Convert the reg* input functions to report (most) errors softly.

This is not really complete, but it catches most cases of practical
interest.  The main omissions are:

* regtype, regprocedure, and regoperator parse type names by
calling the main grammar, so any grammar-detected syntax error
will still be a hard error.  Also, if one includes a type
modifier in such a type specification, errors detected by the
typmodin function will be hard errors.

* Lookup errors are handled just by passing missing_ok = true
to the relevant catalog lookup function.  Because we've used
quite a restrictive definition of "missing_ok", this means that
edge cases such as "the named schema exists, but you lack
USAGE permission on it" are still hard errors.

It would make sense to me to replace most/all missing_ok
parameters with an escontext parameter and then allow these
additional lookup failure cases to be trapped too.  But that's
a job for some other day.

Discussion: https://postgr.es/m/3342239.1671988406@sss.pgh.pa.us

src/backend/catalog/objectaddress.c

@@ -2182,7 +2182,7 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 					 errmsg("name or argument lists may not contain nulls")));
-		typename = typeStringToTypeName(TextDatumGetCString(elems[0]));
+		typename = typeStringToTypeName(TextDatumGetCString(elems[0]), NULL);
 	}
 	else if (type == OBJECT_LARGEOBJECT)
 	{
@@ -2238,7 +2238,8 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 						 errmsg("name or argument lists may not contain nulls")));
 			args = lappend(args,
-						   typeStringToTypeName(TextDatumGetCString(elems[i])));
+						   typeStringToTypeName(TextDatumGetCString(elems[i]),
+												NULL));
 		}
 	}
 	else

src/backend/parser/parse_type.c

@@ -727,10 +727,15 @@ pts_error_callback(void *arg)
  * Given a string that is supposed to be a SQL-compatible type declaration,
  * such as "int4" or "integer" or "character varying(32)", parse
  * the string and return the result as a TypeName.
- * If the string cannot be parsed as a type, an error is raised.
+ *
+ * If the string cannot be parsed as a type, an error is raised,
+ * unless escontext is an ErrorSaveContext node, in which case we may
+ * fill that and return NULL.  But note that the ErrorSaveContext option
+ * is mostly aspirational at present: errors detected by the main
+ * grammar, rather than here, will still be thrown.
  */
 TypeName *
-typeStringToTypeName(const char *str)
+typeStringToTypeName(const char *str, Node *escontext)
 {
 	List	   *raw_parsetree_list;
 	TypeName   *typeName;
@@ -763,49 +768,54 @@ typeStringToTypeName(const char *str)
 	return typeName;
 
 fail:
-	ereport(ERROR,
+	ereturn(escontext, NULL,
 			(errcode(ERRCODE_SYNTAX_ERROR),
 			 errmsg("invalid type name \"%s\"", str)));
-	return NULL;				/* keep compiler quiet */
 }
 
 /*
  * Given a string that is supposed to be a SQL-compatible type declaration,
  * such as "int4" or "integer" or "character varying(32)", parse
  * the string and convert it to a type OID and type modifier.
- * If missing_ok is true, InvalidOid is returned rather than raising an error
+ *
- * when the type name is not found.
+ * If escontext is an ErrorSaveContext node, then errors are reported by
+ * filling escontext and returning false, instead of throwing them.
  */
-void
+bool
-parseTypeString(const char *str, Oid *typeid_p, int32 *typmod_p, bool missing_ok)
+parseTypeString(const char *str, Oid *typeid_p, int32 *typmod_p,
+				Node *escontext)
 {
 	TypeName   *typeName;
 	Type		tup;
 
-	typeName = typeStringToTypeName(str);
+	typeName = typeStringToTypeName(str, escontext);
+	if (typeName == NULL)
+		return false;
 
-	tup = LookupTypeName(NULL, typeName, typmod_p, missing_ok);
+	tup = LookupTypeName(NULL, typeName, typmod_p,
+						 (escontext && IsA(escontext, ErrorSaveContext)));
 	if (tup == NULL)
 	{
-		if (!missing_ok)
+		ereturn(escontext, false,
-			ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("type \"%s\" does not exist",
-							TypeNameToString(typeName)),
+						TypeNameToString(typeName))));
-					 parser_errposition(NULL, typeName->location)));
-		*typeid_p = InvalidOid;
 	}
 	else
 	{
 		Form_pg_type typ = (Form_pg_type) GETSTRUCT(tup);
 
 		if (!typ->typisdefined)
-			ereport(ERROR,
+		{
+			ReleaseSysCache(tup);
+			ereturn(escontext, false,
 					(errcode(ERRCODE_UNDEFINED_OBJECT),
 					 errmsg("type \"%s\" is only a shell",
-							TypeNameToString(typeName)),
+							TypeNameToString(typeName))));
-					 parser_errposition(NULL, typeName->location)));
+		}
 		*typeid_p = typ->oid;
 		ReleaseSysCache(tup);
 	}
+
+	return true;
 }

src/backend/tsearch/dict_thesaurus.c

@@ -599,6 +599,7 @@ thesaurus_init(PG_FUNCTION_ARGS)
 	DictThesaurus *d;
 	char	   *subdictname = NULL;
 	bool		fileloaded = false;
+	List	   *namelist;
 	ListCell   *l;
 
 	d = (DictThesaurus *) palloc0(sizeof(DictThesaurus));
@@ -642,7 +643,8 @@ thesaurus_init(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("missing Dictionary parameter")));
 
