KT-61245 [LL API] Collect correct context for fields

There is a fake field created for the supertypes delegation,
and it needs to be visited by the collector

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/ContextCollector.kt

@@ -460,6 +460,35 @@ private class ContextCollectorVisitor(
         }
     }
 
+    /**
+     * We visit fields to properly handle supertypes delegation:
+     *
+     * ```kt
+     * class Foo : Bar by baz
+     * ```
+     *
+     * In the code above, `baz` expression is saved into a separate synthetic field.
+     * It's not accessible from the delegated constructor, it's just added to the
+     * `Foo` class body.
+     */
+    override fun visitField(field: FirField) = withProcessor {
+        dumpContext(field, ContextKind.SELF)
+
+        processSignatureAnnotations(field)
+
+        onActiveBody {
+            field.lazyResolveToPhase(FirResolvePhase.BODY_RESOLVE)
+
+            context.withField(field) {
+                dumpContext(field, ContextKind.BODY)
+
+                onActive {
+                    process(field.initializer)
+                }
+            }
+        }
+    }
+
     override fun visitPropertyAccessor(propertyAccessor: FirPropertyAccessor) = withProcessor {
         dumpContext(propertyAccessor, ContextKind.SELF)
 

analysis/low-level-api-fir/testdata/contextCollector/propertyDelegateInitializer.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package test
+
+interface MyInterface {
+    operator fun getValue(thisRef: Any, property: Any): MyInterface
+}
+
+class Foo(constructorParam: MyInterface) {
+    val regularProperty: MyInterface
+
+    val property: MyInterface by <expr>constructorParam</expr>
+}

analysis/low-level-api-fir/testdata/contextCollector/propertyDelegateInitializer.txt

@@ -0,0 +1,43 @@
+Tower Data Context:
+    Element 0
+        Scope: FirDefaultStarImportingScope
+    Element 1
+        Scope: FirDefaultSimpleImportingScope
+    Element 2
+        Scope: FirExplicitStarImportingScope
+    Element 3
+        Scope: FirDefaultSimpleImportingScope
+    Element 4
+        Scope: FirDefaultSimpleImportingScope
+    Element 5
+        Scope: FirPackageMemberScope
+    Element 6
+        Scope: FirExplicitSimpleImportingScope
+    Element 7
+        Implicit receiver:
+            FirRegularClassSymbol public final class Foo : R|kotlin/Any|
+                Type: test/Foo
+    Element 8
+        Scope: FirLocalScope
+            Properties:
+                FirValueParameterSymbol constructorParam: R|test/MyInterface|
+
+FILE: [ResolvedTo(IMPORTS)] propertyDelegateInitializer.kt
+    public abstract [ResolvedTo(STATUS)] interface MyInterface : R|kotlin/Any| {
+        public abstract operator [ResolvedTo(CONTRACTS)] fun getValue([ResolvedTo(CONTRACTS)] thisRef: R|kotlin/Any|, [ResolvedTo(CONTRACTS)] property: R|kotlin/Any|): R|test/MyInterface|
+
+    }
+    public final [ResolvedTo(STATUS)] class Foo : R|kotlin/Any| {
+        public [ResolvedTo(STATUS)] constructor([ResolvedTo(STATUS)] constructorParam: R|test/MyInterface|): R|test/Foo| {
+            LAZY_super<R|kotlin/Any|>
+        }
+
+        public final [ResolvedTo(STATUS)] val regularProperty: R|test/MyInterface|
+            public [ResolvedTo(STATUS)] get(): R|test/MyInterface|
+
+        public final [ResolvedTo(BODY_RESOLVE)] val property: R|test/MyInterface|by R|<local>/constructorParam|
+            public [ResolvedTo(BODY_RESOLVE)] get(): R|test/MyInterface| {
+                ^ this@R|test/Foo|.D|test/Foo.property|.R|test/MyInterface.getValue|(this@R|test/Foo|, ::R|test/Foo.property|)
+            }
+
+    }

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/ContextCollectorSourceTestGenerated.java

@@ -90,6 +90,12 @@ public class ContextCollectorSourceTestGenerated extends AbstractContextCollecto
         runTest("analysis/low-level-api-fir/testdata/contextCollector/primaryConstructorParameter.kt");
     }
 
+    @Test
+    @TestMetadata("propertyDelegateInitializer.kt")
+    public void testPropertyDelegateInitializer() throws Exception {
+        runTest("analysis/low-level-api-fir/testdata/contextCollector/propertyDelegateInitializer.kt");
+    }
+
     @Test
     @TestMetadata("simple.kt")
     public void testSimple() throws Exception {