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+---- Thread: A question on Dir-4.9, in a case when a function-like macro and a function are not interchangeable. (/showthread.php?tid=1492)
A question on Dir-4.9, in a case when a function-like macro and a function are not interchangeable. - mz99 - 21-06-2019
Is the use of the function-like macro compliant (shown in Example 1 and 2 below) with Dir-4.9, in a case when a function-like macro and a function are not interchangeable?
Example 1:
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#define ASSIGN( a, b ) ( ( a ) = ( b ) )
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Example 2:
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#define MACRO( a, b )
int32_t var1;
MACRO(var1,var2)
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The macros are not interchangeable with functions,
because in Example 1, the arguments can't be modified if it is defined as a function,
and in Example 2, compile error occurs because var2 is not defined.
Re: A question on Dir-4.9, in a case when a function-like macro and a function are not interchangeable. - misra-c - 25-09-2019
The amplification for directive 4.9 states that the guideline "applies only where a function is permitted by the syntax and constraints of the language standard."
Your examples cannot be re-written as functions and therefore directive 4.9 does not apply. There are no violations of directive 4.9.