[FIR] Preserve information about prefix/postfix-ness

This information is needed for dynamics

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/file/structure/FirElementsRecorder.kt

@@ -113,6 +113,8 @@ internal open class FirElementsRecorder : FirVisitor<Unit, MutableMap<KtElement,
                         // For secondary constructors without explicit delegated constructor call, the PSI tree always create an empty
                         // KtConstructorDelegationCall. In this case, the source in FIR has this fake source kind.
                         it.kind == KtFakeSourceElementKind.ImplicitConstructor ||
+                        it.kind == KtFakeSourceElementKind.DesugaredPrefixNameReference ||
+                        it.kind == KtFakeSourceElementKind.DesugaredPostfixNameReference ||
                         it.isSourceForCompoundAccess(element)
             }.psi as? KtElement
             ?: return

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

@@ -616,7 +616,12 @@ abstract class BaseFirBuilder<T>(val baseSession: FirSession, val context: Conte
         val resultInitializer = buildFunctionCall {
             source = desugaredSource
             calleeReference = buildSimpleNamedReference {
-                source = operationReference?.toFirSourceElement()
+                val kind = if (prefix) {
+                    KtFakeSourceElementKind.DesugaredPrefixNameReference
+                } else {
+                    KtFakeSourceElementKind.DesugaredPostfixNameReference
+                }
+                source = operationReference?.toFirSourceElement(kind)
                 name = callName
             }
             explicitReceiver = if (prefix) {

compiler/frontend.common/src/org/jetbrains/kotlin/KtSourceElement.kt

@@ -110,6 +110,12 @@ sealed class KtFakeSourceElementKind : KtSourceElementKind() {
     // x = x++ -> x = { val <unary> = x; x = <unary>.inc(); <unary> }
     object DesugaredIncrementOrDecrement : KtFakeSourceElementKind()
 
+    // ++x --> `inc` calleeReference
+    object DesugaredPrefixNameReference : KtFakeSourceElementKind()
+
+    // x++ --> `inc` calleeReference
+    object DesugaredPostfixNameReference : KtFakeSourceElementKind()
+
     // x !in list --> !(x in list) where ! and !(x in list) will have a fake source
     object DesugaredInvertedContains : KtFakeSourceElementKind()