[FIR] Support synthetic property setters

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

@@ -15,7 +15,7 @@ import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.symbols.SyntheticSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.ConeClassLikeType
-import org.jetbrains.kotlin.fir.types.coneTypeSafe
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
 import org.jetbrains.kotlin.load.java.propertyNameByGetMethodName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.capitalizeDecapitalize.capitalizeAsciiOnly
@@ -38,24 +38,41 @@ class FirSyntheticPropertiesScope(
     val synthetic: MutableMap<FirCallableSymbol<*>, FirVariableSymbol<*>> = mutableMapOf()
 
     private fun checkGetAndCreateSynthetic(
-        name: Name,
-        symbol: FirFunctionSymbol<*>,
+        propertyName: Name,
+        getterName: Name,
+        getterSymbol: FirFunctionSymbol<*>,
         processor: (FirVariableSymbol<*>) -> Unit
     ) {
-        val fir = symbol.fir as? FirSimpleFunction ?: return
+        val getter = getterSymbol.fir as? FirSimpleFunction ?: return
 
-        if (fir.typeParameters.isNotEmpty()) return
-        if (fir.valueParameters.isNotEmpty()) return
-        if (fir.isStatic) return
-        if (fir.returnTypeRef.coneTypeSafe<ConeClassLikeType>()?.lookupTag?.classId == StandardClassIds.Unit) return
+        if (getter.typeParameters.isNotEmpty()) return
+        if (getter.valueParameters.isNotEmpty()) return
+        if (getter.isStatic) return
+        val getterReturnType = (getter.returnTypeRef as? FirResolvedTypeRef)?.type
+        if ((getterReturnType as? ConeClassLikeType)?.lookupTag?.classId == StandardClassIds.Unit) return
+
+        var matchingSetter: FirSimpleFunction? = null
+        if (getterReturnType != null) {
+            val setterName = setterNameByGetterName(getterName)
+            baseScope.processFunctionsByName(setterName, fun(setterSymbol: FirFunctionSymbol<*>) {
+                if (matchingSetter != null) return
+                val setter = setterSymbol.fir as? FirSimpleFunction ?: return
+                val parameter = setter.valueParameters.singleOrNull() ?: return
+                if (setter.typeParameters.isNotEmpty() || setter.isStatic) return
+                val parameterType = (parameter.returnTypeRef as? FirResolvedTypeRef)?.type ?: return
+                if (parameterType != getterReturnType) return
+                matchingSetter = setter
+            })
+        }
 
         val property = FirSyntheticProperty(
-            session, name,
+            session, propertyName,
             symbol = SyntheticPropertySymbol(
-                accessorId = symbol.callableId,
-                callableId = CallableId(symbol.callableId.packageName, symbol.callableId.className, name)
+                accessorId = getterSymbol.callableId,
+                callableId = CallableId(getterSymbol.callableId.packageName, getterSymbol.callableId.className, propertyName)
             ),
-            delegateGetter = fir
+            delegateGetter = getter,
+            delegateSetter = matchingSetter
         )
         processor(property.symbol)
     }
@@ -64,7 +81,7 @@ class FirSyntheticPropertiesScope(
         val getterNames = possibleGetterNamesByPropertyName(name)
         for (getterName in getterNames) {
             baseScope.processFunctionsByName(getterName) {
-                checkGetAndCreateSynthetic(name, it, processor)
+                checkGetAndCreateSynthetic(name, getterName, it, processor)
             }
         }
     }
@@ -84,6 +101,16 @@ class FirSyntheticPropertiesScope(
             }
         }
 
+        fun setterNameByGetterName(name: Name): Name {
+            val identifier = name.identifier
+            val prefix = when {
+                identifier.startsWith("get") -> "get"
+                identifier.startsWith("is") -> "is"
+                else -> throw IllegalArgumentException()
+            }
+            return Name.identifier("set" + identifier.removePrefix(prefix))
+        }
+
         private const val GETTER_PREFIX = "get"
 
         private const val IS_PREFIX = "is"

compiler/fir/resolve/testData/resolve/problems/propertyFromJavaPlusAssign.kt

@@ -18,5 +18,5 @@ public class B {
 // FILE: main.kt
 
 fun test(b: B) {
-    b.<!VARIABLE_EXPECTED!>text<!> += ""
+    b.text += ""
 }

compiler/fir/resolve/testData/resolve/problems/propertyFromJavaPlusAssign.txt

@@ -1,4 +1,4 @@
 FILE: main.kt
     public final fun test(b: R|B|): R|kotlin/Unit| {
-        <Variable expected># = R|<local>/b|.R|/B.text|.R|kotlin/String.plus|(String())
+        R|/B.text| = R|<local>/b|.R|/B.text|.R|kotlin/String.plus|(String())
     }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/synthetic/FirSyntheticProperty.kt

@@ -22,7 +22,7 @@ import org.jetbrains.kotlin.fir.visitors.FirVisitor
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
-class FirSyntheticProperty(
+class FirSyntheticProperty private constructor(
     override val session: FirSession,
     override val returnTypeRef: FirTypeRef,
     override val name: Name,
@@ -41,12 +41,14 @@ class FirSyntheticProperty(
         session: FirSession,
         name: Name,
         symbol: FirAccessorSymbol,
-        delegateGetter: FirSimpleFunction
+        delegateGetter: FirSimpleFunction,
+        delegateSetter: FirSimpleFunction? = null
     ) : this(
-        session, delegateGetter.returnTypeRef, name, false, symbol,
-        FirDeclarationStatusImpl(delegateGetter.visibility, delegateGetter.modality),
-        delegateGetter.resolvePhase,
-        FirSyntheticPropertyAccessor(delegateGetter, isGetter = true)
+        session, delegateGetter.returnTypeRef, name, isVar = delegateSetter != null, symbol = symbol,
+        status = FirDeclarationStatusImpl(delegateGetter.visibility, delegateGetter.modality),
+        resolvePhase = delegateGetter.resolvePhase,
+        getter = FirSyntheticPropertyAccessor(delegateGetter, isGetter = true),
+        setter = delegateSetter?.let { FirSyntheticPropertyAccessor(it, isGetter = false) }
     )
 
     override val source: FirSourceElement?

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/AbbreviationName.fir.kt

@@ -1,7 +1,7 @@
 // FILE: KotlinFile.kt
 fun foo(javaClass: JavaClass) {
     javaClass.url = javaClass.url + "/"
-    javaClass.<!VARIABLE_EXPECTED!>htmlFile<!> += "1"
+    javaClass.htmlFile += "1"
 
     javaClass.<!UNRESOLVED_REFERENCE!>URL<!>
     javaClass.<!UNRESOLVED_REFERENCE!>uRL<!>

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GenericClass.fir.kt

@@ -1,6 +1,6 @@
 // FILE: KotlinFile.kt
 fun foo(javaClass: JavaClass<String>) {
-    javaClass.<!VARIABLE_EXPECTED!>something<!> += "x"
+    javaClass.something += "x"
 }
 
 // FILE: JavaClass.java

compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava.fir.kt

@@ -22,7 +22,7 @@ fun foo(k: KotlinClass) {
     useString(k.something3)
 
     k.setSomething4("")
-    k.<!VARIABLE_EXPECTED!>something4<!> += ""
+    k.something4 += ""
     k.<!INAPPLICABLE_CANDIDATE!>setSomething4<!>(null)
     k.something4 = null