Add commentary to the ExprList object to explain how zSpan is overloaded.
Add test cases for the new name resolution functionality.
FossilOrigin-Name: 3e7d84db7861911c9b2c7dcdabe0b213bf483d79
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 8a04ab4..6c10c38 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1771,18 +1771,26 @@
** list of "ID = expr" items in an UPDATE. A list of expressions can
** also be used as the argument to a function, in which case the a.zName
** field is not used.
+**
+** By default the Expr.zSpan field holds a human-readable description of
+** the expression that is used in the generation of error messages and
+** column labels. In this case, Expr.zSpan is typically the text of a
+** column expression as it exists in a SELECT statement. However, if
+** the bSpanIsTab flag is set, then zSpan is overloaded to mean the name
+** of the table to which the column of a FROM-clause subquery refers.
*/
struct ExprList {
int nExpr; /* Number of expressions on the list */
int iECursor; /* VDBE Cursor associated with this ExprList */
struct ExprList_item { /* For each expression in the list */
- Expr *pExpr; /* The list of expressions */
- char *zName; /* Token associated with this expression */
- char *zSpan; /* Original text of the expression */
- u8 sortOrder; /* 1 for DESC or 0 for ASC */
- u8 done; /* A flag to indicate when processing is finished */
- u16 iOrderByCol; /* For ORDER BY, column number in result set */
- u16 iAlias; /* Index into Parse.aAlias[] for zName */
+ Expr *pExpr; /* The list of expressions */
+ char *zName; /* Token associated with this expression */
+ char *zSpan; /* Original text of the expression */
+ u8 sortOrder; /* 1 for DESC or 0 for ASC */
+ unsigned done :1; /* A flag to indicate when processing is finished */
+ unsigned bSpanIsTab :1; /* zSpan holds table name, not the span */
+ u16 iOrderByCol; /* For ORDER BY, column number in result set */
+ u16 iAlias; /* Index into Parse.aAlias[] for zName */
} *a; /* Alloc a power of two greater or equal to nExpr */
};