From ef684c0dffc68fd73c217e496f96837881a9c13d Mon Sep 17 00:00:00 2001
From: "Denis.Zharkov" <denis.zharkov@jetbrains.com>
Date: Wed, 8 Sep 2021 11:45:08 +0300
Subject: [PATCH] FIR: Improve error reporting for
 EXPRESSION_EXPECTED_PACKAGE_FOUND

---
 .../resolve/expresssions/innerQualifier.fir.txt        |  2 +-
 .../src/org/jetbrains/kotlin/fir/FirCallResolver.kt    | 10 ++++++++--
 .../tests/PackageInExpressionPosition.fir.kt           |  5 +++--
 .../diagnostics/tests/PackageInExpressionPosition.kt   |  1 +
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/compiler/fir/analysis-tests/testData/resolve/expresssions/innerQualifier.fir.txt b/compiler/fir/analysis-tests/testData/resolve/expresssions/innerQualifier.fir.txt
index 2cb5e764514..b01a138d56c 100644
--- a/compiler/fir/analysis-tests/testData/resolve/expresssions/innerQualifier.fir.txt
+++ b/compiler/fir/analysis-tests/testData/resolve/expresssions/innerQualifier.fir.txt
@@ -12,7 +12,7 @@ FILE: innerQualifier.kt
         }
 
     }
-    public final val x: R|kotlin/Unit| = R|kotlin/Unit|
+    public final val x: R|kotlin/Unit| = Q|Outer.Inner|
         public get(): R|kotlin/Unit|
     public final val klass: R|kotlin/reflect/KClass<Outer.Inner>| = <getClass>(Q|Outer.Inner|)
         public get(): R|kotlin/reflect/KClass<Outer.Inner>|
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt
index b7a4e185b3e..f64e33b439f 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt
@@ -232,7 +232,13 @@ class FirCallResolver(
         val qualifiedAccess = qualifiedAccess.transformExplicitReceiver<FirQualifiedAccess>()
         val nonFatalDiagnosticFromExpression = (qualifiedAccess as? FirPropertyAccessExpression)?.nonFatalDiagnostics
 
-        if (isUsedAsReceiver) {
+        val basicResult by lazy(LazyThreadSafetyMode.NONE) {
+            collectCandidates(qualifiedAccess, callee.name)
+        }
+
+        // Even if it's not receiver, it makes sense to continue qualifier if resolution is unsuccessful
+        // just to try to resolve to package/class and then report meaningful error at FirStandaloneQualifierChecker
+        if (isUsedAsReceiver || !basicResult.applicability.isSuccess) {
             (qualifiedAccess.explicitReceiver as? FirResolvedQualifier)
                 ?.continueQualifier(
                     callee,
@@ -244,7 +250,7 @@ class FirCallResolver(
                 ?.let { return it }
         }
 
-        var result = collectCandidates(qualifiedAccess, callee.name)
+        var result = basicResult
 
         if (qualifiedAccess.explicitReceiver == null) {
             // Even if we successfully resolved to some companion/named object, we should re-try with qualifier resolution
diff --git a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt
index 7e893e84337..11456837617 100644
--- a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt
+++ b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt
@@ -1,3 +1,4 @@
+// COMPARE_WITH_LIGHT_TREE
 package foo
 
 class X {}
@@ -6,7 +7,7 @@ val s = <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>java<!>
 val ss = <!NO_COMPANION_OBJECT!>System<!>
 val sss = <!NO_COMPANION_OBJECT!>X<!>
 val x = "${<!NO_COMPANION_OBJECT!>System<!>}"
-val xs = java.<!UNRESOLVED_REFERENCE!>lang<!>
+val xs = java.<!EXPRESSION_EXPECTED_PACKAGE_FOUND!>lang<!>
 val xss = java.lang.<!NO_COMPANION_OBJECT!>System<!>
 val xsss = foo.<!NO_COMPANION_OBJECT!>X<!>
 val xssss = <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>foo<!>
@@ -16,7 +17,7 @@ fun main() {
     <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>java<!> = null
     <!NO_COMPANION_OBJECT!>System<!> = null
     <!NO_COMPANION_OBJECT!>System<!>!!
-    java.lang.<!NO_COMPANION_OBJECT!>System<!> = null
+    <!NO_COMPANION_OBJECT{LT}!>java.lang.<!NO_COMPANION_OBJECT{PSI}!>System<!><!> = null
     java.lang.<!NO_COMPANION_OBJECT!>System<!>!!
     <!NO_COMPANION_OBJECT!>System<!> is Int
     <!INVISIBLE_REFERENCE!>System<!>()
diff --git a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
index 8b6a963d361..679754bcb5b 100644
--- a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
+++ b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.kt
@@ -1,3 +1,4 @@
+// COMPARE_WITH_LIGHT_TREE
 package foo
 
 class X {}