On 7/21/14, 10:56 PM, I wrote:
Here's a patch which allows you to notice those annoying bugs with INTO
slightly more quickly.  Adding to the next commit phest.


New version, fixed bugs with set operations and VALUES lists.


.marko
*** a/doc/src/sgml/plpgsql.sgml
--- b/doc/src/sgml/plpgsql.sgml
***************
*** 4719,4725 **** a_output := a_output || $$ if v_$$ || referrer_keys.kind || 
$$ like '$$
    <varname>plpgsql.extra_errors</> for errors. Both can be set either to
    a comma-separated list of checks, <literal>"none"</> or <literal>"all"</>.
    The default is <literal>"none"</>. Currently the list of available checks
!   includes only one:
    <variablelist>
     <varlistentry>
      <term><varname>shadowed_variables</varname></term>
--- 4719,4725 ----
    <varname>plpgsql.extra_errors</> for errors. Both can be set either to
    a comma-separated list of checks, <literal>"none"</> or <literal>"all"</>.
    The default is <literal>"none"</>. Currently the list of available checks
!   is as follows:
    <variablelist>
     <varlistentry>
      <term><varname>shadowed_variables</varname></term>
***************
*** 4729,4734 **** a_output := a_output || $$ if v_$$ || referrer_keys.kind || 
$$ like '$$
--- 4729,4744 ----
       </para>
      </listitem>
     </varlistentry>
+    <varlistentry>
+     <term><varname>num_into_expressions</varname></term>
+     <listitem>
+      <para>
+       When possible, checks that the number of expressions specified in the
+       SELECT or RETURNING list of a query matches the number expected by the
+       INTO target.  This check is done on a "best effort" basis.
+      </para>
+     </listitem>
+    </varlistentry>
    </variablelist>
  
    The following example shows the effect of <varname>plpgsql.extra_warnings</>
*** a/src/pl/plpgsql/src/pl_gram.y
--- b/src/pl/plpgsql/src/pl_gram.y
***************
*** 22,27 ****
--- 22,28 ----
  #include "parser/scanner.h"
  #include "parser/scansup.h"
  #include "utils/builtins.h"
+ #include "nodes/nodefuncs.h"
  
  
  /* Location tracking support --- simpler than bison's default */
***************
*** 97,103 **** static  PLpgSQL_row             *make_scalar_list1(char 
*initial_name,
                                                                                
   PLpgSQL_datum *initial_datum,
                                                                                
   int lineno, int location);
  static        void                     check_sql_expr(const char *stmt, int 
location,
!                                                                               
int leaderlen);
  static        void                     plpgsql_sql_error_callback(void *arg);
  static        PLpgSQL_type    *parse_datatype(const char *string, int 
location);
  static        void                     check_labels(const char *start_label,
--- 98,104 ----
                                                                                
   PLpgSQL_datum *initial_datum,
                                                                                
   int lineno, int location);
  static        void                     check_sql_expr(const char *stmt, int 
location,
!                                                                               
int leaderlen, PLpgSQL_row *check_row);
  static        void                     plpgsql_sql_error_callback(void *arg);
  static        PLpgSQL_type    *parse_datatype(const char *string, int 
location);
  static        void                     check_labels(const char *start_label,
***************
*** 106,111 **** static void                     check_labels(const char 
*start_label,
--- 107,115 ----
  static        PLpgSQL_expr    *read_cursor_args(PLpgSQL_var *cursor,
                                                                                
  int until, const char *expected);
  static        List                    *read_raise_options(void);
+ static        bool                    find_a_star_walker(Node *node, void 
*context);
+ static        int                             tlist_result_column_count(Node 
*stmt);
+ 
  
  %}
  
***************
*** 1438,1444 **** for_control          : for_variable K_IN
                                                                
PLpgSQL_stmt_fori       *new;
  
                                                                /* Check first 
expression is well-formed */
!                                                               
check_sql_expr(expr1->query, expr1loc, 7);
  
                                                                /* Read and 
check the second one */
                                                                expr2 = 
read_sql_expression2(K_LOOP, K_BY,
--- 1442,1448 ----
                                                                
PLpgSQL_stmt_fori       *new;
  
                                                                /* Check first 
expression is well-formed */
!                                                               
check_sql_expr(expr1->query, expr1loc, 7, NULL);
  
