Remove support for null pg_locale_t most places.

Previously, passing NULL for pg_locale_t meant "use the libc provider
and the server environment". Now that the database collation is
represented as a proper pg_locale_t (not dependent on setlocale()),
remove special cases for NULL.

Leave wchar2char() and char2wchar() unchanged for now, because the
callers don't always have a libc-based pg_locale_t available.

Discussion: https://postgr.es/m/cfd9eb85-c52a-4ec9-a90e-a5e4de56e57d@eisentraut.org
Reviewed-by: Peter Eisentraut, Andreas Karlsson

7 files changed, 73 insertions, 255 deletions

diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index c3a67b51afe..86f1adecb75 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -268,7 +268,7 @@ hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
 	Oid			collid = PG_GET_COLLATION();
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	Datum		result;
 
 	if (!collid)
@@ -277,8 +277,7 @@ hashtext(PG_FUNCTION_ARGS)
 				 errmsg("could not determine which collation to use for string hashing"),
 				 errhint("Use the COLLATE clause to set the collation explicitly.")));
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (pg_locale_deterministic(mylocale))
 	{
@@ -324,7 +323,7 @@ hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
 	Oid			collid = PG_GET_COLLATION();
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	Datum		result;
 
 	if (!collid)
@@ -333,8 +332,7 @@ hashtextextended(PG_FUNCTION_ARGS)
 				 errmsg("could not determine which collation to use for string hashing"),
 				 errhint("Use the COLLATE clause to set the collation explicitly.")));
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (pg_locale_deterministic(mylocale))
 	{
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index 9d98d10a285..947d73f3e0f 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -67,8 +67,6 @@ typedef enum
 {
 	PG_REGEX_LOCALE_C,			/* C locale (encoding independent) */
 	PG_REGEX_BUILTIN,			/* built-in Unicode semantics */
-	PG_REGEX_LOCALE_WIDE,		/* Use <wctype.h> functions */
-	PG_REGEX_LOCALE_1BYTE,		/* Use <ctype.h> functions */
 	PG_REGEX_LOCALE_WIDE_L,		/* Use locale_t <wctype.h> functions */
 	PG_REGEX_LOCALE_1BYTE_L,	/* Use locale_t <ctype.h> functions */
 	PG_REGEX_LOCALE_ICU,		/* Use ICU uchar.h functions */
@@ -261,13 +259,13 @@ pg_set_regex_collation(Oid collation)
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("nondeterministic collations are not supported for regular expressions")));
 
-		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_BUILTIN)
+		if (pg_regex_locale->provider == COLLPROVIDER_BUILTIN)
 		{
 			Assert(GetDatabaseEncoding() == PG_UTF8);
 			pg_regex_strategy = PG_REGEX_BUILTIN;
 		}
 #ifdef USE_ICU
-		else if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
+		else if (pg_regex_locale->provider == COLLPROVIDER_ICU)
 		{
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
 		}
@@ -275,19 +273,9 @@ pg_set_regex_collation(Oid collation)
 		else
 		{
 			if (GetDatabaseEncoding() == PG_UTF8)
-			{
-				if (pg_regex_locale)
-					pg_regex_strategy = PG_REGEX_LOCALE_WIDE_L;
-				else
-					pg_regex_strategy = PG_REGEX_LOCALE_WIDE;
-			}
+				pg_regex_strategy = PG_REGEX_LOCALE_WIDE_L;
 			else
-			{
-				if (pg_regex_locale)
-					pg_regex_strategy = PG_REGEX_LOCALE_1BYTE_L;
-				else
-					pg_regex_strategy = PG_REGEX_LOCALE_1BYTE;
-			}
+				pg_regex_strategy = PG_REGEX_LOCALE_1BYTE_L;
 		}
 
