From f3a01af29b1941ca7937a45504ab10ef5f99cdff Mon Sep 17 00:00:00 2001
From: Jeff Davis
Date: Wed, 21 Jun 2023 13:18:25 -0700
Subject: ICU: do not convert locale 'C' to 'en-US-u-va-posix'.

Older versions of ICU canonicalize "C" to "en-US-u-va-posix"; but
starting in ICU version 64, the "C" locale is considered
obsolete. Postgres commit ea1db8ae70 introduced code to always
canonicalize "C" to "en-US-u-va-posix" for consistency and
convenience, but it was deemed too confusing.

This commit removes that code, so that "C" is treated like other ICU
locale names: canonicalization is attempted, and if it fails, the
behavior is controlled by icu_validation_level.

A similar change was previously committed as f7faa9976c, then reverted
due to an ICU-version-dependent test failure. This commit un-reverts
it, omitting the test because we now expect the behavior to depend on
the version of ICU being used.

Discussion: https://postgr.es/m/3a200aca-4672-4b37-fc91-5d198a323503%40eisentraut.org
Discussion: https://postgr.es/m/f83f089ee1e9acd5dbbbf3353294d24e1f196e95.camel@j-davis.com
Discussion: https://postgr.es/m/37520ec1ae9591f83132f82dbd625f3fc2d69c16.camel@j-davis.com
---
 src/backend/utils/adt/pg_locale.c | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

(limited to 'src/backend')

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 31e3b16ae00..c8b36f3af2f 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -2784,26 +2784,10 @@ icu_language_tag(const char *loc_str, int elevel)
 {
 #ifdef USE_ICU
 	UErrorCode	status;
-	char		lang[ULOC_LANG_CAPACITY];
 	char	   *langtag;
 	size_t		buflen = 32;	/* arbitrary starting buffer size */
 	const bool	strict = true;
 
-	status = U_ZERO_ERROR;
-	uloc_getLanguage(loc_str, lang, ULOC_LANG_CAPACITY, &status);
-	if (U_FAILURE(status) || status == U_STRING_NOT_TERMINATED_WARNING)
-	{
-		if (elevel > 0)
-			ereport(elevel,
-					(errmsg("could not get language from locale \"%s\": %s",
-							loc_str, u_errorName(status))));
-		return NULL;
-	}
-
-	/* C/POSIX locales aren't handled by uloc_getLanguageTag() */
-	if (strcmp(lang, "c") == 0 || strcmp(lang, "posix") == 0)
-		return pstrdup("en-US-u-va-posix");
-
 	/*
 	 * A BCP47 language tag doesn't have a clearly-defined upper limit (cf.
 	 * RFC5646 section 4.4). Additionally, in older ICU versions,
@@ -2884,8 +2868,7 @@ icu_validate_locale(const char *loc_str)
 
 	/* check for special language name */
 	if (strcmp(lang, "") == 0 ||
-		strcmp(lang, "root") == 0 || strcmp(lang, "und") == 0 ||
-		strcmp(lang, "c") == 0 || strcmp(lang, "posix") == 0)
+		strcmp(lang, "root") == 0 || strcmp(lang, "und") == 0)
 		found = true;
 
 	/* search for matching language within ICU */
-- 
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