-	d->subdictOid = get_ts_dict_oid(stringToQualifiedNameList(subdictname), false);
+	namelist = stringToQualifiedNameList(subdictname, NULL);
+	d->subdictOid = get_ts_dict_oid(namelist, false);
 	d->subdict = lookup_ts_dictionary_cache(d->subdictOid);
 
 	compileTheLexeme(d);

src/backend/utils/adt/misc.c

@@ -724,7 +724,7 @@ pg_input_is_valid_common(FunctionCallInfo fcinfo,
 		Oid			typoid;
 
 		/* Parse type-name argument to obtain type OID and encoded typmod. */
-		parseTypeString(typnamestr, &typoid, &my_extra->typmod, false);
+		(void) parseTypeString(typnamestr, &typoid, &my_extra->typmod, NULL);
 
 		/* Update type-specific info if typoid changed. */
 		if (my_extra->typoid != typoid)

src/backend/utils/adt/regproc.c

@@ -31,7 +31,9 @@
 #include "catalog/pg_ts_dict.h"
 #include "catalog/pg_type.h"
 #include "lib/stringinfo.h"
+#include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "nodes/miscnodes.h"
 #include "parser/parse_type.h"
 #include "parser/scansup.h"
 #include "utils/acl.h"
@@ -43,8 +45,9 @@
 
 static bool parseNumericOid(char *string, Oid *result, Node *escontext);
 static bool parseDashOrOid(char *string, Oid *result, Node *escontext);
-static void parseNameAndArgTypes(const char *string, bool allowNone,
+static bool parseNameAndArgTypes(const char *string, bool allowNone,
-								 List **names, int *nargs, Oid *argtypes);
+								 List **names, int *nargs, Oid *argtypes,
+								 Node *escontext);
 
 
 /*****************************************************************************
@@ -63,12 +66,13 @@ Datum
 regprocin(PG_FUNCTION_ARGS)
 {
 	char	   *pro_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	RegProcedure result;
 	List	   *names;
 	FuncCandidateList clist;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(pro_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(pro_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* Else it's a name, possibly schema-qualified */
@@ -84,15 +88,18 @@ regprocin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_proc entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(pro_name_or_oid);
+	names = stringToQualifiedNameList(pro_name_or_oid, escontext);
-	clist = FuncnameGetCandidates(names, -1, NIL, false, false, false, false);
+	if (names == NIL)
+		PG_RETURN_NULL();
+
+	clist = FuncnameGetCandidates(names, -1, NIL, false, false, false, true);
 
 	if (clist == NULL)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("function \"%s\" does not exist", pro_name_or_oid)));
 	else if (clist->next != NULL)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
 				 errmsg("more than one function named \"%s\"",
 						pro_name_or_oid)));
@@ -113,12 +120,16 @@ to_regproc(PG_FUNCTION_ARGS)
 	char	   *pro_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	List	   *names;
 	FuncCandidateList clist;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name into components and see if it matches any pg_proc
 	 * entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(pro_name);
+	names = stringToQualifiedNameList(pro_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
+
 	clist = FuncnameGetCandidates(names, -1, NIL, false, false, false, true);
 
 	if (clist == NULL || clist->next != NULL)
@@ -222,6 +233,7 @@ Datum
 regprocedurein(PG_FUNCTION_ARGS)
 {
 	char	   *pro_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	RegProcedure result;
 	List	   *names;
 	int			nargs;
@@ -229,7 +241,7 @@ regprocedurein(PG_FUNCTION_ARGS)
 	FuncCandidateList clist;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(pro_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(pro_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -242,10 +254,13 @@ regprocedurein(PG_FUNCTION_ARGS)
 	 * which one exactly matches the given argument types.  (There will not be
 	 * more than one match.)
 	 */
-	parseNameAndArgTypes(pro_name_or_oid, false, &names, &nargs, argtypes);
+	if (!parseNameAndArgTypes(pro_name_or_oid, false,
+							  &names, &nargs, argtypes,
+							  escontext))
+		PG_RETURN_NULL();
 
 	clist = FuncnameGetCandidates(names, nargs, NIL, false, false,
-								  false, false);
+								  false, true);
 
 	for (; clist; clist = clist->next)
 	{
@@ -254,7 +269,7 @@ regprocedurein(PG_FUNCTION_ARGS)
 	}
 
 	if (clist == NULL)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("function \"%s\" does not exist", pro_name_or_oid)));
 
@@ -276,13 +291,17 @@ to_regprocedure(PG_FUNCTION_ARGS)
 	int			nargs;
 	Oid			argtypes[FUNC_MAX_ARGS];
 	FuncCandidateList clist;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name and arguments, look up potential matches in the current
 	 * namespace search list, and scan to see which one exactly matches the
 	 * given argument types.    (There will not be more than one match.)
 	 */
-	parseNameAndArgTypes(pro_name, false, &names, &nargs, argtypes);
+	if (!parseNameAndArgTypes(pro_name, false,
+							  &names, &nargs, argtypes,
+							  (Node *) &escontext))
+		PG_RETURN_NULL();
 
 	clist = FuncnameGetCandidates(names, nargs, NIL, false, false, false, true);
 
