Fix ecpg bugs caused by missing semicolons in the backend grammar.

The Bison documentation clearly states that a semicolon is required
after every grammar rule, and our scripts that generate ecpg's
grammar from the backend's implicitly assumed this is true.  But it
turns out that only ancient versions of Bison actually enforce that.
There have been a couple of rules without trailing semicolons in
gram.y for some time, and as a consequence, ecpg's grammar was faulty
and produced wrong output for the affected statements.

To fix, add the missing semis, and add some cross-checks to ecpg's
scripts so that they'll bleat if we mess this up again.

The cases that were broken were:
* "SET variable = DEFAULT" (but not "SET variable TO DEFAULT"),
  as well as allied syntaxes such as ALTER SYSTEM SET ... DEFAULT.
  These produced syntactically invalid output that the server
  would reject.
* Multiple type names in DROP TYPE/DOMAIN commands.  Only the
  first type name would be listed in the emitted command.

Per report from Daisuke Higuchi.  Back-patch to all supported versions.

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905DB51CE@g01jpexmbkw24

3 files changed, 19 insertions, 2 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d652a3e100..bc65319c2c4 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -1467,6 +1467,7 @@ generic_set:
 					n->name = $1;
 					$$ = n;
 				}
+		;
 
 set_rest_more:	/* Generic SET syntaxes: */
 			generic_set 						{$$ = $1;}
@@ -6375,6 +6376,7 @@ attrs:		'.' attr_name
 type_name_list:
 			Typename								{ $$ = list_make1($1); }
 			| type_name_list ',' Typename			{ $$ = lappend($1, $3); }
+		;
 
 /*****************************************************************************
  *
diff --git a/src/interfaces/ecpg/preproc/check_rules.pl b/src/interfaces/ecpg/preproc/check_rules.pl
index 6c8b0048546..c6a183ec711 100644
--- a/src/interfaces/ecpg/preproc/check_rules.pl
+++ b/src/interfaces/ecpg/preproc/check_rules.pl
@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 # src/interfaces/ecpg/preproc/check_rules.pl
-# test parser generater for ecpg
-# call with backend parser as stdin
+# test parser generator for ecpg
+# call with backend grammar as stdin
 #
 # Copyright (c) 2009-2018, PostgreSQL Global Development Group
 #
@@ -47,6 +47,7 @@ my %replace_line = (
 
 my $block        = '';
 my $yaccmode     = 0;
+my $in_rule      = 0;
 my $brace_indent = 0;
 my (@arr, %found);
 my $comment     = 0;
@@ -131,10 +132,14 @@ while (<$parser_fh>)
 			$found{$block} = 1;
 			$cc++;
 			$block = '';
+			$in_rule = 0 if $arr[$fieldIndexer] eq ';';
 		}
 		elsif (($arr[$fieldIndexer] =~ '[A-Za-z0-9]+:')
 			|| $arr[ $fieldIndexer + 1 ] eq ':')
 		{
+			die "unterminated rule at grammar line $.\n"
+			  if $in_rule;
+			$in_rule     = 1;
 			$non_term_id = $arr[$fieldIndexer];
 			$non_term_id =~ tr/://d;
 		}
@@ -145,6 +150,9 @@ while (<$parser_fh>)
 	}
 }
 
+die "unterminated rule at end of grammar\n"
+  if $in_rule;
+
 close $parser_fh;
 if ($verbose)
 {
diff --git a/src/interfaces/ecpg/preproc/parse.pl b/src/interfaces/ecpg/preproc/parse.pl
index ad87aad2835..863d770e109 100644
--- a/src/interfaces/ecpg/preproc/parse.pl
+++ b/src/interfaces/ecpg/preproc/parse.pl
@@ -22,6 +22,7 @@ $path = "." unless $path;
 my $copymode              = 0;
 my $brace_indent          = 0;
 my $yaccmode              = 0;
+my $in_rule               = 0;
 my $header_included       = 0;
 my $feature_not_supported = 0;
 my $tokenmode             = 0;
@@ -288,6 +289,7 @@ sub main
 				@fields  = ();
 				$infield = 0;
 				$line    = '';
+				$in_rule = 0;
 				next;
 			}
 
@@ -365,6 +367,9 @@ sub main
 				$line    = '';
 				@fields  = ();
 				$infield = 1;
+				die "unterminated rule at grammar line $.\n"
+				  if $in_rule;
+				$in_rule = 1;
 				next;
 			}
 			elsif ($copymode)
@@ -415,6 +420,8 @@ sub main
 			}
 		}
 	}
+	die "unterminated rule at end of grammar\n"
+	  if $in_rule;
 	return;
 }