Tweak parse location assignment for CURRENT_DATE and related constructs.

All these constructs generate parse trees consisting of a Const and
a run-time type coercion (perhaps a FuncExpr or a CoerceViaIO).  Modify
the raw parse output so that we end up with the original token's location
attached to the type coercion node while the Const has location -1;
before, it was the other way around.  This makes no difference in terms
of what exprLocation() will say about the parse tree as a whole, so it
should not have any user-visible impact.  The point of changing it is that
we do not want contrib/pg_stat_statements to treat these constructs as
replaceable constants.  It will do the right thing if the Const has
location -1 rather than a valid location.

This is a pretty ugly hack, but then this code is ugly already; we should
someday replace this translation with special-purpose parse node(s) that
would allow ruleutils.c to reconstruct the original query text.

(See also commit 5d3fcc4c, which also
hacked location assignment rules for the benefit of pg_stat_statements.)

Back-patch to 9.2 where pg_stat_statements grew the ability to recognize
replaceable constants.

Kyotaro Horiguchi

src/backend/parser/gram.y

@@ -11361,10 +11361,10 @@ func_expr: func_application within_group_clause filter_clause over_clause
 		;
 
 /*
- * As func_expr but does not accept WINDOW functions directly (they
- * can still be contained in arguments for functions etc.)
- * Use this when window expressions are not allowed, so to disambiguate
- * the grammar. (e.g. in CREATE INDEX)
+ * As func_expr but does not accept WINDOW functions directly
+ * (but they can still be contained in arguments for functions etc).
+ * Use this when window expressions are not allowed, where needed to
+ * disambiguate the grammar (e.g. in CREATE INDEX).
  */
 func_expr_windowless:
 			func_application						{ $$ = $1; }
@@ -11372,7 +11372,7 @@ func_expr_windowless:
 		;
 
 /*
- * Special expression
+ * Special expressions that are considered to be functions.
  */
 func_expr_common_subexpr:
 			COLLATION FOR '(' a_expr ')'
@@ -11397,10 +11397,15 @@ func_expr_common_subexpr:
 					 * of type-input conversion functions.  (As of PG 7.3
 					 * that is actually possible, but not clear that we want
 					 * to rely on it.)
+					 *
+					 * The token location is attached to the run-time
+					 * typecast, not to the Const, for the convenience of
+					 * pg_stat_statements (which doesn't want these constructs
+					 * to appear to be replaceable constants).
 					 */
 					Node *n;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
-					$$ = makeTypeCast(n, SystemTypeName("date"), -1);
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
+					$$ = makeTypeCast(n, SystemTypeName("date"), @1);
 				}
 			| CURRENT_TIME
 				{
@@ -11409,8 +11414,8 @@ func_expr_common_subexpr:
 					 * See comments for CURRENT_DATE.
 					 */
 					Node *n;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
-					$$ = makeTypeCast(n, SystemTypeName("timetz"), -1);
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
+					$$ = makeTypeCast(n, SystemTypeName("timetz"), @1);
 				}
 			| CURRENT_TIME '(' Iconst ')'
 				{
@@ -11420,10 +11425,10 @@ func_expr_common_subexpr:
 					 */
 					Node *n;
 					TypeName *d;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
 					d = SystemTypeName("timetz");
 					d->typmods = list_make1(makeIntConst($3, @3));
-					$$ = makeTypeCast(n, d, -1);
+					$$ = makeTypeCast(n, d, @1);
 				}
 			| CURRENT_TIMESTAMP
 				{
@@ -11441,10 +11446,10 @@ func_expr_common_subexpr:
 					 */
 					Node *n;
 					TypeName *d;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
 					d = SystemTypeName("timestamptz");
 					d->typmods = list_make1(makeIntConst($3, @3));
-					$$ = makeTypeCast(n, d, -1);
+					$$ = makeTypeCast(n, d, @1);
 				}
 			| LOCALTIME
 				{
@@ -11453,8 +11458,8 @@ func_expr_common_subexpr:
 					 * See comments for CURRENT_DATE.
 					 */
 					Node *n;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
-					$$ = makeTypeCast((Node *)n, SystemTypeName("time"), -1);
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
+					$$ = makeTypeCast((Node *)n, SystemTypeName("time"), @1);
 				}
 			| LOCALTIME '(' Iconst ')'
 				{
@@ -11464,10 +11469,10 @@ func_expr_common_subexpr:
 					 */
 					Node *n;
 					TypeName *d;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
 					d = SystemTypeName("time");
 					d->typmods = list_make1(makeIntConst($3, @3));
-					$$ = makeTypeCast((Node *)n, d, -1);
+					$$ = makeTypeCast((Node *)n, d, @1);
 				}
 			| LOCALTIMESTAMP
 				{
@@ -11476,8 +11481,8 @@ func_expr_common_subexpr:
 					 * See comments for CURRENT_DATE.
 					 */
 					Node *n;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
-					$$ = makeTypeCast(n, SystemTypeName("timestamp"), -1);
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
+					$$ = makeTypeCast(n, SystemTypeName("timestamp"), @1);
 				}
 			| LOCALTIMESTAMP '(' Iconst ')'
 				{
@@ -11487,10 +11492,10 @@ func_expr_common_subexpr:
 					 */
 					Node *n;
 					TypeName *d;
-					n = makeStringConstCast("now", @1, SystemTypeName("text"));
+					n = makeStringConstCast("now", -1, SystemTypeName("text"));
 					d = SystemTypeName("timestamp");
 					d->typmods = list_make1(makeIntConst($3, @3));
-					$$ = makeTypeCast(n, d, -1);
+					$$ = makeTypeCast(n, d, @1);
 				}
 			| CURRENT_ROLE
 				{