Re: Precedence of standard comparison operators - Mailing list pgsql-hackers
| From | Tom Lane |
|---|---|
| Subject | Re: Precedence of standard comparison operators |
| Date | |
| Msg-id | 22908.1424652813@sss.pgh.pa.us Whole thread Raw |
| In response to | Re: Precedence of standard comparison operators (Tom Lane <tgl@sss.pgh.pa.us>) |
| Responses |
Re: Precedence of standard comparison operators
|
| List | pgsql-hackers |
Attached is an improved patch that includes optional warnings for
constructs that changed parsing. It's not quite 100% but I think it's
about 90% correct; the difference in size between this and the previous
patch should be a pretty fair indication of what it's going to cost us
to have a warning capability.
What's missing from this version is that it can't tell the difference
between LIKE/ILIKE/SIMILAR TO and the underlying operators, that is,
it sees "a LIKE b" as "a ~~ b" because that's what the grammar emits.
However, those inputs have different operator-precedence behavior.
Likewise, we can't tell the difference between
xmlexpr IS NOT DOCUMENT
NOT (xmlexpr IS DOCUMENT)
because the grammar converts the former into the latter --- and again,
those two things have different precedence behavior.
It wouldn't take very much additional code to fix these things by changing
what the grammar emits; but I'm running out of energy for today. In any
case, I thought I should put this up and see if this general approach is
going to satisfy people's concerns about making such a change.
regards, tom lane
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 6bcb106..22a2d32 100644
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** dynamic_library_path = 'C:\tools\postgre
*** 6752,6757 ****
--- 6752,6780 ----
</listitem>
</varlistentry>
+ <varlistentry id="guc-operator-precedence-warning" xreflabel="operator_precedence_warning">
+ <term><varname>operator_precedence_warning</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>operator_precedence_warning</> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ When on, the parser will emit a warning for any construct that might
+ have changed meanings since <productname>PostgreSQL</> 9.4 as a result
+ of changes in operator precedence. This is useful for auditing
+ applications to see if precedence changes have broken anything; but it
+ is not meant to be left turned on in production, since it will warn
+ about some perfectly valid, standard-compliant SQL code.
+ The default is <literal>off</>.
+ </para>
+
+ <para>
+ See <xref linkend="sql-precedence"> for more information.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-quote-all-identifiers" xreflabel="quote-all-identifiers">
<term><varname>quote_all_identifiers</varname> (<type>boolean</type>)
<indexterm>
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 4b81b08..e7484c4 100644
*** a/doc/src/sgml/syntax.sgml
--- b/doc/src/sgml/syntax.sgml
*************** CAST ( '<replaceable>string</replaceable
*** 984,993 ****
associativity of the operators in <productname>PostgreSQL</>.
Most operators have the same precedence and are left-associative.
The precedence and associativity of the operators is hard-wired
! into the parser. This can lead to non-intuitive behavior; for
! example the Boolean operators <literal><</> and
! <literal>></> have a different precedence than the Boolean
! operators <literal><=</> and <literal>>=</>. Also, you will
sometimes need to add parentheses when using combinations of
binary and unary operators. For instance:
<programlisting>
--- 984,994 ----
associativity of the operators in <productname>PostgreSQL</>.
Most operators have the same precedence and are left-associative.
The precedence and associativity of the operators is hard-wired
! into the parser.
! </para>
!
! <para>
! You will
sometimes need to add parentheses when using combinations of
binary and unary operators. For instance:
<programlisting>
*************** SELECT (5 !) - 6;
*** 1008,1014 ****
</para>
<table id="sql-precedence-table">
! <title>Operator Precedence (decreasing)</title>
<tgroup cols="3">
<thead>
--- 1009,1015 ----
</para>
<table id="sql-precedence-table">
! <title>Operator Precedence (highest to lowest)</title>
<tgroup cols="3">
<thead>
*************** SELECT (5 !) - 6;
*** 1063,1087 ****
</row>
<row>
! <entry><token>IS</token></entry>
! <entry></entry>
! <entry><literal>IS TRUE</>, <literal>IS FALSE</>, <literal>IS NULL</>, etc</entry>
! </row>
!
