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Fix pg_get_ruledef() so that negative numeric constants are parenthesized.

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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.
This commit is contained in:
Tom Lane 2008-06-06 17:59:29 +00:00
parent 700af334cc
commit c1943dbaef
1 changed files with 11 additions and 2 deletions
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13
src/backend/utils/adt/ruleutils.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.274 2008/05/12 00:00:51 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.275 2008/06/06 17:59:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -4479,10 +4479,19 @@ 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 */
}