@@ -484,12 +503,13 @@ Datum
 regoperin(PG_FUNCTION_ARGS)
 {
 	char	   *opr_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 	FuncCandidateList clist;
 
 	/* Handle "0" or numeric OID */
-	if (parseNumericOid(opr_name_or_oid, &result, fcinfo->context))
+	if (parseNumericOid(opr_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* Else it's a name, possibly schema-qualified */
@@ -502,15 +522,18 @@ regoperin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_operator entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(opr_name_or_oid);
+	names = stringToQualifiedNameList(opr_name_or_oid, escontext);
-	clist = OpernameGetCandidates(names, '\0', false);
+	if (names == NIL)
+		PG_RETURN_NULL();
+
+	clist = OpernameGetCandidates(names, '\0', true);
 
 	if (clist == NULL)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("operator does not exist: %s", opr_name_or_oid)));
 	else if (clist->next != NULL)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
 				 errmsg("more than one operator named %s",
 						opr_name_or_oid)));
@@ -531,12 +554,16 @@ to_regoper(PG_FUNCTION_ARGS)
 	char	   *opr_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	List	   *names;
 	FuncCandidateList clist;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name into components and see if it matches any pg_operator
 	 * entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(opr_name);
+	names = stringToQualifiedNameList(opr_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
+
 	clist = OpernameGetCandidates(names, '\0', true);
 
 	if (clist == NULL || clist->next != NULL)
@@ -646,13 +673,14 @@ Datum
 regoperatorin(PG_FUNCTION_ARGS)
 {
 	char	   *opr_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 	int			nargs;
 	Oid			argtypes[FUNC_MAX_ARGS];
 
 	/* Handle "0" or numeric OID */
-	if (parseNumericOid(opr_name_or_oid, &result, fcinfo->context))
+	if (parseNumericOid(opr_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -665,14 +693,18 @@ regoperatorin(PG_FUNCTION_ARGS)
 	 * which one exactly matches the given argument types.  (There will not be
 	 * more than one match.)
 	 */
-	parseNameAndArgTypes(opr_name_or_oid, true, &names, &nargs, argtypes);
+	if (!parseNameAndArgTypes(opr_name_or_oid, true,
+							  &names, &nargs, argtypes,
+							  escontext))
+		PG_RETURN_NULL();
+
 	if (nargs == 1)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_UNDEFINED_PARAMETER),
 				 errmsg("missing argument"),
 				 errhint("Use NONE to denote the missing argument of a unary operator.")));
 	if (nargs != 2)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
 				 errmsg("too many arguments"),
 				 errhint("Provide two argument types for operator.")));
@@ -680,7 +712,7 @@ regoperatorin(PG_FUNCTION_ARGS)
 	result = OpernameGetOprid(names, argtypes[0], argtypes[1]);
 
 	if (!OidIsValid(result))
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_UNDEFINED_FUNCTION),
 				 errmsg("operator does not exist: %s", opr_name_or_oid)));
 
@@ -700,23 +732,20 @@ to_regoperator(PG_FUNCTION_ARGS)
 	List	   *names;
 	int			nargs;
 	Oid			argtypes[FUNC_MAX_ARGS];
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name and arguments, look up potential matches in the current
 	 * namespace search list, and scan to see which one exactly matches the
 	 * given argument types.    (There will not be more than one match.)
 	 */
-	parseNameAndArgTypes(opr_name_or_oid, true, &names, &nargs, argtypes);
+	if (!parseNameAndArgTypes(opr_name_or_oid, true,
-	if (nargs == 1)
+							  &names, &nargs, argtypes,
-		ereport(ERROR,
+							  (Node *) &escontext))
-				(errcode(ERRCODE_UNDEFINED_PARAMETER),
+		PG_RETURN_NULL();
-				 errmsg("missing argument"),
+
-				 errhint("Use NONE to denote the missing argument of a unary operator.")));
 	if (nargs != 2)
-		ereport(ERROR,
+		PG_RETURN_NULL();
-				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
-				 errmsg("too many arguments"),
-				 errhint("Provide two argument types for operator.")));
 
 	result = OpernameGetOprid(names, argtypes[0], argtypes[1]);
 
@@ -903,11 +932,12 @@ Datum
 regclassin(PG_FUNCTION_ARGS)
 {
 	char	   *class_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(class_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(class_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* Else it's a name, possibly schema-qualified */
@@ -920,10 +950,18 @@ regclassin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_class entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(class_name_or_oid);
+	names = stringToQualifiedNameList(class_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	/* We might not even have permissions on this relation; don't lock it. */
-	result = RangeVarGetRelid(makeRangeVarFromNameList(names), NoLock, false);
+	result = RangeVarGetRelid(makeRangeVarFromNameList(names), NoLock, true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("relation \"%s\" does not exist",
+						NameListToString(names))));
 
 	PG_RETURN_OID(result);
 }
@@ -939,12 +977,15 @@ to_regclass(PG_FUNCTION_ARGS)
 	char	   *class_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	Oid			result;
 	List	   *names;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name into components and see if it matches any pg_class
 	 * entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(class_name);
+	names = stringToQualifiedNameList(class_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	/* We might not even have permissions on this relation; don't lock it. */
 	result = RangeVarGetRelid(makeRangeVarFromNameList(names), NoLock, true);
@@ -1045,11 +1086,12 @@ Datum
 regcollationin(PG_FUNCTION_ARGS)
 {
 	char	   *collation_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(collation_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(collation_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* Else it's a name, possibly schema-qualified */
@@ -1062,9 +1104,17 @@ regcollationin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_collation entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(collation_name_or_oid);
+	names = stringToQualifiedNameList(collation_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
-	result = get_collation_oid(names, false);
+	result = get_collation_oid(names, true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("collation \"%s\" for encoding \"%s\" does not exist",
+						NameListToString(names), GetDatabaseEncodingName())));
 
 	PG_RETURN_OID(result);
 }
@@ -1080,12 +1130,15 @@ to_regcollation(PG_FUNCTION_ARGS)
 	char	   *collation_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	Oid			result;
 	List	   *names;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Parse the name into components and see if it matches any pg_collation
 	 * entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(collation_name);
+	names = stringToQualifiedNameList(collation_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	result = get_collation_oid(names, true);
 
@@ -1192,11 +1245,12 @@ Datum
 regtypein(PG_FUNCTION_ARGS)
 {
 	char	   *typ_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	int32		typmod;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(typ_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(typ_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* Else it's a type name, possibly schema-qualified or decorated */
@@ -1207,9 +1261,10 @@ regtypein(PG_FUNCTION_ARGS)
 
 	/*
 	 * Normal case: invoke the full parser to deal with special cases such as
-	 * array syntax.
+	 * array syntax.  We don't need to check for parseTypeString failure,
+	 * since we'll just return anyway.
 	 */
-	parseTypeString(typ_name_or_oid, &result, &typmod, false);
+	(void) parseTypeString(typ_name_or_oid, &result, &typmod, escontext);
 
 	PG_RETURN_OID(result);
 }
@@ -1225,13 +1280,12 @@ to_regtype(PG_FUNCTION_ARGS)
 	char	   *typ_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	Oid			result;
 	int32		typmod;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
 	/*
 	 * Invoke the full parser to deal with special cases such as array syntax.
 	 */
-	parseTypeString(typ_name, &result, &typmod, true);
+	if (parseTypeString(typ_name, &result, &typmod, (Node *) &escontext))
-
-	if (OidIsValid(result))
 		PG_RETURN_OID(result);
 	else
 		PG_RETURN_NULL();
@@ -1318,11 +1372,12 @@ Datum
 regconfigin(PG_FUNCTION_ARGS)
 {
 	char	   *cfg_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(cfg_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(cfg_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -1333,9 +1388,17 @@ regconfigin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_ts_config entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(cfg_name_or_oid);
+	names = stringToQualifiedNameList(cfg_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
-	result = get_ts_config_oid(names, false);
+	result = get_ts_config_oid(names, true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("text search configuration \"%s\" does not exist",
+						NameListToString(names))));
 
 	PG_RETURN_OID(result);
 }
@@ -1419,11 +1482,12 @@ Datum
 regdictionaryin(PG_FUNCTION_ARGS)
 {
 	char	   *dict_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(dict_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(dict_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -1434,9 +1498,17 @@ regdictionaryin(PG_FUNCTION_ARGS)
 	 * Normal case: parse the name into components and see if it matches any
 	 * pg_ts_dict entries in the current search path.
 	 */
-	names = stringToQualifiedNameList(dict_name_or_oid);
+	names = stringToQualifiedNameList(dict_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
-	result = get_ts_dict_oid(names, false);
+	result = get_ts_dict_oid(names, true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("text search dictionary \"%s\" does not exist",
+						NameListToString(names))));
 
 	PG_RETURN_OID(result);
 }
@@ -1520,11 +1592,12 @@ Datum
 regrolein(PG_FUNCTION_ARGS)
 {
 	char	   *role_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(role_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(role_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -1532,14 +1605,22 @@ regrolein(PG_FUNCTION_ARGS)
 		elog(ERROR, "regrole values must be OIDs in bootstrap mode");
 
 	/* Normal case: see if the name matches any pg_authid entry. */
-	names = stringToQualifiedNameList(role_name_or_oid);
+	names = stringToQualifiedNameList(role_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	if (list_length(names) != 1)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid name syntax")));
 
-	result = get_role_oid(strVal(linitial(names)), false);
+	result = get_role_oid(strVal(linitial(names)), true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("role \"%s\" does not exist",
+						strVal(linitial(names)))));
 
 	PG_RETURN_OID(result);
 }
@@ -1555,13 +1636,14 @@ to_regrole(PG_FUNCTION_ARGS)
 	char	   *role_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	Oid			result;
 	List	   *names;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
-	names = stringToQualifiedNameList(role_name);
+	names = stringToQualifiedNameList(role_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	if (list_length(names) != 1)
-		ereport(ERROR,
+		PG_RETURN_NULL();
-				(errcode(ERRCODE_INVALID_NAME),
-				 errmsg("invalid name syntax")));
 
 	result = get_role_oid(strVal(linitial(names)), true);
 
@@ -1635,11 +1717,12 @@ Datum
 regnamespacein(PG_FUNCTION_ARGS)
 {
 	char	   *nsp_name_or_oid = PG_GETARG_CSTRING(0);
+	Node	   *escontext = fcinfo->context;
 	Oid			result;
 	List	   *names;
 
