postgres.git / summary / log / commit / refs

commit    0bb7588aeeaaacd8a193c2ff45fbb07e50a64ad2
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Fri Jun 06 18:00:00 2008 +0000
First released in: 8.4.0, 7.4.21, 8.0.17, 8.1.13, 8.2.9, 8.3.3

    Fix pg_get_ruledef() so that negative numeric constants are parenthesized.
    This is needed because :: casting binds more tightly than minus, so for
    example -1::integer is not the same as (-1)::integer, and there are cases
    where the difference is important.  In particular this caused a failure
    in SELECT DISTINCT ... ORDER BY ... where expressions that should have
    matched were seen as different by the parser; but I suspect that there
    could be other cases where failure to parenthesize leads to subtler
    semantic differences in reloaded rules.  Per report from Alexandr Popov.


 src/backend/utils/adt/ruleutils.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 34684ac30e9..5d56607f03c 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.188.4.7 2008/01/06 01:03:37 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.188.4.8 2008/06/06 18:00:00 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -3774,10 +3774,19 @@ get_const_expr(Const *constval, deparse_context *context, int showtype)
 				 * In reality we only need to defend against infinity and
 				 * NaN, so we need not get too crazy about pattern
 				 * matching here.
+				 *
+				 * There is a special-case gotcha: if the constant is signed,
+				 * we need to parenthesize it, else the parser might see a
+				 * leading plus/minus as binding less tightly than adjacent
+				 * operators --- particularly, the cast that we might attach
+				 * below.
 				 */
 				if (strspn(extval, "0123456789+-eE.") == strlen(extval))
 				{
-					appendStringInfoString(buf, extval);
+					if (extval[0] == '+' || extval[0] == '-')
+						appendStringInfo(buf, "(%s)", extval);
+					else
+						appendStringInfoString(buf, extval);
 					if (strcspn(extval, "eE.") != strlen(extval))
 						isfloat = true; /* it looks like a float */
 				}


[parent: 52726527206f]