FIR: Support static methods in callable references

^KT-32725 In Progress

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

@@ -284,17 +284,42 @@ class FirCallResolver(
                 name, resultCollector, callableReferenceAccess.explicitReceiver, expectedType, outerConstraintSystemBuilder,
                 lhs
             )
-            is DoubleColonLHS.Type -> createCallableReferencesConsumerForReceiver(
+            is DoubleColonLHS.Type -> createCallableReferencesConsumerForReceivers(
                 name,
                 resultCollector,
-                FirExpressionStub(callableReferenceAccess.psi).apply { replaceTypeRef(FirResolvedTypeRefImpl(null, lhs.type)) },
                 expectedType,
                 outerConstraintSystemBuilder,
-                lhs
+                lhs,
+                FirExpressionStub(callableReferenceAccess.psi).apply { replaceTypeRef(FirResolvedTypeRefImpl(null, lhs.type)) },
+                callableReferenceAccess.explicitReceiver
             )
         }
     }
 
+    private fun createCallableReferencesConsumerForReceivers(
+        name: Name,
+        resultCollector: CandidateCollector,
+        expectedType: ConeKotlinType?,
+        outerConstraintSystemBuilder: ConstraintSystemBuilder?,
+        lhs: DoubleColonLHS?,
+        vararg receivers: FirExpression?
+    ): TowerDataConsumer {
+        if (receivers.size == 1) {
+            return createCallableReferencesConsumerForReceiver(
+                name, resultCollector, receivers[0], expectedType, outerConstraintSystemBuilder, lhs
+            )
+        }
+
+        return PrioritizedTowerDataConsumer(
+            resultCollector,
+            *Array(receivers.size) { index ->
+                createCallableReferencesConsumerForReceiver(
+                    name, resultCollector, receivers[index], expectedType, outerConstraintSystemBuilder, lhs
+                )
+            }
+        )
+    }
+
     private fun createCallableReferencesConsumerForReceiver(
         name: Name,
         resultCollector: CandidateCollector,

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

@@ -177,10 +177,14 @@ internal object CheckCallableReferenceExpectedType : CheckerStage() {
     override suspend fun check(candidate: Candidate, sink: CheckerSink, callInfo: CallInfo) {
         val outerCsBuilder = callInfo.outerCSBuilder ?: return
         val expectedType = callInfo.expectedType ?: return
-        val lhs = callInfo.lhs
+
+        val resultingReceiverType = when (callInfo.lhs) {
+            is DoubleColonLHS.Type -> callInfo.lhs.type.takeIf { callInfo.explicitReceiver !is FirResolvedQualifier }
+            else -> null
+        }
 
         val resultingType: ConeKotlinType = when (val fir = candidate.symbol.fir) {
-            is FirSimpleFunction -> createKFunctionType(fir, lhs)
+            is FirSimpleFunction -> createKFunctionType(fir, resultingReceiverType)
             is FirProperty -> createKPropertyType(fir)
             else -> ConeKotlinErrorType("Unknown callable kind: ${fir::class}")
         }.let(candidate.substitutor::substituteOrSelf)
@@ -212,9 +216,8 @@ private fun createKPropertyType(fir: FirProperty): ConeKotlinType {
 
 private fun createKFunctionType(
     function: FirSimpleFunction,
-    lhs: DoubleColonLHS?
+    receiverType: ConeKotlinType?
 ): ConeKotlinType {
-    val receiverType = (lhs as? DoubleColonLHS.Type)?.type
     val parameterTypes = function.valueParameters.map {
         it.returnTypeRef.coneTypeSafe<ConeKotlinType>() ?: ConeKotlinErrorType("No type for parameter $it")
     }

compiler/fir/resolve/testData/diagnostics/callableReferences/companions.kt

@@ -0,0 +1,43 @@
+// FILE: JavaClass.java
+public class JavaClass {
+    public static int bar(String x) { return 0; }
+    public int bar(CharSequence x) { return 0; }
+}
+
+// FILE: main.kt
+
+class KotlinClass : JavaClass() {
+    fun baz(x: CharSequence): Int = 1
+    companion object {
+        fun baz(x: String): Int = 1
+    }
+}
+
+class KotlinClass2 : JavaClass() {
+    override fun bar(x: CharSequence): Int = 1
+    companion object {
+        fun bar(x: String): Int = 1
+    }
+}
+
+fun foo1(x: (String) -> Int) {}
+
+fun foo2(x: (KotlinClass, CharSequence) -> Int) {}
+
+fun foo3(x: (KotlinClass, CharSequence) -> Int) {}
+fun foo3(x: (String) -> Int) {}
+
+fun main() {
+    foo1(KotlinClass::baz)
+    foo2(KotlinClass::baz)
+    foo3(KotlinClass::baz)
+
+    foo1(KotlinClass::bar)
+    foo2(KotlinClass::bar)
+    foo3(KotlinClass::bar)
+
+    foo1(KotlinClass2::bar)
+    foo2(KotlinClass2::bar)
+    foo3(KotlinClass2::bar)
+}
+

