GCC says "syntax error before numeric constant" in generated header file from bison

gcc enums bison flex-lexer
Kizaru picture Kizaru · Aug 13, 2010 · Viewed 20.2k times · Source

When I compile my .y file with bison parser.y -d -t and then include the parser.tab.h file in my flex file, gcc says "error: syntax error before numeric constant." It's referencing line 32, which is the first line in the enum of yytokentype. 

enum yytokentype {
   BREAK = 258,
   ... }

The error is about the line "BREAK = 258." I honestly don't know why this is happening--I would really like to use the generated yylval and I need it from this header file. Even if I declared yytokentype like this in my flex file, I would get the same error. Anything I could be doing wrong?

Answer

Carl Norum picture Carl Norum · Aug 13, 2010

Is BREAK defined somewhere else in your code? I get a similar error from the following toy example:

#define BREAK 10
enum yytokentype {
    BREAK = 258
};

Build example:

$ cc -c file.c 
file.c:4: error: expected identifier before numeric constant

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