Allow Unicode escapes in any server encoding, not only UTF-8.

SQL includes provisions for numeric Unicode escapes in string
literals and identifiers.  Previously we only accepted those
if they represented ASCII characters or the server encoding
was UTF-8, making the conversion to internal form trivial.
This patch adjusts things so that we'll call the appropriate
encoding conversion function in less-trivial cases, allowing
the escape sequence to be accepted so long as it corresponds
to some character available in the server encoding.

This also applies to processing of Unicode escapes in JSONB.
However, the old restriction still applies to client-side
JSON processing, since that hasn't got access to the server's
encoding conversion infrastructure.

This patch includes some lexer infrastructure that simplifies
throwing errors with error cursors pointing into the middle of
a string (or other complex token).  For the moment I only used
it for errors relating to Unicode escapes, but we might later
expand the usage to some other cases.

Patch by me, reviewed by John Naylor.

Discussion: https://postgr.es/m/2393.1578958316@sss.pgh.pa.us

doc/src/sgml/json.sgml

@@ -61,8 +61,8 @@
  </para>
 
  <para>
-  <productname>PostgreSQL</productname> allows only one character set
-  encoding per database.  It is therefore not possible for the JSON
+  RFC 7159 specifies that JSON strings should be encoded in UTF8.
+  It is therefore not possible for the JSON
   types to conform rigidly to the JSON specification unless the database
   encoding is UTF8. Attempts to directly include characters that
   cannot be represented in the database encoding will fail; conversely,
@@ -77,13 +77,13 @@
   regardless of the database encoding, and are checked only for syntactic
   correctness (that is, that four hex digits follow <literal>\u</literal>).
   However, the input function for <type>jsonb</type> is stricter: it disallows
-  Unicode escapes for non-ASCII characters (those above <literal>U+007F</literal>)
-  unless the database encoding is UTF8.  The <type>jsonb</type> type also
+  Unicode escapes for characters that cannot be represented in the database
+  encoding.  The <type>jsonb</type> type also
   rejects <literal>\u0000</literal> (because that cannot be represented in
   <productname>PostgreSQL</productname>'s <type>text</type> type), and it insists
   that any use of Unicode surrogate pairs to designate characters outside
   the Unicode Basic Multilingual Plane be correct.  Valid Unicode escapes
-  are converted to the equivalent ASCII or UTF8 character for storage;
+  are converted to the equivalent single character for storage;
   this includes folding surrogate pairs into a single character.
  </para>
 
@@ -96,9 +96,8 @@
    not <type>jsonb</type>. The fact that the <type>json</type> input function does
    not make these checks may be considered a historical artifact, although
    it does allow for simple storage (without processing) of JSON Unicode
-   escapes in a non-UTF8 database encoding.  In general, it is best to
-   avoid mixing Unicode escapes in JSON with a non-UTF8 database encoding,
-   if possible.
+   escapes in a database encoding that does not support the represented
+   characters.
   </para>
  </note>
 
@@ -144,8 +143,8 @@
        <row>
         <entry><type>string</type></entry>
         <entry><type>text</type></entry>
-        <entry><literal>\u0000</literal> is disallowed, as are non-ASCII Unicode
-         escapes if database encoding is not UTF8</entry>
+        <entry><literal>\u0000</literal> is disallowed, as are Unicode escapes
+         representing characters not available in the database encoding</entry>
        </row>
        <row>
         <entry><type>number</type></entry>

doc/src/sgml/syntax.sgml

@@ -189,6 +189,23 @@ UPDATE "my_table" SET "a" = 5;
     ampersands.  The length limitation still applies.
    </para>
 
+   <para>
+    Quoting an identifier also makes it case-sensitive, whereas
+    unquoted names are always folded to lower case.  For example, the
+    identifiers <literal>FOO</literal>, <literal>foo</literal>, and
+    <literal>"foo"</literal> are considered the same by
+    <productname>PostgreSQL</productname>, but
+    <literal>"Foo"</literal> and <literal>"FOO"</literal> are
+    different from these three and each other.  (The folding of
+    unquoted names to lower case in <productname>PostgreSQL</productname> is
+    incompatible with the SQL standard, which says that unquoted names
+    should be folded to upper case.  Thus, <literal>foo</literal>
+    should be equivalent to <literal>"FOO"</literal> not
+    <literal>"foo"</literal> according to the standard.  If you want
+    to write portable applications you are advised to always quote a
+    particular name or never quote it.)
+   </para>
+
    <indexterm>
      <primary>Unicode escape</primary>
      <secondary>in identifiers</secondary>
@@ -230,7 +247,8 @@ U&amp;"d!0061t!+000061" UESCAPE '!'
     The escape character can be any single character other than a
     hexadecimal digit, the plus sign, a single quote, a double quote,
     or a whitespace character.  Note that the escape character is
-    written in single quotes, not double quotes.
+    written in single quotes, not double quotes,
+    after <literal>UESCAPE</literal>.
    </para>
 
    <para>
@@ -239,32 +257,18 @@ U&amp;"d!0061t!+000061" UESCAPE '!'
    </para>
 
    <para>
-    The Unicode escape syntax works only when the server encoding is
-    <literal>UTF8</literal>.  When other server encodings are used, only code
-    points in the ASCII range (up to <literal>\007F</literal>) can be
-    specified.  Both the 4-digit and the 6-digit form can be used to
+    Either the 4-digit or the 6-digit escape form can be used to
     specify UTF-16 surrogate pairs to compose characters with code
     points larger than U+FFFF, although the availability of the
     6-digit form technically makes this unnecessary.  (Surrogate
-    pairs are not stored directly, but combined into a single
-    code point that is then encoded in UTF-8.)
+    pairs are not stored directly, but are combined into a single
+    code point.)
    </para>
 
    <para>
-    Quoting an identifier also makes it case-sensitive, whereas
-    unquoted names are always folded to lower case.  For example, the
-    identifiers <literal>FOO</literal>, <literal>foo</literal>, and
-    <literal>"foo"</literal> are considered the same by
-    <productname>PostgreSQL</productname>, but
-    <literal>"Foo"</literal> and <literal>"FOO"</literal> are
-    different from these three and each other.  (The folding of
-    unquoted names to lower case in <productname>PostgreSQL</productname> is
-    incompatible with the SQL standard, which says that unquoted names
-    should be folded to upper case.  Thus, <literal>foo</literal>
-    should be equivalent to <literal>"FOO"</literal> not
-    <literal>"foo"</literal> according to the standard.  If you want
-    to write portable applications you are advised to always quote a
-    particular name or never quote it.)
+    If the server encoding is not UTF-8, the Unicode code point identified
+    by one of these escape sequences is converted to the actual server
+    encoding; an error is reported if that's not possible.
    </para>
   </sect2>
 
