[tests] Add test data for KT-54400

compiler/testData/diagnostics/tests/builderInference/issues/kt54400a.fir.kt

@@ -0,0 +1,25 @@
+// ISSUE: KT-54400
+// CHECK_TYPE_WITH_EXACT
+
+fun test() {
+    val buildee = <!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>build<!> {
+        typeVariableMutableProperty = ""
+    }
+    // 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<String><!>>(buildee)
+}
+
+
+
+
+class Buildee<TV> {
+    var typeVariableMutableProperty: TV
+        get() = storage
+        set(value) { storage = value }
+    private var storage: TV = null!!
+}
+
+fun <PTV> build(instructions: Buildee<PTV>.() -> Unit): Buildee<PTV> {
+    return Buildee<PTV>().apply(instructions)
+}