From 31edbadf4af45dd4eecebcb732702ec6d7ae1819 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 5 Jun 2007 21:31:09 +0000
Subject: Downgrade implicit casts to text to be assignment-only, except for
 the ones from the other string-category types; this eliminates a lot of
 surprising interpretations that the parser could formerly make when there was
 no directly applicable operator.

Create a general mechanism that supports casts to and from the standard string
types (text,varchar,bpchar) for *every* datatype, by invoking the datatype's
I/O functions.  These new casts are assignment-only in the to-string direction,
explicit-only in the other, and therefore should create no surprising behavior.
Remove a bunch of thereby-obsoleted datatype-specific casting functions.

The "general mechanism" is a new expression node type CoerceViaIO that can
actually convert between *any* two datatypes if their external text
representations are compatible.  This is more general than needed for the
immediate feature, but might be useful in plpgsql or other places in future.

This commit does nothing about the issue that applying the concatenation
operator || to non-text types will now fail, often with strange error messages
due to misinterpreting the operator as array concatenation.  Since it often
(not always) worked before, we should either make it succeed or at least give
a more user-friendly error; but details are still under debate.

Peter Eisentraut and Tom Lane
---
 src/backend/utils/adt/int.c | 66 +--------------------------------------------
 1 file changed, 1 insertion(+), 65 deletions(-)

(limited to 'src/backend/utils/adt/int.c')

diff --git a/src/backend/utils/adt/int.c b/src/backend/utils/adt/int.c
index d6d59022077..405b16ecef8 100644
--- a/src/backend/utils/adt/int.c
+++ b/src/backend/utils/adt/int.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.79 2007/02/27 23:48:08 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/int.c,v 1.80 2007/06/05 21:31:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,8 +18,6 @@
  *		 int2in, int2out, int2recv, int2send
  *		 int4in, int4out, int4recv, int4send
  *		 int2vectorin, int2vectorout, int2vectorrecv, int2vectorsend
- *		Conversion routines:
- *		 itoi, int2_text, int4_text
  *		Boolean operators:
  *		 inteq, intne, intlt, intle, intgt, intge
  *		Arithmetic operators:
@@ -343,68 +341,6 @@ i4toi2(PG_FUNCTION_ARGS)
 	PG_RETURN_INT16((int16) arg1);
 }
 
-Datum
-int2_text(PG_FUNCTION_ARGS)
-{
-	int16		arg1 = PG_GETARG_INT16(0);
-	text	   *result = (text *) palloc(7 + VARHDRSZ); /* sign,5 digits, '\0' */
-
-	pg_itoa(arg1, VARDATA(result));
-	SET_VARSIZE(result, strlen(VARDATA(result)) + VARHDRSZ);
-	PG_RETURN_TEXT_P(result);
-}
-
-Datum
-text_int2(PG_FUNCTION_ARGS)
-{
-	text	   *string = PG_GETARG_TEXT_P(0);
-	Datum		result;
-	int			len;
-	char	   *str;
-
-	len = VARSIZE(string) - VARHDRSZ;
-
-	str = palloc(len + 1);
-	memcpy(str, VARDATA(string), len);
-	*(str + len) = '\0';
-
-	result = DirectFunctionCall1(int2in, CStringGetDatum(str));
-	pfree(str);
-
-	return result;
-}
-
-Datum
-int4_text(PG_FUNCTION_ARGS)
-{
-	int32		arg1 = PG_GETARG_INT32(0);
-	text	   *result = (text *) palloc(12 + VARHDRSZ);		/* sign,10 digits,'\0' */
-
-	pg_ltoa(arg1, VARDATA(result));
-	SET_VARSIZE(result, strlen(VARDATA(result)) + VARHDRSZ);
-	PG_RETURN_TEXT_P(result);
-}
-
-Datum
-text_int4(PG_FUNCTION_ARGS)
-{
-	text	   *string = PG_GETARG_TEXT_P(0);
-	Datum		result;
-	int			len;
-	char	   *str;
-
-	len = VARSIZE(string) - VARHDRSZ;
-
-	str = palloc(len + 1);
-	memcpy(str, VARDATA(string), len);
-	*(str + len) = '\0';
-
-	result = DirectFunctionCall1(int4in, CStringGetDatum(str));
-	pfree(str);
-
-	return result;
-}
-
 /* Cast int4 -> bool */
 Datum
 int4_bool(PG_FUNCTION_ARGS)
-- 
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