@@ -427,25 +431,11 @@ SELECT 'foo'      'bar';
     <para>
      It is your responsibility that the byte sequences you create,
      especially when using the octal or hexadecimal escapes, compose
-     valid characters in the server character set encoding.  When the
-     server encoding is UTF-8, then the Unicode escapes or the
+     valid characters in the server character set encoding.
+     A useful alternative is to use Unicode escapes or the
      alternative Unicode escape syntax, explained
-     in <xref linkend="sql-syntax-strings-uescape"/>, should be used
-     instead.  (The alternative would be doing the UTF-8 encoding by
-     hand and writing out the bytes, which would be very cumbersome.)
-    </para>
-
-    <para>
-     The Unicode escape syntax works fully only when the server
-     encoding is <literal>UTF8</literal>.  When other server encodings are
-     used, only code points in the ASCII range (up
-     to <literal>\u007F</literal>) can be specified.  Both the 4-digit and
-     the 8-digit form can be used to specify UTF-16 surrogate pairs to
-     compose characters with code points larger than U+FFFF, although
-     the availability of the 8-digit form technically makes this
-     unnecessary.  (When surrogate pairs are used when the server
-     encoding is <literal>UTF8</literal>, they are first combined into a
-     single code point that is then encoded in UTF-8.)
+     in <xref linkend="sql-syntax-strings-uescape"/>; then the server
+     will check that the character conversion is possible.
     </para>
 
     <caution>
@@ -524,16 +514,23 @@ U&amp;'d!0061t!+000061' UESCAPE '!'
     </para>
 
     <para>
-     The Unicode escape syntax works only when the server encoding is
-     <literal>UTF8</literal>.  When other server encodings are used, only
-     code points in the ASCII range (up to <literal>\007F</literal>)
-     can be specified.  Both the 4-digit and the 6-digit form can be
-     used to specify UTF-16 surrogate pairs to compose characters with
-     code points larger than U+FFFF, although the availability of the
-     6-digit form technically makes this unnecessary.  (When surrogate
-     pairs are used when the server encoding is <literal>UTF8</literal>, they
-     are first combined into a single code point that is then encoded
-     in UTF-8.)
+     To include the escape character in the string literally, write
+     it twice.
+    </para>
+
+    <para>
+     Either the 4-digit or the 6-digit escape form can be used to
+     specify UTF-16 surrogate pairs to compose characters with code
+     points larger than U+FFFF, although the availability of the
+     6-digit form technically makes this unnecessary.  (Surrogate
+     pairs are not stored directly, but are combined into a single
+     code point.)
+    </para>
+
+    <para>
+     If the server encoding is not UTF-8, the Unicode code point identified
+     by one of these escape sequences is converted to the actual server
+     encoding; an error is reported if that's not possible.
     </para>
 
     <para>
@@ -546,11 +543,6 @@ U&amp;'d!0061t!+000061' UESCAPE '!'
      parameter is set to off, this syntax will be rejected with an
      error message.
     </para>
-
-    <para>
-     To include the escape character in the string literally, write it
-     twice.
-    </para>
    </sect3>
 
    <sect3 id="sql-syntax-dollar-quoting">

src/backend/parser/parser.c

@@ -292,22 +292,14 @@ hexval(unsigned char c)
 	return 0;					/* not reached */
 }
 
-/* is Unicode code point acceptable in database's encoding? */
+/* is Unicode code point acceptable? */
 static void
-check_unicode_value(pg_wchar c, int pos, core_yyscan_t yyscanner)
+check_unicode_value(pg_wchar c)
 {
-	/* See also addunicode() in scan.l */
-	if (c == 0 || c > 0x10FFFF)
+	if (!is_valid_unicode_codepoint(c))
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
-				 errmsg("invalid Unicode escape value"),
-				 scanner_errposition(pos, yyscanner)));
-
-	if (c > 0x7F && GetDatabaseEncoding() != PG_UTF8)
-		ereport(ERROR,
-				(errcode(ERRCODE_SYNTAX_ERROR),
-				 errmsg("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8"),
-				 scanner_errposition(pos, yyscanner)));
+				 errmsg("invalid Unicode escape value")));
 }
 
 /* is 'escape' acceptable as Unicode escape character (UESCAPE syntax) ? */
@@ -338,20 +330,39 @@ str_udeescape(const char *str, char escape,
 	const char *in;
 	char	   *new,
 			   *out;
+	size_t		new_len;
 	pg_wchar	pair_first = 0;
+	ScannerCallbackState scbstate;
 
 	/*
-	 * This relies on the subtle assumption that a UTF-8 expansion cannot be
-	 * longer than its escaped representation.
+	 * Guesstimate that result will be no longer than input, but allow enough
+	 * padding for Unicode conversion.
 	 */
-	new = palloc(strlen(str) + 1);
+	new_len = strlen(str) + MAX_UNICODE_EQUIVALENT_STRING + 1;
+	new = palloc(new_len);
 
 	in = str;
 	out = new;
 	while (*in)
 	{
+		/* Enlarge string if needed */
+		size_t		out_dist = out - new;
+
+		if (out_dist > new_len - (MAX_UNICODE_EQUIVALENT_STRING + 1))
+		{
+			new_len *= 2;
+			new = repalloc(new, new_len);
+			out = new + out_dist;
+		}
+
 		if (in[0] == escape)
 		{
+			/*
+			 * Any errors reported while processing this escape sequence will
+			 * have an error cursor pointing at the escape.
+			 */
+			setup_scanner_errposition_callback(&scbstate, yyscanner,
+											   in - str + position + 3);	/* 3 for U&" */
 			if (in[1] == escape)
 			{
 				if (pair_first)
@@ -370,9 +381,7 @@ str_udeescape(const char *str, char escape,
 					(hexval(in[2]) << 8) +
 					(hexval(in[3]) << 4) +
 					hexval(in[4]);
-				check_unicode_value(unicode,
-									in - str + position + 3,	/* 3 for U&" */
-									yyscanner);
+				check_unicode_value(unicode);
 				if (pair_first)
 				{
 					if (is_utf16_surrogate_second(unicode))
@@ -390,8 +399,8 @@ str_udeescape(const char *str, char escape,
 					pair_first = unicode;
 				else
 				{
-					unicode_to_utf8(unicode, (unsigned char *) out);
-					out += pg_mblen(out);
+					pg_unicode_to_server(unicode, (unsigned char *) out);
+					out += strlen(out);
 				}
 				in += 5;
 			}
@@ -411,9 +420,7 @@ str_udeescape(const char *str, char escape,
 					(hexval(in[5]) << 8) +
 					(hexval(in[6]) << 4) +
 					hexval(in[7]);
-				check_unicode_value(unicode,
-									in - str + position + 3,	/* 3 for U&" */
-									yyscanner);
+				check_unicode_value(unicode);
 				if (pair_first)
 				{
 					if (is_utf16_surrogate_second(unicode))
@@ -431,17 +438,18 @@ str_udeescape(const char *str, char escape,
 					pair_first = unicode;
 				else
 				{
-					unicode_to_utf8(unicode, (unsigned char *) out);
-					out += pg_mblen(out);
+					pg_unicode_to_server(unicode, (unsigned char *) out);
+					out += strlen(out);
 				}
 				in += 8;
 			}
 			else
 				ereport(ERROR,
 						(errcode(ERRCODE_SYNTAX_ERROR),
-						 errmsg("invalid Unicode escape value"),
-						 scanner_errposition(in - str + position + 3,	/* 3 for U&" */
-											 yyscanner)));
+						 errmsg("invalid Unicode escape"),
+						 errhint("Unicode escapes must be \\XXXX or \\+XXXXXX.")));
+
+			cancel_scanner_errposition_callback(&scbstate);
 		}
 		else
 		{
@@ -457,15 +465,13 @@ str_udeescape(const char *str, char escape,
 		goto invalid_pair;
 
