c++c-preprocessorcompiler-warningssuppress-warnings

How to require a semicolon after a macro

So I am writing a library that has to build with -pedantic -ansi -std=c++98 -Werror and -Weverything for clang and -Wall -Wextra for gcc and I have this macro TESTSUITE(X) which is intended to be used in global scope like this:

TESTSUITE(current testsuite);

and what it does is call a function (on program startup by initializing a dummy var) with the string:

#define TESTSUITE(name) \
static int ANONYMOUS_VARIABLE(SOME_PREFIX) = setTestSuiteName(#name)

The problem is that this generates a warning under clang for -Wglobal-constructors.

If I surround it with _Pragma like this:

#define TESTSUITE(name)                                              \
_Pragma("clang diagnostic push");                                    \
_Pragma("clang diagnostic ignored \"-Wglobal-constructors\"");       \
static int ANONYMOUS_VARIABLE(SOME_PREFIX) = setTestSuiteName(#name) \
_Pragma("clang diagnostic pop")

the semicolon after using the macro will not be required for compilation (and when it is missing -pedantic gives an error).

If I add this at the end of the macro

static int ANONYMOUS_VARIABLE(SOME_PREFIX) = 5

the semicolon will be required but I will get a warning for an unused variable which I cannot silence (because if I surround it with _Pragma statements I will be back to square 1 not requiring a semicolon).

So does anyone have an idea how I can require the semicolon and also have 0 warnings?

Solution

  • You can add a function declaration at the end of the macro:

    #define TESTSUITE(name)  \
//...                    \
void ANONYMOUS_FUNCTION()

    Demo

    The function name doesn't even have to be different across different TESTSUITE macros. It's sufficient if it's just not used anywhere else so it doesn't participate in any overloading.