! <row>
! <entry><token>ISNULL</token></entry>
! <entry></entry>
! <entry>test for null</entry>
! </row>
!
! <row>
! <entry><token>NOTNULL</token></entry>
! <entry></entry>
! <entry>test for not null</entry>
! </row>
!
! <row>
! <entry>(any other)</entry>
<entry>left</entry>
<entry>all other native and user-defined operators</entry>
</row>
--- 1064,1070 ----
</row>
<row>
! <entry>(any other operator)</entry>
<entry>left</entry>
<entry>all other native and user-defined operators</entry>
</row>
*************** SELECT (5 !) - 6;
*** 1111,1125 ****
</row>
<row>
! <entry><token><</token> <token>></token></entry>
<entry></entry>
! <entry>less than, greater than</entry>
</row>
<row>
! <entry><token>=</token></entry>
! <entry>right</entry>
! <entry>equality, assignment</entry>
</row>
<row>
--- 1094,1110 ----
</row>
<row>
! <entry><token><</token> <token>></token> <token>=</token> <token><=</token> <token>>=</token>
<token><></token>
! </entry>
<entry></entry>
! <entry>comparison operators</entry>
</row>
<row>
! <entry><token>IS</token> <token>ISNULL</token> <token>NOTNULL</token></entry>
! <entry></entry>
! <entry><literal>IS TRUE</>, <literal>IS FALSE</>, <literal>IS
! NULL</>, <literal>IS DISTINCT FROM</>, etc</entry>
</row>
<row>
*************** SELECT (5 !) - 6;
*** 1159,1167 ****
SELECT 3 OPERATOR(pg_catalog.+) 4;
</programlisting>
the <literal>OPERATOR</> construct is taken to have the default precedence
! shown in <xref linkend="sql-precedence-table"> for <quote>any other</> operator. This is true no matter
which specific operator appears inside <literal>OPERATOR()</>.
</para>
</sect2>
</sect1>
--- 1144,1172 ----
SELECT 3 OPERATOR(pg_catalog.+) 4;
</programlisting>
the <literal>OPERATOR</> construct is taken to have the default precedence
! shown in <xref linkend="sql-precedence-table"> for
! <quote>any other operator</>. This is true no matter
which specific operator appears inside <literal>OPERATOR()</>.
</para>
+
+ <note>
+ <para>
+ <productname>PostgreSQL</> versions prior to 9.5 used a slightly
+ different operator precedence rule; in particular, <token><=</token>
+ <token>>=</token> and <token><></token> used to be treated as
+ generic operators, and <literal>IS</> tests used to have higher priority.
+ This was changed for better compliance with the SQL standard, and because
+ treating these operators differently from the other comparison operators
+ <token><</token> <token>></token> and <token>=</token> was
+ confusing. In most cases, this change will result in no behavioral
+ change or obvious <quote>no such operator</> failures; however there are
+ corner cases in which a query might change behavior without any parsing
+ error being reported. If you are concerned about whether this change has
+ silently broken something, you can test your application with the
+ configuration parameter <xref linkend="guc-operator-precedence-warning">
+ turned on to see if any warnings are logged.
