From c2529a4abb877f5d9634a25b0f1fe2e4e589d1bd Mon Sep 17 00:00:00 2001
From: Mark Punzalan <markpun@google.com>
Date: Sat, 28 Aug 2021 06:40:47 +0000
Subject: [PATCH] HL API: Handle resolve case when source for
 FirResolvedQualifier is a KtCallExpression.

---
 .../kotlin/idea/references/FirReferenceResolveHelper.kt  | 9 +++------
 .../referenceResolve/ResolveClassNameInCallExpression.kt | 6 ++++++
 .../ResolveClassNameInCallExpression.txt                 | 2 ++
 .../fir/frontend/api/ReferenceResolveTestGenerated.java  | 6 ++++++
 4 files changed, 17 insertions(+), 6 deletions(-)
 create mode 100644 idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.kt
 create mode 100644 idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.txt

diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt
index b9caa913b4a..2f4b7b97a38 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/references/FirReferenceResolveHelper.kt
@@ -399,13 +399,10 @@ internal object FirReferenceResolveHelper {
         val referencedClass = referencedSymbol.fir
         val referencedSymbolsByFir = listOfNotNull(symbolBuilder.buildSymbol(referencedClass))
         val firSourcePsi = fir.source.psi ?: referencedSymbolsByFir
-        // The source of an `FirResolvedQualifier` is either a KtNamedReferenceExpression or a KtDotQualifiedExpression. In the former case,
-        // it implies the qualifier is an atomic reference and therefore, it should be identical with the `expression`. In the latter case,
-        // we need to manually break up the qualified access and resolve individual parts of it because in FIR, the entire qualified access
-        // is one element.
-        if (firSourcePsi === expression) return referencedSymbolsByFir
-        require(firSourcePsi is KtDotQualifiedExpression)
+        if (firSourcePsi !is KtDotQualifiedExpression) return referencedSymbolsByFir
 
+        // When the source of an `FirResolvedQualifier` is a KtDotQualifiedExpression, we need to manually break up the qualified access and
+        // resolve individual parts of it because in FIR, the entire qualified access is one element.
         if (referencedClass.isLocal) {
             // TODO: handle local classes after KT-47135 is fixed
             return referencedSymbolsByFir
diff --git a/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.kt b/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.kt
new file mode 100644
index 00000000000..78eb4a5681e
--- /dev/null
+++ b/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.kt
@@ -0,0 +1,6 @@
+class Test<T>
+
+// The lack of `()` in the constructor call is intentional. The addition of type arguments is also needed so we have a KtCallExpression.
+// We want to test finding the symbol for a FirResolvedQualifier (and not a FirFunctionCall) whose source is a KtCallExpression
+// (and not a KtSimpleNameExpression).
+val t = <caret>Test<Int>
diff --git a/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.txt b/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.txt
new file mode 100644
index 00000000000..ddacf7fe83e
--- /dev/null
+++ b/idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.txt
@@ -0,0 +1,2 @@
+Resolved to:
+0: (in ROOT) class Test<T>
\ No newline at end of file
diff --git a/idea/idea-frontend-fir/tests/org/jetbrains/kotlin/idea/fir/frontend/api/ReferenceResolveTestGenerated.java b/idea/idea-frontend-fir/tests/org/jetbrains/kotlin/idea/fir/frontend/api/ReferenceResolveTestGenerated.java
index d842acfc152..696e268932b 100644
--- a/idea/idea-frontend-fir/tests/org/jetbrains/kotlin/idea/fir/frontend/api/ReferenceResolveTestGenerated.java
+++ b/idea/idea-frontend-fir/tests/org/jetbrains/kotlin/idea/fir/frontend/api/ReferenceResolveTestGenerated.java
@@ -378,6 +378,12 @@ public class ReferenceResolveTestGenerated extends AbstractReferenceResolveTest
         runTest("idea/idea-frontend-fir/testData/referenceResolve/ResolveClass.kt");
     }
 
+    @Test
+    @TestMetadata("ResolveClassNameInCallExpression.kt")
+    public void testResolveClassNameInCallExpression() throws Exception {
+        runTest("idea/idea-frontend-fir/testData/referenceResolve/ResolveClassNameInCallExpression.kt");
+    }
+
     @Test
     @TestMetadata("ResolvePackageInProperty.kt")
     public void testResolvePackageInProperty() throws Exception {