On 13 Dec 2006, at 11:33, Evan Lavelle wrote:
Once upon the time, Bison had an informal support for the C-parser
to be compiled as C++, but this was dropped, being too difficult
to maintain. Instead, a separate C++ skeleton was developed.
So, for C++, it is best to use the C++ skeleton file.
I have a lot of C++ code in my .y file, and no problems. This is
1.875c - has this support been dropped since then?
Yeah, somewhere around there. The compile C as C++ was never
official. And if you define an YYSTYPE with nontrivial copy
constructors, they will not be invoked during parser stack
reallocation. Plus, there was some parser stack implementation that
cause compiled under C++ failing.
I do not remember the details. But it is safest to switch to the C++
skeleton of some of the latest Bison versions
But then, I can't immediately see why any C++ support is required,
as long as you use the union/struct mechanism for passing data.
It is OK if you use %union or a struct or calls which is POD.
My YYSTYPE is a struct which contains reference-counted classes.
A C++ struct, is just a class in which contents is declared public.
If you use a reference count in a class, and put that in YYSTYPE, noy
merely a pointer, it will not be invoked when the C parser stack
reallocates. It will probably bomb when objects are deleted twice.
Maybe this is the confusion? Do you only need the C++ skeleton if
your YYSTYPE is a real C++ class?
Yes. When the class is a non-POD, "plain-ol'-data", essentially the C
structs as a C++ language subset.
BTW, you don't even need Satya's 'extern "C"' declarations if
you're using gcc; don't know about other compilers.
C++ names are essentially mangled C names, and 'extern "C"'
essentially says: do not mangle the names. So if you start to play
around with this stuff, though possible, funny things may start to
happen.
Hans Aberg
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