FIR: Allow to skip specifying type arguments for members from raw type

^KT-54666 Fixed
^KT-54526 Related

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

@@ -24181,6 +24181,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                     runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/kt47459.kt");
                 }
 
+                @Test
+                @TestMetadata("noTypeArgumentsForRawScopedMembers.kt")
+                public void testNoTypeArgumentsForRawScopedMembers() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.kt");
+                }
+
                 @Test
                 @TestMetadata("nonGenericRawMember.kt")
                 public void testNonGenericRawMember() throws Exception {

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

@@ -24181,6 +24181,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/kt47459.kt");
                 }
 
+                @Test
+                @TestMetadata("noTypeArgumentsForRawScopedMembers.kt")
+                public void testNoTypeArgumentsForRawScopedMembers() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.kt");
+                }
+
                 @Test
                 @TestMetadata("nonGenericRawMember.kt")
                 public void testNonGenericRawMember() throws Exception {

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

@@ -24181,6 +24181,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                     runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/kt47459.kt");
                 }
 
+                @Test
+                @TestMetadata("noTypeArgumentsForRawScopedMembers.kt")
+                public void testNoTypeArgumentsForRawScopedMembers() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.kt");
+                }
+
                 @Test
                 @TestMetadata("nonGenericRawMember.kt")
                 public void testNonGenericRawMember() throws Exception {

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

@@ -5,11 +5,17 @@
 
 package org.jetbrains.kotlin.fir.resolve.calls
 
+import org.jetbrains.kotlin.fir.declarations.FirCallableDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirDeclarationOrigin
 import org.jetbrains.kotlin.fir.declarations.FirTypeParameterRefsOwner
+import org.jetbrains.kotlin.fir.types.ConeTypeIntersector
 import org.jetbrains.kotlin.fir.types.FirTypeProjection
 import org.jetbrains.kotlin.fir.types.builder.buildPlaceholderProjection
+import org.jetbrains.kotlin.fir.types.builder.buildTypeProjectionWithVariance
+import org.jetbrains.kotlin.fir.types.isRaw
+import org.jetbrains.kotlin.fir.types.toFirResolvedTypeRef
+import org.jetbrains.kotlin.types.Variance
 
 sealed class TypeArgumentMapping {
     abstract operator fun get(typeParameterIndex: Int): FirTypeProjection
@@ -28,13 +34,17 @@ sealed class TypeArgumentMapping {
 internal object MapTypeArguments : ResolutionStage() {
     override suspend fun check(candidate: Candidate, callInfo: CallInfo, sink: CheckerSink, context: ResolutionContext) {
         val typeArguments = callInfo.typeArguments
+        val owner = candidate.symbol.fir as FirTypeParameterRefsOwner
+
         if (typeArguments.isEmpty()) {
-            candidate.typeArgumentMapping = TypeArgumentMapping.NoExplicitArguments
+            if (owner is FirCallableDeclaration && owner.dispatchReceiverType?.isRaw() == true) {
+                candidate.typeArgumentMapping = computeDefaultMappingForRawTypeMember(owner, context)
+            } else {
+                candidate.typeArgumentMapping = TypeArgumentMapping.NoExplicitArguments
+            }
             return
         }
 
-        val owner = candidate.symbol.fir as FirTypeParameterRefsOwner
-
         if (
             typeArguments.size == owner.typeParameters.size ||
             callInfo.callKind == CallKind.DelegatingConstructorCall ||
@@ -46,6 +56,28 @@ internal object MapTypeArguments : ResolutionStage() {
             sink.yieldDiagnostic(InapplicableCandidate)
         }
     }
+
+    private fun computeDefaultMappingForRawTypeMember(
+        owner: FirTypeParameterRefsOwner,
+        context: ResolutionContext
+    ): TypeArgumentMapping.Mapped {
+        // There might be some minor inconsistencies where in K2, there might be a raw type, while in K1, there was a regular flexible type
+        // And in that case for K2 we would start a regular inference process leads to TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER because raw scopes
+        // don't leave type variables there (see KT-54526)
+        // Also, it might be a separate feature of K2, because even in cases where both compilers had a raw type, it's convenient not to
+        // require explicit type arguments for the places where it doesn't make sense
+        // (See `generic1.foo(w)` call in testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.fir.kt)
+        val resultArguments = owner.typeParameters.map { typeParameterRef ->
+            buildTypeProjectionWithVariance {
+                typeRef =
+                    ConeTypeIntersector.intersectTypes(
+                        context.typeContext, typeParameterRef.symbol.resolvedBounds.map { it.type }
+                    ).toFirResolvedTypeRef()
+                variance = Variance.INVARIANT
+            }
+        }
+        return TypeArgumentMapping.Mapped(resultArguments)
+    }
 }
 
 internal object NoTypeArguments : ResolutionStage() {

compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.fir.kt

@@ -0,0 +1,23 @@
+// SKIP_TXT
+// FILE: Generic.java
+public class Generic<T> {
+    public static class ML<E> {}
+    public static Generic create() { return null; }
+    public <E> void foo(ML<E> w) { }
+}
+
+// FILE: main.kt
+import Generic.ML
+
+fun main(w: ML<String>) {
+    val generic1 = Generic.create()
+    val generic2 = Generic.create() ?: return
+
+    // Not enough information to infer E (both K1 and K2 after KT-41794 is done)
+    // Because generic information is erased from the raw type scope of `generic1`
+    // But the parameter E is still there (that is a questionable behavior)
+    generic1.foo(w)
+
+    // `generic2` does have just non-raw type `Generic<Any!>..Generic<*>?`
+    generic2.foo(w) // OK in K1, fails in K2 after KT-41794 is done
+}

compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.kt

@@ -0,0 +1,23 @@
+// SKIP_TXT
+// FILE: Generic.java
+public class Generic<T> {
+    public static class ML<E> {}
+    public static Generic create() { return null; }
+    public <E> void foo(ML<E> w) { }
+}
+
+// FILE: main.kt
+import Generic.ML
+
+fun main(w: ML<String>) {
+    val generic1 = Generic.create()
+    val generic2 = Generic.create() ?: return
+
+    // Not enough information to infer E (both K1 and K2 after KT-41794 is done)
+    // Because generic information is erased from the raw type scope of `generic1`
+    // But the parameter E is still there (that is a questionable behavior)
+    generic1.<!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>foo<!>(w)
+
+    // `generic2` does have just non-raw type `Generic<Any!>..Generic<*>?`
+    generic2.foo(w) // OK in K1, fails in K2 after KT-41794 is done
+}

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

@@ -24187,6 +24187,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/kt47459.kt");
                 }
 
+                @Test
+                @TestMetadata("noTypeArgumentsForRawScopedMembers.kt")
+                public void testNoTypeArgumentsForRawScopedMembers() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/platformTypes/rawTypes/noTypeArgumentsForRawScopedMembers.kt");
+                }
+
                 @Test
                 @TestMetadata("nonGenericRawMember.kt")
                 public void testNonGenericRawMember() throws Exception {