+ </para>
+ </note>
</sect2>
</sect1>
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 98aa5f0..a6d0c5e 100644
*** a/src/backend/nodes/outfuncs.c
--- b/src/backend/nodes/outfuncs.c
*************** _outAExpr(StringInfo str, const A_Expr *
*** 2532,2537 ****
--- 2532,2540 ----
appendStringInfoString(str, " NOT_BETWEEN_SYM ");
WRITE_NODE_FIELD(name);
break;
+ case AEXPR_PAREN:
+ appendStringInfoString(str, " PAREN");
+ break;
default:
appendStringInfoString(str, " ??");
break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 76b0aff..3c28349 100644
*** a/src/backend/parser/gram.y
--- b/src/backend/parser/gram.y
***************
*** 58,63 ****
--- 58,64 ----
#include "nodes/nodeFuncs.h"
#include "parser/gramparse.h"
#include "parser/parser.h"
+ #include "parser/parse_expr.h"
#include "storage/lmgr.h"
#include "utils/date.h"
#include "utils/datetime.h"
*************** static Node *makeRecursiveViewSelect(cha
*** 532,537 ****
--- 533,539 ----
%token <str> IDENT FCONST SCONST BCONST XCONST Op
%token <ival> ICONST PARAM
%token TYPECAST DOT_DOT COLON_EQUALS
+ %token LESS_EQUALS GREATER_EQUALS NOT_EQUALS
/*
* If you want to make any keyword changes, update the keyword table in
*************** static Node *makeRecursiveViewSelect(cha
*** 645,652 ****
%left OR
%left AND
%right NOT
! %right '='
! %nonassoc '<' '>'
%nonassoc LIKE ILIKE SIMILAR
%nonassoc ESCAPE
%nonassoc OVERLAPS
--- 647,654 ----
%left OR
%left AND
%right NOT
! %nonassoc IS ISNULL NOTNULL /* IS sets precedence for IS NULL, etc */
! %nonassoc '<' '>' '=' LESS_EQUALS GREATER_EQUALS NOT_EQUALS
%nonassoc LIKE ILIKE SIMILAR
%nonassoc ESCAPE
%nonassoc OVERLAPS
*************** static Node *makeRecursiveViewSelect(cha
*** 676,684 ****
%nonassoc UNBOUNDED /* ideally should have same precedence as IDENT */
%nonassoc IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING
%left Op OPERATOR /* multi-character ops and user-defined operators */
- %nonassoc NOTNULL
- %nonassoc ISNULL
- %nonassoc IS /* sets precedence for IS NULL, etc */
%left '+' '-'
%left '*' '/' '%'
%left '^'
--- 678,683 ----
*************** a_expr: c_expr { $$ = $1; }
*** 11204,11209 ****
--- 11203,11214 ----
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, ">", $1, $3, @2); }
| a_expr '=' a_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "=", $1, $3, @2); }
+ | a_expr LESS_EQUALS a_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "<=", $1, $3, @2); }
+ | a_expr GREATER_EQUALS a_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, ">=", $1, $3, @2); }
+ | a_expr NOT_EQUALS a_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "<>", $1, $3, @2); }
| a_expr qual_Op a_expr %prec Op
{ $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, $3, @2); }
*************** b_expr: c_expr
*** 11564,11569 ****
--- 11569,11580 ----
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, ">", $1, $3, @2); }
| b_expr '=' b_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "=", $1, $3, @2); }
+ | b_expr LESS_EQUALS b_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "<=", $1, $3, @2); }
+ | b_expr GREATER_EQUALS b_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, ">=", $1, $3, @2); }
+ | b_expr NOT_EQUALS b_expr
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "<>", $1, $3, @2); }
| b_expr qual_Op b_expr %prec Op
{ $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, $3, @2); }
| qual_Op b_expr %prec Op
*************** c_expr: columnref { $$ = $1; }
*** 11635,11640 ****
--- 11646,11669 ----
n->indirection = check_indirection($4, yyscanner);
$$ = (Node *)n;
}
+ else if (operator_precedence_warning)
+ {
+ /*
+ * If precedence warnings are enabled, insert
+ * AEXPR_PAREN nodes wrapping all explicitly
+ * parenthesized subexpressions; this prevents bogus
+ * warnings from being issued when the ordering has
+ * been forced by parentheses.
+ *
+ * In principle we should not be relying on a GUC to
+ * decide whether to insert AEXPR_PAREN nodes.
+ * However, since they have no effect except to
+ * suppress warnings, it's probably safe enough; and
+ * we'd just as soon not waste cycles on dummy parse
+ * nodes if we don't have to.
