Apply code-reviewed version of for-scalar-list patch: mostly, fixing

it to report reasonable errors in error cases.

Author: tglsfdc

doc/src/sgml/plpgsql.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.85 2006/02/12 06:03:38 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.86 2006/02/12 06:37:05 tgl Exp $
 -->
 
 <chapter id="plpgsql"> 
@@ -1968,10 +1968,12 @@ END LOOP <optional> <replaceable>label</replaceable> </optional>;
 </synopsis>
 
        <para>
-        This form of <literal>FOR</> creates a loop that iterates over a range of integer
-        values. The variable 
+        This form of <literal>FOR</> creates a loop that iterates over a range
+        of integer values. The variable 
         <replaceable>name</replaceable> is automatically defined as type
-        <type>integer</> and exists only inside the loop. The two expressions giving
+        <type>integer</> and exists only inside the loop (any existing
+        definition of the variable name is ignored within the loop).
+        The two expressions giving
         the lower and upper bound of the range are evaluated once when entering
         the loop. The iteration step is normally 1, but is -1 when <literal>REVERSE</> is
         specified.
@@ -2012,9 +2014,9 @@ FOR <replaceable>target</replaceable> IN <replaceable>query</replaceable> LOOP
     <replaceable>statements</replaceable>
 END LOOP <optional> <replaceable>label</replaceable> </optional>;
 </synopsis>
-     <replaceable>Target</replaceable> is a record variable, row variable, 
-     or a comma-separated list of  simple variables and record/row fields
-     which is successively assigned each row
+     The <replaceable>target</replaceable> is a record variable, row variable,
+     or comma-separated list of scalar variables.
+     The <replaceable>target</replaceable> is successively assigned each row
      resulting from the <replaceable>query</replaceable> (which must be a
      <command>SELECT</command> command) and the loop body is executed for each
      row. Here is an example:
@@ -2069,7 +2071,8 @@ END LOOP <optional> <replaceable>label</replaceable> </optional>;
      <literal>IN</> and <literal>LOOP</>.  If <literal>..</> is not seen then
      the loop is presumed to be a loop over rows.  Mistyping the <literal>..</>
      is thus likely to lead to a complaint along the lines of
-     <quote>loop variable of loop over rows must be a record or row or scalar variable</>,
+     <quote>loop variable of loop over rows must be a record or row variable
+     or list of scalar variables</>,
      rather than the simple syntax error one might expect to get.
     </para>
     </note>

src/pl/plpgsql/src/gram.y

@@ -4,7 +4,7 @@
  *						  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.84 2006/02/12 06:03:38 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.85 2006/02/12 06:37:05 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -54,13 +54,14 @@ static	PLpgSQL_stmt	*make_fetch_stmt(void);
 static	void			 check_assignable(PLpgSQL_datum *datum);
 static	PLpgSQL_row		*read_into_scalar_list(const char *initial_name,
 											   PLpgSQL_datum *initial_datum);
+static PLpgSQL_row		*make_scalar_list1(const char *initial_name,
+										   PLpgSQL_datum *initial_datum,
+										   int lineno);
 static	void			 check_sql_expr(const char *stmt);
 static	void			 plpgsql_sql_error_callback(void *arg);
 static	void			 check_labels(const char *start_label,
 									  const char *end_label);
-static PLpgSQL_row       *make_scalar_list1(const char *name,
-					    PLpgSQL_datum *variable);
- 
+
 %}
 
 %union {
@@ -76,9 +77,9 @@ static PLpgSQL_row       *make_scalar_list1(const char *name,
 		{
 			char *name;
 			int  lineno;
+			PLpgSQL_datum   *scalar;
 			PLpgSQL_rec     *rec;
 			PLpgSQL_row     *row;
-		        PLpgSQL_datum   *scalar;
 		}						forvariable;
 		struct
 		{
@@ -895,13 +896,14 @@ for_control		:
 							}
 							else if ($2.scalar)
 							{
-						        new->row = make_scalar_list1($2.name, $2.scalar);
-								check_assignable((PLpgSQL_datum *) new->row);
+								/* convert single scalar to list */
+								new->row = make_scalar_list1($2.name, $2.scalar, $2.lineno);
+								/* no need for check_assignable */
 							}
 							else
 							{
-								plpgsql_error_lineno = $1;
-								yyerror("loop variable of loop over rows must be a record, row, or scalar variable");
+								plpgsql_error_lineno = $2.lineno;
+								yyerror("loop variable of loop over rows must be a record or row variable or list of scalar variables");
 							}
 							new->query = expr;
 
@@ -950,24 +952,24 @@ for_control		:
 								PLpgSQL_expr		*expr2;
 								PLpgSQL_var			*fvar;
 								PLpgSQL_stmt_fori	*new;
+								char				*varname;
 
 								/* First expression is well-formed */
 								check_sql_expr(expr1->query);
 
 								expr2 = plpgsql_read_expression(K_LOOP, "LOOP");
 