                                                                /* Read and 
check the second one */
                                                                expr2 = 
read_sql_expression2(K_LOOP, K_BY,
***************
*** 1500,1506 **** for_control          : for_variable K_IN
                                                                
pfree(expr1->query);
                                                                expr1->query = 
tmp_query;
  
!                                                               
check_sql_expr(expr1->query, expr1loc, 0);
  
                                                                new = 
palloc0(sizeof(PLpgSQL_stmt_fors));
                                                                new->cmd_type = 
PLPGSQL_STMT_FORS;
--- 1504,1510 ----
                                                                
pfree(expr1->query);
                                                                expr1->query = 
tmp_query;
  
!                                                               
check_sql_expr(expr1->query, expr1loc, 0, NULL);
  
                                                                new = 
palloc0(sizeof(PLpgSQL_stmt_fors));
                                                                new->cmd_type = 
PLPGSQL_STMT_FORS;
***************
*** 2592,2598 **** read_sql_construct(int until,
        pfree(ds.data);
  
        if (valid_sql)
!               check_sql_expr(expr->query, startlocation, strlen(sqlstart));
  
        return expr;
  }
--- 2596,2602 ----
        pfree(ds.data);
  
        if (valid_sql)
!               check_sql_expr(expr->query, startlocation, strlen(sqlstart), 
NULL);
  
        return expr;
  }
***************
*** 2815,2821 **** make_execsql_stmt(int firsttoken, int location)
        expr->ns                        = plpgsql_ns_top();
        pfree(ds.data);
  
!       check_sql_expr(expr->query, location, 0);
  
        execsql = palloc(sizeof(PLpgSQL_stmt_execsql));
        execsql->cmd_type = PLPGSQL_STMT_EXECSQL;
--- 2819,2825 ----
        expr->ns                        = plpgsql_ns_top();
        pfree(ds.data);
  
!       check_sql_expr(expr->query, location, 0, row);
  
        execsql = palloc(sizeof(PLpgSQL_stmt_execsql));
        execsql->cmd_type = PLPGSQL_STMT_EXECSQL;
***************
*** 3409,3421 **** make_scalar_list1(char *initial_name,
   * (typically "SELECT ") prefixed to the source text.  We use this assumption
   * to transpose any error cursor position back to the function source text.
   * If no error cursor is provided, we'll just point at "location".
   */
  static void
! check_sql_expr(const char *stmt, int location, int leaderlen)
  {
        sql_error_callback_arg cbarg;
        ErrorContextCallback  syntax_errcontext;
        MemoryContext oldCxt;
  
        if (!plpgsql_check_syntax)
                return;
--- 3413,3430 ----
   * (typically "SELECT ") prefixed to the source text.  We use this assumption
   * to transpose any error cursor position back to the function source text.
   * If no error cursor is provided, we'll just point at "location".
+  *
+  * If check_row is not NULL and PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS is 
enabled,
+  * the statement's result column count is compared against it when the exact
+  * number of columns is known and an error or a warning is reported.
   */
  static void
! check_sql_expr(const char *stmt, int location, int leaderlen, PLpgSQL_row 
*check_row)
  {
        sql_error_callback_arg cbarg;
        ErrorContextCallback  syntax_errcontext;
        MemoryContext oldCxt;
+       List *raw_parsetree_list;
  
        if (!plpgsql_check_syntax)
                return;
***************
*** 3429,3441 **** check_sql_expr(const char *stmt, int location, int leaderlen)
        error_context_stack = &syntax_errcontext;
  
        oldCxt = MemoryContextSwitchTo(compile_tmp_cxt);
!       (void) raw_parser(stmt);
        MemoryContextSwitchTo(oldCxt);
  
        /* Restore former ereport callback */
        error_context_stack = syntax_errcontext.previous;
  }
  
  static void
  plpgsql_sql_error_callback(void *arg)
  {
--- 3438,3535 ----
        error_context_stack = &syntax_errcontext;
  