+ */
+ $$ = (Node *) makeA_Expr(AEXPR_PAREN, NIL, $2, NULL, @1);
+ }
else
$$ = $2;
}
*************** MathOp: '+' { $$ = "+"; }
*** 12483,12488 ****
--- 12512,12520 ----
| '<' { $$ = "<"; }
| '>' { $$ = ">"; }
| '=' { $$ = "="; }
+ | LESS_EQUALS { $$ = "<="; }
+ | GREATER_EQUALS { $$ = ">="; }
+ | NOT_EQUALS { $$ = "<>"; }
;
qual_Op: Op
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index f314745..de19502 100644
*** a/src/backend/parser/parse_expr.c
--- b/src/backend/parser/parse_expr.c
***************
*** 37,42 ****
--- 37,44 ----
#include "utils/xml.h"
+ /* GUC parameters */
+ bool operator_precedence_warning = false;
bool Transform_null_equals = false;
static Node *transformExprRecurse(ParseState *pstate, Node *expr);
*************** static Node *make_row_distinct_op(ParseS
*** 76,81 ****
--- 78,88 ----
RowExpr *lrow, RowExpr *rrow, int location);
static Expr *make_distinct_op(ParseState *pstate, List *opname,
Node *ltree, Node *rtree, int location);
+ static int operator_precedence_group(Node *node, const char **nodename);
+ static void emit_precedence_warnings(ParseState *pstate,
+ int opgroup, const char *opname,
+ Node *lchild, Node *rchild,
+ int location);
/*
*************** transformExprRecurse(ParseState *pstate,
*** 188,193 ****
--- 195,203 ----
case AEXPR_NOT_BETWEEN_SYM:
result = transformAExprBetween(pstate, a);
break;
+ case AEXPR_PAREN:
+ result = transformExprRecurse(pstate, a->lexpr);
+ break;
default:
elog(ERROR, "unrecognized A_Expr kind: %d", a->kind);
result = NULL; /* keep compiler quiet */
*************** transformExprRecurse(ParseState *pstate,
*** 249,254 ****
--- 259,269 ----
{
NullTest *n = (NullTest *) expr;
+ if (operator_precedence_warning)
+ emit_precedence_warnings(pstate, 1, "IS",
+ (Node *) n->arg, NULL,
+ n->location);
+
n->arg = (Expr *) transformExprRecurse(pstate, (Node *) n->arg);
/* the argument can be any type, so don't coerce it */
n->argisrow = type_is_rowtype(exprType((Node *) n->arg));
*************** transformAExprOp(ParseState *pstate, A_E
*** 773,778 ****
--- 788,805 ----
Node *rexpr = a->rexpr;
Node *result;
+ if (operator_precedence_warning)
+ {
+ int opgroup;
+ const char *opname;
+
+ opgroup = operator_precedence_group((Node *) a, &opname);
+ if (opgroup > 0)
+ emit_precedence_warnings(pstate, opgroup, opname,
+ lexpr, rexpr,
+ a->location);
+ }
+
/*
* Special-case "foo = NULL" and "NULL = foo" for compatibility with
* standards-broken products (like Microsoft's). Turn these into IS NULL
*************** transformAExprOpAll(ParseState *pstate,
*** 877,884 ****
static Node *
transformAExprDistinct(ParseState *pstate, A_Expr *a)
{
! Node *lexpr = transformExprRecurse(pstate, a->lexpr);
! Node *rexpr = transformExprRecurse(pstate, a->rexpr);
if (lexpr && IsA(lexpr, RowExpr) &&
rexpr && IsA(rexpr, RowExpr))
--- 904,919 ----
static Node *
transformAExprDistinct(ParseState *pstate, A_Expr *a)
{
! Node *lexpr = a->lexpr;
! Node *rexpr = a->rexpr;
!
! if (operator_precedence_warning)
! emit_precedence_warnings(pstate, 1, "IS",
! lexpr, rexpr,
! a->location);
!
