[FIR] Use stubs for creating lazy bodies of backing field initializer

Ninth step for ^KT-52615

Merge-request: KT-MR-8756
Merged-by: Egor Kulikov <Egor.Kulikov@jetbrains.com>

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -1705,7 +1705,7 @@ open class RawFirBuilder(
 
         private fun KtDeclarationWithInitializer.toInitializerExpression() =
             runIf(hasInitializer()) {
-                buildOrLazyExpression(initializer?.toFirSourceElement()) {
+                buildOrLazyExpression(null) {
                     initializer.toFirExpression("Should have initializer")
                 }
             }

compiler/psi/src/org/jetbrains/kotlin/psi/KtBackingField.java

@@ -62,11 +62,19 @@ public class KtBackingField extends KtDeclarationStub<KotlinBackingFieldStub>
     @Nullable
     @Override
     public KtExpression getInitializer() {
+        KotlinBackingFieldStub stub = getStub();
+        if (stub != null && !stub.hasInitializer()) {
+            return null;
+        }
         return PsiTreeUtil.getNextSiblingOfType(getEqualsToken(), KtExpression.class);
     }
 
     @Override
     public boolean hasInitializer() {
+        KotlinBackingFieldStub stub = getStub();
+        if (stub != null) {
+            return stub.hasInitializer();
+        }
         return getInitializer() != null;
     }
 

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/KotlinStubVersions.kt

@@ -23,7 +23,7 @@ object KotlinStubVersions {
     // Though only kotlin declarations (no code in the bodies) are stubbed, please do increase this version
     //      if you are not 100% sure it can be avoided.
     // Increasing this version will lead to reindexing of all kotlin source files on the first IDE startup with the new version.
-    const val SOURCE_STUB_VERSION = 145
+    const val SOURCE_STUB_VERSION = 146
 
     // Binary stub version should be increased if stub format (org.jetbrains.kotlin.psi.stubs.impl) is changed
     //      or changes are made to the core stub building code (org.jetbrains.kotlin.idea.decompiler.stubBuilder).

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt

@@ -127,7 +127,9 @@ interface KotlinPropertyAccessorStub : StubElement<KtPropertyAccessor> {
     fun hasBlockBody(): Boolean
 }
 
-interface KotlinBackingFieldStub : StubElement<KtBackingField>
+interface KotlinBackingFieldStub : StubElement<KtBackingField> {
+    fun hasInitializer(): Boolean
+}
 
 interface KotlinPropertyStub : KotlinCallableStubBase<KtProperty> {
     fun isVar(): Boolean

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/elements/KtBackingFieldElementType.java

@@ -34,15 +34,18 @@ public class KtBackingFieldElementType extends KtStubElementType<KotlinBackingFi
 
     @Override
     public KotlinBackingFieldStub createStub(@NotNull KtBackingField psi, StubElement parentStub) {
-        return new KotlinBackingFieldStubImpl(parentStub);
+        return new KotlinBackingFieldStubImpl(parentStub, psi.hasInitializer());
     }
 
     @Override
-    public void serialize(@NotNull KotlinBackingFieldStub stub, @NotNull StubOutputStream dataStream) throws IOException {}
+    public void serialize(@NotNull KotlinBackingFieldStub stub, @NotNull StubOutputStream dataStream) throws IOException {
+        dataStream.writeBoolean(stub.hasInitializer());
+    }
 
     @NotNull
     @Override
     public KotlinBackingFieldStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
-        return new KotlinBackingFieldStubImpl(parentStub);
+        boolean hasInitializer = dataStream.readBoolean();
+        return new KotlinBackingFieldStubImpl(parentStub, hasInitializer);
     }
 }

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinBackingFieldStubImpl.java

@@ -23,7 +23,14 @@ import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes;
 
 public class KotlinBackingFieldStubImpl extends KotlinStubBaseImpl<KtBackingField>
         implements KotlinBackingFieldStub {
-    public KotlinBackingFieldStubImpl(StubElement<?> parent) {
+    private final boolean hasInitializer;
+    public KotlinBackingFieldStubImpl(StubElement<?> parent, boolean hasInitializer) {
         super(parent, KtStubElementTypes.BACKING_FIELD);
+        this.hasInitializer = hasInitializer;
+    }
+
+    @Override
+    public boolean hasInitializer() {
+        return hasInitializer;
     }
 }