 	/* Handle "-" or numeric OID */
-	if (parseDashOrOid(nsp_name_or_oid, &result, fcinfo->context))
+	if (parseDashOrOid(nsp_name_or_oid, &result, escontext))
 		PG_RETURN_OID(result);
 
 	/* The rest of this wouldn't work in bootstrap mode */
@@ -1647,14 +1730,22 @@ regnamespacein(PG_FUNCTION_ARGS)
 		elog(ERROR, "regnamespace values must be OIDs in bootstrap mode");
 
 	/* Normal case: see if the name matches any pg_namespace entry. */
-	names = stringToQualifiedNameList(nsp_name_or_oid);
+	names = stringToQualifiedNameList(nsp_name_or_oid, escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	if (list_length(names) != 1)
-		ereport(ERROR,
+		ereturn(escontext, (Datum) 0,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid name syntax")));
 
-	result = get_namespace_oid(strVal(linitial(names)), false);
+	result = get_namespace_oid(strVal(linitial(names)), true);
+
+	if (!OidIsValid(result))
+		ereturn(escontext, (Datum) 0,
+				(errcode(ERRCODE_UNDEFINED_SCHEMA),
+				 errmsg("schema \"%s\" does not exist",
+						strVal(linitial(names)))));
 
 	PG_RETURN_OID(result);
 }
@@ -1670,13 +1761,14 @@ to_regnamespace(PG_FUNCTION_ARGS)
 	char	   *nsp_name = text_to_cstring(PG_GETARG_TEXT_PP(0));
 	Oid			result;
 	List	   *names;
+	ErrorSaveContext escontext = {T_ErrorSaveContext};
 
-	names = stringToQualifiedNameList(nsp_name);
+	names = stringToQualifiedNameList(nsp_name, (Node *) &escontext);
+	if (names == NIL)
+		PG_RETURN_NULL();
 
 	if (list_length(names) != 1)
-		ereport(ERROR,
+		PG_RETURN_NULL();
-				(errcode(ERRCODE_INVALID_NAME),
-				 errmsg("invalid name syntax")));
 
 	result = get_namespace_oid(strVal(linitial(names)), true);
 
@@ -1763,9 +1855,13 @@ text_regclass(PG_FUNCTION_ARGS)
 
 /*
  * Given a C string, parse it into a qualified-name list.
+ *
+ * If escontext is an ErrorSaveContext node, invalid input will be
+ * reported there instead of being thrown, and we return NIL.
+ * (NIL is not possible as a success return, since empty-input is an error.)
  */
 List *
-stringToQualifiedNameList(const char *string)
+stringToQualifiedNameList(const char *string, Node *escontext)
 {
 	char	   *rawname;
 	List	   *result = NIL;
@@ -1776,12 +1872,12 @@ stringToQualifiedNameList(const char *string)
 	rawname = pstrdup(string);
 
 	if (!SplitIdentifierString(rawname, '.', &namelist))
-		ereport(ERROR,
+		ereturn(escontext, NIL,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid name syntax")));
 
 	if (namelist == NIL)
-		ereport(ERROR,
+		ereturn(escontext, NIL,
 				(errcode(ERRCODE_INVALID_NAME),
 				 errmsg("invalid name syntax")));
 
@@ -1858,10 +1954,14 @@ parseDashOrOid(char *string, Oid *result, Node *escontext)
  *
  * If allowNone is true, accept "NONE" and return it as InvalidOid (this is
  * for unary operators).
+ *
+ * Returns true on success, false on failure (the latter only possible
+ * if escontext is an ErrorSaveContext node).
  */
-static void
+static bool
 parseNameAndArgTypes(const char *string, bool allowNone, List **names,
-					 int *nargs, Oid *argtypes)
+					 int *nargs, Oid *argtypes,
+					 Node *escontext)
 {
 	char	   *rawname;
 	char	   *ptr;
@@ -1886,13 +1986,15 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 			break;
 	}
 	if (*ptr == '\0')
-		ereport(ERROR,
+		ereturn(escontext, false,
 				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 				 errmsg("expected a left parenthesis")));
 
 	/* Separate the name and parse it into a list */
 	*ptr++ = '\0';
-	*names = stringToQualifiedNameList(rawname);
+	*names = stringToQualifiedNameList(rawname, escontext);
+	if (*names == NIL)
+		return false;
 
 	/* Check for the trailing right parenthesis and remove it */
 	ptr2 = ptr + strlen(ptr);
@@ -1902,7 +2004,7 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 			break;
 	}
 	if (*ptr2 != ')')
-		ereport(ERROR,
+		ereturn(escontext, false,
 				(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 				 errmsg("expected a right parenthesis")));
 
@@ -1921,7 +2023,7 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 		{
 			/* End of string.  Okay unless we had a comma before. */
 			if (had_comma)
-				ereport(ERROR,
+				ereturn(escontext, false,
 						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 						 errmsg("expected a type name")));
 			break;
@@ -1953,7 +2055,7 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 			}
 		}
 		if (in_quote || paren_count != 0)
-			ereport(ERROR,
+			ereturn(escontext, false,
 					(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
 					 errmsg("improper type name")));
 