 		pg_regex_collation = collation;
@@ -304,13 +292,6 @@ pg_wc_isdigit(pg_wchar c)
 					(pg_char_properties[c] & PG_ISDIGIT));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isdigit(c, true);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswdigit((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isdigit((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswdigit_l((wint_t) c, pg_regex_locale->info.lt);
@@ -338,13 +319,6 @@ pg_wc_isalpha(pg_wchar c)
 					(pg_char_properties[c] & PG_ISALPHA));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isalpha(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswalpha((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isalpha((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswalpha_l((wint_t) c, pg_regex_locale->info.lt);
@@ -372,13 +346,6 @@ pg_wc_isalnum(pg_wchar c)
 					(pg_char_properties[c] & PG_ISALNUM));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isalnum(c, true);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswalnum((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isalnum((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswalnum_l((wint_t) c, pg_regex_locale->info.lt);
@@ -415,13 +382,6 @@ pg_wc_isupper(pg_wchar c)
 					(pg_char_properties[c] & PG_ISUPPER));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isupper(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswupper((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isupper((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswupper_l((wint_t) c, pg_regex_locale->info.lt);
@@ -449,13 +409,6 @@ pg_wc_islower(pg_wchar c)
 					(pg_char_properties[c] & PG_ISLOWER));
 		case PG_REGEX_BUILTIN:
 			return pg_u_islower(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswlower((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					islower((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswlower_l((wint_t) c, pg_regex_locale->info.lt);
@@ -483,13 +436,6 @@ pg_wc_isgraph(pg_wchar c)
 					(pg_char_properties[c] & PG_ISGRAPH));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isgraph(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswgraph((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isgraph((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswgraph_l((wint_t) c, pg_regex_locale->info.lt);
@@ -517,13 +463,6 @@ pg_wc_isprint(pg_wchar c)
 					(pg_char_properties[c] & PG_ISPRINT));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isprint(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswprint((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isprint((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswprint_l((wint_t) c, pg_regex_locale->info.lt);
@@ -551,13 +490,6 @@ pg_wc_ispunct(pg_wchar c)
 					(pg_char_properties[c] & PG_ISPUNCT));
 		case PG_REGEX_BUILTIN:
 			return pg_u_ispunct(c, true);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswpunct((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					ispunct((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswpunct_l((wint_t) c, pg_regex_locale->info.lt);
@@ -585,13 +517,6 @@ pg_wc_isspace(pg_wchar c)
 					(pg_char_properties[c] & PG_ISSPACE));
 		case PG_REGEX_BUILTIN:
 			return pg_u_isspace(c);
-		case PG_REGEX_LOCALE_WIDE:
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return iswspace((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			return (c <= (pg_wchar) UCHAR_MAX &&
-					isspace((unsigned char) c));
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return iswspace_l((wint_t) c, pg_regex_locale->info.lt);
@@ -620,20 +545,6 @@ pg_wc_toupper(pg_wchar c)
 			return c;
 		case PG_REGEX_BUILTIN:
 			return unicode_uppercase_simple(c);
-		case PG_REGEX_LOCALE_WIDE:
-			/* force C behavior for ASCII characters, per comments above */
-			if (c <= (pg_wchar) 127)
-				return pg_ascii_toupper((unsigned char) c);
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return towupper((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			/* force C behavior for ASCII characters, per comments above */
-			if (c <= (pg_wchar) 127)
-				return pg_ascii_toupper((unsigned char) c);
-			if (c <= (pg_wchar) UCHAR_MAX)
-				return toupper((unsigned char) c);
-			return c;
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return towupper_l((wint_t) c, pg_regex_locale->info.lt);
@@ -662,20 +573,6 @@ pg_wc_tolower(pg_wchar c)
 			return c;
 		case PG_REGEX_BUILTIN:
 			return unicode_lowercase_simple(c);
-		case PG_REGEX_LOCALE_WIDE:
-			/* force C behavior for ASCII characters, per comments above */
-			if (c <= (pg_wchar) 127)
-				return pg_ascii_tolower((unsigned char) c);
-			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
-				return towlower((wint_t) c);
-			/* FALL THRU */
-		case PG_REGEX_LOCALE_1BYTE:
-			/* force C behavior for ASCII characters, per comments above */
-			if (c <= (pg_wchar) 127)
-				return pg_ascii_tolower((unsigned char) c);
-			if (c <= (pg_wchar) UCHAR_MAX)
-				return tolower((unsigned char) c);
-			return c;
 		case PG_REGEX_LOCALE_WIDE_L:
 			if (sizeof(wchar_t) >= 4 || c <= (pg_wchar) 0xFFFF)
 				return towlower_l((wint_t) c, pg_regex_locale->info.lt);
@@ -829,11 +726,9 @@ pg_ctype_get_cache(pg_wc_probefunc probefunc, int cclasscode)
 		case PG_REGEX_BUILTIN:
 			max_chr = (pg_wchar) MAX_SIMPLE_CHR;
 			break;
-		case PG_REGEX_LOCALE_WIDE:
 		case PG_REGEX_LOCALE_WIDE_L:
 			max_chr = (pg_wchar) MAX_SIMPLE_CHR;
 			break;
-		case PG_REGEX_LOCALE_1BYTE:
 		case PG_REGEX_LOCALE_1BYTE_L:
 #if MAX_SIMPLE_CHR >= UCHAR_MAX
 			max_chr = (pg_wchar) UCHAR_MAX;
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 8736ada4be2..68069fcfd3b 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -1665,7 +1665,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
 		mylocale = pg_newlocale_from_collation(collid);
 