! lexpr = transformExprRecurse(pstate, lexpr);
! rexpr = transformExprRecurse(pstate, rexpr);
if (lexpr && IsA(lexpr, RowExpr) &&
rexpr && IsA(rexpr, RowExpr))
*************** transformAExprNullIf(ParseState *pstate,
*** 935,954 ****
return (Node *) result;
}
static Node *
transformAExprOf(ParseState *pstate, A_Expr *a)
{
! /*
! * Checking an expression for match to a list of type names. Will result
! * in a boolean constant node.
! */
! Node *lexpr = transformExprRecurse(pstate, a->lexpr);
Const *result;
ListCell *telem;
Oid ltype,
rtype;
bool matched = false;
ltype = exprType(lexpr);
foreach(telem, (List *) a->rexpr)
{
--- 970,996 ----
return (Node *) result;
}
+ /*
+ * Checking an expression for match to a list of type names. Will result
+ * in a boolean constant node.
+ */
static Node *
transformAExprOf(ParseState *pstate, A_Expr *a)
{
! Node *lexpr = a->lexpr;
Const *result;
ListCell *telem;
Oid ltype,
rtype;
bool matched = false;
+ if (operator_precedence_warning)
+ emit_precedence_warnings(pstate, 1, "IS",
+ lexpr, NULL,
+ a->location);
+
+ lexpr = transformExprRecurse(pstate, lexpr);
+
ltype = exprType(lexpr);
foreach(telem, (List *) a->rexpr)
{
*************** transformBooleanTest(ParseState *pstate,
*** 2157,2162 ****
--- 2199,2209 ----
{
const char *clausename;
+ if (operator_precedence_warning)
+ emit_precedence_warnings(pstate, 1, "IS",
+ (Node *) b->arg, NULL,
+ b->location);
+
switch (b->booltesttype)
{
case IS_TRUE:
*************** make_distinct_op(ParseState *pstate, Lis
*** 2674,2679 ****
--- 2721,2904 ----
}
/*
+ * Identify node's group for operator precedence warnings
+ *
+ * Groups are:
+ * 0: everything not classified below
+ * 1: IS tests (NullTest, BooleanTest, etc)
+ * 2: < > =
+ * 3: <= => <>
+ * 4: LIKE ILIKE SIMILAR BETWEEN IN
+ * 5: generic Op
+ *
+ * For items in nonzero groups, also return a suitable node name into *nodename
+ *
+ * Note: group zero is used for nodes that are higher or lower precedence
+ * than everything that changed precedence; we need never issue warnings
+ * related to such nodes. Also, nodes in group 4 do have precedences
+ * relative to each other, but we don't care since those did not change.
+ */
+ static int
+ operator_precedence_group(Node *node, const char **nodename)
+ {
+ int group = 0;
+
+ *nodename = NULL;
+ if (node == NULL)
+ return 0;
+
+ if (IsA(node, A_Expr))
+ {
+ A_Expr *aexpr = (A_Expr *) node;
+
+ if (aexpr->kind == AEXPR_OP &&
+ aexpr->lexpr != NULL &&
+ aexpr->rexpr != NULL)
+ {
+ /* binary operator */
+ if (list_length(aexpr->name) == 1)
+ {
+ *nodename = strVal(linitial(aexpr->name));
+ /* Ignore if op was always higher priority than IS-tests */
+ if (strcmp(*nodename, "+") == 0 ||
+ strcmp(*nodename, "-") == 0 ||
+ strcmp(*nodename, "*") == 0 ||
+ strcmp(*nodename, "/") == 0 ||
+ strcmp(*nodename, "%") == 0 ||
+ strcmp(*nodename, "^") == 0)
+ group = 0;
+ else if (strcmp(*nodename, "~") == 0 ||
+ strcmp(*nodename, "!~") == 0 ||
+ strcmp(*nodename, "~~") == 0 ||