 	*out = '\0';
+	return new;
 
 	/*
-	 * We could skip pg_verifymbstr if we didn't process any non-7-bit-ASCII
-	 * codes; but it's probably not worth the trouble, since this isn't likely
-	 * to be a performance-critical path.
+	 * We might get here with the error callback active, or not.  Call
+	 * scanner_errposition to make sure an error cursor appears; if the
+	 * callback is active, this is duplicative but harmless.
 	 */
-	pg_verifymbstr(new, out - new, false);
-	return new;
-
 invalid_pair:
 	ereport(ERROR,
 			(errcode(ERRCODE_SYNTAX_ERROR),

src/backend/parser/scan.l

@@ -106,6 +106,18 @@ const uint16 ScanKeywordTokens[] = {
  */
 #define ADVANCE_YYLLOC(delta)  ( *(yylloc) += (delta) )
 
+/*
+ * Sometimes, we do want yylloc to point into the middle of a token; this is
+ * useful for instance to throw an error about an escape sequence within a
+ * string literal.  But if we find no error there, we want to revert yylloc
+ * to the token start, so that that's the location reported to the parser.
+ * Use PUSH_YYLLOC/POP_YYLLOC to save/restore yylloc around such code.
+ * (Currently the implied "stack" is just one location, but someday we might
+ * need to nest these.)
+ */
+#define PUSH_YYLLOC()	(yyextra->save_yylloc = *(yylloc))
+#define POP_YYLLOC()	(*(yylloc) = yyextra->save_yylloc)
+
 #define startlit()	( yyextra->literallen = 0 )
 static void addlit(char *ytext, int yleng, core_yyscan_t yyscanner);
 static void addlitchar(unsigned char ychar, core_yyscan_t yyscanner);
@@ -605,8 +617,18 @@ other			.
 <xe>{xeunicode} {
 					pg_wchar	c = strtoul(yytext + 2, NULL, 16);
 
+					/*
+					 * For consistency with other productions, issue any
+					 * escape warning with cursor pointing to start of string.
+					 * We might want to change that, someday.
+					 */
 					check_escape_warning(yyscanner);
 
+					/* Remember start of overall string token ... */
+					PUSH_YYLLOC();
+					/* ... and set the error cursor to point at this esc seq */
+					SET_YYLLOC();
+
 					if (is_utf16_surrogate_first(c))
 					{
 						yyextra->utf16_first_part = c;
@@ -616,10 +638,18 @@ other			.
 						yyerror("invalid Unicode surrogate pair");
 					else
 						addunicode(c, yyscanner);
+
+					/* Restore yylloc to be start of string token */
+					POP_YYLLOC();
 				}
 <xeu>{xeunicode} {
 					pg_wchar	c = strtoul(yytext + 2, NULL, 16);
 
+					/* Remember start of overall string token ... */
+					PUSH_YYLLOC();
+					/* ... and set the error cursor to point at this esc seq */
+					SET_YYLLOC();
+
 					if (!is_utf16_surrogate_second(c))
 						yyerror("invalid Unicode surrogate pair");
 
@@ -627,12 +657,21 @@ other			.
 
 					addunicode(c, yyscanner);
 
+					/* Restore yylloc to be start of string token */
+					POP_YYLLOC();
+
 					BEGIN(xe);
 				}
-<xeu>.			{ yyerror("invalid Unicode surrogate pair"); }
-<xeu>\n			{ yyerror("invalid Unicode surrogate pair"); }
-<xeu><<EOF>>	{ yyerror("invalid Unicode surrogate pair"); }
+<xeu>. |
+<xeu>\n |
+<xeu><<EOF>>	{
+					/* Set the error cursor to point at missing esc seq */
+					SET_YYLLOC();
+					yyerror("invalid Unicode surrogate pair");
+				}
 <xe,xeu>{xeunicodefail}	{
+					/* Set the error cursor to point at malformed esc seq */
+					SET_YYLLOC();
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
 							 errmsg("invalid Unicode escape"),
@@ -1029,12 +1068,13 @@ other			.
  * scanner_errposition
  *		Report a lexer or grammar error cursor position, if possible.
  *
- * This is expected to be used within an ereport() call.  The return value
+ * This is expected to be used within an ereport() call, or via an error
+ * callback such as setup_scanner_errposition_callback().  The return value
  * is a dummy (always 0, in fact).
  *
  * Note that this can only be used for messages emitted during raw parsing
- * (essentially, scan.l and gram.y), since it requires the yyscanner struct
- * to still be available.
+ * (essentially, scan.l, parser.c, and gram.y), since it requires the
+ * yyscanner struct to still be available.
  */
 int
 scanner_errposition(int location, core_yyscan_t yyscanner)
@@ -1050,6 +1090,62 @@ scanner_errposition(int location, core_yyscan_t yyscanner)
 	return errposition(pos);
 }
 
+/*
+ * Error context callback for inserting scanner error location.
+ *
+ * Note that this will be called for *any* error occurring while the
+ * callback is installed.  We avoid inserting an irrelevant error location
+ * if the error is a query cancel --- are there any other important cases?
+ */
+static void
+scb_error_callback(void *arg)
+{
+	ScannerCallbackState *scbstate = (ScannerCallbackState *) arg;
+
+	if (geterrcode() != ERRCODE_QUERY_CANCELED)
+		(void) scanner_errposition(scbstate->location, scbstate->yyscanner);
+}
+
+/*
+ * setup_scanner_errposition_callback
+ *		Arrange for non-scanner errors to report an error position
+ *
+ * Sometimes the scanner calls functions that aren't part of the scanner
+ * subsystem and can't reasonably be passed the yyscanner pointer; yet
+ * we would like any errors thrown in those functions to be tagged with an
+ * error location.  Use this function to set up an error context stack
+ * entry that will accomplish that.  Usage pattern:
+ *
+ *		declare a local variable "ScannerCallbackState scbstate"
+ *		...
+ *		setup_scanner_errposition_callback(&scbstate, yyscanner, location);
+ *		call function that might throw error;
+ *		cancel_scanner_errposition_callback(&scbstate);
+ */
+void
+setup_scanner_errposition_callback(ScannerCallbackState *scbstate,
+								   core_yyscan_t yyscanner,
+								   int location)
+{
+	/* Setup error traceback support for ereport() */
+	scbstate->yyscanner = yyscanner;
+	scbstate->location = location;
+	scbstate->errcallback.callback = scb_error_callback;
+	scbstate->errcallback.arg = (void *) scbstate;
+	scbstate->errcallback.previous = error_context_stack;
+	error_context_stack = &scbstate->errcallback;
+}
+
+/*
+ * Cancel a previously-set-up errposition callback.
+ */
+void
+cancel_scanner_errposition_callback(ScannerCallbackState *scbstate)
+{
+	/* Pop the error context stack */
+	error_context_stack = scbstate->errcallback.previous;
+}
+
 /*
  * scanner_yyerror
  *		Report a lexer or grammar error.
@@ -1226,19 +1322,20 @@ process_integer_literal(const char *token, YYSTYPE *lval)
 static void
 addunicode(pg_wchar c, core_yyscan_t yyscanner)
 {
-	char		buf[8];
+	ScannerCallbackState scbstate;
+	char		buf[MAX_UNICODE_EQUIVALENT_STRING + 1];
 