 #ifdef USE_ICU
-		if (mylocale && mylocale->provider == COLLPROVIDER_ICU)
+		if (mylocale->provider == COLLPROVIDER_ICU)
 		{
 			int32_t		len_uchar;
 			int32_t		len_conv;
@@ -1681,7 +1681,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 #endif
-		if (mylocale && mylocale->provider == COLLPROVIDER_BUILTIN)
+		if (mylocale->provider == COLLPROVIDER_BUILTIN)
 		{
 			const char *src = buff;
 			size_t		srclen = nbytes;
@@ -1710,7 +1710,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 		{
-			Assert(!mylocale || mylocale->provider == COLLPROVIDER_LIBC);
+			Assert(mylocale->provider == COLLPROVIDER_LIBC);
 
 			if (pg_database_encoding_max_length() > 1)
 			{
@@ -1730,12 +1730,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
 				char2wchar(workspace, nbytes + 1, buff, nbytes, mylocale);
 
 				for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
-				{
-					if (mylocale)
-						workspace[curr_char] = towlower_l(workspace[curr_char], mylocale->info.lt);
-					else
-						workspace[curr_char] = towlower(workspace[curr_char]);
-				}
+					workspace[curr_char] = towlower_l(workspace[curr_char], mylocale->info.lt);
 
 				/*
 				 * Make result large enough; case change might change number
@@ -1761,12 +1756,7 @@ str_tolower(const char *buff, size_t nbytes, Oid collid)
 				 * collations you get exactly what the collation says.
 				 */
 				for (p = result; *p; p++)
-				{
-					if (mylocale)
-						*p = tolower_l((unsigned char) *p, mylocale->info.lt);
-					else
-						*p = pg_tolower((unsigned char) *p);
-				}
+					*p = tolower_l((unsigned char) *p, mylocale->info.lt);
 			}
 		}
 	}
@@ -1813,7 +1803,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
 		mylocale = pg_newlocale_from_collation(collid);
 
 #ifdef USE_ICU
-		if (mylocale && mylocale->provider == COLLPROVIDER_ICU)
+		if (mylocale->provider == COLLPROVIDER_ICU)
 		{
 			int32_t		len_uchar,
 						len_conv;
@@ -1829,7 +1819,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 #endif
-		if (mylocale && mylocale->provider == COLLPROVIDER_BUILTIN)
+		if (mylocale->provider == COLLPROVIDER_BUILTIN)
 		{
 			const char *src = buff;
 			size_t		srclen = nbytes;
@@ -1858,7 +1848,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 		{
-			Assert(!mylocale || mylocale->provider == COLLPROVIDER_LIBC);
+			Assert(mylocale->provider == COLLPROVIDER_LIBC);
 
 			if (pg_database_encoding_max_length() > 1)
 			{
@@ -1878,12 +1868,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
 				char2wchar(workspace, nbytes + 1, buff, nbytes, mylocale);
 
 				for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
-				{
-					if (mylocale)
-						workspace[curr_char] = towupper_l(workspace[curr_char], mylocale->info.lt);
-					else
-						workspace[curr_char] = towupper(workspace[curr_char]);
-				}
+					workspace[curr_char] = towupper_l(workspace[curr_char], mylocale->info.lt);
 
 				/*
 				 * Make result large enough; case change might change number
@@ -1909,12 +1894,7 @@ str_toupper(const char *buff, size_t nbytes, Oid collid)
 				 * collations you get exactly what the collation says.
 				 */
 				for (p = result; *p; p++)
-				{
-					if (mylocale)
-						*p = toupper_l((unsigned char) *p, mylocale->info.lt);
-					else
-						*p = pg_toupper((unsigned char) *p);
-				}
+					*p = toupper_l((unsigned char) *p, mylocale->info.lt);
 			}
 		}
 	}
@@ -2003,7 +1983,7 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
 		mylocale = pg_newlocale_from_collation(collid);
 
 #ifdef USE_ICU
-		if (mylocale && mylocale->provider == COLLPROVIDER_ICU)
+		if (mylocale->provider == COLLPROVIDER_ICU)
 		{
 			int32_t		len_uchar,
 						len_conv;
@@ -2019,7 +1999,7 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 #endif
-		if (mylocale && mylocale->provider == COLLPROVIDER_BUILTIN)
+		if (mylocale->provider == COLLPROVIDER_BUILTIN)
 		{
 			const char *src = buff;
 			size_t		srclen = nbytes;
@@ -2060,7 +2040,7 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
 		}
 		else
 		{
-			Assert(!mylocale || mylocale->provider == COLLPROVIDER_LIBC);
+			Assert(mylocale->provider == COLLPROVIDER_LIBC);
 
 			if (pg_database_encoding_max_length() > 1)
 			{
@@ -2081,22 +2061,11 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
 
 				for (curr_char = 0; workspace[curr_char] != 0; curr_char++)
 				{
-					if (mylocale)
-					{
-						if (wasalnum)
-							workspace[curr_char] = towlower_l(workspace[curr_char], mylocale->info.lt);
-						else
-							workspace[curr_char] = towupper_l(workspace[curr_char], mylocale->info.lt);
-						wasalnum = iswalnum_l(workspace[curr_char], mylocale->info.lt);
-					}
+					if (wasalnum)
+						workspace[curr_char] = towlower_l(workspace[curr_char], mylocale->info.lt);
 					else
-					{
-						if (wasalnum)
-							workspace[curr_char] = towlower(workspace[curr_char]);
-						else
-							workspace[curr_char] = towupper(workspace[curr_char]);
-						wasalnum = iswalnum(workspace[curr_char]);
-					}
+						workspace[curr_char] = towupper_l(workspace[curr_char], mylocale->info.lt);
+					wasalnum = iswalnum_l(workspace[curr_char], mylocale->info.lt);
 				}
 
 				/*
@@ -2124,22 +2093,11 @@ str_initcap(const char *buff, size_t nbytes, Oid collid)
 				 */
 				for (p = result; *p; p++)
 				{
-					if (mylocale)
-					{
-						if (wasalnum)
-							*p = tolower_l((unsigned char) *p, mylocale->info.lt);
-						else
-							*p = toupper_l((unsigned char) *p, mylocale->info.lt);
-						wasalnum = isalnum_l((unsigned char) *p, mylocale->info.lt);
-					}
+					if (wasalnum)
+						*p = tolower_l((unsigned char) *p, mylocale->info.lt);
 					else
-					{
-						if (wasalnum)
-							*p = pg_tolower((unsigned char) *p);
-						else
-							*p = pg_toupper((unsigned char) *p);
-						wasalnum = isalnum((unsigned char) *p);
-					}
+						*p = toupper_l((unsigned char) *p, mylocale->info.lt);
+					wasalnum = isalnum_l((unsigned char) *p, mylocale->info.lt);
 				}
 			}
 		}
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 57ead66b5aa..0ecc96d48e5 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -174,8 +174,7 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 			   *p;
 	int			slen,
 				plen;
-	pg_locale_t locale = 0;
-	bool		locale_is_c = false;
+	pg_locale_t locale;
 
 	if (!OidIsValid(collation))
 	{
@@ -189,10 +188,7 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 				 errhint("Use the COLLATE clause to set the collation explicitly.")));
 	}
 
-	if (lc_ctype_is_c(collation))
-		locale_is_c = true;
-	else
-		locale = pg_newlocale_from_collation(collation);
+	locale = pg_newlocale_from_collation(collation);
 
 	if (!pg_locale_deterministic(locale))
 		ereport(ERROR,
@@ -228,7 +224,7 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 		plen = VARSIZE_ANY_EXHDR(pat);
 		s = VARDATA_ANY(str);
 		slen = VARSIZE_ANY_EXHDR(str);
-		return SB_IMatchText(s, slen, p, plen, locale, locale_is_c);
+		return SB_IMatchText(s, slen, p, plen, locale, locale->ctype_is_c);
 	}
 }
 