+ strcmp(*nodename, "!~~") == 0 ||
+ strcmp(*nodename, "~~*") == 0 ||
+ strcmp(*nodename, "!~~*") == 0)
+ group = 4; /* LIKE, ILIKE, SIMILAR */
+ else if (strcmp(*nodename, "<=") == 0 ||
+ strcmp(*nodename, ">=") == 0 ||
+ strcmp(*nodename, "<>") == 0)
+ group = 3;
+ else if (strcmp(*nodename, "<") == 0 ||
+ strcmp(*nodename, ">") == 0 ||
+ strcmp(*nodename, "=") == 0)
+ group = 2;
+ else
+ group = 5;
+ }
+ else
+ {
+ /* schema-qualified operator syntax */
+ *nodename = "OPERATOR()";
+ group = 5;
+ }
+ }
+ else if (aexpr->kind == AEXPR_DISTINCT ||
+ aexpr->kind == AEXPR_OF)
+ {
+ *nodename = "IS";
+ group = 1;
+ }
+ else if (aexpr->kind == AEXPR_IN)
+ {
+ *nodename = "IN";
+ group = 4;
+ }
+ else if (aexpr->kind == AEXPR_BETWEEN ||
+ aexpr->kind == AEXPR_NOT_BETWEEN ||
+ aexpr->kind == AEXPR_BETWEEN_SYM ||
+ aexpr->kind == AEXPR_NOT_BETWEEN_SYM)
+ {
+ Assert(list_length(aexpr->name) == 1);
+ *nodename = strVal(linitial(aexpr->name));
+ group = 4;
+ }
+ }
+ else if (IsA(node, NullTest) ||IsA(node, BooleanTest))
+ {
+ *nodename = "IS";
+ group = 1;
+ }
+ else if (IsA(node, XmlExpr))
+ {
+ XmlExpr *x = (XmlExpr *) node;
+
+ if (x->op == IS_DOCUMENT)
+ {
+ *nodename = "IS";
+ group = 1;
+ }
+ /* XXX what of IS NOT DOCUMENT? */
+ }
+
+ return group;
+ }
+
+ /*
+ * helper routine for delivering 9.4-to-9.5 operator precedence warnings
+ *
+ * opgroup/opname/location represent some parent node
+ * lchild, rchild are its left and right children (either could be NULL)
+ *
+ * This should be called before transforming the child nodes, since if a
+ * precedence-driven parsing change has occurred in a query that used to work,
+ * it's quite possible that we'll get a semantic failure while analyzing the
+ * child expression. We want to produce the warning before that happens.
+ * In any case, operator_precedence_group() expects untransformed input.
+ */
+ static void
+ emit_precedence_warnings(ParseState *pstate,
+ int opgroup, const char *opname,
+ Node *lchild, Node *rchild,
+ int location)
+ {
+ /*----------
+ * Map precedence groupings to old precedence ordering
+ *
+ * Old precedence order:
+ * 2: < > =
+ * 4: LIKE ILIKE SIMILAR BETWEEN IN
+ * 5: generic Op, inclding 3: <= => <>
+ * 1: IS tests (NullTest, BooleanTest, etc)
+ *----------
+ */
+ static const int oldprecedence[] = {0, 4, 1, 3, 2, 3};
+ int cgroup;
+ const char *copname;
+
+ Assert(opgroup > 0);
+
+ /*
+ * Complain if left child, which should be same or higher precedence
+ * according to current rules, used to be lower precedence.
+ */
+ cgroup = operator_precedence_group(lchild, &copname);
+ if (cgroup > 0)
+ {
+ Assert(opgroup <= cgroup);
+ if (oldprecedence[cgroup] < oldprecedence[opgroup])
+ ereport(WARNING,
+ (errmsg("operator precedence change: %s is now lower precedence than %s",
+ opname, copname),
+ parser_errposition(pstate, location)));
+ }
+
+ /*
+ * Complain if right child, which should be higher precedence according to
+ * current rules, used to be same or lower precedence.
