K2: Merge all expected-type related resolution modes into single class

It looks more natural and allows to combine different properties
of these cases

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

@@ -33,9 +33,22 @@ sealed class ResolutionMode {
         val expectedTypeRef: FirTypeRef,
         val mayBeCoercionToUnitApplied: Boolean = false,
         val expectedTypeMismatchIsReportedInChecker: Boolean = false,
+        val fromCast: Boolean = false,
+        // It might be ok if the types turn out to be incompatible
+        // Consider the following examples with properties and their backing fields:
+        //
+        // val items: List field = mutableListOf()
+        // val s: String field = 10 get() = ...
+        // In these examples we should try using the property type information while resolving the initializer,
+        // but it's ok if it's not applicable
+        val shouldBeStrictlyEnforced: Boolean = true,
     ) : ResolutionMode() {
         override fun toString(): String {
-            return "WithExpectedType: ${expectedTypeRef.prettyString()}"
+            return "WithExpectedType: ${expectedTypeRef.prettyString()}, " +
+                    "mayBeCoercionToUnitApplied=${mayBeCoercionToUnitApplied}, " +
+                    "expectedTypeMismatchIsReportedInChecker=${expectedTypeMismatchIsReportedInChecker}, " +
+                    "fromCast=${fromCast}, " +
+                    "shouldBeStrictlyEnforced=${shouldBeStrictlyEnforced}, "
         }
     }
 
@@ -51,41 +64,6 @@ sealed class ResolutionMode {
         }
     }
 
-    class WithExpectedTypeFromCast(
-        val expectedTypeRef: FirTypeRef,
-    ) : ResolutionMode() {
-        override fun toString(): String {
-            return "WithExpectedTypeFromCast: ${expectedTypeRef.prettyString()}"
-        }
-    }
-
-    /**
-     * This resolution mode is similar to
-     * WithExpectedType, but it's ok if the
-     * types turn out to be incompatible.
-     * Consider the following examples with
-     * properties and their backing fields:
-     *
-     * val items: List<T>
-     *     field = mutableListOf()
-     *
-     * val s: String
-     *     field = 10
-     *     get() = ...
-     *
-     * In these examples we should try using
-     * the property type information while
-     * resolving the initializer, but it's ok
-     * if it's not applicable.
-     */
-    class WithSuggestedType(
-        val suggestedTypeRef: FirTypeRef,
-    ) : ResolutionMode() {
-        override fun toString(): String {
-            return "WithSuggestedType: ${suggestedTypeRef.prettyString()}"
-        }
-    }
-
     /**
      * This resolution mode is used for resolving the LHS of assignments.
      *
@@ -110,13 +88,11 @@ sealed class ResolutionMode {
     }
 }
 
-fun ResolutionMode.expectedType(components: BodyResolveComponents, allowFromCast: Boolean = false): FirTypeRef? = when (this) {
-    is ResolutionMode.WithExpectedType -> expectedTypeRef
+fun ResolutionMode.expectedType(components: BodyResolveComponents): FirTypeRef? = when (this) {
+    is ResolutionMode.WithExpectedType -> expectedTypeRef.takeIf { !this.fromCast }
     is ResolutionMode.ContextIndependent,
     is ResolutionMode.AssignmentLValue,
     is ResolutionMode.ReceiverResolution -> components.noExpectedType
-    is ResolutionMode.WithExpectedTypeFromCast -> expectedTypeRef.takeIf { allowFromCast }
-    is ResolutionMode.WithSuggestedType -> suggestedTypeRef
     else -> null
 }
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirCallCompleter.kt

@@ -76,8 +76,8 @@ class FirCallCompleter(
             data.expectedType(components, allowFromCast = true),
             (data as? ResolutionMode.WithExpectedType)?.mayBeCoercionToUnitApplied == true,
             (data as? ResolutionMode.WithExpectedType)?.expectedTypeMismatchIsReportedInChecker == true,
-            isFromCast = data is ResolutionMode.WithExpectedTypeFromCast,
-            shouldEnforceExpectedType = data !is ResolutionMode.WithSuggestedType,
+            isFromCast = (data as? ResolutionMode.WithExpectedType)?.fromCast == true,
+            shouldEnforceExpectedType = (data as? ResolutionMode.WithExpectedType)?.shouldBeStrictlyEnforced == true,
         )
 
     private fun <T> completeCall(

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirDeclarationsResolveTransformer.kt

@@ -728,11 +728,9 @@ open class FirDeclarationsResolveTransformer(transformer: FirAbstractBodyResolve
             }
             is ResolutionMode.WithExpectedType ->
                 transformAnonymousFunctionWithExpectedType(anonymousFunction, data.expectedTypeRef, data)
-            is ResolutionMode.WithSuggestedType ->
-                transformAnonymousFunctionWithExpectedType(anonymousFunction, data.suggestedTypeRef, data)
             is ResolutionMode.ContextIndependent, is ResolutionMode.AssignmentLValue, is ResolutionMode.ReceiverResolution ->
                 transformAnonymousFunctionWithExpectedType(anonymousFunction, buildImplicitTypeRef(), data)
-            is ResolutionMode.WithStatus, is ResolutionMode.WithExpectedTypeFromCast ->
+            is ResolutionMode.WithStatus ->
                 throw AssertionError("Should not be here in WithStatus/WithExpectedTypeFromCast mode")
         }
     }
@@ -888,7 +886,7 @@ open class FirDeclarationsResolveTransformer(transformer: FirAbstractBodyResolve
         val initializerData = if (backingField.returnTypeRef is FirResolvedTypeRef) {
             withExpectedType(backingField.returnTypeRef)
         } else if (propertyType != null) {
-            ResolutionMode.WithSuggestedType(propertyType)
+            ResolutionMode.WithExpectedType(propertyType, shouldBeStrictlyEnforced = false)
         } else {
             ResolutionMode.ContextDependent
         }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt

@@ -800,7 +800,7 @@ open class FirExpressionsResolveTransformer(transformer: FirAbstractBodyResolveT
                 }
 
                 if (expectedType != null) {
-                    val newMode = ResolutionMode.WithExpectedTypeFromCast(conversionTypeRef.withReplacedConeType(expectedType))
+                    val newMode = ResolutionMode.WithExpectedType(conversionTypeRef.withReplacedConeType(expectedType), fromCast = true)
                     return transformOtherChildren(transformer, newMode)
                 }
             }