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Could preprocessor warn for unsafe macros and side-effects?


Reading about macro pitfalls and eg duplication side-effects

would it be possible to let the preprocessor generate warnings for any of these pitfalls?

Maybe all language specific parts are not know at this early preprocessing stage, but possibly some info could be stored for use in later pass?

I'm thinking of eg. for "function-like macros" with arguments, checking


* IF function-like macro expands/duplicates an argument more than once THEN
    WARN if function() is part as the argument
    WARN if unary ++ or -- is used on variable as part of argument
    WARN if assignment operator = is part of argument
    WARN if volatile variable part as the argument


* WARN if macro argument contains an expression with operator(s), an a _higher_ precedence operator is used within the macro on this argument, without parenthesis around

I'm not sure its even possible at preprocessing stage, but it would be nice to have,
I saw some static code analysis tools like Coverity detects these

Of course it might generate some false-positives so warning might not be enabled by default, maybe just -Wall or -Wextra,
but perhaps it hard to solve, and I'm not sure where and how to implement the checking algorithm.

Thanks for any feedback!

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