From cfa48b5cc0449fc10788c13333f44c58bfc36857 Mon Sep 17 00:00:00 2001
From: Brian Norman <brian.norman@jetbrains.com>
Date: Thu, 16 Nov 2023 10:27:32 -0600
Subject: [PATCH] [FIR] Add null implications to both sides of equality when
 appropriate

When both sides of an equality expression are null or Nothing?, only the
right side is receiving implications within the data-flow. Make sure the
left side has implications add as well. This is important for boolean
conditions when implications from both sides need to be combined.

^KT-63535 Fixed
---
 .../fir/resolve/dfa/FirDataFlowAnalyzer.kt    |  6 +-
 .../diagnostics/notLinked/dfa/pos/6.fir.kt    | 86 +++++++++----------
 2 files changed, 47 insertions(+), 45 deletions(-)

diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt
index af389137a93..703e74f79c1 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt
@@ -431,8 +431,10 @@ abstract class FirDataFlowAnalyzer(
         node.mergeIncomingFlow { _, flow ->
             when {
                 leftConst != null && rightConst != null -> return@mergeIncomingFlow
-                leftIsNull -> processEqNull(flow, equalityOperatorCall, rightOperand, operation.isEq())
-                rightIsNull -> processEqNull(flow, equalityOperatorCall, leftOperand, operation.isEq())
+                leftIsNull || rightIsNull -> {
+                    if (leftIsNull) processEqNull(flow, equalityOperatorCall, rightOperand, operation.isEq())
+                    if (rightIsNull) processEqNull(flow, equalityOperatorCall, leftOperand, operation.isEq())
+                }
                 leftConst != null -> processEqConst(flow, equalityOperatorCall, rightOperand, leftConst, operation.isEq())
                 rightConst != null -> processEqConst(flow, equalityOperatorCall, leftOperand, rightConst, operation.isEq())
                 else -> processEq(flow, lhsExitNode.flow, equalityOperatorCall, leftOperand, rightOperand, operation)
diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
index 28ffd634a1b..e1eba841726 100644
--- a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
@@ -47,8 +47,8 @@ fun case_1(x: Any?) {
 fun case_2(x: Nothing?) {
     val y = null
     if (<!SENSELESS_COMPARISON!>x !== y<!>) {
-        <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing?")!>x<!>
-        <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing?")!>x<!>.hashCode()
+        <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing? & kotlin.Nothing")!>x<!>
+        <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Nothing? & kotlin.Nothing")!>x<!>.hashCode()
     }
 }
 
@@ -129,16 +129,16 @@ fun case_7(x: EmptyObject?) {
     val y = null
 
     if (x != y || <!SENSELESS_COMPARISON!><!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & kotlin.Nothing?")!>x<!> != y<!>) {
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!><!UNSAFE_CALL!>.<!>equals(null)
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.propT
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!><!UNSAFE_CALL!>.<!>propAny
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.propNullableT
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.propNullableAny
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.funT()
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!><!UNSAFE_CALL!>.<!>funAny()
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.funNullableT()
-        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject?")!>x<!>.funNullableAny()
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.equals(null)
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.propT
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.propAny
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.propNullableT
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.propNullableAny
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.funT()
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.funAny()
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.funNullableT()
+        <!DEBUG_INFO_EXPRESSION_TYPE("EmptyObject? & EmptyObject")!>x<!>.funNullableAny()
     }
 }
 
@@ -211,16 +211,16 @@ fun case_11(x: TypealiasNullableString<!REDUNDANT_NULLABLE!>?<!>, y: TypealiasNu
         if (y != z) {
             if (nullableStringProperty == z) {
                 if (u != z || <!SENSELESS_COMPARISON!>u != v<!>) {
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.equals(null)
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.propT
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!><!UNSAFE_CALL!>.<!>propAny
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.propNullableT
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.propNullableAny
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.funT()
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!><!UNSAFE_CALL!>.<!>funAny()
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.funNullableT()
-                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString?")!>x<!>.funNullableAny()
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.equals(null)
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.propT
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.propAny
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.propNullableT
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.propNullableAny
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.funT()
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.funAny()
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.funNullableT()
+                    <!DEBUG_INFO_EXPRESSION_TYPE("TypealiasNullableString? & kotlin.String")!>x<!>.funNullableAny()
                 }
             }
         }
@@ -448,16 +448,16 @@ fun case_23(a: ((Float) -> Int?)?, b: Float?, z: Nothing?) {
     if (a != z && <!FORBIDDEN_IDENTITY_EQUALS_WARNING!>b !== z<!> && <!FORBIDDEN_IDENTITY_EQUALS_WARNING, SENSELESS_COMPARISON!>b !== z<!>) {
         val x = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>a(<!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Float? & kotlin.Float")!>b<!>)<!>
         if (x != z || <!FORBIDDEN_IDENTITY_EQUALS_WARNING, SENSELESS_COMPARISON!>x !== implicitNullableNothingProperty<!>) {
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>equals(null)
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propT
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>propAny
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propNullableT
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propNullableAny
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funT()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>funAny()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funNullableT()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funNullableAny()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.equals(null)
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propT
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propAny
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propNullableT
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propNullableAny
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funT()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funAny()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funNullableT()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funNullableAny()
         }
     }
 }
@@ -497,7 +497,7 @@ fun case_25(b: Boolean, z: Nothing?) {
     val y = if (b) x else z
 
     if (y !== z || <!SENSELESS_COMPARISON!>y != implicitNullableNothingProperty<!>) {
-        val z1 = <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!><!UNSAFE_IMPLICIT_INVOKE_CALL!>y<!>()<!>
+        val z1 = <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!>y()<!>
 
         if (z1 != z && <!SENSELESS_COMPARISON!>implicitNullableNothingProperty !== z1<!>) {
             <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>? & <anonymous>")!>z1<!>.a
@@ -663,16 +663,16 @@ fun case_33(a: ((Float) -> Int?)?, b: Float?, c: Boolean?) {
         if (x == z == true && <!FORBIDDEN_IDENTITY_EQUALS_WARNING, SENSELESS_COMPARISON!>x === z<!> || (c != z && !c)) {
 
         } else {
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>equals(null)
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propT
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>propAny
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propNullableT
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.propNullableAny
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funT()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!><!UNSAFE_CALL!>.<!>funAny()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funNullableT()
-            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int?")!>x<!>.funNullableAny()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.equals(null)
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propT
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propAny
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propNullableT
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.propNullableAny
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funT()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funAny()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funNullableT()
+            <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Int? & kotlin.Int")!>x<!>.funNullableAny()
         }
     }
 }