-	/* See also check_unicode_value() in parser.c */
-	if (c == 0 || c > 0x10FFFF)
+	if (!is_valid_unicode_codepoint(c))
 		yyerror("invalid Unicode escape value");
-	if (c > 0x7F)
-	{
-		if (GetDatabaseEncoding() != PG_UTF8)
-			yyerror("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8");
-		yyextra->saw_non_ascii = true;
-	}
-	unicode_to_utf8(c, (unsigned char *) buf);
-	addlit(buf, pg_mblen(buf), yyscanner);
+
+	/*
+	 * We expect that pg_unicode_to_server() will complain about any
+	 * unconvertible code point, so we don't have to set saw_non_ascii.
+	 */
+	setup_scanner_errposition_callback(&scbstate, yyscanner, *(yylloc));
+	pg_unicode_to_server(c, (unsigned char *) buf);
+	cancel_scanner_errposition_callback(&scbstate);
+	addlit(buf, strlen(buf), yyscanner);
 }
 
 static unsigned char

src/backend/utils/adt/jsonpath_scan.l

@@ -486,13 +486,6 @@ hexval(char c)
 static void
 addUnicodeChar(int ch)
 {
-	/*
-	 * For UTF8, replace the escape sequence by the actual
-	 * utf8 character in lex->strval. Do this also for other
-	 * encodings if the escape designates an ASCII character,
-	 * otherwise raise an error.
-	 */
-
 	if (ch == 0)
 	{
 		/* We can't allow this, since our TEXT type doesn't */
@@ -501,40 +494,20 @@ addUnicodeChar(int ch)
 				 errmsg("unsupported Unicode escape sequence"),
 				  errdetail("\\u0000 cannot be converted to text.")));
 	}
-	else if (GetDatabaseEncoding() == PG_UTF8)
-	{
-		char utf8str[5];
-		int utf8len;
-
-		unicode_to_utf8(ch, (unsigned char *) utf8str);
-		utf8len = pg_utf_mblen((unsigned char *) utf8str);
-		addstring(false, utf8str, utf8len);
-	}
-	else if (ch <= 0x007f)
-	{
-		/*
-		 * This is the only way to designate things like a
-		 * form feed character in JSON, so it's useful in all
-		 * encodings.
-		 */
-		addchar(false, (char) ch);
-	}
 	else
 	{
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
-				 errmsg("invalid input syntax for type %s", "jsonpath"),
-				 errdetail("Unicode escape values cannot be used for code "
-						   "point values above 007F when the server encoding "
-						   "is not UTF8.")));
+		char		cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1];
+
+		pg_unicode_to_server(ch, (unsigned char *) cbuf);
+		addstring(false, cbuf, strlen(cbuf));
 	}
 }
 
-/* Add unicode character and process its hi surrogate */
+/* Add unicode character, processing any surrogate pairs */
 static void
 addUnicode(int ch, int *hi_surrogate)
 {
-	if (ch >= 0xd800 && ch <= 0xdbff)
+	if (is_utf16_surrogate_first(ch))
 	{
 		if (*hi_surrogate != -1)
 			ereport(ERROR,
@@ -542,10 +515,10 @@ addUnicode(int ch, int *hi_surrogate)
 					 errmsg("invalid input syntax for type %s", "jsonpath"),
 					 errdetail("Unicode high surrogate must not follow "
 							   "a high surrogate.")));
-		*hi_surrogate = (ch & 0x3ff) << 10;
+		*hi_surrogate = ch;
 		return;
 	}
-	else if (ch >= 0xdc00 && ch <= 0xdfff)
+	else if (is_utf16_surrogate_second(ch))
 	{
 		if (*hi_surrogate == -1)
 			ereport(ERROR,
@@ -553,7 +526,7 @@ addUnicode(int ch, int *hi_surrogate)
 					 errmsg("invalid input syntax for type %s", "jsonpath"),
 					 errdetail("Unicode low surrogate must follow a high "
 							   "surrogate.")));
-		ch = 0x10000 + *hi_surrogate + (ch & 0x3ff);
+		ch = surrogate_pair_to_codepoint(*hi_surrogate, ch);
 		*hi_surrogate = -1;
 	}
 	else if (*hi_surrogate != -1)

src/backend/utils/adt/xml.c

@@ -2085,26 +2085,6 @@ map_sql_identifier_to_xml_name(const char *ident, bool fully_escaped,
 }
 
 
-/*
- * Map a Unicode codepoint into the current server encoding.
- */
-static char *
-unicode_to_sqlchar(pg_wchar c)
-{
-	char		utf8string[8];	/* need room for trailing zero */
-	char	   *result;
-
-	memset(utf8string, 0, sizeof(utf8string));
-	unicode_to_utf8(c, (unsigned char *) utf8string);
-
-	result = pg_any_to_server(utf8string, strlen(utf8string), PG_UTF8);
-	/* if pg_any_to_server didn't strdup, we must */
-	if (result == utf8string)
-		result = pstrdup(result);
-	return result;
-}
-
-
 /*
  * Map XML name to SQL identifier; see SQL/XML:2008 section 9.3.
  */
@@ -2125,10 +2105,12 @@ map_xml_name_to_sql_identifier(const char *name)
 			&& isxdigit((unsigned char) *(p + 5))
 			&& *(p + 6) == '_')
 		{
+			char		cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1];
 			unsigned int u;
 
 			sscanf(p + 2, "%X", &u);
-			appendStringInfoString(&buf, unicode_to_sqlchar(u));
+			pg_unicode_to_server(u, (unsigned char *) cbuf);
+			appendStringInfoString(&buf, cbuf);
 			p += 6;
 		}
 		else

src/backend/utils/mb/mbutils.c

@@ -67,6 +67,13 @@ static List *ConvProcList = NIL;	/* List of ConvProcInfo */
 static FmgrInfo *ToServerConvProc = NULL;
 static FmgrInfo *ToClientConvProc = NULL;
 
