From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <amitlangote09@gmail.com>
cc: Andrew Dunstan <andrew@dunslane.net>,
        pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Add basic JSON_TABLE() functionality
In-reply-to: <603615.1712245382@sss.pgh.pa.us>
References: <E1rsL9y-000S60-Pn@gemulon.postgresql.org>
 <f8402aef-c66c-4207-992c-fdee5e59c612@dunslane.net>
 <CA+HiwqF8KeHyoNi8TM-fUuE_002GYANbM55ybqEWi5QRinX5YQ@mail.gmail.com>
 <49c3a0cc-2998-4e25-8bc3-e70b3cba87eb@dunslane.net>
 <601996.1712244407@sss.pgh.pa.us> <603615.1712245382@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Thu, 04 Apr 2024 11:43:02 -0400"
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Date: Thu, 04 Apr 2024 12:55:08 -0400
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I wrote:
> We need to either nuke that ecpg warning entirely, or find a more
> robust way of detecting whether the gram.y complaint is conditional.
> I'll put a brown paper bag on my head before suggesting that maybe
> we could pay attention to how far the errcode is indented.  Perhaps
> a slightly nicer way is to assume it's conditional if any earlier
> line in the rule starts with "if".

The latter seems considerably safer, so I modified parse.pl along
those lines.  Eyeball comparison of gram.y with preproc.y verifies
that now ecpg will emit the warning only in rules where the backend
unconditionally reports FEATURE_NOT_SUPPORTED.

I suppose this needs to be back-patched.

			regards, tom lane


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diff --git a/src/interfaces/ecpg/preproc/parse.pl b/src/interfaces/ecpg/pr=
eproc/parse.pl
index 87b512b2a1..fe8d3e5178 100644
--- a/src/interfaces/ecpg/preproc/parse.pl
+++ b/src/interfaces/ecpg/preproc/parse.pl
@@ -34,7 +34,8 @@ my $brace_indent =3D 0;
 my $yaccmode =3D 0;
 my $in_rule =3D 0;
 my $header_included =3D 0;
-my $feature_not_supported =3D 0;
+my $has_feature_not_supported =3D 0;
+my $has_if_command =3D 0;
 my $tokenmode =3D 0;
 =

 my (%buff, $infield, $comment, %tokens, %addons);
@@ -151,12 +152,6 @@ sub main
 {
   line: while (<$parserfh>)
 	{
-		if (/ERRCODE_FEATURE_NOT_SUPPORTED/)
-		{
-			$feature_not_supported =3D 1;
-			next line;
-		}
-
 		chomp;
 =

 		# comment out the line below to make the result file match (blank line =
wise)
@@ -182,6 +177,13 @@ sub main
 			$infield =3D 0;
 		}
 =

+		if ($yaccmode =3D=3D 1)
+		{
+			# Check for rules that throw FEATURE_NOT_SUPPORTED
+			$has_feature_not_supported =3D 1 if /ERRCODE_FEATURE_NOT_SUPPORTED/;
+			$has_if_command =3D 1 if /^\s*if/;
+		}
+
 		my $prec =3D 0;
 =

 		# Make sure any braces are split
@@ -541,20 +543,17 @@ sub dump_fields
 =

 		#Normal
 		add_to_buffer('rules', $ln);
-		if ($feature_not_supported =3D=3D 1)
+		if ($has_feature_not_supported and not $has_if_command)
 		{
-
-			# we found an unsupported feature, but we have to
-			# filter out ExecuteStmt: CREATE OptTemp TABLE ...
-			# because the warning there is only valid in some situations
-			if ($flds->[0] ne 'create' || $flds->[2] ne 'table')
-			{
-				add_to_buffer('rules',
-					'mmerror(PARSE_ERROR, ET_WARNING, "unsupported feature will be passe=
d to server");'
-				);
-			}
-			$feature_not_supported =3D 0;
+			# The backend unconditionally reports
+			# FEATURE_NOT_SUPPORTED in this rule, so let's emit
+			# a warning on the ecpg side.
+			add_to_buffer('rules',
+				'mmerror(PARSE_ERROR, ET_WARNING, "unsupported feature will be passed=
 to server");'
+			);
 		}
+		$has_feature_not_supported =3D 0;
+		$has_if_command =3D 0;
 =

 		if ($len =3D=3D 0)
 		{

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