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 02f64f957d1..4e076904585 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1464,11 +1464,7 @@ make_icu_collator(const char *iculocstr,
 bool
 pg_locale_deterministic(pg_locale_t locale)
 {
-	/* default locale must always be deterministic */
-	if (locale == NULL)
-		return true;
-	else
-		return locale->deterministic;
+	return locale->deterministic;
 }
 
 /*
@@ -1812,7 +1808,7 @@ get_collation_actual_version(char collprovider, const char *collcollate)
  * pg_strncoll_libc_win32_utf8
  *
  * Win32 does not have UTF-8. Convert UTF8 arguments to wide characters and
- * invoke wcscoll() or wcscoll_l().
+ * invoke wcscoll_l().
  */
 #ifdef WIN32
 static int
@@ -1828,7 +1824,7 @@ pg_strncoll_libc_win32_utf8(const char *arg1, size_t len1, const char *arg2,
 	int			r;
 	int			result;
 
-	Assert(!locale || locale->provider == COLLPROVIDER_LIBC);
+	Assert(locale->provider == COLLPROVIDER_LIBC);
 	Assert(GetDatabaseEncoding() == PG_UTF8);
 #ifndef WIN32
 	Assert(false);
@@ -1868,10 +1864,7 @@ pg_strncoll_libc_win32_utf8(const char *arg1, size_t len1, const char *arg2,
 	((LPWSTR) a2p)[r] = 0;
 
 	errno = 0;
-	if (locale)
-		result = wcscoll_l((LPWSTR) a1p, (LPWSTR) a2p, locale->info.lt);
-	else
-		result = wcscoll((LPWSTR) a1p, (LPWSTR) a2p);
+	result = wcscoll_l((LPWSTR) a1p, (LPWSTR) a2p, locale->info.lt);
 	if (result == 2147483647)	/* _NLSCMPERROR; missing from mingw headers */
 		ereport(ERROR,
 				(errmsg("could not compare Unicode strings: %m")));
@@ -1886,9 +1879,9 @@ pg_strncoll_libc_win32_utf8(const char *arg1, size_t len1, const char *arg2,
 /*
  * pg_strcoll_libc
  *
- * Call strcoll(), strcoll_l(), wcscoll(), or wcscoll_l() as appropriate for
- * the given locale, platform, and database encoding. If the locale is NULL,
- * use the database collation.
+ * Call strcoll_l() or wcscoll_l() as appropriate for the given locale,
+ * platform, and database encoding. If the locale is NULL, use the database
+ * collation.
  *
  * Arguments must be encoded in the database encoding and nul-terminated.
  */
@@ -1897,7 +1890,7 @@ pg_strcoll_libc(const char *arg1, const char *arg2, pg_locale_t locale)
 {
 	int			result;
 
-	Assert(!locale || locale->provider == COLLPROVIDER_LIBC);
+	Assert(locale->provider == COLLPROVIDER_LIBC);
 #ifdef WIN32
 	if (GetDatabaseEncoding() == PG_UTF8)
 	{
@@ -1908,10 +1901,7 @@ pg_strcoll_libc(const char *arg1, const char *arg2, pg_locale_t locale)
 	}
 	else
 #endif							/* WIN32 */
-	if (locale)
 		result = strcoll_l(arg1, arg2, locale->info.lt);
-	else
-		result = strcoll(arg1, arg2);
 
 	return result;
 }
@@ -1933,7 +1923,7 @@ pg_strncoll_libc(const char *arg1, size_t len1, const char *arg2, size_t len2,
 	char	   *arg2n;
 	int			result;
 
-	Assert(!locale || locale->provider == COLLPROVIDER_LIBC);
+	Assert(locale->provider == COLLPROVIDER_LIBC);
 