@@ -1985,10 +2087,11 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 		else
 		{
 			/* Use full parser to resolve the type name */
-			parseTypeString(typename, &typeid, &typmod, false);
+			if (!parseTypeString(typename, &typeid, &typmod, escontext))
+				return false;
 		}
 		if (*nargs >= FUNC_MAX_ARGS)
-			ereport(ERROR,
+			ereturn(escontext, false,
 					(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
 					 errmsg("too many arguments")));
 
@@ -1997,4 +2100,6 @@ parseNameAndArgTypes(const char *string, bool allowNone, List **names,
 	}
 
 	pfree(rawname);
+
+	return true;
 }

src/backend/utils/adt/tsvector_op.c

@@ -2652,7 +2652,7 @@ tsvector_update_trigger(PG_FUNCTION_ARGS, bool config_column)
 	{
 		List	   *names;
 
-		names = stringToQualifiedNameList(trigger->tgargs[1]);
+		names = stringToQualifiedNameList(trigger->tgargs[1], NULL);
 		/* require a schema so that results are not search path dependent */
 		if (list_length(names) < 2)
 			ereport(ERROR,

src/backend/utils/cache/ts_cache.c

@@ -38,6 +38,7 @@
 #include "catalog/pg_ts_template.h"
 #include "commands/defrem.h"
 #include "miscadmin.h"
+#include "nodes/miscnodes.h"
 #include "tsearch/ts_cache.h"
 #include "utils/builtins.h"
 #include "utils/catcache.h"
@@ -556,6 +557,8 @@ lookup_ts_config_cache(Oid cfgId)
 Oid
 getTSCurrentConfig(bool emitError)
 {
+	List	   *namelist;
+
 	/* if we have a cached value, return it */
 	if (OidIsValid(TSCurrentConfigCache))
 		return TSCurrentConfigCache;
@@ -576,9 +579,22 @@ getTSCurrentConfig(bool emitError)
 	}
 
 	/* Look up the config */
-	TSCurrentConfigCache =
+	if (emitError)
-		get_ts_config_oid(stringToQualifiedNameList(TSCurrentConfig),
+	{
-						  !emitError);
+		namelist = stringToQualifiedNameList(TSCurrentConfig, NULL);
+		TSCurrentConfigCache = get_ts_config_oid(namelist, false);
+	}
+	else
+	{
+		ErrorSaveContext escontext = {T_ErrorSaveContext};
+
+		namelist = stringToQualifiedNameList(TSCurrentConfig,
+											 (Node *) &escontext);
+		if (namelist != NIL)
+			TSCurrentConfigCache = get_ts_config_oid(namelist, true);
+		else
+			TSCurrentConfigCache = InvalidOid;	/* bad name list syntax */
+	}
 
 	return TSCurrentConfigCache;
 }
@@ -594,12 +610,19 @@ check_default_text_search_config(char **newval, void **extra, GucSource source)
 	 */
 	if (IsTransactionState() && MyDatabaseId != InvalidOid)
 	{
+		ErrorSaveContext escontext = {T_ErrorSaveContext};
+		List	   *namelist;
 		Oid			cfgId;
 		HeapTuple	tuple;
 		Form_pg_ts_config cfg;
 		char	   *buf;
 
-		cfgId = get_ts_config_oid(stringToQualifiedNameList(*newval), true);
+		namelist = stringToQualifiedNameList(*newval,
+											 (Node *) &escontext);
+		if (namelist != NIL)
+			cfgId = get_ts_config_oid(namelist, true);
+		else
+			cfgId = InvalidOid; /* bad name list syntax */
 
 		/*
 		 * When source == PGC_S_TEST, don't throw a hard error for a

src/backend/utils/fmgr/funcapi.c

@@ -1876,7 +1876,7 @@ RelationNameGetTupleDesc(const char *relname)
 	List	   *relname_list;
 
 	/* Open relation and copy the tuple description */
-	relname_list = stringToQualifiedNameList(relname);
+	relname_list = stringToQualifiedNameList(relname, NULL);
 	relvar = makeRangeVarFromNameList(relname_list);
 	rel = relation_openrv(relvar, AccessShareLock);
 	tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));

src/include/parser/parse_type.h

@@ -51,8 +51,9 @@ extern Datum stringTypeDatum(Type tp, char *string, int32 atttypmod);
 extern Oid	typeidTypeRelid(Oid type_id);
 extern Oid	typeOrDomainTypeRelid(Oid type_id);
 
-extern TypeName *typeStringToTypeName(const char *str);
+extern TypeName *typeStringToTypeName(const char *str, Node *escontext);
-extern void parseTypeString(const char *str, Oid *typeid_p, int32 *typmod_p, bool missing_ok);
+extern bool parseTypeString(const char *str, Oid *typeid_p, int32 *typmod_p,
+							Node *escontext);
 
 /* true if typeid is composite, or domain over composite, but not RECORD */
 #define ISCOMPLEX(typeid) (typeOrDomainTypeRelid(typeid) != InvalidOid)

src/include/utils/regproc.h

@@ -25,7 +25,7 @@ extern char *format_procedure_extended(Oid procedure_oid, bits16 flags);
 #define FORMAT_OPERATOR_FORCE_QUALIFY	0x02	/* force qualification */
 extern char *format_operator_extended(Oid operator_oid, bits16 flags);
 
