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In this noncompliant code example, the programmer has written a macro called {{EXEC_BUMP()}} to call a specified function and increment a global counter \[[Dewhurst 02|AA. C References#Dewhurst 02]\].  When the expansion of a macro is used within the body of a function, as in this example, identifiers refer to the declarations in scope where the body occurs.  As a result, when the macro is called in the {{aFunc()}} function, it inadvertently increments a local counter with the same name as the global variable. Note that this example also violates [DCL01-C. Do not reuse variable names in subscopes].

GNU C (and some other compilers) supported inline functions before they were added to C99 and as a result have significantly different semantics.  Richard Kettlewell provides a good explanation of differences between the C99 and GNU C rules \[[Kettlewell 03|AA. C References#Kettlewell 03]\].

\[[FSF 05|AA. C References#FSF 05]\] Section 5.34, "[An Inline Function Is as Fast as a Macro|http://gcc.gnu.org/onlinedocs/gcc/Inline.html]"
\[[Dewhurst 02|AA. C References#Dewhurst 02]\] Gotcha #26, "#define Pseudofunctions"
\[[ISO/IEC 9899:1999|AA. C References#ISO/IEC 9899-1999]\] Section 6.7.4, "Function specifiers"
\[[ISO/IEC PDTR 24772|AA. C References#ISO/IEC PDTR 24772]\] "NMP Pre-processor Directives"
\[[Kettlewell 03|AA. C References#Kettlewell 03]\]
\[[MISRA 04|AA. C References#MISRA 04]\] Rule 19.7
\[[Summit 05|AA. C References#Summit 05]\] Question 10.4