Don't fail for bad GUCs in CREATE FUNCTION with check_function_bodies off.

The previous coding attempted to activate all the GUC settings specified
in SET clauses, so that the function validator could operate in the GUC
environment expected by the function body.  However, this is problematic
when restoring a dump, since the SET clauses might refer to database
objects that don't exist yet.  We already have the parameter
check_function_bodies that's meant to prevent forward references in
function definitions from breaking dumps, so let's change CREATE FUNCTION
to not install the SET values if check_function_bodies is off.

Authors of function validators were already advised not to make any
"context sensitive" checks when check_function_bodies is off, if indeed
they're checking anything at all in that mode.  But extend the
documentation to point out the GUC issue in particular.

(Note that we still check the SET clauses to some extent; the behavior
with !check_function_bodies is now approximately equivalent to what ALTER
DATABASE/ROLE have been doing for awhile with context-dependent GUCs.)

This problem can be demonstrated in all active branches, so back-patch
all the way.

doc/src/sgml/plhandler.sgml

@@ -200,6 +200,13 @@ CREATE LANGUAGE plsample
     of having a validator is not to let the call handler omit checks, but
     to notify the user immediately if there are obvious errors in a
     <command>CREATE FUNCTION</> command.)
+    While the choice of exactly what to check is mostly left to the
+    discretion of the validator function, note that the core
+    <command>CREATE FUNCTION</> code only executes <literal>SET</> clauses
+    attached to a function when <varname>check_function_bodies</> is on.
+    Therefore, checks whose results might be affected by GUC parameters
+    definitely should be skipped when <varname>check_function_bodies</> is
+    off, to avoid false failures when reloading a dump.
    </para>
 
    <para>

src/backend/catalog/pg_proc.c

@@ -668,24 +668,34 @@ ProcedureCreate(const char *procedureName,
 	/* Verify function body */
 	if (OidIsValid(languageValidator))
 	{
-		ArrayType  *set_items;
-		int			save_nestlevel;
+		ArrayType  *set_items = NULL;
+		int			save_nestlevel = 0;
 
 		/* Advance command counter so new tuple can be seen by validator */
 		CommandCounterIncrement();
 
-		/* Set per-function configuration parameters */
-		set_items = (ArrayType *) DatumGetPointer(proconfig);
-		if (set_items)			/* Need a new GUC nesting level */
+		/*
+		 * Set per-function configuration parameters so that the validation is
+		 * done with the environment the function expects.	However, if
+		 * check_function_bodies is off, we don't do this, because that would
+		 * create dump ordering hazards that pg_dump doesn't know how to deal
+		 * with.  (For example, a SET clause might refer to a not-yet-created
+		 * text search configuration.)	This means that the validator
+		 * shouldn't complain about anything that might depend on a GUC
+		 * parameter when check_function_bodies is off.
+		 */
+		if (check_function_bodies)
 		{
-			save_nestlevel = NewGUCNestLevel();
-			ProcessGUCArray(set_items,
-							(superuser() ? PGC_SUSET : PGC_USERSET),
-							PGC_S_SESSION,
-							GUC_ACTION_SAVE);
+			set_items = (ArrayType *) DatumGetPointer(proconfig);
+			if (set_items)		/* Need a new GUC nesting level */
+			{
+				save_nestlevel = NewGUCNestLevel();
+				ProcessGUCArray(set_items,
+								(superuser() ? PGC_SUSET : PGC_USERSET),
+								PGC_S_SESSION,
+								GUC_ACTION_SAVE);
+			}
 		}
-		else
-			save_nestlevel = 0; /* keep compiler quiet */
 
 		OidFunctionCall1(languageValidator, ObjectIdGetDatum(retval));
 

src/test/regress/expected/guc.out

@@ -718,3 +718,19 @@ select myfunc(1), current_setting('work_mem');
  2MB    | 2MB
 (1 row)
 
+-- Normally, CREATE FUNCTION should complain about invalid values in
+-- function SET options; but not if check_function_bodies is off,
+-- because that creates ordering hazards for pg_dump
+create function func_with_bad_set() returns int as $$ select 1 $$
+language sql
+set default_text_search_config = no_such_config;
+NOTICE:  text search configuration "no_such_config" does not exist
+ERROR:  invalid value for parameter "default_text_search_config": "no_such_config"
+set check_function_bodies = off;
+create function func_with_bad_set() returns int as $$ select 1 $$
+language sql
+set default_text_search_config = no_such_config;
+NOTICE:  text search configuration "no_such_config" does not exist
+select func_with_bad_set();
+ERROR:  invalid value for parameter "default_text_search_config": "no_such_config"
+reset check_function_bodies;

src/test/regress/sql/guc.sql

@@ -257,3 +257,21 @@ set work_mem = '1MB';
 select myfunc(0);
 select current_setting('work_mem');
 select myfunc(1), current_setting('work_mem');
+
+-- Normally, CREATE FUNCTION should complain about invalid values in
+-- function SET options; but not if check_function_bodies is off,
+-- because that creates ordering hazards for pg_dump
+
+create function func_with_bad_set() returns int as $$ select 1 $$
+language sql
+set default_text_search_config = no_such_config;
+
+set check_function_bodies = off;
+
+create function func_with_bad_set() returns int as $$ select 1 $$
+language sql
+set default_text_search_config = no_such_config;
+
+select func_with_bad_set();
+
+reset check_function_bodies;