How to Best Silence Unused Variable Warnings in Cross-Platform Development?

Silencing Warnings about Unused Variables in Cross-Platform Development

When developing cross-platform applications, it is common to encounter warnings from compilers such as GCC about unused variables in functions. While there are multiple approaches to addressing these warnings, there are preferred methods for ensuring code readability and maintaining proper program flow.

Avoid #ifdef Macros for Conditional Compilation

Using #ifdef macros to conditionally compile code around unused variables can lead to unsightly and confusing code. It is not the recommended approach as it can complicate maintenance and make code difficult to follow.

Assigning Zero to Variables

Assigning zero to unused variables at the end of functions to silence warnings is discouraged. Altering program flow solely to suppress compiler messages can obscure the actual logic of the code and lead to potential misunderstandings or bugs.

Proper Way: "do { (void)(var); } while (0)" Expression

The preferred method to silence warnings about unused variables is to use the "(void)var;" expression. This expression evaluates to nothing but it forces the compiler to acknowledge that the variable is being used, thereby suppressing the warning.

The syntax for this expression is:

do { (void)(var); } while (0)

For example:

void foo(int param1, int param2)
{
    (void)param2;
    bar(param1);
}

Alternative: UNUSED Macro

An alternative to the "(void)var;" expression is to use a macro such as UNUSED. This macro can be defined as follows:

#define UNUSED(expr) do { (void)(expr); } while (0)

Then, within your code, you can use the macro like this:

void foo(int param1, int param2)
{
    UNUSED(param2);
    bar(param1);
}

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