Re: How to use flex and bison with the C++ interface ?

[Timothy Madden]

On 06/16/2012 12:40 PM, Stefano Lattarini wrote:
> On 06/15/2012 03:19 PM, Timothy Madden wrote:
> > Hello
> >
> > Can automake use flex and bison to generate .cc files from lexer.ll and 
> > parser.yy files ?
[...]
> You should use something like this instead:
>
>      bin_PROGRAMS = code-formatter
>      code_formatter_SOURCES = lexer.ll parser.yy
>
> In case this suggestion doesn't solve your problem, please answer the
> following questions (the details you've given would be too few for us
> to attempt a proper diagnosis otherwise):
>
>    - Which automake version are you using?
>    - Which ylwrap version exactly?
>    - On which system you are on?
>    - What flex version are you using?
>    - How do the relevant parts of the generated Makefile.in appear?
>      (You can find this with "grep -C4 ylwrap Makefile.in").

Thank you,
Sorry for the missing version and all. I am using GNU automake 1.11.1 on 
CentOS release 6.2 64-bit. It generates ylwrap 2009-04-28.21 for me in 
my project, which wraps and invokes flex 2.5.35 and 2.4.1

The Makefile looks ok, here's the `grep -C4 ylwrap` result on it:
subdir = .
DIST_COMMON = $(am__configure_deps) $(srcdir)/Makefile.am \
        $(srcdir)/Makefile.in $(top_srcdir)/configure \
        code-formatter-lexer.cc code-formatter-parser.cc \
        code-formatter-parser.h depcomp install-sh missing ylwrap
ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
am__aclocal_m4_deps = $(top_srcdir)/configure.ac
am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
        $(ACLOCAL_M4)
--
CXXLD = $(CXX)
CXXLINK = $(CXXLD) $(AM_CXXFLAGS) $(CXXFLAGS) $(AM_LDFLAGS) $(LDFLAGS) \
        -o $@
LEXCOMPILE = $(LEX) $(LFLAGS) $(AM_LFLAGS)
YLWRAP = $(top_srcdir)/ylwrap
YACCCOMPILE = $(YACC) $(YFLAGS) $(AM_YFLAGS)
COMPILE = $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) \
        $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
CCLD = $(CC)

I really did not expect code-formatter.ll and code-formatter.yy to 
produce a file name conflict in the build process, since flex and bison 
themselves take care to output different files in this case, so I would 
have expected automake to do the same.

But the real problem seemed to be that flex will output lex.yy.cc when 
using the C++ interface, instead of lex.yy.c which automake expects. I 
have seen a similar problem with bison, too.

Changing the file name to lexer.ll does not by itself solve this, as 
flex will still output lexer.yy.cc, while automake expects lexer.yy.c 
May I dare say I think automake should be updated to expect the correct 
file name in this case ? Or better yet, is there a macro similar to 
AM_PROG_LEX that will look for and find flex++ ?

Happily both flex and bison can be instructed to use different file 
names as output. Is there a way to let automake know that my lex file 
will result in code-formatter.yy.cc, and my yacc file will result in 
code-formatter.tab.cc ?

Thank you,
Timothy Madden