-								/* T_SCALAR identifier waits for converting */
-								if ($2.scalar)
-								{
-								    char *name;
-								    plpgsql_convert_ident($2.name, &name, 1);
-								    pfree($2.name);
-								    $2.name = name;
-								}
+								/* should have had a single variable name */
+								plpgsql_error_lineno = $2.lineno;
+								if ($2.scalar && $2.row)
+									ereport(ERROR,
+											(errcode(ERRCODE_SYNTAX_ERROR),
+											 errmsg("integer FOR loop must have just one target variable")));
 
 								/* create loop's private variable */
+								plpgsql_convert_ident($2.name, &varname, 1);
 								fvar = (PLpgSQL_var *)
-									plpgsql_build_variable($2.name,
+									plpgsql_build_variable(varname,
 														   $2.lineno,
 														   plpgsql_build_datatype(INT4OID,
 																				  -1),
@@ -1021,13 +1023,14 @@ for_control		:
 								}
 								else if ($2.scalar)
 								{
-							        new->row = make_scalar_list1($2.name, $2.scalar);
-									check_assignable((PLpgSQL_datum *) new->row);
+									/* convert single scalar to list */
+									new->row = make_scalar_list1($2.name, $2.scalar, $2.lineno);
+									/* no need for check_assignable */
 								}
 								else
 								{
-									plpgsql_error_lineno = $1;
-									yyerror("loop variable of loop over rows must be record, row, or scalar variable");
+									plpgsql_error_lineno = $2.lineno;
+									yyerror("loop variable of loop over rows must be a record or row variable or list of scalar variables");
 								}
 
 								new->query = expr1;
@@ -1047,55 +1050,63 @@ for_control		:
  * if any, because that's what we need for the loop-over-query case.  Note
  * that we must NOT apply check_assignable() or any other semantic check
  * until we know what's what.
+ *
+ * However, if we see a comma-separated list of names, we know that it
+ * can't be an integer FOR loop and so it's OK to check the variables
+ * immediately.  In particular, for T_WORD followed by comma, we should
+ * complain that the name is not known rather than say it's a syntax error.
+ * Note that the non-error result of this case sets *both* $$.scalar and
+ * $$.row; see the for_control production.
  */
 for_variable	: T_SCALAR
-  					{
-						int tok;
-						char		*name;
-						
-						name = pstrdup(yytext);
-						$$.scalar = yylval.scalar;
-						$$.lineno = plpgsql_scanner_lineno();
+					{
+						int			tok;
 
-						if((tok = yylex()) == ',')
-						{
-						    plpgsql_push_back_token(tok);
-						    $$.name = NULL;
-						    $$.row = read_into_scalar_list(name, $$.scalar);
-						    $$.rec = NULL;
-						    $$.scalar = NULL;
-						    
-						    pfree(name);
-						}
-						else
-						{
-						    plpgsql_push_back_token(tok);
-						    $$.name = name;
-						    $$.row = NULL;
-						    $$.rec = NULL;
-						}
+						$$.name = pstrdup(yytext);
+						$$.lineno  = plpgsql_scanner_lineno();
+						$$.scalar = yylval.scalar;
+						$$.rec = NULL;
+						$$.row = NULL;
+						/* check for comma-separated list */
+						tok = yylex();
+						plpgsql_push_back_token(tok);
+						if (tok == ',')
+							$$.row = read_into_scalar_list($$.name, $$.scalar);
 					}
 				| T_WORD
 					{
-						char		*name;
+						int			tok;
 
-						plpgsql_convert_ident(yytext, &name, 1);
-						$$.name = name;
+						$$.name = pstrdup(yytext);
 						$$.lineno  = plpgsql_scanner_lineno();
+						$$.scalar = NULL;
 						$$.rec = NULL;
 						$$.row = NULL;
+						/* check for comma-separated list */
+						tok = yylex();
+						plpgsql_push_back_token(tok);
+						if (tok == ',')
+						{
+							plpgsql_error_lineno = $$.lineno;
+							ereport(ERROR,
+									(errcode(ERRCODE_SYNTAX_ERROR),
+									 errmsg("\"%s\" is not a scalar variable",
+											$$.name)));
+						}
 					}
 				| T_RECORD
 					{
-						$$.name = NULL;
+						$$.name = pstrdup(yytext);
 						$$.lineno  = plpgsql_scanner_lineno();
+						$$.scalar = NULL;
 						$$.rec = yylval.rec;
 						$$.row = NULL;
 					}
 				| T_ROW
 					{
-					        $$.name = NULL;
+						$$.name = pstrdup(yytext);
 						$$.lineno  = plpgsql_scanner_lineno();
+						$$.scalar = NULL;
 						$$.row = yylval.row;
 						$$.rec = NULL;
 					}
@@ -2121,30 +2132,6 @@ make_fetch_stmt(void)
 }
 