compiler/fir/resolve/testData/diagnostics/callableReferences/companions.txt

@@ -0,0 +1,62 @@
+FILE: main.kt
+    public final class KotlinClass : R|JavaClass| {
+        public constructor(): R|KotlinClass| {
+            super<R|JavaClass|>()
+        }
+
+        public final fun baz(x: R|kotlin/CharSequence|): R|kotlin/Int| {
+            ^baz Int(1)
+        }
+
+        public final companion object Companion : R|kotlin/Any| {
+            private constructor(): R|KotlinClass.Companion| {
+                super<R|kotlin/Any|>()
+            }
+
+            public final fun baz(x: R|kotlin/String|): R|kotlin/Int| {
+                ^baz Int(1)
+            }
+
+        }
+
+    }
+    public final class KotlinClass2 : R|JavaClass| {
+        public constructor(): R|KotlinClass2| {
+            super<R|JavaClass|>()
+        }
+
+        public final override fun bar(x: R|kotlin/CharSequence|): R|kotlin/Int| {
+            ^bar Int(1)
+        }
+
+        public final companion object Companion : R|kotlin/Any| {
+            private constructor(): R|KotlinClass2.Companion| {
+                super<R|kotlin/Any|>()
+            }
+
+            public final fun bar(x: R|kotlin/String|): R|kotlin/Int| {
+                ^bar Int(1)
+            }
+
+        }
+
+    }
+    public final fun foo1(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo2(x: R|kotlin/Function2<KotlinClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo3(x: R|kotlin/Function2<KotlinClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo3(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun main(): R|kotlin/Unit| {
+        R|/foo1|(Q|KotlinClass|::R|/KotlinClass.Companion.baz|)
+        R|/foo2|(Q|KotlinClass|::R|/KotlinClass.baz|)
+        <Ambiguity: foo3, [/foo3, /foo3]>#(Q|KotlinClass|::baz#)
+        R|/foo1|(Q|KotlinClass|::R|/JavaClass.bar|)
+        R|/foo2|(Q|KotlinClass|::R|/JavaClass.bar|)
+        <Ambiguity: foo3, [/foo3, /foo3]>#(Q|KotlinClass|::bar#)
+        R|/foo1|(Q|KotlinClass2|::R|/JavaClass.bar|)
+        <Inapplicable(INAPPLICABLE): [/foo2]>#(Q|KotlinClass2|::bar#)
+        R|/foo3|(Q|KotlinClass2|::R|/JavaClass.bar|)
+    }

compiler/fir/resolve/testData/diagnostics/callableReferences/javaStatic.kt

@@ -0,0 +1,20 @@
+// FILE: JavaClass.java
+public class JavaClass {
+    public static int bar(String x) { return 0; }
+    public int bar(CharSequence x) { return 0; }
+}
+
+// FILE: main.kt
+
+fun foo1(x: (String) -> Int) {}
+
+fun foo2(x: (JavaClass, CharSequence) -> Int) {}
+
+fun foo3(x: (JavaClass, CharSequence) -> Int) {}
+fun foo3(x: (String) -> Int) {}
+
+fun main() {
+    foo1(JavaClass::bar)
+    foo2(JavaClass::bar)
+    foo3(JavaClass::bar)
+}

compiler/fir/resolve/testData/diagnostics/callableReferences/javaStatic.txt

@@ -0,0 +1,14 @@
+FILE: main.kt
+    public final fun foo1(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo2(x: R|kotlin/Function2<JavaClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo3(x: R|kotlin/Function2<JavaClass, kotlin/CharSequence, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun foo3(x: R|kotlin/Function1<kotlin/String, kotlin/Int>|): R|kotlin/Unit| {
+    }
+    public final fun main(): R|kotlin/Unit| {
+        R|/foo1|(Q|JavaClass|::R|/JavaClass.bar|)
+        R|/foo2|(Q|JavaClass|::R|/JavaClass.bar|)
+        <Ambiguity: foo3, [/foo3, /foo3]>#(Q|JavaClass|::bar#)
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -40,6 +40,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/fir/resolve/testData/diagnostics/callableReferences"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("companions.kt")
+        public void testCompanions() throws Exception {
+            runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/companions.kt");
+        }
+
         @TestMetadata("differentLevels.kt")
         public void testDifferentLevels() throws Exception {
             runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/differentLevels.kt");
@@ -55,6 +60,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
             runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/inferenceFromExpectedType.kt");
         }
 
+        @TestMetadata("javaStatic.kt")
+        public void testJavaStatic() throws Exception {
+            runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/javaStatic.kt");
+        }
+
         @TestMetadata("manyCandidatesInference.kt")
         public void testManyCandidatesInference() throws Exception {
             runTest("compiler/fir/resolve/testData/diagnostics/callableReferences/manyCandidatesInference.kt");