Add a test of OID::to_string

This is our canary in the coalmine for std::to_string respecting
locale

1 files changed, 36 insertions, 0 deletions

diff --git a/src/tests/test_oid.cpp b/src/tests/test_oid.cpp
index 430d4fe4b..f803b2d05 100644
--- a/src/tests/test_oid.cpp
+++ b/src/tests/test_oid.cpp
@@ -16,6 +16,41 @@ namespace {
 
 #if defined(BOTAN_HAS_ASN1)
 
+Test::Result test_OID_to_string()
+   {
+   /*
+   See #2730 and #2237
+
+   Certain locales format integers with thousands seperators.  This
+   caused a subtle bug which caused OID comparisons to fail because
+   OID::to_string(), which used ostringstream, introduced a thousands
+   seperator when the OID component had a value >= 1000. But this
+   only failed in certain locales (pt_BR was reported).
+
+   Nominally C++ requires std::to_string to also be locale-respecting.
+   But, libc++, libstdc++, and MSVC's STL library all implement
+   std::to_string in a way that ignores locales, because adding locale
+   support means std::to_string will be both slow and a serialization
+   point. So as a stopgap we assume this behavior from std::to_string.
+
+   Here we test the original issue of #2237 to verify it works. If
+   the compiler implements std::to_string in a way that respects locale,
+   *and* this test is run in a locale that uses thousands seperators,
+   then it will fail. Which is much better than a very subtle failure.
+   However if it ever does fail then we must replace nearly every
+   call to std::to_string with something else that ignores locale.
+   */
+
+   Botan::OID oid{1,2,1000,1001,1002000};
+
+   Test::Result result("OID::to_string");
+
+   result.test_eq("OID::to_string behaves as we expect",
+                  oid.to_string(), "1.2.1000.1001.1002000");
+
+   return result;
+   }
+
 Test::Result test_add_have_OID()
    {
    Test::Result result("OID add");
@@ -83,6 +118,7 @@ class OID_Tests final : public Test
 
          std::vector<std::function<Test::Result()>> fns =
             {
+            test_OID_to_string,
             test_add_have_OID,
             test_add_have_OID_str,
             test_add_and_lookup,