Change the case of identifiers without a locale

How to do it

In Turkish and Azeri, "I" lower-cases to dotless "ı" and "i" upper-cases to "İ". A server whose default locale is Turkish turns TITLE into tıtle, so header names, enum values and lookups stop matching. JavaScript's toLowerCase() ignores the locale, while toLocaleLowerCase() uses it. Java's toLowerCase() uses the default locale, so pass Locale.ROOT. In C#, use ToLowerInvariant(). Compare user names and email addresses through the canonical key in Compare email addresses and usernames in one canonical form.

Examples

Java example

import java.util.Locale;
String header = "TITLE";
header.toLowerCase(Locale.ROOT);              // "title" on every server
header.toLowerCase(Locale.forLanguageTag("tr")); // "tıtle", for Turkish display text only

JavaScript example

'TITLE'.toLowerCase();             // "title", never locale-dependent
'TITLE'.toLocaleLowerCase('tr');   // "tıtle", for Turkish display text only

Python example

"TITLE".lower()      # "title", Python's str methods ignore the locale
"Straße".casefold()  # "strasse", for case-insensitive comparison

How to check

Run the test suite with the default locale set to Turkish, such as -Duser.language=tr for Java or LC_ALL=tr_TR.UTF-8, and it passes. A lint rule finds no locale-dependent case call on a key, header or enum.

Sources

• Unicode SpecialCasing.txt (Turkish and Azeri mappings)
• ECMA-262 (String.prototype.toLowerCase)

Related rules

• ACC-4 Compare email addresses and usernames in one canonical form in Accounts and identity