-extern List *stringToQualifiedNameList(const char *string);
+extern List *stringToQualifiedNameList(const char *string, Node *escontext);
 extern char *format_procedure(Oid procedure_oid);
 extern char *format_procedure_qualified(Oid procedure_oid);
 extern void format_procedure_parts(Oid procedure_oid, List **objnames,

src/pl/plperl/plperl.c

@@ -3613,7 +3613,7 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
 			char	   *typstr;
 
 			typstr = sv2cstr(argv[i]);
-			parseTypeString(typstr, &typId, &typmod, false);
+			(void) parseTypeString(typstr, &typId, &typmod, NULL);
 			pfree(typstr);
 
 			getTypeInputInfo(typId, &typInput, &typIOParam);

src/pl/plpgsql/src/pl_gram.y

@@ -3725,7 +3725,7 @@ parse_datatype(const char *string, int location)
 	error_context_stack = &syntax_errcontext;
 
 	/* Let the main parser try to parse it under standard SQL rules */
-	typeName = typeStringToTypeName(string);
+	typeName = typeStringToTypeName(string, NULL);
 	typenameTypeIdAndMod(NULL, typeName, &type_id, &typmod);
 
 	/* Restore former ereport callback */

src/pl/plpython/plpy_spi.c

@@ -105,7 +105,7 @@ PLy_spi_prepare(PyObject *self, PyObject *args)
 			 *information for input conversion.
 			 ********************************************************/
 
-			parseTypeString(sptr, &typeId, &typmod, false);
+			(void) parseTypeString(sptr, &typeId, &typmod, NULL);
 
 			Py_DECREF(optr);
 

src/pl/tcl/pltcl.c

@@ -615,7 +615,7 @@ call_pltcl_start_proc(Oid prolang, bool pltrusted)
 	error_context_stack = &errcallback;
 
 	/* Parse possibly-qualified identifier and look up the function */
-	namelist = stringToQualifiedNameList(start_proc);
+	namelist = stringToQualifiedNameList(start_proc, NULL);
 	procOid = LookupFuncName(namelist, 0, NULL, false);
 
 	/* Current user must have permission to call function */
@@ -2603,7 +2603,8 @@ pltcl_SPI_prepare(ClientData cdata, Tcl_Interp *interp,
 						typIOParam;
 			int32		typmod;
 
-			parseTypeString(Tcl_GetString(argsObj[i]), &typId, &typmod, false);
+			(void) parseTypeString(Tcl_GetString(argsObj[i]),
+								   &typId, &typmod, NULL);
 
 			getTypeInputInfo(typId, &typInput, &typIOParam);
 

src/test/regress/expected/regproc.out

@@ -245,7 +245,7 @@ LINE 1: SELECT regtype('int3');
                        ^
 -- with schemaname
 SELECT regoper('ng_catalog.||/');
-ERROR:  schema "ng_catalog" does not exist
+ERROR:  operator does not exist: ng_catalog.||/
 LINE 1: SELECT regoper('ng_catalog.||/');
                        ^
 SELECT regoperator('ng_catalog.+(int4,int4)');
@@ -253,15 +253,15 @@ ERROR:  operator does not exist: ng_catalog.+(int4,int4)
 LINE 1: SELECT regoperator('ng_catalog.+(int4,int4)');
                            ^
 SELECT regproc('ng_catalog.now');
-ERROR:  schema "ng_catalog" does not exist
+ERROR:  function "ng_catalog.now" does not exist
 LINE 1: SELECT regproc('ng_catalog.now');
                        ^
 SELECT regprocedure('ng_catalog.abs(numeric)');
-ERROR:  schema "ng_catalog" does not exist
+ERROR:  function "ng_catalog.abs(numeric)" does not exist
 LINE 1: SELECT regprocedure('ng_catalog.abs(numeric)');
                             ^
 SELECT regclass('ng_catalog.pg_class');
-ERROR:  schema "ng_catalog" does not exist
+ERROR:  relation "ng_catalog.pg_class" does not exist
 LINE 1: SELECT regclass('ng_catalog.pg_class');
                         ^
 SELECT regtype('ng_catalog.int4');
@@ -269,7 +269,7 @@ ERROR:  schema "ng_catalog" does not exist
 LINE 1: SELECT regtype('ng_catalog.int4');
                        ^
 SELECT regcollation('ng_catalog."POSIX"');
-ERROR:  schema "ng_catalog" does not exist
+ERROR:  collation "ng_catalog.POSIX" for encoding "SQL_ASCII" does not exist
 LINE 1: SELECT regcollation('ng_catalog."POSIX"');
                             ^
 -- schemaname not applicable
@@ -406,7 +406,11 @@ SELECT to_regrole('"regress_regrole_test"');
 (1 row)
 
 SELECT to_regrole('foo.bar');
-ERROR:  invalid name syntax
+ to_regrole 
+------------
+ 
+(1 row)
+
 SELECT to_regrole('Nonexistent');
  to_regrole 
 ------------
@@ -420,7 +424,11 @@ SELECT to_regrole('"Nonexistent"');
 (1 row)
 
 SELECT to_regrole('foo.bar');
-ERROR:  invalid name syntax
+ to_regrole 
+------------
+ 
+(1 row)
+
 SELECT to_regnamespace('Nonexistent');
  to_regnamespace 
 -----------------
@@ -434,4 +442,105 @@ SELECT to_regnamespace('"Nonexistent"');
 (1 row)
 