+/*
+ * This variable stores the conversion function to convert from UTF-8
+ * to the server encoding.  It's NULL if the server encoding *is* UTF-8,
+ * or if we lack a conversion function for this.
+ */
+static FmgrInfo *Utf8ToServerConvProc = NULL;
+
 /*
  * These variables track the currently-selected encodings.
  */
@@ -273,6 +280,8 @@ SetClientEncoding(int encoding)
 void
 InitializeClientEncoding(void)
 {
+	int			current_server_encoding;
+
 	Assert(!backend_startup_complete);
 	backend_startup_complete = true;
 
@@ -289,6 +298,35 @@ InitializeClientEncoding(void)
 						pg_enc2name_tbl[pending_client_encoding].name,
 						GetDatabaseEncodingName())));
 	}
+
+	/*
+	 * Also look up the UTF8-to-server conversion function if needed.  Since
+	 * the server encoding is fixed within any one backend process, we don't
+	 * have to do this more than once.
+	 */
+	current_server_encoding = GetDatabaseEncoding();
+	if (current_server_encoding != PG_UTF8 &&
+		current_server_encoding != PG_SQL_ASCII)
+	{
+		Oid			utf8_to_server_proc;
+
+		Assert(IsTransactionState());
+		utf8_to_server_proc =
+			FindDefaultConversionProc(PG_UTF8,
+									  current_server_encoding);
+		/* If there's no such conversion, just leave the pointer as NULL */
+		if (OidIsValid(utf8_to_server_proc))
+		{
+			FmgrInfo   *finfo;
+
+			finfo = (FmgrInfo *) MemoryContextAlloc(TopMemoryContext,
+													sizeof(FmgrInfo));
+			fmgr_info_cxt(utf8_to_server_proc, finfo,
+						  TopMemoryContext);
+			/* Set Utf8ToServerConvProc only after data is fully valid */
+			Utf8ToServerConvProc = finfo;
+		}
+	}
 }
 
 /*
@@ -752,6 +790,73 @@ perform_default_encoding_conversion(const char *src, int len,
 	return result;
 }
 
+/*
+ * Convert a single Unicode code point into a string in the server encoding.
+ *
+ * The code point given by "c" is converted and stored at *s, which must
+ * have at least MAX_UNICODE_EQUIVALENT_STRING+1 bytes available.
+ * The output will have a trailing '\0'.  Throws error if the conversion
+ * cannot be performed.
+ *
+ * Note that this relies on having previously looked up any required
+ * conversion function.  That's partly for speed but mostly because the parser
+ * may call this outside any transaction, or in an aborted transaction.
+ */
+void
+pg_unicode_to_server(pg_wchar c, unsigned char *s)
+{
+	unsigned char c_as_utf8[MAX_MULTIBYTE_CHAR_LEN + 1];
+	int			c_as_utf8_len;
+	int			server_encoding;
+
+	/*
+	 * Complain if invalid Unicode code point.  The choice of errcode here is
+	 * debatable, but really our caller should have checked this anyway.
+	 */
+	if (!is_valid_unicode_codepoint(c))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid Unicode code point")));
+
+	/* Otherwise, if it's in ASCII range, conversion is trivial */
+	if (c <= 0x7F)
+	{
+		s[0] = (unsigned char) c;
+		s[1] = '\0';
+		return;
+	}
+
+	/* If the server encoding is UTF-8, we just need to reformat the code */
+	server_encoding = GetDatabaseEncoding();
+	if (server_encoding == PG_UTF8)
+	{
+		unicode_to_utf8(c, s);
+		s[pg_utf_mblen(s)] = '\0';
+		return;
+	}
+
+	/* For all other cases, we must have a conversion function available */
+	if (Utf8ToServerConvProc == NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("conversion between %s and %s is not supported",
+						pg_enc2name_tbl[PG_UTF8].name,
+						GetDatabaseEncodingName())));
+
+	/* Construct UTF-8 source string */
+	unicode_to_utf8(c, c_as_utf8);
+	c_as_utf8_len = pg_utf_mblen(c_as_utf8);
+	c_as_utf8[c_as_utf8_len] = '\0';
+
+	/* Convert, or throw error if we can't */
+	FunctionCall5(Utf8ToServerConvProc,
+				  Int32GetDatum(PG_UTF8),
+				  Int32GetDatum(server_encoding),
+				  CStringGetDatum(c_as_utf8),
+				  CStringGetDatum(s),
+				  Int32GetDatum(c_as_utf8_len));
+}
+
 
 /* convert a multibyte string to a wchar */
 int

src/common/jsonapi.c

@@ -744,21 +744,21 @@ json_lex_string(JsonLexContext *lex)
 				}
 				if (lex->strval != NULL)
 				{
-					char		utf8str[5];
-					int			utf8len;
-
-					if (ch >= 0xd800 && ch <= 0xdbff)
+					/*
+					 * Combine surrogate pairs.
+					 */
+					if (is_utf16_surrogate_first(ch))
 					{
 						if (hi_surrogate != -1)
 							return JSON_UNICODE_HIGH_SURROGATE;
-						hi_surrogate = (ch & 0x3ff) << 10;
+						hi_surrogate = ch;
 						continue;
 					}
-					else if (ch >= 0xdc00 && ch <= 0xdfff)
+					else if (is_utf16_surrogate_second(ch))
 					{
 						if (hi_surrogate == -1)
 							return JSON_UNICODE_LOW_SURROGATE;
-						ch = 0x10000 + hi_surrogate + (ch & 0x3ff);
+						ch = surrogate_pair_to_codepoint(hi_surrogate, ch);
 						hi_surrogate = -1;
 					}
 
@@ -766,35 +766,52 @@ json_lex_string(JsonLexContext *lex)
 						return JSON_UNICODE_LOW_SURROGATE;
 
 					/*
-					 * For UTF8, replace the escape sequence by the actual
-					 * utf8 character in lex->strval. Do this also for other
-					 * encodings if the escape designates an ASCII character,
-					 * otherwise raise an error.
+					 * Reject invalid cases.  We can't have a value above
+					 * 0xFFFF here (since we only accepted 4 hex digits
+					 * above), so no need to test for out-of-range chars.
 					 */
-
 					if (ch == 0)
 					{
 						/* We can't allow this, since our TEXT type doesn't */
 						return JSON_UNICODE_CODE_POINT_ZERO;
 					}
-					else if (lex->input_encoding == PG_UTF8)
+
+					/*
+					 * Add the represented character to lex->strval.  In the
+					 * backend, we can let pg_unicode_to_server() handle any
+					 * required character set conversion; in frontend, we can
+					 * only deal with trivial conversions.
+					 *
+					 * Note: pg_unicode_to_server() will throw an error for a
+					 * conversion failure, rather than returning a failure
+					 * indication.  That seems OK.
+					 */
+#ifndef FRONTEND
+					{
+						char		cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1];
+
+						pg_unicode_to_server(ch, (unsigned char *) cbuf);
+						appendStringInfoString(lex->strval, cbuf);
+					}
+#else
+					if (lex->input_encoding == PG_UTF8)
 					{
+						/* OK, we can map the code point to UTF8 easily */
+						char		utf8str[5];
+						int			utf8len;
+
 						unicode_to_utf8(ch, (unsigned char *) utf8str);
 						utf8len = pg_utf_mblen((unsigned char *) utf8str);
 						appendBinaryStringInfo(lex->strval, utf8str, utf8len);
 					}
 					else if (ch <= 0x007f)
 					{
-						/*
-						 * This is the only way to designate things like a
-						 * form feed character in JSON, so it's useful in all
-						 * encodings.
-						 */
+						/* The ASCII range is the same in all encodings */
 						appendStringInfoChar(lex->strval, (char) ch);
 					}
 					else
 						return JSON_UNICODE_HIGH_ESCAPE;
-
+#endif							/* FRONTEND */
 				}
 			}
 			else if (lex->strval != NULL)
@@ -1083,7 +1100,8 @@ json_errdetail(JsonParseErrorType error, JsonLexContext *lex)
 		case JSON_UNICODE_ESCAPE_FORMAT:
 			return _("\"\\u\" must be followed by four hexadecimal digits.");
 		case JSON_UNICODE_HIGH_ESCAPE:
-			return _("Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.");
+			/* note: this case is only reachable in frontend not backend */
+			return _("Unicode escape values cannot be used for code point values above 007F when the encoding is not UTF8.");
 		case JSON_UNICODE_HIGH_SURROGATE:
 			return _("Unicode high surrogate must not follow a high surrogate.");
 		case JSON_UNICODE_LOW_SURROGATE:

src/include/mb/pg_wchar.h

@@ -315,6 +315,15 @@ typedef enum pg_enc
  */
 #define MAX_CONVERSION_GROWTH  4
 
+/*
+ * Maximum byte length of the string equivalent to any one Unicode code point,
+ * in any backend encoding.  The current value assumes that a 4-byte UTF-8
+ * character might expand by MAX_CONVERSION_GROWTH, which is a huge
+ * overestimate.  But in current usage we don't allocate large multiples of
+ * this, so there's little point in being stingy.
+ */
+#define MAX_UNICODE_EQUIVALENT_STRING	16
+
 /*
  * Table for mapping an encoding number to official encoding name and
  * possibly other subsidiary data.  Be careful to check encoding number
@@ -505,6 +514,12 @@ typedef uint32 (*utf_local_conversion_func) (uint32 code);
 /*
  * Some handy functions for Unicode-specific tests.
  */
+static inline bool
+is_valid_unicode_codepoint(pg_wchar c)
+{
+	return (c > 0 && c <= 0x10FFFF);
+}
+
 static inline bool
 is_utf16_surrogate_first(pg_wchar c)
 {
@@ -603,6 +618,8 @@ extern char *pg_server_to_client(const char *s, int len);
 extern char *pg_any_to_server(const char *s, int len, int encoding);
 extern char *pg_server_to_any(const char *s, int len, int encoding);
 
+extern void pg_unicode_to_server(pg_wchar c, unsigned char *s);
+
 extern unsigned short BIG5toCNS(unsigned short big5, unsigned char *lc);
 extern unsigned short CNStoBIG5(unsigned short cns, unsigned char lc);
 

src/include/parser/scanner.h

@@ -99,9 +99,13 @@ typedef struct core_yy_extra_type
 	int			literallen;		/* actual current string length */
 	int			literalalloc;	/* current allocated buffer size */
 
+	/*
+	 * Random assorted scanner state.
+	 */
 	int			state_before_str_stop;	/* start cond. before end quote */
 	int			xcdepth;		/* depth of nesting in slash-star comments */
 	char	   *dolqstart;		/* current $foo$ quote start string */
+	YYLTYPE		save_yylloc;	/* one-element stack for PUSH_YYLLOC() */
 
 	/* first part of UTF16 surrogate pair for Unicode escapes */
 	int32		utf16_first_part;
@@ -116,6 +120,14 @@ typedef struct core_yy_extra_type
  */
 typedef void *core_yyscan_t;
 
+/* Support for scanner_errposition_callback function */
+typedef struct ScannerCallbackState
+{
+	core_yyscan_t yyscanner;
+	int			location;
+	ErrorContextCallback errcallback;
+} ScannerCallbackState;
+
 
 /* Constant data exported from parser/scan.l */
 extern PGDLLIMPORT const uint16 ScanKeywordTokens[];
@@ -129,6 +141,10 @@ extern void scanner_finish(core_yyscan_t yyscanner);
 extern int	core_yylex(core_YYSTYPE *lvalp, YYLTYPE *llocp,
 					   core_yyscan_t yyscanner);
 extern int	scanner_errposition(int location, core_yyscan_t yyscanner);
+extern void setup_scanner_errposition_callback(ScannerCallbackState *scbstate,
+											   core_yyscan_t yyscanner,
+											   int location);
+extern void cancel_scanner_errposition_callback(ScannerCallbackState *scbstate);
 extern void scanner_yyerror(const char *message, core_yyscan_t yyscanner) pg_attribute_noreturn();
 
 #endif							/* SCANNER_H */

src/test/regress/expected/json_encoding.out

+--
 -- encoding-sensitive tests for json and jsonb
+--
+-- We provide expected-results files for UTF8 (json_encoding.out)
+-- and for SQL_ASCII (json_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+SELECT getdatabaseencoding();           -- just to label the results files
+ getdatabaseencoding 
+---------------------
+ UTF8
+(1 row)
+
 -- first json
 -- basic unicode input
 SELECT '"\u"'::json;			-- ERROR, incomplete escape

src/test/regress/expected/json_encoding_1.out

+--
 -- encoding-sensitive tests for json and jsonb
+--
+-- We provide expected-results files for UTF8 (json_encoding.out)
+-- and for SQL_ASCII (json_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+SELECT getdatabaseencoding();           -- just to label the results files
+ getdatabaseencoding 
+---------------------
+ SQL_ASCII
+(1 row)
+
 -- first json
 -- basic unicode input
 SELECT '"\u"'::json;			-- ERROR, incomplete escape
@@ -33,9 +48,7 @@ SELECT '"\uaBcD"'::json;		-- OK, uppercase and lower case both OK
 