+ */
+ cgroup = operator_precedence_group(rchild, &copname);
+ if (cgroup > 0)
+ {
+ Assert(opgroup < cgroup);
+ if (oldprecedence[cgroup] <= oldprecedence[opgroup])
+ ereport(WARNING,
+ (errmsg("operator precedence change: %s is now lower precedence than %s",
+ opname, copname),
+ parser_errposition(pstate, location)));
+ }
+ }
+
+ /*
* Produce a string identifying an expression by kind.
*
* Note: when practical, use a simple SQL keyword for the result. If that
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 3724330..2d85cf0 100644
*** a/src/backend/parser/parse_target.c
--- b/src/backend/parser/parse_target.c
*************** FigureColnameInternal(Node *node, char *
*** 1654,1665 ****
*name = strVal(llast(((FuncCall *) node)->funcname));
return 2;
case T_A_Expr:
- /* make nullif() act like a regular function */
if (((A_Expr *) node)->kind == AEXPR_NULLIF)
{
*name = "nullif";
return 2;
}
break;
case T_TypeCast:
strength = FigureColnameInternal(((TypeCast *) node)->arg,
--- 1654,1670 ----
*name = strVal(llast(((FuncCall *) node)->funcname));
return 2;
case T_A_Expr:
if (((A_Expr *) node)->kind == AEXPR_NULLIF)
{
+ /* make nullif() act like a regular function */
*name = "nullif";
return 2;
}
+ if (((A_Expr *) node)->kind == AEXPR_PAREN)
+ {
+ /* look through dummy parenthesis node */
+ return FigureColnameInternal(((A_Expr *) node)->lexpr, name);
+ }
break;
case T_TypeCast:
strength = FigureColnameInternal(((TypeCast *) node)->arg,
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index a78ce03..7ce7a47 100644
*** a/src/backend/parser/scan.l
--- b/src/backend/parser/scan.l
*************** ident_cont [A-Za-z\200-\377_0-9\$]
*** 331,339 ****
--- 331,344 ----
identifier {ident_start}{ident_cont}*
+ /* Assorted special-case operators and operator-like tokens */
typecast "::"
dot_dot \.\.
colon_equals ":="
+ less_equals "<="
+ greater_equals ">="
+ less_greater "<>"
+ not_equals "!="
/*
* "self" is the set of chars that should be returned as single-character
*************** other .
*** 808,813 ****
--- 813,840 ----
return COLON_EQUALS;
}
+ {less_equals} {
+ SET_YYLLOC();
+ return LESS_EQUALS;
+ }
+
+ {greater_equals} {
+ SET_YYLLOC();
+ return GREATER_EQUALS;
+ }
+
+ {less_greater} {
+ /* We accept both "<>" and "!=" as meaning NOT_EQUALS */
+ SET_YYLLOC();
+ return NOT_EQUALS;
+ }
+
+ {not_equals} {
+ /* We accept both "<>" and "!=" as meaning NOT_EQUALS */
+ SET_YYLLOC();
+ return NOT_EQUALS;
+ }
+
{self} {
SET_YYLLOC();
return yytext[0];