        oldCxt = MemoryContextSwitchTo(compile_tmp_cxt);
!       raw_parsetree_list = raw_parser(stmt);
! 
!       if (check_row != NULL &&
!               (plpgsql_curr_compile->extra_warnings & 
PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS ||
!                plpgsql_curr_compile->extra_errors & 
PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS))
!       {
!               Node *raw_parse_tree;
!               int ncols;
!               int fnum;
!               int expected_ncols = 0;
! 
!               for (fnum = 0; fnum < check_row->nfields; fnum++)
!               {
!                       if (check_row->varnos[fnum] < 0)
!                               continue;
!                       expected_ncols++;
!               }
! 
!               raw_parse_tree = linitial(raw_parsetree_list);
!               ncols = tlist_result_column_count(raw_parse_tree);
!               if (ncols >= 0 && ncols != expected_ncols)
!                       ereport(plpgsql_curr_compile->extra_errors & 
PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS ? ERROR : WARNING,
!                               (errcode(ERRCODE_SYNTAX_ERROR),
!                               errmsg("the number of result expressions does 
not match that expected by the INTO target"),
!                               errdetail("INTO target expects %d expressions, 
but the query returns %d", expected_ncols, ncols)));
!       }
        MemoryContextSwitchTo(oldCxt);
  
        /* Restore former ereport callback */
        error_context_stack = syntax_errcontext.previous;
  }
  
+ /*
+  * Expression tree walker for tlist_result_column_count.  Returns true if the
+  * expression tree contains an A_Star node, false otherwise.
+  */
+ static bool
+ find_a_star_walker(Node *node, void *context)
+ {
+       if (node == NULL)
+               return false;
+       if (IsA(node, A_Star))
+               return true;
+       if (IsA(node, ColumnRef))
+       {
+               ColumnRef *ref = (ColumnRef *) node;
+               /* A_Star can only be the last element */
+               if (IsA(llast(ref->fields), A_Star))
+                       return true;
+       }
+       return raw_expression_tree_walker((Node *) node,
+                                                                         
find_a_star_walker,
+                                                                         
context);
+ }
+ 
+ /*
+  * Find the number of columns in a raw statement's target list (if SELECT) or
+  * returningList (if INSERT, UPDATE or DELETE).  Returns -1 if the number of
+  * columns could not be determined because of an A_Star.
+  */
+ static int
+ tlist_result_column_count(Node *stmt)
+ {
+       List *tlist;
+ 
+       if (IsA(stmt, SelectStmt))
+       {
+               SelectStmt *s = (SelectStmt *) stmt;
+               if (s->valuesLists)
+                       tlist = (List *) linitial(s->valuesLists);
+               else if (s->op == SETOP_NONE)
+                       tlist = s->targetList;
+               else
+                       return tlist_result_column_count((Node *) s->larg);
+       }
+       else if (IsA(stmt, InsertStmt))
+               tlist = ((InsertStmt *) stmt)->returningList;
+       else if (IsA(stmt, UpdateStmt))
+               tlist = ((UpdateStmt *) stmt)->returningList;
+       else if (IsA(stmt, DeleteStmt))
+               tlist = ((DeleteStmt *) stmt)->returningList;
+       else
+               elog(ERROR, "unknown nodeTag %d", nodeTag(stmt));
+ 
+       if (tlist == NIL)
+               return 0;
+ 
+       if (raw_expression_tree_walker((Node *) tlist, find_a_star_walker, 
NULL))
+               return -1;
+       return list_length(tlist);
+ }
+ 
  static void
  plpgsql_sql_error_callback(void *arg)
  {
*** a/src/pl/plpgsql/src/pl_handler.c
--- b/src/pl/plpgsql/src/pl_handler.c
***************
*** 87,92 **** plpgsql_extra_checks_check_hook(char **newvalue, void **extra, 
GucSource source)
--- 87,94 ----
  
                        if (pg_strcasecmp(tok, "shadowed_variables") == 0)
                                extrachecks |= PLPGSQL_XCHECK_SHADOWVAR;
+                       else if (pg_strcasecmp(tok, "num_into_expressions") == 
0)
+                               extrachecks |= 
PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS;
                        else if (pg_strcasecmp(tok, "all") == 0 || 
pg_strcasecmp(tok, "none") == 0)
                        {
                                GUC_check_errdetail("Key word \"%s\" cannot be 
combined with other key words.", tok);
*** a/src/pl/plpgsql/src/plpgsql.h
--- b/src/pl/plpgsql/src/plpgsql.h
***************
*** 886,894 **** extern int     plpgsql_variable_conflict;
  extern bool plpgsql_print_strict_params;
  
  /* extra compile-time checks */
! #define PLPGSQL_XCHECK_NONE                   0
! #define PLPGSQL_XCHECK_SHADOWVAR      1
! #define PLPGSQL_XCHECK_ALL                    ((int) ~0)
  
  extern int    plpgsql_extra_warnings;
  extern int    plpgsql_extra_errors;
--- 886,895 ----
  extern bool plpgsql_print_strict_params;
  
