Re: [sr #110032] For C++98 stack_symbol_type defines only non-const operator=

[Akim Demaille]

Hi!

> Le 25 sept. 2019 à 18:38, anonymous <address@hidden> a écrit :
> 
> URL:
>  <https://savannah.gnu.org/support/?110032>
> 
>                 Summary: For C++98 stack_symbol_type defines only non-const
> operator=
>                 Project: Bison
>            Submitted by: None
>            Submitted on: Wed 25 Sep 2019 04:38:56 PM UTC
>                Category: None
>                Priority: 5 - Normal
>                Severity: 3 - Normal
>                  Status: None
>                 Privacy: Public
>             Assigned to: None
>        Originator Email: address@hidden
>             Open/Closed: Open
>         Discussion Lock: Any
>        Operating System: None

For the record, what version of Bison was this?  It's amazing that the bug 
report form does not ask for such an information piece of information...


> Details:
> 
> Setting the output language to C++ and compiling the output with a C++98
> compiler, compilation fails on the IAR C++ compiler (version 6.70.2.6274).

I have never heard of this compiler before.  It does not seem possible to use 
it in our CI, that's a pity.  Have to tried to run Bison's test suite with this 
C++ compiler?  It would be nice to get the result, and in the future to have 
someone agree to check betas of Bisons :)

> The std::vector class of the IAR compiler relies on operator= in its push_back
> implementation. Defining 'stack_symbol_type &operator=(stack_symbol_type &)'
> stops the compiler implicitly generating operator= for other arguments.
> Specifically 'const stack_symbol_type &operator=(const stack_symbol_type &) is
> missing which is needed by std::vector::push_back.
> 
> The lalr1.cc skeleton needs to be changed to also define the const operator=
> for stack_symbol_type (and also others like sematic_type when using variants)

Doh.

That was introduced in 
https://github.com/akimd/bison/commit/2116ad3a280f79ab28eba244a00d7d1358f141ef, 
released in 3.2.4.


Could you please try this?

commit bdadd076ed2d8ef237965a607cd3112aa2cc1246
Author: Akim Demaille <address@hidden>
Date:   Wed Sep 25 19:34:34 2019 +0200

    WIP: add copy ctors
    
    * #: .

diff --git a/data/skeletons/lalr1.cc b/data/skeletons/lalr1.cc
index d1c30403..cfca80b2 100644
--- a/data/skeletons/lalr1.cc
+++ b/data/skeletons/lalr1.cc
@@ -335,6 +335,9 @@ m4_define([b4_shared_declarations],
       /// Assignment, needed by push_back by some old implementations.
       /// Moves the contents of that.
       stack_symbol_type& operator= (stack_symbol_type& that);
+
+      /// Assignment, needed by push_back by other implementations.
+      stack_symbol_type& operator= (const stack_symbol_type& that);
 #endif
     };
 
@@ -627,6 +630,17 @@ m4_if(b4_prefix, [yy], [],
   }
 
 #if YY_CPLUSPLUS < 201103L
+  ]b4_parser_class[::stack_symbol_type&
+  ]b4_parser_class[::stack_symbol_type::operator= (const stack_symbol_type& 
that)
+  {
+    state = that.state;
+    ]b4_variant_if([b4_symbol_variant([that.type_get ()],
+                                      [value], [copy], [that.value])],
+                   [[value = that.value;]])[]b4_locations_if([
+    location = that.location;])[
+    return *this;
+  }
+
   ]b4_parser_class[::stack_symbol_type&
   ]b4_parser_class[::stack_symbol_type::operator= (stack_symbol_type& that)
   {