[FE] Don't fail with exception if ESVisitor tries to visit ESLambda

#KT-45243 Fixed

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -32152,6 +32152,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     runTest("compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.kt");
                 }
 
+                @Test
+                @TestMetadata("kt45243.kt")
+                public void testKt45243() throws Exception {
+                    runTest("compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/kt45243.kt");
+                }
+
                 @Test
                 @TestMetadata("require.kt")
                 public void testRequire() throws Exception {

compiler/frontend/src/org/jetbrains/kotlin/contracts/ESDataFlowValue.kt

@@ -78,6 +78,6 @@ class ESReceiverWithDataFlowValue(
  */
 class ESLambda(val lambda: KtLambdaExpression) : AbstractESValue(null) {
     override fun <T> accept(visitor: ESExpressionVisitor<T>): T {
-        throw IllegalStateException("Lambdas shouldn't be visited by ESExpressionVisitor")
+        return visitor.visitLambda(this)
     }
-}
+}

compiler/resolution/src/org/jetbrains/kotlin/contracts/model/ESExpressionVisitor.kt

@@ -30,4 +30,7 @@ interface ESExpressionVisitor<out T> {
     fun visitConstant(esConstant: ESConstant): T
 
     fun visitReceiver(esReceiver: ESReceiver): T
-}
+
+    // ESLambda is invisible in this module
+    fun visitLambda(lambda: ESValue): T
+}

compiler/resolution/src/org/jetbrains/kotlin/contracts/model/visitors/InfoCollector.kt

@@ -17,10 +17,7 @@
 package org.jetbrains.kotlin.contracts.model.visitors
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
-import org.jetbrains.kotlin.contracts.model.ConditionalEffect
-import org.jetbrains.kotlin.contracts.model.ESEffect
-import org.jetbrains.kotlin.contracts.model.ESExpressionVisitor
-import org.jetbrains.kotlin.contracts.model.MutableContextInfo
+import org.jetbrains.kotlin.contracts.model.*
 import org.jetbrains.kotlin.contracts.model.structure.*
 
 class InfoCollector(private val observedEffect: ESEffect, private val builtIns: KotlinBuiltIns) : ESExpressionVisitor<MutableContextInfo> {
@@ -83,6 +80,8 @@ class InfoCollector(private val observedEffect: ESEffect, private val builtIns:
 
     override fun visitReceiver(esReceiver: ESReceiver): MutableContextInfo = MutableContextInfo.EMPTY
 
+    override fun visitLambda(lambda: ESValue): MutableContextInfo = MutableContextInfo.EMPTY
+
     private fun <R> inverted(block: () -> R): R {
         isInverted = isInverted.not()
         val result = block()

compiler/resolution/src/org/jetbrains/kotlin/contracts/model/visitors/Reducer.kt

@@ -66,8 +66,8 @@ class Reducer(private val builtIns: KotlinBuiltIns) : ESExpressionVisitor<ESExpr
         return ESConstants.booleanValue(result.xor(isOperator.functor.isNegated))
     }
 
-    override fun visitEqual(equal: ESEqual): ESExpression {
-        val reducedLeft = equal.left.accept(this) as ESValue
+    override fun visitEqual(equal: ESEqual): ESExpression? {
+        val reducedLeft = equal.left.accept(this) as ESValue? ?: return null
         val reducedRight = equal.right
 
         if (reducedLeft is ESConstant) return ESConstants.booleanValue((reducedLeft == reducedRight).xor(equal.functor.isNegated))
@@ -114,4 +114,8 @@ class Reducer(private val builtIns: KotlinBuiltIns) : ESExpressionVisitor<ESExpr
     override fun visitConstant(esConstant: ESConstant): ESConstant = esConstant
 
     override fun visitReceiver(esReceiver: ESReceiver): ESReceiver = esReceiver
+
+    override fun visitLambda(lambda: ESValue): ESExpression? {
+        return null
+    }
 }

compiler/resolution/src/org/jetbrains/kotlin/contracts/model/visitors/Substitutor.kt

@@ -16,10 +16,7 @@
 
 package org.jetbrains.kotlin.contracts.model.visitors
 
-import org.jetbrains.kotlin.contracts.model.Computation
-import org.jetbrains.kotlin.contracts.model.ESExpression
-import org.jetbrains.kotlin.contracts.model.ESExpressionVisitor
-import org.jetbrains.kotlin.contracts.model.ESTypeSubstitution
+import org.jetbrains.kotlin.contracts.model.*
 import org.jetbrains.kotlin.contracts.model.structure.*
 
 /**
@@ -60,9 +57,11 @@ class Substitutor(
         return CallComputation(ESBooleanType, or.functor.invokeWithArguments(left, right))
     }
 
-    override fun visitVariable(esVariable: ESVariable): Computation? = substitutions[esVariable] ?: esVariable
+    override fun visitVariable(esVariable: ESVariable): Computation = substitutions[esVariable] ?: esVariable
 
-    override fun visitConstant(esConstant: ESConstant): Computation? = esConstant
+    override fun visitConstant(esConstant: ESConstant): Computation = esConstant
 
     override fun visitReceiver(esReceiver: ESReceiver): ESReceiver = esReceiver
+
+    override fun visitLambda(lambda: ESValue): Computation = lambda
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/kt45243.fir.kt

@@ -0,0 +1,19 @@
+// ISSUE: KT-45243
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+@ExperimentalContracts
+fun <T> assertNotNull(actual: T) {
+    <!WRONG_IMPLIES_CONDITION!>contract { returns() implies (actual != null) }<!>
+}
+
+@ExperimentalContracts
+fun test_1() {
+    assertNotNull { }
+}
+
+@ExperimentalContracts
+fun test_2() {
+    assertNotNull({ })
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/kt45243.kt

@@ -0,0 +1,19 @@
+// ISSUE: KT-45243
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+@ExperimentalContracts
+fun <T> assertNotNull(actual: T) {
+    contract { returns() implies (actual != null) }
+}
+
+@ExperimentalContracts
+fun test_1() {
+    assertNotNull { }
+}
+
+@ExperimentalContracts
+fun test_2() {
+    assertNotNull({ })
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/kt45243.txt

@@ -0,0 +1,8 @@
+package
+
+@kotlin.contracts.ExperimentalContracts public fun </*0*/ T> assertNotNull(/*0*/ actual: T): kotlin.Unit
+    Returns(WILDCARD) -> actual != null
+
+@kotlin.contracts.ExperimentalContracts public fun test_1(): kotlin.Unit
+@kotlin.contracts.ExperimentalContracts public fun test_2(): kotlin.Unit
+

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -32248,6 +32248,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.kt");
                 }
 
+                @Test
+                @TestMetadata("kt45243.kt")
+                public void testKt45243() throws Exception {
+                    runTest("compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/kt45243.kt");
+                }
+
                 @Test
                 @TestMetadata("require.kt")
                 public void testRequire() throws Exception {