 #ifdef WIN32
 	/* check for this case before doing the work for nul-termination */
@@ -2064,9 +2054,9 @@ pg_strncoll_icu(const char *arg1, int32_t len1, const char *arg2, int32_t len2,
 /*
  * pg_strcoll
  *
- * Call ucol_strcollUTF8(), ucol_strcoll(), strcoll(), strcoll_l(), wcscoll(),
- * or wcscoll_l() as appropriate for the given locale, platform, and database
- * encoding. If the locale is not specified, use the database collation.
+ * Call ucol_strcollUTF8(), ucol_strcoll(), strcoll_l() or wcscoll_l() as
+ * appropriate for the given locale, platform, and database encoding. If the
+ * locale is not specified, use the database collation.
  *
  * Arguments must be encoded in the database encoding and nul-terminated.
  *
@@ -2079,7 +2069,7 @@ pg_strcoll(const char *arg1, const char *arg2, pg_locale_t locale)
 {
 	int			result;
 
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 		result = pg_strcoll_libc(arg1, arg2, locale);
 #ifdef USE_ICU
 	else if (locale->provider == COLLPROVIDER_ICU)
@@ -2095,9 +2085,9 @@ pg_strcoll(const char *arg1, const char *arg2, pg_locale_t locale)
 /*
  * pg_strncoll
  *
- * Call ucol_strcollUTF8(), ucol_strcoll(), strcoll(), strcoll_l(), wcscoll(),
- * or wcscoll_l() as appropriate for the given locale, platform, and database
- * encoding. If the locale is not specified, use the database collation.
+ * Call ucol_strcollUTF8(), ucol_strcoll(), strcoll_l() or wcscoll_l() as
+ * appropriate for the given locale, platform, and database encoding. If the
+ * locale is not specified, use the database collation.
  *
  * Arguments must be encoded in the database encoding.
  *
@@ -2115,7 +2105,7 @@ pg_strncoll(const char *arg1, size_t len1, const char *arg2, size_t len2,
 {
 	int			result;
 
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 		result = pg_strncoll_libc(arg1, len1, arg2, len2, locale);
 #ifdef USE_ICU
 	else if (locale->provider == COLLPROVIDER_ICU)
@@ -2133,13 +2123,10 @@ static size_t
 pg_strxfrm_libc(char *dest, const char *src, size_t destsize,
 				pg_locale_t locale)
 {
-	Assert(!locale || locale->provider == COLLPROVIDER_LIBC);
+	Assert(locale->provider == COLLPROVIDER_LIBC);
 
 #ifdef TRUST_STRXFRM
-	if (locale)
-		return strxfrm_l(dest, src, destsize, locale->info.lt);
-	else
-		return strxfrm(dest, src, destsize);
+	return strxfrm_l(dest, src, destsize, locale->info.lt);
 #else
 	/* shouldn't happen */
 	PGLOCALE_SUPPORT_ERROR(locale->provider);
@@ -2156,7 +2143,7 @@ pg_strnxfrm_libc(char *dest, const char *src, size_t srclen, size_t destsize,
 	size_t		bufsize = srclen + 1;
 	size_t		result;
 
-	Assert(!locale || locale->provider == COLLPROVIDER_LIBC);
+	Assert(locale->provider == COLLPROVIDER_LIBC);
 
 	if (bufsize > TEXTBUFLEN)
 		buf = palloc(bufsize);
@@ -2328,7 +2315,7 @@ pg_strnxfrm_prefix_icu(char *dest, const char *src, int32_t srclen,
 bool
 pg_strxfrm_enabled(pg_locale_t locale)
 {
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 #ifdef TRUST_STRXFRM
 		return true;
 #else
@@ -2362,7 +2349,7 @@ pg_strxfrm(char *dest, const char *src, size_t destsize, pg_locale_t locale)
 {
 	size_t		result = 0;		/* keep compiler quiet */
 
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 		result = pg_strxfrm_libc(dest, src, destsize, locale);
 #ifdef USE_ICU
 	else if (locale->provider == COLLPROVIDER_ICU)
@@ -2399,7 +2386,7 @@ pg_strnxfrm(char *dest, size_t destsize, const char *src, size_t srclen,
 {
 	size_t		result = 0;		/* keep compiler quiet */
 
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 		result = pg_strnxfrm_libc(dest, src, srclen, destsize, locale);
 #ifdef USE_ICU
 	else if (locale->provider == COLLPROVIDER_ICU)
@@ -2419,7 +2406,7 @@ pg_strnxfrm(char *dest, size_t destsize, const char *src, size_t srclen,
 bool
 pg_strxfrm_prefix_enabled(pg_locale_t locale)
 {
-	if (!locale || locale->provider == COLLPROVIDER_LIBC)
+	if (locale->provider == COLLPROVIDER_LIBC)
 		return false;
 	else if (locale->provider == COLLPROVIDER_ICU)
 		return true;
@@ -2449,13 +2436,11 @@ pg_strxfrm_prefix(char *dest, const char *src, size_t destsize,
 {
 	size_t		result = 0;		/* keep compiler quiet */
 