 -- handling of unicode surrogate pairs
 select json '{ "a":  "\ud83d\ude04\ud83d\udc36" }' -> 'a' as correct_in_utf8;
-ERROR:  unsupported Unicode escape sequence
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: { "a":...
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 select json '{ "a":  "\ud83d\ud83d" }' -> 'a'; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type json
 DETAIL:  Unicode high surrogate must not follow a high surrogate.
@@ -84,9 +97,7 @@ select json '{ "a":  "null \\u0000 escape" }' as not_an_escape;
 (1 row)
 
 select json '{ "a":  "the Copyright \u00a9 sign" }' ->> 'a' as correct_in_utf8;
-ERROR:  unsupported Unicode escape sequence
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: { "a":...
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 select json '{ "a":  "dollar \u0024 character" }' ->> 'a' as correct_everywhere;
  correct_everywhere 
 --------------------
@@ -144,18 +155,14 @@ CONTEXT:  JSON data, line 1: ...
 -- use octet_length here so we don't get an odd unicode char in the
 -- output
 SELECT octet_length('"\uaBcD"'::jsonb::text); -- OK, uppercase and lower case both OK
-ERROR:  unsupported Unicode escape sequence
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT octet_length('"\uaBcD"'::jsonb::text);
                             ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: ...
 -- handling of unicode surrogate pairs
 SELECT octet_length((jsonb '{ "a":  "\ud83d\ude04\ud83d\udc36" }' -> 'a')::text) AS correct_in_utf8;
-ERROR:  unsupported Unicode escape sequence
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT octet_length((jsonb '{ "a":  "\ud83d\ude04\ud83d\udc3...
                                    ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: { "a":...
 SELECT jsonb '{ "a":  "\ud83d\ud83d" }' -> 'a'; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type json
 LINE 1: SELECT jsonb '{ "a":  "\ud83d\ud83d" }' -> 'a';
@@ -182,11 +189,9 @@ DETAIL:  Unicode low surrogate must follow a high surrogate.
 CONTEXT:  JSON data, line 1: { "a":...
 -- handling of simple unicode escapes
 SELECT jsonb '{ "a":  "the Copyright \u00a9 sign" }' as correct_in_utf8;
-ERROR:  unsupported Unicode escape sequence
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT jsonb '{ "a":  "the Copyright \u00a9 sign" }' as corr...
                      ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: { "a":...
 SELECT jsonb '{ "a":  "dollar \u0024 character" }' as correct_everywhere;
      correct_everywhere      
 -----------------------------
@@ -212,11 +217,9 @@ SELECT jsonb '{ "a":  "null \\u0000 escape" }' as not_an_escape;
 (1 row)
 
 SELECT jsonb '{ "a":  "the Copyright \u00a9 sign" }' ->> 'a' as correct_in_utf8;
-ERROR:  unsupported Unicode escape sequence
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT jsonb '{ "a":  "the Copyright \u00a9 sign" }' ->> 'a'...
                      ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
-CONTEXT:  JSON data, line 1: { "a":...
 SELECT jsonb '{ "a":  "dollar \u0024 character" }' ->> 'a' as correct_everywhere;
  correct_everywhere 
 --------------------

src/test/regress/expected/json_encoding_2.out

+--
+-- encoding-sensitive tests for json and jsonb
+--
+-- We provide expected-results files for UTF8 (json_encoding.out)
+-- and for SQL_ASCII (json_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit

src/test/regress/expected/jsonpath_encoding.out

+--
 -- encoding-sensitive tests for jsonpath
+--
+-- We provide expected-results files for UTF8 (jsonpath_encoding.out)
+-- and for SQL_ASCII (jsonpath_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+SELECT getdatabaseencoding();           -- just to label the results files
+ getdatabaseencoding 
+---------------------
+ UTF8
+(1 row)
+
 -- checks for double-quoted values
 -- basic unicode input
 SELECT '"\u"'::jsonpath;		-- ERROR, incomplete escape

src/test/regress/expected/jsonpath_encoding_1.out

+--
 -- encoding-sensitive tests for jsonpath
+--
+-- We provide expected-results files for UTF8 (jsonpath_encoding.out)
+-- and for SQL_ASCII (jsonpath_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+SELECT getdatabaseencoding();           -- just to label the results files
+ getdatabaseencoding 
+---------------------
+ SQL_ASCII
+(1 row)
+
 -- checks for double-quoted values
 -- basic unicode input
 SELECT '"\u"'::jsonpath;		-- ERROR, incomplete escape
@@ -19,16 +34,14 @@ LINE 1: SELECT '"\u0000"'::jsonpath;
                ^
 DETAIL:  \u0000 cannot be converted to text.
 SELECT '"\uaBcD"'::jsonpath;	-- OK, uppercase and lower case both OK
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT '"\uaBcD"'::jsonpath;
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 -- handling of unicode surrogate pairs
 select '"\ud83d\ude04\ud83d\udc36"'::jsonpath as correct_in_utf8;
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: select '"\ud83d\ude04\ud83d\udc36"'::jsonpath as correct_in_...
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 select '"\ud83d\ud83d"'::jsonpath; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type jsonpath
 LINE 1: select '"\ud83d\ud83d"'::jsonpath;
@@ -51,10 +64,9 @@ LINE 1: select '"\ude04X"'::jsonpath;
 DETAIL:  Unicode low surrogate must follow a high surrogate.
 --handling of simple unicode escapes
 select '"the Copyright \u00a9 sign"'::jsonpath as correct_in_utf8;
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: select '"the Copyright \u00a9 sign"'::jsonpath as correct_in...
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 select '"dollar \u0024 character"'::jsonpath as correct_everywhere;
   correct_everywhere  
 ----------------------
@@ -98,16 +110,14 @@ LINE 1: SELECT '$."\u0000"'::jsonpath;
                ^
 DETAIL:  \u0000 cannot be converted to text.
 SELECT '$."\uaBcD"'::jsonpath;	-- OK, uppercase and lower case both OK
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: SELECT '$."\uaBcD"'::jsonpath;
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 -- handling of unicode surrogate pairs
 select '$."\ud83d\ude04\ud83d\udc36"'::jsonpath as correct_in_utf8;
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: select '$."\ud83d\ude04\ud83d\udc36"'::jsonpath as correct_i...
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 select '$."\ud83d\ud83d"'::jsonpath; -- 2 high surrogates in a row
 ERROR:  invalid input syntax for type jsonpath
 LINE 1: select '$."\ud83d\ud83d"'::jsonpath;
@@ -130,10 +140,9 @@ LINE 1: select '$."\ude04X"'::jsonpath;
 DETAIL:  Unicode low surrogate must follow a high surrogate.
 --handling of simple unicode escapes
 select '$."the Copyright \u00a9 sign"'::jsonpath as correct_in_utf8;
-ERROR:  invalid input syntax for type jsonpath
+ERROR:  conversion between UTF8 and SQL_ASCII is not supported
 LINE 1: select '$."the Copyright \u00a9 sign"'::jsonpath as correct_...
                ^
-DETAIL:  Unicode escape values cannot be used for code point values above 007F when the server encoding is not UTF8.
 select '$."dollar \u0024 character"'::jsonpath as correct_everywhere;
    correct_everywhere   
 ------------------------

src/test/regress/expected/jsonpath_encoding_2.out

+--
+-- encoding-sensitive tests for jsonpath
+--
+-- We provide expected-results files for UTF8 (jsonpath_encoding.out)
+-- and for SQL_ASCII (jsonpath_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit

src/test/regress/expected/strings.out

@@ -35,6 +35,12 @@ SELECT U&'d!0061t\+000061' UESCAPE '!' AS U&"d*0061t\+000061" UESCAPE '*';
  dat\+000061
 (1 row)
 
+SELECT U&'a\\b' AS "a\b";
+ a\b 
+-----
+ a\b
+(1 row)
+
 SELECT U&' \' UESCAPE '!' AS "tricky";
  tricky 
 --------
@@ -48,13 +54,15 @@ SELECT 'tricky' AS U&"\" UESCAPE '!';
 (1 row)
 
