Fixed BUG#14376: MySQL crash on scoped variable (re)initialization

  Added finer scope control for default clauses of local variable
  declarations.


mysql-test/r/sp.result:
  New test case for BUG#14376.
mysql-test/t/sp.test:
  New test case for BUG#14376.
sql/sp_pcontext.cc:
  Added boundary variable for local parameters/variables,
  for better scope control of default values.
sql/sp_pcontext.h:
  Added boundary variable for local parameters/variables,
  for better scope control of default values.
sql/sql_yacc.yy:
  Make the variables of the current DECLARE "invisible" to its DEFAULT clause.

mysql-test/r/sp.result

@@ -3575,4 +3575,33 @@ DROP VIEW bug13095_v1
 DROP PROCEDURE IF EXISTS bug13095;
 DROP VIEW IF EXISTS bug13095_v1;
 DROP TABLE IF EXISTS bug13095_t1;
+drop procedure if exists bug14376|
+create procedure bug14376()
+begin
+declare x int default x;
+end|
+call bug14376()|
+ERROR 42S22: Unknown column 'x' in 'field list'
+drop procedure bug14376|
+create procedure bug14376()
+begin
+declare x int default 42;
+begin
+declare x int default x;
+select x;
+end;
+end|
+call bug14376()|
+x
+42
+drop procedure bug14376|
+create procedure bug14376(x int)
+begin
+declare x int default x;
+select x;
+end|
+call bug14376(4711)|
+x
+4711
+drop procedure bug14376|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -4489,6 +4489,51 @@ DROP TABLE IF EXISTS bug13095_t1;
 delimiter |;
 
 
+#
+# BUG#14376: MySQL crash on scoped variable (re)initialization
+#
+--disable_warnings
+drop procedure if exists bug14376|
+--enable_warnings
+
+create procedure bug14376()
+begin
+  declare x int default x;
+end|
+
+# Not the error we want, but that's what we got for now...
+--error ER_BAD_FIELD_ERROR
+call bug14376()|
+drop procedure bug14376|
+
+create procedure bug14376()
+begin
+  declare x int default 42;
+
+  begin
+    declare x int default x;
+
+    select x;
+  end;
+end|
+
+call bug14376()|
+
+drop procedure bug14376|
+
+create procedure bug14376(x int)
+begin
+  declare x int default x;
+
+  select x;
+end|
+
+call bug14376(4711)|
+
+drop procedure bug14376|
+
+
+
 #
 # BUG#NNNN: New bug synopsis
 #

sql/sp_pcontext.cc

@@ -52,7 +52,7 @@ sp_cond_check(LEX_STRING *sqlstate)
 
 sp_pcontext::sp_pcontext(sp_pcontext *prev)
   : Sql_alloc(), m_psubsize(0), m_csubsize(0), m_hsubsize(0),
-    m_handlers(0), m_parent(prev)
+    m_handlers(0), m_parent(prev), m_pboundary(0)
 {
   VOID(my_init_dynamic_array(&m_pvar, sizeof(sp_pvar_t *), 16, 8));
   VOID(my_init_dynamic_array(&m_cond, sizeof(sp_cond_type_t *), 16, 8));
@@ -150,7 +150,7 @@ sp_pcontext::diff_cursors(sp_pcontext *ctx)
 sp_pvar_t *
 sp_pcontext::find_pvar(LEX_STRING *name, my_bool scoped)
 {
-  uint i= m_pvar.elements;
+  uint i= m_pboundary;
 
   while (i--)
   {
@@ -186,6 +186,7 @@ sp_pcontext::push_pvar(LEX_STRING *name, enum enum_field_types type,
     p->offset= current_pvars();
     p->dflt= NULL;
     insert_dynamic(&m_pvar, (gptr)&p);
+    m_pboundary= m_pvar.elements;
   }
 }
 

sql/sp_pcontext.h

@@ -164,6 +164,7 @@ class sp_pcontext : public Sql_alloc
   {
     while (num--)
       pop_dynamic(&m_pvar);
+    m_pboundary= m_pvar.elements;
   }
 
   // Find by name
@@ -183,6 +184,14 @@ class sp_pcontext : public Sql_alloc
     return p;
   }
 
+  // Set the current scope boundary (for default values)
+  // The argument is the number of variables to skip.
+  inline void
+  declare_var_boundary(uint n)
+  {
+    m_pboundary= m_pvar.elements-n;
+  }
+
   //
   // Labels
   //
@@ -287,6 +296,13 @@ class sp_pcontext : public Sql_alloc
 
   uint m_poffset;		// Variable offset for this context
   uint m_coffset;		// Cursor offset for this context
+  /*
+    Boundary for finding variables in this in this context.
+    This is normally the same as m_pvar.elements, but differs during
+    parsing of DECLARE ... DEFAULT, to get the scope right for DEFAULT
+    values.
+  */
+  uint m_pboundary;
 
   DYNAMIC_ARRAY m_pvar;		// Parameters/variables
   DYNAMIC_ARRAY m_cond;		// Conditions

sql/sql_yacc.yy

@@ -1660,7 +1660,12 @@ sp_decls:
 
 sp_decl:
           DECLARE_SYM sp_decl_idents type 
-          { Lex->sphead->reset_lex(YYTHD); }
+          {
+	    LEX *lex= Lex;
+
+	    lex->sphead->reset_lex(YYTHD);
+	    lex->spcont->declare_var_boundary($2);
+	  }
           sp_opt_default
           {
             LEX *lex= Lex;
@@ -1690,6 +1695,7 @@ sp_decl:
               lex->sphead->add_instr(in);
               ctx->set_default(i, it);
             }
+	    ctx->declare_var_boundary(0);
             lex->sphead->restore_lex(YYTHD);
             $$.vars= $2;
             $$.conds= $$.hndlrs= $$.curs= 0;