*************** other .
*** 885,895 ****
if (nchars >= NAMEDATALEN)
yyerror("operator too long");
! /* Convert "!=" operator to "<>" for compatibility */
! if (strcmp(yytext, "!=") == 0)
! yylval->str = pstrdup("<>");
! else
! yylval->str = pstrdup(yytext);
return Op;
}
--- 912,918 ----
if (nchars >= NAMEDATALEN)
yyerror("operator too long");
! yylval->str = pstrdup(yytext);
return Op;
}
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 9572777..360dad9 100644
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
*************** static struct config_bool ConfigureNames
*** 1514,1519 ****
--- 1514,1529 ----
},
{
+ {"operator_precedence_warning", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
+ gettext_noop("Emit a warning for constructs that changed meaning since PostgreSQL 9.4."),
+ NULL,
+ },
+ &operator_precedence_warning,
+ false,
+ NULL, NULL, NULL
+ },
+
+ {
{"quote_all_identifiers", PGC_USERSET, COMPAT_OPTIONS_PREVIOUS,
gettext_noop("When generating SQL fragments, quote all identifiers."),
NULL,
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index b053659..9b2ca28 100644
*** a/src/backend/utils/misc/postgresql.conf.sample
--- b/src/backend/utils/misc/postgresql.conf.sample
***************
*** 582,587 ****
--- 582,588 ----
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
+ #operator_precedence_warning = off
#quote_all_identifiers = off
#sql_inheritance = on
#standard_conforming_strings = on
diff --git a/src/bin/psql/psqlscan.l b/src/bin/psql/psqlscan.l
index fb3fa11..a37cd2c 100644
*** a/src/bin/psql/psqlscan.l
--- b/src/bin/psql/psqlscan.l
*************** ident_cont [A-Za-z\200-\377_0-9\$]
*** 355,363 ****
--- 355,368 ----
identifier {ident_start}{ident_cont}*
+ /* Assorted special-case operators and operator-like tokens */
typecast "::"
dot_dot \.\.
colon_equals ":="
+ less_equals "<="
+ greater_equals ">="
+ less_greater "<>"
+ not_equals "!="
/*
* "self" is the set of chars that should be returned as single-character
*************** other .
*** 669,674 ****
--- 674,695 ----
ECHO;
}
+ {less_equals} {
+ ECHO;
+ }
+
+ {greater_equals} {
+ ECHO;
+ }
+
+ {less_greater} {
+ ECHO;
+ }
+
+ {not_equals} {
+ ECHO;
+ }
+
/*
* These rules are specific to psql --- they implement parenthesis
* counting and detection of command-ending semicolon. These must
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index d7b6148..1987313 100644
*** a/src/include/nodes/parsenodes.h
--- b/src/include/nodes/parsenodes.h
*************** typedef enum A_Expr_Kind
*** 236,242 ****
AEXPR_BETWEEN, /* name must be "BETWEEN" */
AEXPR_NOT_BETWEEN, /* name must be "NOT BETWEEN" */
AEXPR_BETWEEN_SYM, /* name must be "BETWEEN SYMMETRIC" */
! AEXPR_NOT_BETWEEN_SYM /* name must be "NOT BETWEEN SYMMETRIC" */
} A_Expr_Kind;
typedef struct A_Expr
--- 236,243 ----
AEXPR_BETWEEN, /* name must be "BETWEEN" */
AEXPR_NOT_BETWEEN, /* name must be "NOT BETWEEN" */
AEXPR_BETWEEN_SYM, /* name must be "BETWEEN SYMMETRIC" */
! AEXPR_NOT_BETWEEN_SYM, /* name must be "NOT BETWEEN SYMMETRIC" */
! AEXPR_PAREN /* nameless dummy node for parentheses */
} A_Expr_Kind;
typedef struct A_Expr
diff --git a/src/include/parser/parse_expr.h b/src/include/parser/parse_expr.h
index 66391df..fbc3f17 100644
*** a/src/include/parser/parse_expr.h
--- b/src/include/parser/parse_expr.h
***************
*** 16,21 ****
--- 16,22 ----
#include "parser/parse_node.h"
/* GUC parameters */
+ extern bool operator_precedence_warning;
extern bool Transform_null_equals;
extern Node *transformExpr(ParseState *pstate, Node *expr, ParseExprKind exprKind);
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 506a313..761cfab 100644
*** a/src/pl/plpgsql/src/pl_gram.y
--- b/src/pl/plpgsql/src/pl_gram.y
*************** static void check_raise_parameters(PLp
*** 227,232 ****
--- 227,233 ----
%token <str> IDENT FCONST SCONST BCONST XCONST Op
%token <ival> ICONST PARAM
%token TYPECAST DOT_DOT COLON_EQUALS
+ %token LESS_EQUALS GREATER_EQUALS NOT_EQUALS
/*
* Other tokens recognized by plpgsql's lexer interface layer (pl_scanner.c).
pgsql-hackers by date: