[SR-3842] Add test from the bug report. We want to keep this working in Swift 3

(cherry picked from commit e44257d7fd6cc25e58e52467099c77eac5fdc0f8)
diff --git a/test/Compatibility/sr3842_map_string_init.swift b/test/Compatibility/sr3842_map_string_init.swift
new file mode 100644
index 0000000..38e1252
--- /dev/null
+++ b/test/Compatibility/sr3842_map_string_init.swift
@@ -0,0 +1,6 @@
+// RUN: %target-typecheck-verify-swift -swift-version 3
+
+// SR-3842
+func test(years: [Int]) {
+  _ = years.map(String.init)
+}