FIR: Use more refined names instead of "safe"

^KT-38444 Fixed

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/FirDoubleColonExpressionResolver.kt

@@ -71,7 +71,7 @@ class FirDoubleColonExpressionResolver(
 
     private fun shouldTryResolveLHSAsExpression(expression: FirCallableReferenceAccess): Boolean {
         val lhs = expression.explicitReceiver ?: return false
-        return lhs.canBeConsideredProperExpression() && !expression.safe
+        return lhs.canBeConsideredProperExpression() && !expression.hasQuestionMarkAtLHS
     }
 
     private fun shouldTryResolveLHSAsType(expression: FirCallableReferenceAccess): Boolean {
@@ -172,7 +172,7 @@ class FirDoubleColonExpressionResolver(
                     else -> ConeStarProjection
                 }
             },
-            isNullable = expression.safe
+            isNullable = resolvedExpression.isNullableLHSForCallableReference
         )
 
         return DoubleColonLHS.Type(type)

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

@@ -511,8 +511,8 @@ class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransformer) :
         callableReferenceAccess.annotations.forEach { it.accept(this, data) }
         val explicitReceiver = callableReferenceAccess.explicitReceiver
         val transformedLHS = explicitReceiver?.transformSingle(this, ResolutionMode.ContextIndependent)?.apply {
-            if (this is FirResolvedQualifier && callableReferenceAccess.safe) {
-                replaceSafe(true)
+            if (this is FirResolvedQualifier && callableReferenceAccess.hasQuestionMarkAtLHS) {
+                replaceIsNullableLHSForCallableReference(true)
             }
         }