Remove deprecated syntax from CREATE/DROP LANGUAGE

Remove the option to specify the language name as a single-quoted
string.  This has been obsolete since ee8ed85d.  Removing it allows
better grammar refactoring.

The syntax of the CREATE FUNCTION LANGUAGE clause is not changed.

Discussion: https://www.postgresql.org/message-id/flat/163c00a5-f634-ca52-fc7c-0e53deda8735%402ndquadrant.com

doc/src/sgml/ref/create_language.sgml

@@ -110,11 +110,6 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
        The name of the new procedural language.
        The name must be unique among the languages in the database.
       </para>
-
-      <para>
-       For backward compatibility, the name can be enclosed by single
-       quotes.
-      </para>
      </listitem>
     </varlistentry>
 

doc/src/sgml/ref/drop_language.sgml

@@ -63,8 +63,7 @@ DROP [ PROCEDURAL ] LANGUAGE [ IF EXISTS ] <replaceable class="parameter">name</
     <term><replaceable class="parameter">name</replaceable></term>
     <listitem>
      <para>
-      The name of an existing procedural language.  For backward
-      compatibility, the name can be enclosed by single quotes.
+      The name of an existing procedural language.
      </para>
     </listitem>
    </varlistentry>

src/backend/parser/gram.y

@@ -4346,7 +4346,7 @@ NumericOnly_list:	NumericOnly						{ $$ = list_make1($1); }
  *****************************************************************************/
 
 CreatePLangStmt:
-			CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE NonReservedWord_or_Sconst
+			CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE name
 			{
 				/*
 				 * We now interpret parameterless CREATE LANGUAGE as
@@ -4361,7 +4361,7 @@ CreatePLangStmt:
 				n->options = NIL;
 				$$ = (Node *)n;
 			}
-			| CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE NonReservedWord_or_Sconst
+			| CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE name
 			  HANDLER handler_name opt_inline_handler opt_validator
 			{
 				CreatePLangStmt *n = makeNode(CreatePLangStmt);
@@ -4405,7 +4405,7 @@ opt_validator:
 		;
 
 DropPLangStmt:
-			DROP opt_procedural LANGUAGE NonReservedWord_or_Sconst opt_drop_behavior
+			DROP opt_procedural LANGUAGE name opt_drop_behavior
 				{
 					DropStmt *n = makeNode(DropStmt);
 					n->removeType = OBJECT_LANGUAGE;
@@ -4415,7 +4415,7 @@ DropPLangStmt:
 					n->concurrent = false;
 					$$ = (Node *)n;
 				}
-			| DROP opt_procedural LANGUAGE IF_P EXISTS NonReservedWord_or_Sconst opt_drop_behavior
+			| DROP opt_procedural LANGUAGE IF_P EXISTS name opt_drop_behavior
 				{
 					DropStmt *n = makeNode(DropStmt);
 					n->removeType = OBJECT_LANGUAGE;