[tests] Add test data for KT-61310

compiler/testData/codegen/box/builderInference/issues/kt61310.kt

@@ -0,0 +1,31 @@
+// ISSUE: KT-61310
+
+// IGNORE_LIGHT_ANALYSIS
+// IGNORE_BACKEND_K2: ANY
+// REASON: red code (see corresponding diagnostic test)
+
+fun box(): String {
+    build {
+        if (true) {
+            setTypeVariable(GenericBox())
+        } else {
+            setTypeVariable(GenericBox<TargetType>())
+        }
+    }
+    return "OK"
+}
+
+
+
+
+class TargetType
+class GenericBox<T>
+
+class Buildee<TV> {
+    fun setTypeVariable(value: TV) { storage = value }
+    private var storage: TV = GenericBox<TargetType>() as TV
+}
+
+fun <PTV> build(instructions: Buildee<PTV>.() -> Unit): Buildee<PTV> {
+    return Buildee<PTV>().apply(instructions)
+}

compiler/testData/diagnostics/tests/builderInference/issues/kt61310.fir.kt

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+// ISSUE: KT-61310
+// CHECK_TYPE_WITH_EXACT
+
+fun test() {
+    val buildee = <!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>build<!> {
+        if (true) {
+            setTypeVariable(<!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>GenericBox<!>())
+        } else {
+            setTypeVariable(GenericBox<TargetType>())
+        }
+    }
+    // exact type equality check — turns unexpected compile-time behavior into red code
+    // considered to be non-user-reproducible code for the purposes of these tests
+    <!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>checkExactType<!><<!CANNOT_INFER_PARAMETER_TYPE!>Buildee<GenericBox<TargetType>><!>>(buildee)
+}
+
+
+
+
+class TargetType
+class GenericBox<T>
+
+class Buildee<TV> {
+    fun setTypeVariable(value: TV) { storage = value }
+    private var storage: TV = null!!
+}
+
+fun <PTV> build(instructions: Buildee<PTV>.() -> Unit): Buildee<PTV> {
+    return Buildee<PTV>().apply(instructions)
+}

compiler/testData/diagnostics/tests/builderInference/issues/kt61310.kt

@@ -0,0 +1,30 @@
+// ISSUE: KT-61310
+// CHECK_TYPE_WITH_EXACT
+
+fun test() {
+    val buildee = build {
+        if (true) {
+            setTypeVariable(GenericBox())
+        } else {
+            setTypeVariable(GenericBox<TargetType>())
+        }
+    }
+    // exact type equality check — turns unexpected compile-time behavior into red code
+    // considered to be non-user-reproducible code for the purposes of these tests
+    checkExactType<Buildee<GenericBox<TargetType>>>(buildee)
+}
+
+
+
+
+class TargetType
+class GenericBox<T>
+
+class Buildee<TV> {
+    fun setTypeVariable(value: TV) { storage = value }
+    private var storage: TV = null!!
+}
+
+fun <PTV> build(instructions: Buildee<PTV>.() -> Unit): Buildee<PTV> {
+    return Buildee<PTV>().apply(instructions)
+}