FIR IDE: implement assignment statement references

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/UnusedChecker.kt

@@ -256,7 +256,6 @@ object UnusedChecker : FirControlFlowChecker() {
             vararg qualifiedAccesses: FirQualifiedAccess,
         ): PathAwareVariableStatusInfo {
             fun retrieveSymbol(qualifiedAccess: FirQualifiedAccess): FirPropertySymbol? {
-                if (qualifiedAccess.source?.kind is FirFakeSourceElementKind) return null
                 val reference = qualifiedAccess.calleeReference as? FirResolvedNamedReference ?: return null
                 val symbol = reference.resolvedSymbol as? FirPropertySymbol ?: return null
                 return if (symbol !in localProperties) null else symbol

compiler/fir/raw-fir/raw-fir.common/src/org/jetbrains/kotlin/fir/builder/BaseFirBuilder.kt

@@ -873,8 +873,9 @@ abstract class BaseFirBuilder<T>(val baseSession: FirSession, val context: Conte
             return buildAssignmentOperatorStatement {
                 source = baseSource
                 this.operation = operation
-                // TODO: take good psi
-                leftArgument = this@generateAssignment?.convert() ?: buildErrorExpression {
+                leftArgument = withDefaultSourceElementKind(FirFakeSourceElementKind.DesugaredCompoundAssignment) {
+                    this@generateAssignment?.convert()
+                } ?: buildErrorExpression {
                     source = null
                     diagnostic = ConeSimpleDiagnostic(
                         "Unsupported left value of assignment: ${baseSource?.psi?.text}", DiagnosticKind.ExpressionRequired

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

@@ -353,7 +353,7 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
             explicitReceiver = leftArgument
             argumentList = buildUnaryArgumentList(rightArgument)
             calleeReference = buildSimpleNamedReference {
-                source = assignmentOperatorStatement.source
+                source = assignmentOperatorStatement.source?.fakeElement(FirFakeSourceElementKind.DesugaredCompoundAssignment)
                 this.name = name
                 candidateSymbol = null
             }

idea/idea-fir/tests/org/jetbrains/kotlin/idea/resolve/FirReferenceResolveTestGenerated.java

@@ -254,6 +254,16 @@ public class FirReferenceResolveTestGenerated extends AbstractFirReferenceResolv
         runTest("idea/testData/resolve/references/JavaReference.kt");
     }
 
+    @TestMetadata("KotlinPropertyAssignment.kt")
+    public void testKotlinPropertyAssignment() throws Exception {
+        runTest("idea/testData/resolve/references/KotlinPropertyAssignment.kt");
+    }
+
+    @TestMetadata("KotlinPropertyWithGetterAndSetterAssignment.kt")
+    public void testKotlinPropertyWithGetterAndSetterAssignment() throws Exception {
+        runTest("idea/testData/resolve/references/KotlinPropertyWithGetterAndSetterAssignment.kt");
+    }
+
     @TestMetadata("MultiDeclarationExtension.kt")
     public void testMultiDeclarationExtension() throws Exception {
         runTest("idea/testData/resolve/references/MultiDeclarationExtension.kt");

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt

@@ -156,12 +156,20 @@ internal object FirReferenceResolveHelper {
             }
             is FirReturnExpression -> getSymbolsByReturnExpression(expression, fir, symbolBuilder)
             is FirErrorNamedReference -> getSymbolsByErrorNamedReference(fir, symbolBuilder)
+            is FirVariableAssignment -> getSymbolsByVariableAssignment(fir, session, symbolBuilder)
             is FirResolvable -> getSymbolsByResolvable(fir, expression, session, symbolBuilder)
             is FirNamedArgumentExpression -> getSymbolsByNameArgumentExpression(expression, analysisSession, symbolBuilder)
             else -> handleUnknownFirElement(expression, analysisSession, session, symbolBuilder)
         }
     }
 
+    @OptIn(ExperimentalStdlibApi::class)
+    private fun getSymbolsByVariableAssignment(
+        fir: FirVariableAssignment,
+        session: FirSession,
+        symbolBuilder: KtSymbolByFirBuilder
+    ): Collection<KtSymbol> = fir.calleeReference.toTargetSymbol(session, symbolBuilder)
+
     private fun getSymbolsByNameArgumentExpression(
         expression: KtSimpleNameExpression,
         analysisSession: KtFirAnalysisSession,

idea/testData/resolve/references/KotlinPropertyAssignment.kt

@@ -0,0 +1,27 @@
+class A {
+    var something: Int = 10
+}
+
+fun A.foo(a: A) {
+    print(a.<caret>something)
+    a.<caret>something = 1
+    a.<caret>something += 1
+    a.<caret>something++
+    --a.<caret>something
+
+    <caret>something++
+    (<caret>something)++
+    (<caret>something) = 1
+    (a.<caret>something) = 1
+}
+
+// MULTIRESOLVE
+// REF1: (in A).something
+// REF2: (in A).something
+// REF3: (in A).something
+// REF4: (in A).something
+// REF5: (in A).something
+// REF6: (in A).something
+// REF7: (in A).something
+// REF8: (in A).something
+// REF9: (in A).something

idea/testData/resolve/references/KotlinPropertyWithGetterAndSetterAssignment.kt

@@ -0,0 +1,29 @@
+class A {
+    var something: Int
+        set(value) {}
+        get() = 10
+}
+
+fun A.foo(a: A) {
+    print(a.<caret>something)
+    a.<caret>something = 1
+    a.<caret>something += 1
+    a.<caret>something++
+    --a.<caret>something
+
+    <caret>something++
+    (<caret>something)++
+    (<caret>something) = 1
+    (a.<caret>something) = 1
+}
+
+// MULTIRESOLVE
+// REF1: (in A).something
+// REF2: (in A).something
+// REF3: (in A).something
+// REF4: (in A).something
+// REF5: (in A).something
+// REF6: (in A).something
+// REF7: (in A).something
+// REF8: (in A).something
+// REF9: (in A).something

idea/tests/org/jetbrains/kotlin/idea/resolve/ReferenceResolveTestGenerated.java

@@ -254,6 +254,16 @@ public class ReferenceResolveTestGenerated extends AbstractReferenceResolveTest
         runTest("idea/testData/resolve/references/JavaReference.kt");
     }
 
+    @TestMetadata("KotlinPropertyAssignment.kt")
+    public void testKotlinPropertyAssignment() throws Exception {
+        runTest("idea/testData/resolve/references/KotlinPropertyAssignment.kt");
+    }
+
+    @TestMetadata("KotlinPropertyWithGetterAndSetterAssignment.kt")
+    public void testKotlinPropertyWithGetterAndSetterAssignment() throws Exception {
+        runTest("idea/testData/resolve/references/KotlinPropertyWithGetterAndSetterAssignment.kt");
+    }
+
     @TestMetadata("MultiDeclarationExtension.kt")
     public void testMultiDeclarationExtension() throws Exception {
         runTest("idea/testData/resolve/references/MultiDeclarationExtension.kt");