Move /src/test to /tests

tests/ui/duplicate_entry_error.rs

@@ -0,0 +1,16 @@
+// normalize-stderr-test "loaded from .*libstd-.*.rlib" -> "loaded from SYSROOT/libstd-*.rlib"
+// note-pattern: first defined in crate `std`.
+
+// Test for issue #31788 and E0152
+
+#![feature(lang_items)]
+
+use std::panic::PanicInfo;
+
+#[lang = "panic_impl"]
+fn panic_impl(info: &PanicInfo) -> ! {
+//~^ ERROR: found duplicate lang item `panic_impl`
+    loop {}
+}
+
+fn main() {}