To: Merlin Moncure <mmoncure@gmail.com>,
	Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	Robert Haas <robertmhaas@gmail.com>,
	Jon Nelson <jnelson+pgsql@jamponi.net>, pgsql-bugs@postgresql.org
Subject: Re: [PERFORM] typoed column name, but postgres didn't grump 
In-reply-to: <11057.1288889780@sss.pgh.pa.us> 
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Thu, 04 Nov 2010 12:56:20 -0400"
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Date: Fri, 05 Nov 2010 15:17:24 -0400
Message-ID: <29497.1288984644@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

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I wrote:
> Ah.  No, that would still work after the change.  The case that I'm
> proposing to break is using function-ish notation to invoke a cast
> from a composite type to some other type whose name you use as if it
> were a function.  Even there, if you've created such a cast following
> the usual convention of naming the cast function after the target type,
> it'll still act the same.  It's just the built-in I/O-based casts that
> will stop working this way (for lack of a matching underlying function).

Here's a proposed patch, sans documentation as yet.

			regards, tom lane


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diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_fu=
nc.c
index b50bce448728280f63c695a688c004bd15bf84cf..9bb100e0c1e83c63b554f65300=
c03afed563373a 100644
*** a/src/backend/parser/parse_func.c
--- b/src/backend/parser/parse_func.c
*************** func_get_detail(List *funcname,
*** 985,992 ****
  		 * can't write "foo[] (something)" as a function call.  In theory
  		 * someone might want to invoke it as "_foo (something)" but we have
  		 * never supported that historically, so we can insist that people
! 		 * write it as a normal cast instead.  Lack of historical support is
! 		 * also the reason for not considering composite-type casts here.
  		 *
  		 * NB: it's important that this code does not exceed what coerce_type
  		 * can do, because the caller will try to apply coerce_type if we
--- 985,997 ----
  		 * can't write "foo[] (something)" as a function call.  In theory
  		 * someone might want to invoke it as "_foo (something)" but we have
  		 * never supported that historically, so we can insist that people
! 		 * write it as a normal cast instead.
! 		 *
! 		 * We also reject the specific case of COERCEVIAIO for a composite
! 		 * source type and a string-category target type.  This is a case that
! 		 * find_coercion_pathway() allows by default, but experience has shown
! 		 * that it's too commonly invoked by mistake.  So, again, insist that
! 		 * people use cast syntax if they want to do that.
  		 *
  		 * NB: it's important that this code does not exceed what coerce_type
  		 * can do, because the caller will try to apply coerce_type if we
*************** func_get_detail(List *funcname,
*** 1017,1024 ****
  					cpathtype =3D find_coercion_pathway(targetType, sourceType,
  													  COERCION_EXPLICIT,
  													  &cfuncid);
! 					iscoercion =3D (cpathtype =3D=3D COERCION_PATH_RELABELTYPE ||
! 								  cpathtype =3D=3D COERCION_PATH_COERCEVIAIO);
  				}
  =

  				if (iscoercion)
--- 1022,1044 ----
  					cpathtype =3D find_coercion_pathway(targetType, sourceType,
  													  COERCION_EXPLICIT,
  													  &cfuncid);
! 					switch (cpathtype)
! 					{
! 						case COERCION_PATH_RELABELTYPE:
! 							iscoercion =3D true;
! 							break;
! 						case COERCION_PATH_COERCEVIAIO:
! 							if ((sourceType =3D=3D RECORDOID ||
! 								 ISCOMPLEX(sourceType)) &&
! 								TypeCategory(targetType) =3D=3D TYPCATEGORY_STRING)
! 								iscoercion =3D false;
! 							else
! 								iscoercion =3D true;
! 							break;
! 						default:
! 							iscoercion =3D false;
! 							break;
! 					}
  				}
  =

  				if (iscoercion)

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