Use ICU by default at initdb time.

If the ICU locale is not specified, initialize the default collator
and retrieve the locale name from that.

Discussion: https://postgr.es/m/510d284759f6e943ce15096167760b2edcb2e700.camel@j-davis.com
Reviewed-by: Peter Eisentraut

contrib/citext/expected/citext_utf8.out

@@ -1,9 +1,16 @@
 /*
  * This test must be run in a database with UTF-8 encoding
  * and a Unicode-aware locale.
+ *
+ * Also disable this file for ICU, because the test for the the
+ * Turkish dotted I is not correct for many ICU locales. citext always
+ * uses the default collation, so it's not easy to restrict the test
+ * to the "tr-TR-x-icu" collation where it will succeed.
  */
 SELECT getdatabaseencoding() <> 'UTF8' OR
-       current_setting('lc_ctype') = 'C'
+       current_setting('lc_ctype') = 'C' OR
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
        AS skip_test \gset
 \if :skip_test
 \quit

contrib/citext/expected/citext_utf8_1.out

@@ -1,9 +1,16 @@
 /*
  * This test must be run in a database with UTF-8 encoding
  * and a Unicode-aware locale.
+ *
+ * Also disable this file for ICU, because the test for the the
+ * Turkish dotted I is not correct for many ICU locales. citext always
+ * uses the default collation, so it's not easy to restrict the test
+ * to the "tr-TR-x-icu" collation where it will succeed.
  */
 SELECT getdatabaseencoding() <> 'UTF8' OR
-       current_setting('lc_ctype') = 'C'
+       current_setting('lc_ctype') = 'C' OR
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
        AS skip_test \gset
 \if :skip_test
 \quit

contrib/citext/sql/citext_utf8.sql

@@ -1,10 +1,17 @@
 /*
  * This test must be run in a database with UTF-8 encoding
  * and a Unicode-aware locale.
+ *
+ * Also disable this file for ICU, because the test for the the
+ * Turkish dotted I is not correct for many ICU locales. citext always
+ * uses the default collation, so it's not easy to restrict the test
+ * to the "tr-TR-x-icu" collation where it will succeed.
  */
 
 SELECT getdatabaseencoding() <> 'UTF8' OR
-       current_setting('lc_ctype') = 'C'
+       current_setting('lc_ctype') = 'C' OR
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
        AS skip_test \gset
 \if :skip_test
 \quit

contrib/unaccent/expected/unaccent.out

@@ -1,3 +1,12 @@
+-- unaccent is broken if the default collation is provided by ICU and
+-- LC_CTYPE=C
+SELECT current_setting('lc_ctype') = 'C' AND
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
+	AS skip_test \gset
+\if :skip_test
+\quit
+\endif
 CREATE EXTENSION unaccent;
 -- must have a UTF8 database
 SELECT getdatabaseencoding();

contrib/unaccent/expected/unaccent_1.out

@@ -0,0 +1,8 @@
+-- unaccent is broken if the default collation is provided by ICU and
+-- LC_CTYPE=C
+SELECT current_setting('lc_ctype') = 'C' AND
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
+	AS skip_test \gset
+\if :skip_test
+\quit

contrib/unaccent/sql/unaccent.sql

@@ -1,3 +1,14 @@
+
+-- unaccent is broken if the default collation is provided by ICU and
+-- LC_CTYPE=C
+SELECT current_setting('lc_ctype') = 'C' AND
+       (SELECT datlocprovider='i' FROM pg_database
+        WHERE datname=current_database())
+	AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+
 CREATE EXTENSION unaccent;
 
 -- must have a UTF8 database

doc/src/sgml/ref/initdb.sgml

@@ -89,10 +89,28 @@ PostgreSQL documentation
    and character set encoding. These can also be set separately for each
    database when it is created. <command>initdb</command> determines those
    settings for the template databases, which will serve as the default for
-   all other databases.  By default, <command>initdb</command> uses the
-   locale provider <literal>libc</literal>, takes the locale settings from
-   the environment, and determines the encoding from the locale settings.
-   This is almost always sufficient, unless there are special requirements.
+   all other databases.
+  </para>
+
+  <para>
+   By default, <command>initdb</command> uses the ICU library to provide
+   locale services if the server was built with ICU support; otherwise it uses
+   the <literal>libc</literal> locale provider (see <xref
+   linkend="locale-providers"/>). To choose the specific ICU locale ID to
+   apply, use the option <option>--icu-locale</option>.  Note that for
+   implementation reasons and to support legacy code,
+   <command>initdb</command> will still select and initialize libc locale
+   settings when the ICU locale provider is used.
+  </para>
+
+  <para>
+   Alternatively, <command>initdb</command> can use the locale provider
+   <literal>libc</literal>. To select this option, specify
+   <literal>--locale-provider=libc</literal>, or build the server without ICU
+   support. The <literal>libc</literal> locale provider takes the locale
+   settings from the environment, and determines the encoding from the locale
+   settings.  This is almost always sufficient, unless there are special
+   requirements.
   </para>
 
   <para>
@@ -103,17 +121,6 @@ PostgreSQL documentation
    categories can give nonsensical results, so this should be used with care.
   </para>
 
-  <para>
-   Alternatively, the ICU library can be used to provide locale services.
-   (Again, this only sets the default for subsequently created databases.)  To
-   select this option, specify <literal>--locale-provider=icu</literal>.
-   To choose the specific ICU locale ID to apply, use the option
-   <option>--icu-locale</option>.  Note that
-   for implementation reasons and to support legacy code,
-   <command>initdb</command> will still select and initialize libc locale
-   settings when the ICU locale provider is used.
-  </para>
-
   <para>
    When <command>initdb</command> runs, it will print out the locale settings
    it has chosen.  If you have complex requirements or specified multiple
@@ -234,7 +241,13 @@ PostgreSQL documentation
       <term><option>--icu-locale=<replaceable>locale</replaceable></option></term>
       <listitem>
        <para>
-        Specifies the ICU locale ID, if the ICU locale provider is used.
+        Specifies the ICU locale when the ICU provider is used. Locale support
+        is described in <xref linkend="locale"/>.
+       </para>
+       <para>
+        If this option is not specified, the locale is inherited from the
+        environment in which <command>initdb</command> runs. The environment's
+        locale is matched to a similar ICU locale name, if possible.
        </para>
       </listitem>
      </varlistentry>
@@ -307,10 +320,12 @@ PostgreSQL documentation
       <term><option>--locale-provider={<literal>libc</literal>|<literal>icu</literal>}</option></term>
       <listitem>
        <para>
-        This option sets the locale provider for databases created in the
-        new cluster.  It can be overridden in the <command>CREATE
+        This option sets the locale provider for databases created in the new
+        cluster.  It can be overridden in the <command>CREATE
         DATABASE</command> command when new databases are subsequently
-        created.  The default is <literal>libc</literal>.
+        created.  The default is <literal>icu</literal> if the server was
+        built with ICU support; otherwise the default is
+        <literal>libc</literal> (see <xref linkend="locale-providers"/>).
        </para>
       </listitem>
      </varlistentry>

src/bin/initdb/Makefile

@@ -16,7 +16,7 @@ subdir = src/bin/initdb
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(CPPFLAGS)
+override CPPFLAGS := -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(ICU_CFLAGS) $(CPPFLAGS)
 
 # Note: it's important that we link to encnames.o from libpgcommon, not
 # from libpq, else we have risks of version skew if we run with a libpq
@@ -24,7 +24,7 @@ override CPPFLAGS := -I$(libpq_srcdir) -I$(top_srcdir)/src/timezone $(CPPFLAGS)
 # should ensure that that happens.
 #
 # We need libpq only because fe_utils does.
-LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
+LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport) $(ICU_LIBS)
 
 # use system timezone data?
 ifneq (,$(with_system_tzdata))

src/bin/initdb/initdb.c

@@ -53,6 +53,9 @@
 #include <netdb.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
+#ifdef USE_ICU
+#include <unicode/ucol.h>
+#endif
 #include <unistd.h>
 #include <signal.h>
 #include <time.h>
@@ -133,7 +136,11 @@ static char *lc_monetary = NULL;
 static char *lc_numeric = NULL;
 static char *lc_time = NULL;
 static char *lc_messages = NULL;
+#ifdef USE_ICU
+static char locale_provider = COLLPROVIDER_ICU;
+#else
 static char locale_provider = COLLPROVIDER_LIBC;
+#endif
 static char *icu_locale = NULL;
 static char *icu_rules = NULL;
 static const char *default_text_search_config = NULL;
@@ -2028,6 +2035,50 @@ check_icu_locale_encoding(int user_enc)
 	return true;
 }
 
+/*
+ * Check that ICU accepts the locale name; or if not specified, retrieve the
+ * default ICU locale.
+ */
+static void
+check_icu_locale(void)
+{
+#ifdef USE_ICU
+	UCollator	*collator;
+	UErrorCode   status;
+
+	status = U_ZERO_ERROR;
+	collator = ucol_open(icu_locale, &status);
+	if (U_FAILURE(status))
+	{
+		if (icu_locale)
+			pg_fatal("could not open collator for locale \"%s\": %s",
+					 icu_locale, u_errorName(status));
+		else
+			pg_fatal("could not open collator for default locale: %s",
+					 u_errorName(status));
+	}
+
+	/* if not specified, get locale from default collator */
+	if (icu_locale == NULL)
+	{
+		const char	*default_locale;
+
+		status = U_ZERO_ERROR;
+		default_locale = ucol_getLocaleByType(collator, ULOC_VALID_LOCALE,
+											  &status);
+		if (U_FAILURE(status))
+		{
+			ucol_close(collator);
+			pg_fatal("could not determine default ICU locale");
+		}
+
+		icu_locale = pg_strdup(default_locale);
+	}
+
+	ucol_close(collator);
+#endif
+}
+
 /*
  * set up the locale variables
  *
@@ -2081,8 +2132,7 @@ setlocales(void)
 
 	if (locale_provider == COLLPROVIDER_ICU)
 	{
-		if (!icu_locale)
-			pg_fatal("ICU locale must be specified");
+		check_icu_locale();
 
 		/*
 		 * In supported builds, the ICU locale ID will be checked by the

src/bin/initdb/t/001_initdb.pl

@@ -97,11 +97,6 @@ SKIP:
 
 if ($ENV{with_icu} eq 'yes')
 {
-	command_fails_like(
-		[ 'initdb', '--no-sync', '--locale-provider=icu', "$tempdir/data2" ],
-		qr/initdb: error: ICU locale must be specified/,
-		'locale provider ICU requires --icu-locale');
-
 	command_ok(
 		[
 			'initdb',                '--no-sync',
@@ -116,7 +111,7 @@ if ($ENV{with_icu} eq 'yes')
 			'--locale-provider=icu', '--icu-locale=@colNumeric=lower',
 			"$tempdir/dataX"
 		],
-		qr/FATAL:  could not open collator for locale/,
+		qr/error: could not open collator for locale/,
 		'fails for invalid ICU locale');
 
 	command_fails_like(

src/bin/pg_dump/t/002_pg_dump.pl

@@ -1758,7 +1758,7 @@ my %tests = (
 		create_sql =>
 		  "CREATE DATABASE dump_test2 LOCALE = 'C' TEMPLATE = template0;",
 		regexp => qr/^
-			\QCREATE DATABASE dump_test2 \E.*\QLOCALE = 'C';\E
+			\QCREATE DATABASE dump_test2 \E.*\QLOCALE = 'C'\E
 			/xm,
 		like => { pg_dumpall_dbprivs => 1, },
 	},

src/bin/scripts/t/020_createdb.pl

@@ -13,7 +13,7 @@ program_version_ok('createdb');
 program_options_handling_ok('createdb');
 
 my $node = PostgreSQL::Test::Cluster->new('main');
-$node->init;
+$node->init(extra => ['--locale-provider=libc']);
 $node->start;
 
 $node->issues_sql_like(

src/interfaces/ecpg/test/Makefile

@@ -14,9 +14,6 @@ override CPPFLAGS := \
 	'-DSHELLPROG="$(SHELL)"' \
 	$(CPPFLAGS)
 
-# default encoding for regression tests
-ENCODING = SQL_ASCII
-
 ifneq ($(build_os),mingw32)
 abs_builddir := $(shell pwd)
 else

src/interfaces/ecpg/test/connect/test5.pgc

@@ -55,7 +55,7 @@ exec sql end declare section;
 	exec sql connect to 'unix:postgresql://localhost/ecpg2_regression' as main user :user USING "connectpw";
 	exec sql disconnect main;
 
-	exec sql connect to unix:postgresql://localhost/ecpg2_regression?connect_timeout=180&client_encoding=latin1 as main user regress_ecpg_user1/connectpw;
+	exec sql connect to unix:postgresql://localhost/ecpg2_regression?connect_timeout=180&client_encoding=sql_ascii as main user regress_ecpg_user1/connectpw;
 	exec sql disconnect main;
 
 	exec sql connect to "unix:postgresql://200.46.204.71/ecpg2_regression" as main user regress_ecpg_user1/connectpw;

src/interfaces/ecpg/test/expected/connect-test5.c

@@ -117,7 +117,7 @@ main(void)
 #line 56 "test5.pgc"
 
 
-	{ ECPGconnect(__LINE__, 0, "unix:postgresql://localhost/ecpg2_regression?connect_timeout=180 & client_encoding=latin1" , "regress_ecpg_user1" , "connectpw" , "main", 0); }
+	{ ECPGconnect(__LINE__, 0, "unix:postgresql://localhost/ecpg2_regression?connect_timeout=180 & client_encoding=sql_ascii" , "regress_ecpg_user1" , "connectpw" , "main", 0); }
 #line 58 "test5.pgc"
 
 	{ ECPGdisconnect(__LINE__, "main");}

src/interfaces/ecpg/test/expected/connect-test5.stderr

@@ -50,7 +50,7 @@
 [NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_finish: connection main closed
 [NO_PID]: sqlca: code: 0, state: 00000
-[NO_PID]: ECPGconnect: opening database ecpg2_regression on <DEFAULT> port <DEFAULT> with options connect_timeout=180 & client_encoding=latin1 for user regress_ecpg_user1
+[NO_PID]: ECPGconnect: opening database ecpg2_regression on <DEFAULT> port <DEFAULT> with options connect_timeout=180 & client_encoding=sql_ascii for user regress_ecpg_user1
 [NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_finish: connection main closed
 [NO_PID]: sqlca: code: 0, state: 00000

src/interfaces/ecpg/test/meson.build

@@ -69,7 +69,6 @@ ecpg_test_files = files(
 ecpg_regress_args = [
   '--dbname=ecpg1_regression,ecpg2_regression',
   '--create-role=regress_ecpg_user1,regress_ecpg_user2',
-  '--encoding=SQL_ASCII',
 ]
 
 tests += {

src/test/icu/t/010_database.pl

@@ -12,7 +12,7 @@ if ($ENV{with_icu} ne 'yes')
 }
 
 my $node1 = PostgreSQL::Test::Cluster->new('node1');
-$node1->init;
+$node1->init(extra => ['--locale-provider=libc']);
 $node1->start;
 
 $node1->safe_psql('postgres',