Filter: Add separate instruction for uninitialized variable declaration

The previous approach (use VOID constant for variable initialization)
failed due to dynamic type check failure.

Thanks to Alexander Zubkov <green@qrator.net> for the bugreport.

3 files changed, 22 insertions, 10 deletions

diff --git a/filter/config.Y b/filter/config.Y
index 2a298843..e02af182 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -324,7 +324,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
 %nonassoc ELSE
 
 %type <xp> cmds_int cmd_prep
-%type <x> term term_bs cmd cmd_var cmds cmds_scoped constant constructor print_list var var_init var_list function_call symbol_value bgp_path_expr bgp_path bgp_path_tail
+%type <x> term term_bs cmd cmd_var cmds cmds_scoped constant constructor print_list var var_list function_call symbol_value bgp_path_expr bgp_path bgp_path_tail
 %type <fda> dynamic_attr
 %type <fsa> static_attr
 %type <f> filter where_filter
@@ -895,16 +895,16 @@ print_list: /* EMPTY */ { $$ = NULL; }
    }
  ;
 
-var_init:
-   /* empty */ { $$ = f_new_inst(FI_CONSTANT, (struct f_val) { }); }
- | '=' term { $$ = $2; }
- ;
-
 var:
-   type symbol var_init ';' {
+   type symbol '=' term ';' {
      struct symbol *sym = cf_define_symbol($2, SYM_VARIABLE | $1, offset, f_new_var(sym_->scope));
-     $$ = f_new_inst(FI_VAR_INIT, $3, sym);
+     $$ = f_new_inst(FI_VAR_INIT, $4, sym);
    }
+ | type symbol ';' {
+     struct symbol *sym = cf_define_symbol($2, SYM_VARIABLE | $1, offset, f_new_var(sym_->scope));
+     $$ = f_new_inst(FI_VAR_INIT0, sym);
+   }
+ ;
 
 for_var:
    type symbol { $$ = cf_define_symbol($2, SYM_VARIABLE | $1, offset, f_new_var(sym_->scope)); }
diff --git a/filter/f-inst.c b/filter/f-inst.c
index 8a2f474e..b63fc1f4 100644
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -506,6 +506,7 @@
     RESULT(T_BOOL, i, ipa_is_ip4(v1.val.ip));
   }
 
+  /* Add initialized variable */
   INST(FI_VAR_INIT, 1, 0) {
     NEVER_CONSTANT;
     ARG_ANY(1);
@@ -518,6 +519,17 @@
     fstk->vcnt = pos + 1;
   }
 
+  /* Add uninitialized variable */
+  INST(FI_VAR_INIT0, 0, 0) {
+    NEVER_CONSTANT;
+    SYMBOL;
+
+    /* New variable is always the last on stack */
+    uint pos = curline.vbase + sym->offset;
+    fstk->vstk[pos] = (struct f_val) { };
+    fstk->vcnt = pos + 1;
+  }
+
   /* Set to indirect value prepared in v1 */
   INST(FI_VAR_SET, 1, 0) {
     NEVER_CONSTANT;
diff --git a/filter/test.conf b/filter/test.conf
index c014dadd..c74c2691 100644
--- a/filter/test.conf
+++ b/filter/test.conf
@@ -630,8 +630,8 @@ bt_test_suite(t_prefix_set, "Testing prefix sets");
  */
 
 function t_prefix6()
-prefix px;
 {
+	prefix px;
 	px = 1020::/18;
 	bt_assert(format(px) = "1020::/18");
 	bt_assert(1020:3040:5060:: ~ 1020:3040:5000::/40);
@@ -976,8 +976,8 @@ bt_test_suite(t_clist, "Testing lists of communities");
  */
 
 function t_ec()
-ec cc;
 {
+	ec cc;
 	cc = (rt, 12345, 200000);
 	bt_assert(format(cc) = "(rt, 12345, 200000)");