warning Bison compilation
am developping a compiler using flex/bison. I have this warning in my build output.
warning: type c开发者_开发问答lash ('s' '') on default action
any help please?
It seems to be related to your %token and %type declaration in your source. without the source line and the related token and type declaration it is difficult to help you.
If you specify an expr of type val and definer an ID token of type tptr
%{
#include "parser.h"
%}
%type <val> expr
%token <tptr> ID
If you write without any action bison will emit a warning
expr : ID;
warning: type clash ('tptr' 'val') on default action
Note that the bison level I am currently using print a slighty different message in this case.
foo.by:10.12:warning: type clash on default action : <tptr> != <val>
To fix this warning you need an explicit action:
expr : ID { $$ = some_conversion_code($1); }
http://www.gnu.org/s/bison/manual/bison.html#Token-Decl
Use the union definition to type your given tokens from lex.
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