  /* extra compile-time checks */
! #define PLPGSQL_XCHECK_NONE                                           0
! #define PLPGSQL_XCHECK_SHADOWVAR                              1
! #define PLPGSQL_XCHECK_NUM_INTO_EXPRESSIONS           2
! #define PLPGSQL_XCHECK_ALL                                            ((int) 
~0)
  
  extern int    plpgsql_extra_warnings;
  extern int    plpgsql_extra_errors;
*** a/src/test/regress/expected/plpgsql.out
--- b/src/test/regress/expected/plpgsql.out
***************
*** 5340,5342 **** NOTICE:  outer_func() done
--- 5340,5404 ----
  drop function outer_outer_func(int);
  drop function outer_func(int);
  drop function inner_func(int);
+ create temporary table somecols(a int, b int);
+ set plpgsql.extra_warnings to 'num_into_expressions';
+ -- INTO column counts
+ create or replace function into_counts()
+ returns void as $$
+ declare
+   myresult int;
+   myrec record;
+   mycols somecols;
+ begin
+   -- no warning
+   select 1 into myresult;
+   -- we don't know the column count without parse analysis, no warning
+   select * into myresult from somecols;
+   -- records are OK
+   select 1, 2 into myrec;
+   -- warning
+   select a, b into myresult from somecols;
+   -- warning
+   select into myresult from somecols;
+   -- no warning
+   select 1, 2 into mycols;
+   -- warning
+   select 1 into mycols;
+   -- warning
+   select 1, 2, 3 into mycols;
+   -- set operations; OK
+   select 1 into myresult union all select 2;
+   -- set operations; not OK
+   select 1,2 into myresult union all select 2,3;
+   -- values; OK
+   values (1), (2) into myresult;
+   -- values; not OK
+   values (1,2),(2,3) into myresult;
+ end;
+ $$ language plpgsql;
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 15:   select a, b into myresult from somecols;
+            ^
+ DETAIL:  INTO target expects 1 expressions, but the query returns 2
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 17:   select into myresult from somecols;
+            ^
+ DETAIL:  INTO target expects 1 expressions, but the query returns 0
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 21:   select 1 into mycols;
+            ^
+ DETAIL:  INTO target expects 2 expressions, but the query returns 1
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 23:   select 1, 2, 3 into mycols;
+            ^
+ DETAIL:  INTO target expects 2 expressions, but the query returns 3
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 27:   select 1,2 into myresult union all select 2,3;
+            ^
+ DETAIL:  INTO target expects 1 expressions, but the query returns 2
+ WARNING:  the number of result expressions does not match that expected by 
the INTO target
+ LINE 31:   values (1,2),(2,3) into myresult;
+            ^
+ DETAIL:  INTO target expects 1 expressions, but the query returns 2
+ drop table somecols;
+ reset plpgsql.extra_warnings;
*** a/src/test/regress/sql/plpgsql.sql
--- b/src/test/regress/sql/plpgsql.sql
***************
*** 4193,4195 **** select outer_outer_func(20);
--- 4193,4238 ----
  drop function outer_outer_func(int);
  drop function outer_func(int);
  drop function inner_func(int);
+ 
+ create temporary table somecols(a int, b int);
+ 
+ set plpgsql.extra_warnings to 'num_into_expressions';
+ 
+ -- INTO column counts
+ create or replace function into_counts()
+ returns void as $$
+ declare
+   myresult int;
+   myrec record;
+   mycols somecols;
+ begin
+   -- no warning
+   select 1 into myresult;
+   -- we don't know the column count without parse analysis, no warning
+   select * into myresult from somecols;
+   -- records are OK
+   select 1, 2 into myrec;
+   -- warning
+   select a, b into myresult from somecols;
+   -- warning
+   select into myresult from somecols;
+   -- no warning
+   select 1, 2 into mycols;
+   -- warning
+   select 1 into mycols;
+   -- warning
+   select 1, 2, 3 into mycols;
+   -- set operations; OK
+   select 1 into myresult union all select 2;
+   -- set operations; not OK
+   select 1,2 into myresult union all select 2,3;
+   -- values; OK
+   values (1), (2) into myresult;
+   -- values; not OK
+   values (1,2),(2,3) into myresult;
+ end;
+ $$ language plpgsql;
+ 
+ drop table somecols;
+ 
+ reset plpgsql.extra_warnings;
-- 
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