gen_guc_tables.pl: Validate required GUC fields before code generation

Previously, gen_guc_tables.pl would emit "Use of uninitialized value"
warnings if required fields were missing in guc_parameters.dat (for
example, when an integer or real GUC omitted the 'max' value).  The
resulting error messages were unclear and did not identify which GUC
entry was problematic.

Add explicit validation of required fields depending on the parameter
type, and fail with a clear and specific message such as:

    guc_parameters.dat:1909: error: entry "max_index_keys" of type "int" is missing required field "max"

No changes to generated guc_tables.c.

Author: Chao Li <lic@highgo.com>
Reviewed-by: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://www.postgresql.org/message-id/flat/CAEoWx2%3DoP4LgHi771_OKhPPUS7B-CTqCs%3D%3DuQcNXWrwBoAm5Vg%40mail.gmail.com

1 files changed, 48 insertions, 0 deletions

diff --git a/src/backend/utils/misc/gen_guc_tables.pl b/src/backend/utils/misc/gen_guc_tables.pl
index 601c34ec30b..562819b7832 100644
--- a/src/backend/utils/misc/gen_guc_tables.pl
+++ b/src/backend/utils/misc/gen_guc_tables.pl
@@ -38,6 +38,52 @@ sub dquote
 	return q{"} . $s =~ s/"/\\"/gr . q{"};
 }
 
+sub validate_guc_entry
+{
+	my ($entry) = @_;
+
+	my @required_common =
+	  qw(name type context group short_desc variable boot_val);
+
+	my %required_by_type = (
+		int => [qw(min max)],
+		real => [qw(min max)],
+		enum => [qw(options)],
+		bool => [],      # no extra required fields
+		string => [],    # no extra required fields
+	);
+
+	for my $f (@required_common)
+	{
+		unless (defined $entry->{$f})
+		{
+			die sprintf(
+				qq{%s:%d: error: entry "%s" is missing required field "%s"\n},
+				$input_fname, $entry->{line_number},
+				$entry->{name} // '<unknown>', $f);
+		}
+	}
+
+	unless (exists $required_by_type{ $entry->{type} })
+	{
+		die sprintf(
+			qq{%s:%d: error: entry "%s" has unrecognized GUC type "%s"\n},
+			$input_fname, $entry->{line_number},
+			$entry->{name}, $entry->{type} // '<unknown>');
+	}
+
+	for my $f (@{ $required_by_type{ $entry->{type} } })
+	{
+		unless (defined $entry->{$f})
+		{
+			die sprintf(
+				qq{%s:%d: error: entry "%s" of type "%s" is missing required field "%s"\n},
+				$input_fname, $entry->{line_number}, $entry->{name},
+				$entry->{type}, $f);
+		}
+	}
+}
+
 # Print GUC table.
 sub print_table
 {
@@ -50,6 +96,8 @@ sub print_table
 
 	foreach my $entry (@{$parse})
 	{
+		validate_guc_entry($entry);
+
 		if (defined($prev_name) && lc($prev_name) ge lc($entry->{name}))
 		{
 			die sprintf(