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

1 files changed, 1 insertions, 22 deletions

diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index d0a7329f10..5ff4fe738f 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.294 2007/06/01 23:40:19 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.295 2007/06/05 21:31:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -71,7 +71,6 @@ extern Datum boolout(PG_FUNCTION_ARGS);
 extern Datum boolrecv(PG_FUNCTION_ARGS);
 extern Datum boolsend(PG_FUNCTION_ARGS);
 extern Datum booltext(PG_FUNCTION_ARGS);
-extern Datum textbool(PG_FUNCTION_ARGS);
 extern Datum booleq(PG_FUNCTION_ARGS);
 extern Datum boolne(PG_FUNCTION_ARGS);
 extern Datum boollt(PG_FUNCTION_ARGS);
@@ -115,8 +114,6 @@ extern Datum enum_ne(PG_FUNCTION_ARGS);
 extern Datum enum_ge(PG_FUNCTION_ARGS);
 extern Datum enum_gt(PG_FUNCTION_ARGS);
 extern Datum enum_cmp(PG_FUNCTION_ARGS);
-extern Datum enum_text(PG_FUNCTION_ARGS);
-extern Datum text_enum(PG_FUNCTION_ARGS);
 extern Datum enum_smaller(PG_FUNCTION_ARGS);
 extern Datum enum_larger(PG_FUNCTION_ARGS);
 extern Datum enum_first(PG_FUNCTION_ARGS);
@@ -140,12 +137,8 @@ extern Datum int4recv(PG_FUNCTION_ARGS);
 extern Datum int4send(PG_FUNCTION_ARGS);
 extern Datum i2toi4(PG_FUNCTION_ARGS);
 extern Datum i4toi2(PG_FUNCTION_ARGS);
-extern Datum int2_text(PG_FUNCTION_ARGS);
-extern Datum text_int2(PG_FUNCTION_ARGS);
 extern Datum int4_bool(PG_FUNCTION_ARGS);
 extern Datum bool_int4(PG_FUNCTION_ARGS);
-extern Datum int4_text(PG_FUNCTION_ARGS);
-extern Datum text_int4(PG_FUNCTION_ARGS);
 extern Datum int4eq(PG_FUNCTION_ARGS);
 extern Datum int4ne(PG_FUNCTION_ARGS);
 extern Datum int4lt(PG_FUNCTION_ARGS);
@@ -334,10 +327,6 @@ extern Datum i4tof(PG_FUNCTION_ARGS);
 extern Datum i2tof(PG_FUNCTION_ARGS);
 extern Datum ftoi4(PG_FUNCTION_ARGS);
 extern Datum ftoi2(PG_FUNCTION_ARGS);
-extern Datum text_float8(PG_FUNCTION_ARGS);
-extern Datum text_float4(PG_FUNCTION_ARGS);
-extern Datum float8_text(PG_FUNCTION_ARGS);
-extern Datum float4_text(PG_FUNCTION_ARGS);
 extern Datum dround(PG_FUNCTION_ARGS);
 extern Datum dceil(PG_FUNCTION_ARGS);
 extern Datum dfloor(PG_FUNCTION_ARGS);
@@ -446,8 +435,6 @@ extern Datum oidge(PG_FUNCTION_ARGS);
 extern Datum oidgt(PG_FUNCTION_ARGS);
 extern Datum oidlarger(PG_FUNCTION_ARGS);
 extern Datum oidsmaller(PG_FUNCTION_ARGS);
-extern Datum oid_text(PG_FUNCTION_ARGS);
-extern Datum text_oid(PG_FUNCTION_ARGS);
 extern Datum oidvectorin(PG_FUNCTION_ARGS);
 extern Datum oidvectorout(PG_FUNCTION_ARGS);
 extern Datum oidvectorrecv(PG_FUNCTION_ARGS);
@@ -782,8 +769,6 @@ extern Datum network_show(PG_FUNCTION_ARGS);
 extern Datum inet_abbrev(PG_FUNCTION_ARGS);
 extern Datum cidr_abbrev(PG_FUNCTION_ARGS);
 extern double convert_network_to_scalar(Datum value, Oid typid);
-extern Datum text_cidr(PG_FUNCTION_ARGS);
-extern Datum text_inet(PG_FUNCTION_ARGS);
 extern Datum inet_to_cidr(PG_FUNCTION_ARGS);
 extern Datum inet_set_masklen(PG_FUNCTION_ARGS);
 extern Datum cidr_set_masklen(PG_FUNCTION_ARGS);
@@ -814,8 +799,6 @@ extern Datum macaddr_ge(PG_FUNCTION_ARGS);
 extern Datum macaddr_gt(PG_FUNCTION_ARGS);
 extern Datum macaddr_ne(PG_FUNCTION_ARGS);
 extern Datum macaddr_trunc(PG_FUNCTION_ARGS);
-extern Datum macaddr_text(PG_FUNCTION_ARGS);
-extern Datum text_macaddr(PG_FUNCTION_ARGS);
 extern Datum hashmacaddr(PG_FUNCTION_ARGS);
 
 /* numeric.c */
@@ -866,8 +849,6 @@ extern Datum numeric_float8(PG_FUNCTION_ARGS);
 extern Datum numeric_float8_no_overflow(PG_FUNCTION_ARGS);
 extern Datum float4_numeric(PG_FUNCTION_ARGS);
 extern Datum numeric_float4(PG_FUNCTION_ARGS);
-extern Datum text_numeric(PG_FUNCTION_ARGS);
-extern Datum numeric_text(PG_FUNCTION_ARGS);
 extern Datum numeric_accum(PG_FUNCTION_ARGS);
 extern Datum numeric_avg_accum(PG_FUNCTION_ARGS);
 extern Datum int2_accum(PG_FUNCTION_ARGS);
@@ -970,7 +951,5 @@ extern Datum uuid_gt(PG_FUNCTION_ARGS);
 extern Datum uuid_ne(PG_FUNCTION_ARGS);
 extern Datum uuid_cmp(PG_FUNCTION_ARGS);
 extern Datum uuid_hash(PG_FUNCTION_ARGS);
-extern Datum text_uuid(PG_FUNCTION_ARGS);
-extern Datum uuid_text(PG_FUNCTION_ARGS);
 
 #endif   /* BUILTINS_H */