Complete language variants filled in for LANG var

Part of #80072

src/vs/workbench/contrib/terminal/common/terminalEnvironment.ts

@@ -96,23 +96,63 @@ function _getLangEnvVariable(locale?: string) {
 		return 'en_US.UTF-8';
 	}
 	if (n === 1) {
-		// app.getLocale can return just a language without a variant, fill in the variant for
-		// supported languages as many shells expect a 2-part locale.
+		// The local may only contain the language, not the variant, if this is the case guess the
+		// variant such that it can be used as a valid $LANG variable. The language variant chosen
+		// is the original and/or most prominent with help from
+		// https://stackoverflow.com/a/2502675/1156119
+		// The list of locales was generated by running `locale -a` on macOS
 		const languageVariants: { [key: string]: string } = {
+			af: 'ZA',
+			am: 'ET',
+			be: 'BY',
+			bg: 'BG',
+			ca: 'ES',
 			cs: 'CZ',
+			da: 'DK',
+			// de: 'AT',
+			// de: 'CH',
 			de: 'DE',
+			el: 'GR',
+			// en: 'AU',
+			// en: 'CA',
+			// en: 'GB',
+			// en: 'IE',
+			// en: 'NZ',
 			en: 'US',
 			es: 'ES',
+			et: 'EE',
+			eu: 'ES',
 			fi: 'FI',
+			// fr: 'BE',
+			// fr: 'CA',
+			// fr: 'CH',
 			fr: 'FR',
+			he: 'IL',
+			hr: 'HR',
 			hu: 'HU',
+			hy: 'AM',
+			is: 'IS',
+			// it: 'CH',
 			it: 'IT',
 			ja: 'JP',
+			kk: 'KZ',
 			ko: 'KR',
+			lt: 'LT',
+			// nl: 'BE',
+			nl: 'NL',
+			no: 'NO',
 			pl: 'PL',
+			pt: 'BR',
+			// pt: 'PT',
+			ro: 'RO',
 			ru: 'RU',
 			sk: 'SK',
-			zh: 'CN'
+			sl: 'SI',
+			sr: 'YU',
+			sv: 'SE',
+			tr: 'TR',
+			uk: 'UA',
+			zh: 'CN',
 		};
 		if (parts[0] in languageVariants) {
 			parts.push(languageVariants[parts[0]]);