Re: %define api.value.automove false doesn't work (fix email format)

Fix sent to bison-patches, 
https://lists.gnu.org/archive/html/bison-patches/2025-07/msg00000.html

On 7/12/2025 8:35 AM, Z. Majeed wrote:

The api.value.automove directive doesn't honor an explicit false setting.

-------------------------------------------

// test_automove.y

%skeleton "lalr1.cc"
%require "3.8"
%language "c++"

%define api.value.automove false

%token <int> VAL
%nterm <int> x

%%

x: VAL

-------------------------------------------

bison -o test_automove.cpp test_automove.y

grep -B2 "yylhs.value.int" test_automove.cpp


   case 2: // x: VAL
#line 14 "test_automove.y"
    { (yylhs.value.int) = YY_MOVE ((yystack_[0].value.int)); }

bison --version

bison (GNU Bison) 3.8.2

-------------------------------------------

The problem is in skeletons/lalr1.cc where b4_percent_define_ifdef 
applies YY_MOVE as long as api.value.automove is defined without 
considering its value

The default value of api.value.automove is false - omitting the 
directive does prevent YY_MOVE from being applied

m4_define([b4_rhs_value],
[b4_percent_define_ifdef([api.value.automove],
                          [YY_MOVE (_b4_rhs_value($@))],
                          [_b4_rhs_value($@)])])

-------------------------------------------

b4_percent_define_ifdef is defined in skeletons/bison.m4

# _b4_percent_define_ifdef(VARIABLE, IF-TRUE, [IF-FALSE])
# ------------------------------------------------------
# If the %define variable VARIABLE is defined, expand IF-TRUE, else expand
# IF-FALSE.  Don't record usage of VARIABLE.

-------------------------------------------

I'll send a fix for lalr1.cc shortly to bison-patches that looks like this

111a112,114
 > # api.value.automove boolean default value false
 > b4_percent_define_default([[api.value.automove]], [[false]])
 >
113,115c116,118
< [b4_percent_define_ifdef([api.value.automove],
<                          [YY_MOVE (_b4_rhs_value($@))],
<                          [_b4_rhs_value($@)])])
---
 > [b4_percent_define_flag_if([api.value.automove],
 >                          [YY_MOVE (_b4_rhs_value($@))],
 >                          [_b4_rhs_value($@)])])


Zartaj