SWIG compilation failing because of C++ style comment (#1795)

Hi,
I tried to compile the latest version of SWIG with the latest version of bison 3.6 and I get the following error:


make[1]: Entering directory 'XXX/swig/Source'
make  all-am
make[2]: Entering directory 'XXX/swig/Source'
depbase=`echo CParse/parser.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
gcc -DHAVE_CONFIG_H   -I../Source/Include -I../Source/CParse -I../Source/Include -I../Source/DOH -I../Source/CParse -I../Source/Doxygen -I../Source/Preprocessor -I../Source/Swig -I../Source/Modules   -g -O2 -Wall -W -ansi -pedantic -MT CParse/parser.o -MD -MP -MF $depbase.Tpo -c -o CParse/parser.o CParse/parser.c &&\
mv -f $depbase.Tpo $depbase.Po
CParse/parser.c: In function ‘yyparse’:
CParse/parser.c:13053:3: error: C++ style comments are not allowed in ISO C90
   // Pop stack until we find a state that shifts the error token.
   ^
CParse/parser.c:13053:3: error: (this will be reported only once per input file)
Makefile:930: recipe for target 'CParse/parser.o' failed
make[2]: *** [CParse/parser.o] Error 1
make[2]: Leaving directory 'XXX/swig/Source'
Makefile:599: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory 'XXX/swig/Source'
Makefile:37: recipe for target 'source' failed
make: *** [source] Error 2

This is due to the fact that a C++ style comment is used in a .c file and SWIG compiles with the —pedantic option. Since the comment in parser.c does not come from SWIG’s parser.y, this might be a problem with bison.

I opened the following issue on SWIG as well: https://github.com/swig/swig/issues/1795

Best wishes,
Rocco Meli