Revert changes about warnings/errors for placeholders.

Revert commits 5609cc01c, 2ed8a8cc5, and 75d22069e until we have
a less broken idea of how this should work in parallel workers.
Per buildfarm.

Discussion: https://postgr.es/m/1640909.1640638123@sss.pgh.pa.us

5 files changed, 3 insertions, 29 deletions

diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 25722d87ccc..8ec623ac527 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -91,7 +91,7 @@ _PG_init(void)
 							NULL,
 							NULL);
 
-	MarkGUCPrefixReserved("delay_execution");
+	EmitWarningsOnPlaceholders("delay_execution");
 
 	/* Install our hook */
 	prev_planner_hook = planner_hook;
diff --git a/src/test/modules/ssl_passphrase_callback/ssl_passphrase_func.c b/src/test/modules/ssl_passphrase_callback/ssl_passphrase_func.c
index 7c469fd57e8..3ba33e501c3 100644
--- a/src/test/modules/ssl_passphrase_callback/ssl_passphrase_func.c
+++ b/src/test/modules/ssl_passphrase_callback/ssl_passphrase_func.c
@@ -49,7 +49,7 @@ _PG_init(void)
 							   NULL,
 							   NULL);
 
-	MarkGUCPrefixReserved("ssl_passphrase");
+	EmitWarningsOnPlaceholders("ssl_passphrase");
 
 	if (ssl_passphrase)
 		openssl_tls_init_hook = set_rot13;
diff --git a/src/test/modules/worker_spi/worker_spi.c b/src/test/modules/worker_spi/worker_spi.c
index 3e9227aa8ae..adb02d8cb83 100644
--- a/src/test/modules/worker_spi/worker_spi.c
+++ b/src/test/modules/worker_spi/worker_spi.c
@@ -322,7 +322,7 @@ _PG_init(void)
 							   0,
 							   NULL, NULL, NULL);
 
-	MarkGUCPrefixReserved("worker_spi");
+	EmitWarningsOnPlaceholders("worker_spi");
 
 	/* set up common data for all our workers */
 	memset(&worker, 0, sizeof(worker));
diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out
index 5ad7477f618..59da91ff04d 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -548,23 +548,6 @@ ERROR:  invalid configuration parameter name "special.weird name"
 DETAIL:  Custom parameter names must be two or more simple identifiers separated by dots.
 SHOW special."weird name";
 ERROR:  unrecognized configuration parameter "special.weird name"
--- Check what happens when you try to set a "custom" GUC within the
--- namespace of an extension.
-SET plpgsql.bogus_setting = 42;  -- allowed if plpgsql is not loaded yet
-LOAD 'plpgsql';  -- this will now warn about it
-WARNING:  unrecognized configuration parameter "plpgsql.bogus_setting"
-SET plpgsql.extra_foo_warnings = false;  -- but now, it's an error
-ERROR:  invalid configuration parameter name "plpgsql.extra_foo_warnings"
-DETAIL:  "plpgsql" is a reserved prefix.
-SHOW plpgsql.extra_foo_warnings;
-ERROR:  unrecognized configuration parameter "plpgsql.extra_foo_warnings"
-SET plpgsql.bogus_setting = 43;  -- you can still use the pre-existing variable
-SHOW plpgsql.bogus_setting;
- plpgsql.bogus_setting 
------------------------
- 43
-(1 row)
-
 --
 -- Test DISCARD TEMP
 --
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index f97f4e44884..c39c11388d5 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -163,15 +163,6 @@ SHOW custom."bad-guc";
 SET special."weird name" = 'foo';  -- could be allowed, but we choose not to
 SHOW special."weird name";
 
--- Check what happens when you try to set a "custom" GUC within the
--- namespace of an extension.
-SET plpgsql.bogus_setting = 42;  -- allowed if plpgsql is not loaded yet
-LOAD 'plpgsql';  -- this will now warn about it
-SET plpgsql.extra_foo_warnings = false;  -- but now, it's an error
-SHOW plpgsql.extra_foo_warnings;
-SET plpgsql.bogus_setting = 43;  -- you can still use the pre-existing variable
-SHOW plpgsql.bogus_setting;
-
 --
 -- Test DISCARD TEMP
 --