Add "void value expression" check to the parser.

1 files changed, 52 insertions, 26 deletions

diff --git a/mrbgems/mruby-compiler/core/parse.y b/mrbgems/mruby-compiler/core/parse.y
index 90b8812b9..ea7f809f3 100644
--- a/mrbgems/mruby-compiler/core/parse.y
+++ b/mrbgems/mruby-compiler/core/parse.y
@@ -41,6 +41,7 @@ static void yyerror(parser_state *p, const char *s);
 static void yywarn(parser_state *p, const char *s);
 static void yywarning(parser_state *p, const char *s);
 static void backref_error(parser_state *p, node *n);
+static void void_expr_error(parser_state *p, node *n);
 static void tokadd(parser_state *p, int32_t c);
 
 #define identchar(c) (ISALNUM(c) || (c) == '_' || !ISASCII(c))
@@ -1097,7 +1098,7 @@ heredoc_end(parser_state *p)
 %type <nd> literal numeric cpath symbol
 %type <nd> top_compstmt top_stmts top_stmt
 %type <nd> bodystmt compstmt stmts stmt expr arg primary command command_call method_call
-%type <nd> expr_value arg_value arg_rhs primary_value
+%type <nd> expr_value arg0 arg_rhs primary_value
 %type <nd> if_tail opt_else case_body cases opt_rescue exc_list exc_var opt_ensure
 %type <nd> args call_args opt_call_args
 %type <nd> paren_args opt_paren_args variable
@@ -1322,7 +1323,7 @@ stmt            : keyword_alias fsym {p->lstate = EXPR_FNAME;} fsym
                     {
                       $$ = new_asgn(p, $1, new_array(p, $3));
                     }
-                | mlhs '=' arg_value
+                | mlhs '=' arg
                     {
                       $$ = new_masgn(p, $1, $3);
                     }
@@ -1395,13 +1396,16 @@ expr            : command_call
                     {
                       $$ = call_uni_op(p, cond($2), "!");
                     }
-                | arg
+                | arg0
                 ;
 
 expr_value      : expr
                     {
                       if (!$1) $$ = new_nil(p);
-                      else $$ = $1;
+                      else {
+                        void_expr_error(p, $1);
+                        $$ = $1;
+                      }
                     }
                 ;
 
@@ -1734,7 +1738,7 @@ reswords        : keyword__LINE__ | keyword__FILE__ | keyword__ENCODING__
                 | keyword_while | keyword_until
                 ;
 
-arg             : lhs '=' arg_rhs
+arg0            : lhs '=' arg_rhs
                     {
                       $$ = new_asgn(p, $1, $3);
                     }
@@ -1907,10 +1911,13 @@ arg             : lhs '=' arg_rhs
                     }
                 ;
 
-arg_value       : arg
+arg             : arg0
                     {
-                      $$ = $1;
-                      if (!$$) $$ = new_nil(p);
+                      if (!$1) $$ = new_nil(p);
+                      else {
+                        void_expr_error(p, $1);
+                        $$ = $1;
+                      }
                     }
                 ;
 
@@ -1931,7 +1938,7 @@ aref_args       : none
                     }
                 ;
 
-arg_rhs         : arg   %prec tOP_ASGN
+arg_rhs         : arg %prec tOP_ASGN
                 | arg modifier_rescue arg
                     {
                       $$ = new_mod_rescue(p, $1, $3);
@@ -2005,7 +2012,7 @@ command_args    :  {
                     }
                 ;
 
-block_arg       : tAMPER arg_value
+block_arg       : tAMPER arg
                     {
                       $$ = new_block_arg(p, $2);
                     }
@@ -2021,43 +2028,43 @@ opt_block_arg   : ',' block_arg
                     }
                 ;
 
-args            : arg_value
+args            : arg
                     {
                       $$ = cons($1, 0);
                       NODE_LINENO($$, $1);
                     }
-                | tSTAR arg_value
+                | tSTAR arg
                     {
                       $$ = cons(new_splat(p, $2), 0);
                       NODE_LINENO($$, $2);
                     }
-                | args ',' arg_value
+                | args ',' arg
                     {
                       $$ = push($1, $3);
                     }
-                | args ',' tSTAR arg_value
+                | args ',' tSTAR arg
                     {
                       $$ = push($1, new_splat(p, $4));
                     }
-                | args ',' heredoc_bodies arg_value
+                | args ',' heredoc_bodies arg
                     {
                       $$ = push($1, $4);
                     }
-                | args ',' heredoc_bodies tSTAR arg_value
+                | args ',' heredoc_bodies tSTAR arg
                     {
                       $$ = push($1, new_splat(p, $5));
                     }
                 ;
 
-mrhs            : args ',' arg_value
+mrhs            : args ',' arg
                     {
                       $$ = push($1, $3);
                     }
-                | args ',' tSTAR arg_value
+                | args ',' tSTAR arg
                     {
                       $$ = push($1, new_splat(p, $4));
                     }
-                | tSTAR arg_value
+                | tSTAR arg
                     {
                       $$ = list1(new_splat(p, $2));
                     }
@@ -2688,7 +2695,7 @@ opt_rescue      : keyword_rescue exc_list exc_var then
                 | none
                 ;
 
-exc_list        : arg_value
+exc_list        : arg
                     {
                         $$ = list1($1);
                     }
@@ -3115,7 +3122,7 @@ f_opt_asgn      : tIDENTIFIER '='
                     }
                 ;
 
-f_opt           : f_opt_asgn arg_value
+f_opt           : f_opt_asgn arg
                     {
                       $$ = cons(nsym($1), $2);
                     }
@@ -3233,23 +3240,23 @@ assocs          : assoc
                     }
                 ;
 
-assoc           : arg_value tASSOC arg_value
+assoc           : arg tASSOC arg
                     {
                       $$ = cons($1, $3);
                     }
-                | tLABEL arg_value
+                | tLABEL arg
                     {
                       $$ = cons(new_sym(p, $1), $2);
                     }
-                | tLABEL_END arg_value
+                | tLABEL_END arg
                     {
                       $$ = cons(new_sym(p, new_strsym(p, $1)), $2);
                     }
-                | tSTRING_BEG tLABEL_END arg_value
+                | tSTRING_BEG tLABEL_END arg
                     {
                       $$ = cons(new_sym(p, new_strsym(p, $2)), $3);
                     }
-                | tSTRING_BEG string_rep tLABEL_END arg_value
+                | tSTRING_BEG string_rep tLABEL_END arg
                     {
                       $$ = cons(new_dsym(p, push($2, $3)), $4);
                     }
@@ -3430,6 +3437,25 @@ backref_error(parser_state *p, node *n)
   }
 }
 
+static void
+void_expr_error(parser_state *p, node *n)
+{
+  int c;
+
+  c = (int)(intptr_t)n->car;
+  switch (c) {
+  case NODE_BREAK:
+  case NODE_RETURN:
+  case NODE_NEXT:
+  case NODE_REDO:
+  case NODE_RETRY:
+    yyerror(p, "void value expression");
+    break;
+  default:
+    break;
+  }
+}
+
 static void pushback(parser_state *p, int c);
 static mrb_bool peeks(parser_state *p, const char *s);
 static mrb_bool skips(parser_state *p, const char *s);