 SELECT to_regnamespace('foo.bar');
-ERROR:  invalid name syntax
+ to_regnamespace 
+-----------------
+ 
+(1 row)
+
+-- Test soft-error API
+SELECT pg_input_error_message('ng_catalog.pg_class', 'regclass');
+            pg_input_error_message             
+-----------------------------------------------
+ relation "ng_catalog.pg_class" does not exist
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog."POSIX"', 'regcollation');
+                        pg_input_error_message                        
+----------------------------------------------------------------------
+ collation "ng_catalog.POSIX" for encoding "SQL_ASCII" does not exist
+(1 row)
+
+SELECT pg_input_error_message('no_such_config', 'regconfig');
+                  pg_input_error_message                   
+-----------------------------------------------------------
+ text search configuration "no_such_config" does not exist
+(1 row)
+
+SELECT pg_input_error_message('no_such_dictionary', 'regdictionary');
+                   pg_input_error_message                   
+------------------------------------------------------------
+ text search dictionary "no_such_dictionary" does not exist
+(1 row)
+
+SELECT pg_input_error_message('Nonexistent', 'regnamespace');
+       pg_input_error_message        
+-------------------------------------
+ schema "nonexistent" does not exist
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog.||/', 'regoper');
+         pg_input_error_message          
+-----------------------------------------
+ operator does not exist: ng_catalog.||/
+(1 row)
+
+SELECT pg_input_error_message('-', 'regoper');
+     pg_input_error_message     
+--------------------------------
+ more than one operator named -
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog.+(int4,int4)', 'regoperator');
+              pg_input_error_message              
+--------------------------------------------------
+ operator does not exist: ng_catalog.+(int4,int4)
+(1 row)
+
+SELECT pg_input_error_message('-', 'regoperator');
+   pg_input_error_message    
+-----------------------------
+ expected a left parenthesis
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog.now', 'regproc');
+          pg_input_error_message          
+------------------------------------------
+ function "ng_catalog.now" does not exist
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog.abs(numeric)', 'regprocedure');
+              pg_input_error_message               
+---------------------------------------------------
+ function "ng_catalog.abs(numeric)" does not exist
+(1 row)
+
+SELECT pg_input_error_message('ng_catalog.abs(numeric', 'regprocedure');
+    pg_input_error_message    
+------------------------------
+ expected a right parenthesis
+(1 row)
+
+SELECT pg_input_error_message('regress_regrole_test', 'regrole');
+           pg_input_error_message           
+--------------------------------------------
+ role "regress_regrole_test" does not exist
+(1 row)
+
+SELECT pg_input_error_message('no_such_type', 'regtype');
+       pg_input_error_message       
+------------------------------------
+ type "no_such_type" does not exist
+(1 row)
+
+-- Some cases that should be soft errors, but are not yet
+SELECT pg_input_error_message('incorrect type name syntax', 'regtype');
+ERROR:  syntax error at or near "type"
+LINE 1: SELECT pg_input_error_message('incorrect type name syntax', ...
+                  ^
+CONTEXT:  invalid type name "incorrect type name syntax"
+SELECT pg_input_error_message('numeric(1,2,3)', 'regtype');  -- bogus typmod
+ERROR:  invalid NUMERIC type modifier
+SELECT pg_input_error_message('way.too.many.names', 'regtype');
+ERROR:  improper qualified name (too many dotted names): way.too.many.names
+SELECT pg_input_error_message('no_such_catalog.schema.name', 'regtype');
+ERROR:  cross-database references are not implemented: no_such_catalog.schema.name

src/test/regress/sql/regproc.sql

@@ -120,3 +120,26 @@ SELECT to_regrole('foo.bar');
 SELECT to_regnamespace('Nonexistent');
 SELECT to_regnamespace('"Nonexistent"');
 SELECT to_regnamespace('foo.bar');
+
+-- Test soft-error API
+
+SELECT pg_input_error_message('ng_catalog.pg_class', 'regclass');
+SELECT pg_input_error_message('ng_catalog."POSIX"', 'regcollation');
+SELECT pg_input_error_message('no_such_config', 'regconfig');
+SELECT pg_input_error_message('no_such_dictionary', 'regdictionary');
+SELECT pg_input_error_message('Nonexistent', 'regnamespace');
+SELECT pg_input_error_message('ng_catalog.||/', 'regoper');
+SELECT pg_input_error_message('-', 'regoper');
+SELECT pg_input_error_message('ng_catalog.+(int4,int4)', 'regoperator');
+SELECT pg_input_error_message('-', 'regoperator');
+SELECT pg_input_error_message('ng_catalog.now', 'regproc');
+SELECT pg_input_error_message('ng_catalog.abs(numeric)', 'regprocedure');
+SELECT pg_input_error_message('ng_catalog.abs(numeric', 'regprocedure');
+SELECT pg_input_error_message('regress_regrole_test', 'regrole');
+SELECT pg_input_error_message('no_such_type', 'regtype');
+
+-- Some cases that should be soft errors, but are not yet
+SELECT pg_input_error_message('incorrect type name syntax', 'regtype');
+SELECT pg_input_error_message('numeric(1,2,3)', 'regtype');  -- bogus typmod
+SELECT pg_input_error_message('way.too.many.names', 'regtype');
+SELECT pg_input_error_message('no_such_catalog.schema.name', 'regtype');