorityToPreserveCompatibilityDiagnostic)
+}
+
 internal object EagerResolveOfCallableReferences : CheckerStage() {
     override suspend fun check(candidate: Candidate, callInfo: CallInfo, sink: CheckerSink, context: ResolutionContext) {
         if (candidate.postponedAtoms.isEmpty()) return
@@ -368,7 +399,7 @@ internal object EagerResolveOfCallableReferences : CheckerStage() {
                     sink.yieldDiagnostic(InapplicableCandidate)
                 } else when (applicability) {
                     CandidateApplicability.RESOLVED_NEED_PRESERVE_COMPATIBILITY ->
-                        candidate.addDiagnostic(LowerPriorityToPreserveCompatibilityDiagnostic)
+                        sink.reportDiagnostic(LowerPriorityToPreserveCompatibilityDiagnostic)
                     else -> {
                     }
                 }

compiler/testData/diagnostics/tests/samConversions/samPriorityVsGeneric.kt

@@ -0,0 +1,13 @@
+// SKIP_TXT
+// FIR_IDENTICAL
+// FULL_JDK
+
+fun <T> bar(action: () -> T): T = action()
+fun bar(action: java.lang.Runnable) { }
+
+fun foo(): String = ""
+
+fun main() {
+    val x = bar() { foo() } // OK with default current 1.5/1.6, Error with DisableCompatibilityModeForNewInference enabled
+    x.length
+}

compiler/testData/diagnostics/tests/samConversions/samPriorityVsGenericCompatibilityDisabled.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +DisableCompatibilityModeForNewInference
+// SKIP_TXT
+// FIR_IDENTICAL
+// FULL_JDK
+
+fun <T> bar(action: () -> T): T = action()
+fun bar(action: java.lang.Runnable) { }
+
+fun foo(): String = ""
+
+fun main() {
+    val x = bar() { foo() } // OK with default current 1.5/1.6, Error with DisableCompatibilityModeForNewInference enabled
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -25261,6 +25261,18 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/samConversions/samConversionsWithSmartCasts.kt");
             }
 
+            @Test
+            @TestMetadata("samPriorityVsGeneric.kt")
+            public void testSamPriorityVsGeneric() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGeneric.kt");
+            }
+
+            @Test
+            @TestMetadata("samPriorityVsGenericCompatibilityDisabled.kt")
+            public void testSamPriorityVsGenericCompatibilityDisabled() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/samConversions/samPriorityVsGenericCompatibilityDisabled.kt");
+            }
+
             @Test
             @TestMetadata("sameCandidatesFromKotlinAndJavaInOneScope.kt")
             public void testSameCandidatesFromKotlinAndJavaInOneScope() throws Exception {