 SELECT U&'wrong: \061';
-ERROR:  invalid Unicode escape value
+ERROR:  invalid Unicode escape
 LINE 1: SELECT U&'wrong: \061';
                          ^
+HINT:  Unicode escapes must be \XXXX or \+XXXXXX.
 SELECT U&'wrong: \+0061';
-ERROR:  invalid Unicode escape value
+ERROR:  invalid Unicode escape
 LINE 1: SELECT U&'wrong: \+0061';
                          ^
+HINT:  Unicode escapes must be \XXXX or \+XXXXXX.
 SELECT U&'wrong: +0061' UESCAPE +;
 ERROR:  UESCAPE must be followed by a simple string literal at or near "+"
 LINE 1: SELECT U&'wrong: +0061' UESCAPE +;
@@ -63,6 +71,77 @@ SELECT U&'wrong: +0061' UESCAPE '+';
 ERROR:  invalid Unicode escape character at or near "'+'"
 LINE 1: SELECT U&'wrong: +0061' UESCAPE '+';
                                         ^
+SELECT U&'wrong: \db99';
+ERROR:  invalid Unicode surrogate pair
+LINE 1: SELECT U&'wrong: \db99';
+                              ^
+SELECT U&'wrong: \db99xy';
+ERROR:  invalid Unicode surrogate pair
+LINE 1: SELECT U&'wrong: \db99xy';
+                              ^
+SELECT U&'wrong: \db99\\';
+ERROR:  invalid Unicode surrogate pair
+LINE 1: SELECT U&'wrong: \db99\\';
+                              ^
+SELECT U&'wrong: \db99\0061';
+ERROR:  invalid Unicode surrogate pair
+LINE 1: SELECT U&'wrong: \db99\0061';
+                              ^
+SELECT U&'wrong: \+00db99\+000061';
+ERROR:  invalid Unicode surrogate pair
+LINE 1: SELECT U&'wrong: \+00db99\+000061';
+                                 ^
+SELECT U&'wrong: \+2FFFFF';
+ERROR:  invalid Unicode escape value
+LINE 1: SELECT U&'wrong: \+2FFFFF';
+                         ^
+-- while we're here, check the same cases in E-style literals
+SELECT E'd\u0061t\U00000061' AS "data";
+ data 
+------
+ data
+(1 row)
+
+SELECT E'a\\b' AS "a\b";
+ a\b 
+-----
+ a\b
+(1 row)
+
+SELECT E'wrong: \u061';
+ERROR:  invalid Unicode escape
+LINE 1: SELECT E'wrong: \u061';
+                        ^
+HINT:  Unicode escapes must be \uXXXX or \UXXXXXXXX.
+SELECT E'wrong: \U0061';
+ERROR:  invalid Unicode escape
+LINE 1: SELECT E'wrong: \U0061';
+                        ^
+HINT:  Unicode escapes must be \uXXXX or \UXXXXXXXX.
+SELECT E'wrong: \udb99';
+ERROR:  invalid Unicode surrogate pair at or near "'"
+LINE 1: SELECT E'wrong: \udb99';
+                              ^
+SELECT E'wrong: \udb99xy';
+ERROR:  invalid Unicode surrogate pair at or near "x"
+LINE 1: SELECT E'wrong: \udb99xy';
+                              ^
+SELECT E'wrong: \udb99\\';
+ERROR:  invalid Unicode surrogate pair at or near "\"
+LINE 1: SELECT E'wrong: \udb99\\';
+                              ^
+SELECT E'wrong: \udb99\u0061';
+ERROR:  invalid Unicode surrogate pair at or near "\u0061"
+LINE 1: SELECT E'wrong: \udb99\u0061';
+                              ^
+SELECT E'wrong: \U0000db99\U00000061';
+ERROR:  invalid Unicode surrogate pair at or near "\U00000061"
+LINE 1: SELECT E'wrong: \U0000db99\U00000061';
+                                  ^
+SELECT E'wrong: \U002FFFFF';
+ERROR:  invalid Unicode escape value at or near "\U002FFFFF"
+LINE 1: SELECT E'wrong: \U002FFFFF';
+                        ^
 SET standard_conforming_strings TO off;
 SELECT U&'d\0061t\+000061' AS U&"d\0061t\+000061";
 ERROR:  unsafe use of string constant with Unicode escapes

src/test/regress/sql/json_encoding.sql

-
+--
 -- encoding-sensitive tests for json and jsonb
+--
+
+-- We provide expected-results files for UTF8 (json_encoding.out)
+-- and for SQL_ASCII (json_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+
+SELECT getdatabaseencoding();           -- just to label the results files
 
 -- first json
 

src/test/regress/sql/jsonpath_encoding.sql

-
+--
 -- encoding-sensitive tests for jsonpath
+--
+
+-- We provide expected-results files for UTF8 (jsonpath_encoding.out)
+-- and for SQL_ASCII (jsonpath_encoding_1.out).  Skip otherwise.
+SELECT getdatabaseencoding() NOT IN ('UTF8', 'SQL_ASCII')
+       AS skip_test \gset
+\if :skip_test
+\quit
+\endif
+
+SELECT getdatabaseencoding();           -- just to label the results files
 
 -- checks for double-quoted values
 

src/test/regress/sql/strings.sql

@@ -21,6 +21,7 @@ SET standard_conforming_strings TO on;
 
 SELECT U&'d\0061t\+000061' AS U&"d\0061t\+000061";
 SELECT U&'d!0061t\+000061' UESCAPE '!' AS U&"d*0061t\+000061" UESCAPE '*';
+SELECT U&'a\\b' AS "a\b";
 
 SELECT U&' \' UESCAPE '!' AS "tricky";
 SELECT 'tricky' AS U&"\" UESCAPE '!';
@@ -30,6 +31,25 @@ SELECT U&'wrong: \+0061';
 SELECT U&'wrong: +0061' UESCAPE +;
 SELECT U&'wrong: +0061' UESCAPE '+';
 
+SELECT U&'wrong: \db99';
+SELECT U&'wrong: \db99xy';
+SELECT U&'wrong: \db99\\';
+SELECT U&'wrong: \db99\0061';
+SELECT U&'wrong: \+00db99\+000061';
+SELECT U&'wrong: \+2FFFFF';
+
+-- while we're here, check the same cases in E-style literals
+SELECT E'd\u0061t\U00000061' AS "data";
+SELECT E'a\\b' AS "a\b";
+SELECT E'wrong: \u061';
+SELECT E'wrong: \U0061';
+SELECT E'wrong: \udb99';
+SELECT E'wrong: \udb99xy';
+SELECT E'wrong: \udb99\\';
+SELECT E'wrong: \udb99\u0061';
+SELECT E'wrong: \U0000db99\U00000061';
+SELECT E'wrong: \U002FFFFF';
+
 SET standard_conforming_strings TO off;
 
 SELECT U&'d\0061t\+000061' AS U&"d\0061t\+000061";