Introduce "builtin" collation provider.

New provider for collations, like "libc" or "icu", but without any
external dependency.

Initially, the only locale supported by the builtin provider is "C",
which is identical to the libc provider's "C" locale. The libc
provider's "C" locale has always been treated as a special case that
uses an internal implementation, without using libc at all -- so the
new builtin provider uses the same implementation.

The builtin provider's locale is independent of the server environment
variables LC_COLLATE and LC_CTYPE. Using the builtin provider, the
database collation locale can be "C" while LC_COLLATE and LC_CTYPE are
set to "en_US", which is impossible with the libc provider.

By offering a new builtin provider, it clarifies that the semantics of
a collation using this provider will never depend on libc, and makes
it easier to document the behavior.

Discussion: https://postgr.es/m/ab925f69-5f9d-f85e-b87c-bd2a44798659@joeconway.com
Discussion: https://postgr.es/m/dd9261f4-7a98-4565-93ec-336c1c110d90@manitou-mail.org
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Daniel Vérité, Peter Eisentraut, Jeremy Schneider

1 files changed, 15 insertions, 4 deletions

diff --git a/src/bin/scripts/createdb.c b/src/bin/scripts/createdb.c
index 14970a6a5f8..007061e756f 100644
--- a/src/bin/scripts/createdb.c
+++ b/src/bin/scripts/createdb.c
@@ -40,8 +40,9 @@ main(int argc, char *argv[])
 		{"locale", required_argument, NULL, 'l'},
 		{"maintenance-db", required_argument, NULL, 3},
 		{"locale-provider", required_argument, NULL, 4},
-		{"icu-locale", required_argument, NULL, 5},
-		{"icu-rules", required_argument, NULL, 6},
+		{"builtin-locale", required_argument, NULL, 5},
+		{"icu-locale", required_argument, NULL, 6},
+		{"icu-rules", required_argument, NULL, 7},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -67,6 +68,7 @@ main(int argc, char *argv[])
 	char	   *lc_ctype = NULL;
 	char	   *locale = NULL;
 	char	   *locale_provider = NULL;
+	char	   *builtin_locale = NULL;
 	char	   *icu_locale = NULL;
 	char	   *icu_rules = NULL;
 
@@ -134,9 +136,12 @@ main(int argc, char *argv[])
 				locale_provider = pg_strdup(optarg);
 				break;
 			case 5:
-				icu_locale = pg_strdup(optarg);
+				builtin_locale = pg_strdup(optarg);
 				break;
 			case 6:
+				icu_locale = pg_strdup(optarg);
+				break;
+			case 7:
 				icu_rules = pg_strdup(optarg);
 				break;
 			default:
@@ -216,6 +221,11 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(&sql, " LOCALE ");
 		appendStringLiteralConn(&sql, locale, conn);
 	}
+	if (builtin_locale)
+	{
+		appendPQExpBufferStr(&sql, " BUILTIN_LOCALE ");
+		appendStringLiteralConn(&sql, builtin_locale, conn);
+	}
 	if (lc_collate)
 	{
 		appendPQExpBufferStr(&sql, " LC_COLLATE ");
@@ -294,9 +304,10 @@ help(const char *progname)
 	printf(_("  -l, --locale=LOCALE          locale settings for the database\n"));
 	printf(_("      --lc-collate=LOCALE      LC_COLLATE setting for the database\n"));
 	printf(_("      --lc-ctype=LOCALE        LC_CTYPE setting for the database\n"));
+	printf(_("      --builtin-locale=LOCALE  builtin locale setting for the database\n"));
 	printf(_("      --icu-locale=LOCALE      ICU locale setting for the database\n"));
 	printf(_("      --icu-rules=RULES        ICU rules setting for the database\n"));
-	printf(_("      --locale-provider={libc|icu}\n"
+	printf(_("      --locale-provider={builtin|libc|icu}\n"
 			 "                               locale provider for the database's default collation\n"));
 	printf(_("  -O, --owner=OWNER            database user to own the new database\n"));
 	printf(_("  -S, --strategy=STRATEGY      database creation strategy wal_log or file_copy\n"));