 
-static PLpgSQL_row *
-make_scalar_list1(const char *name,
- 				  PLpgSQL_datum *variable)
-{
- 	PLpgSQL_row		*row;
- 	check_assignable(variable);
- 	
- 	row = palloc(sizeof(PLpgSQL_row));
- 	row->dtype = PLPGSQL_DTYPE_ROW;
- 	row->refname = pstrdup("*internal*");
- 	row->lineno = plpgsql_scanner_lineno();
- 	row->rowtupdesc = NULL;
- 	row->nfields = 1;
- 	row->fieldnames = palloc(sizeof(char *) * 1);
- 	row->varnos = palloc(sizeof(int) * 1);
- 	row->fieldnames[0] = pstrdup(name);
- 	row->varnos[0] = variable->dno;
- 
- 	plpgsql_adddatum((PLpgSQL_datum *)row);
- 
- 	return row;
-} 
-
-
 static void
 check_assignable(PLpgSQL_datum *datum)
 {
@@ -2256,6 +2243,37 @@ read_into_scalar_list(const char *initial_name,
 	return row;
 }
 
+/*
+ * Convert a single scalar into a "row" list.  This is exactly
+ * like read_into_scalar_list except we never consume any input.
+ * In fact, since this can be invoked long after the source
+ * input was actually read, the lineno has to be passed in.
+ */
+static PLpgSQL_row *
+make_scalar_list1(const char *initial_name,
+				  PLpgSQL_datum *initial_datum,
+				  int lineno)
+{
+	PLpgSQL_row		*row;
+
+	check_assignable(initial_datum);
+
+	row = palloc(sizeof(PLpgSQL_row));
+	row->dtype = PLPGSQL_DTYPE_ROW;
+	row->refname = pstrdup("*internal*");
+	row->lineno = lineno;
+	row->rowtupdesc = NULL;
+	row->nfields = 1;
+	row->fieldnames = palloc(sizeof(char *));
+	row->varnos = palloc(sizeof(int));
+	row->fieldnames[0] = pstrdup(initial_name);
+	row->varnos[0] = initial_datum->dno;
+
+	plpgsql_adddatum((PLpgSQL_datum *)row);
+
+	return row;
+}
+
 /*
  * When the PL/PgSQL parser expects to see a SQL statement, it is very
  * liberal in what it accepts; for example, we often assume an

src/test/regress/expected/plpgsql.out

@@ -2722,22 +2722,53 @@ $$ language plpgsql;
 ERROR:  end label "outer_label" specified for unlabelled block
 CONTEXT:  compile of PL/pgSQL function "end_label4" near line 5
 -- using list of scalars in fori and fore stmts
-create function for_vect() returns void as $$
+create function for_vect() returns void as $proc$
 <<lbl>>declare a integer; b varchar; c varchar; r record;
 begin
-  -- old fori
-  for i in 1 .. 10 loop
+  -- fori
+  for i in 1 .. 3 loop
     raise notice '%', i;
   end loop;
-  for a in select 1 from generate_series(1,4) loop
+  -- fore with record var
+  for r in select gs as aa, 'BB' as bb, 'CC' as cc from generate_series(1,4) gs loop
+    raise notice '% % %', r.aa, r.bb, r.cc;
+  end loop;
+  -- fore with single scalar
+  for a in select gs from generate_series(1,4) gs loop
     raise notice '%', a;
   end loop;
-  for a,b,c in select generate_series, 'BB','CC' from generate_series(1,4) loop
+  -- fore with multiple scalars
+  for a,b,c in select gs, 'BB','CC' from generate_series(1,4) gs loop
     raise notice '% % %', a, b, c;
   end loop;
   -- using qualified names in fors, fore is enabled, disabled only for fori
-  for lbl.a, lbl.b, lbl.c in execute E'select generate_series, \'bb\',\'cc\' from generate_series(1,4)' loop
+  for lbl.a, lbl.b, lbl.c in execute $$select gs, 'bb','cc' from generate_series(1,4) gs$$ loop
     raise notice '% % %', a, b, c;
   end loop;
 end;
-$$ language plpgsql;
+$proc$ language plpgsql;
+select for_vect();
+NOTICE:  1
+NOTICE:  2
+NOTICE:  3
+NOTICE:  1 BB CC
+NOTICE:  2 BB CC
+NOTICE:  3 BB CC
+NOTICE:  4 BB CC
+NOTICE:  1
+NOTICE:  2
+NOTICE:  3
+NOTICE:  4
+NOTICE:  1 BB CC
+NOTICE:  2 BB CC
+NOTICE:  3 BB CC
+NOTICE:  4 BB CC
+NOTICE:  1 bb cc
+NOTICE:  2 bb cc
+NOTICE:  3 bb cc
+NOTICE:  4 bb cc
+ for_vect 
+----------
+ 
+(1 row)
+