-	if (!locale)
-		PGLOCALE_SUPPORT_ERROR(COLLPROVIDER_LIBC);
 #ifdef USE_ICU
-	else if (locale->provider == COLLPROVIDER_ICU)
+	if (locale->provider == COLLPROVIDER_ICU)
 		result = pg_strnxfrm_prefix_icu(dest, src, -1, destsize, locale);
-#endif
 	else
+#endif
 		PGLOCALE_SUPPORT_ERROR(locale->provider);
 
 	return result;
@@ -2484,13 +2469,11 @@ pg_strnxfrm_prefix(char *dest, size_t destsize, const char *src,
 {
 	size_t		result = 0;		/* keep compiler quiet */
 
-	if (!locale)
-		PGLOCALE_SUPPORT_ERROR(COLLPROVIDER_LIBC);
 #ifdef USE_ICU
-	else if (locale->provider == COLLPROVIDER_ICU)
+	if (locale->provider == COLLPROVIDER_ICU)
 		result = pg_strnxfrm_prefix_icu(dest, src, -1, destsize, locale);
-#endif
 	else
+#endif
 		PGLOCALE_SUPPORT_ERROR(locale->provider);
 
 	return result;
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 1ba5f9d9f6c..0c219dcc779 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -999,7 +999,7 @@ hashbpchar(PG_FUNCTION_ARGS)
 	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	Datum		result;
 
 	if (!collid)
@@ -1011,8 +1011,7 @@ hashbpchar(PG_FUNCTION_ARGS)
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (pg_locale_deterministic(mylocale))
 	{
@@ -1056,7 +1055,7 @@ hashbpcharextended(PG_FUNCTION_ARGS)
 	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	Datum		result;
 
 	if (!collid)
@@ -1068,8 +1067,7 @@ hashbpcharextended(PG_FUNCTION_ARGS)
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (pg_locale_deterministic(mylocale))
 	{
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index d2e2e9bbba0..52ab8c43c66 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1217,12 +1217,11 @@ text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 
 	check_collation_set(collid);
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (!pg_locale_deterministic(mylocale))
 		ereport(ERROR,
@@ -1619,18 +1618,14 @@ Datum
 texteq(PG_FUNCTION_ARGS)
 {
 	Oid			collid = PG_GET_COLLATION();
-	bool		locale_is_c = false;
 	pg_locale_t mylocale = 0;
 	bool		result;
 
 	check_collation_set(collid);
 
-	if (lc_collate_is_c(collid))
-		locale_is_c = true;
-	else
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || pg_locale_deterministic(mylocale))
+	if (pg_locale_deterministic(mylocale))
 	{
 		Datum		arg1 = PG_GETARG_DATUM(0);
 		Datum		arg2 = PG_GETARG_DATUM(1);
@@ -1678,18 +1673,14 @@ Datum
 textne(PG_FUNCTION_ARGS)
 {
 	Oid			collid = PG_GET_COLLATION();
-	bool		locale_is_c = false;
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	bool		result;
 
 	check_collation_set(collid);
 
-	if (lc_collate_is_c(collid))
-		locale_is_c = true;
-	else
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
-	if (locale_is_c || pg_locale_deterministic(mylocale))
+	if (pg_locale_deterministic(mylocale))
 	{
 		Datum		arg1 = PG_GETARG_DATUM(0);
 		Datum		arg2 = PG_GETARG_DATUM(1);
@@ -1793,15 +1784,14 @@ text_starts_with(PG_FUNCTION_ARGS)
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	Oid			collid = PG_GET_COLLATION();
-	pg_locale_t mylocale = 0;
+	pg_locale_t mylocale;
 	bool		result;
 	Size		len1,
 				len2;
 
 	check_collation_set(collid);
 
-	if (!lc_collate_is_c(collid))
-		mylocale = pg_newlocale_from_collation(collid);
+	mylocale = pg_newlocale_from_collation(collid);
 
 	if (!pg_locale_deterministic(mylocale))
 		ereport(ERROR,