On 03/08/2020 14:42, Joel Sherrill wrote:
On Mon, Aug 3, 2020 at 3:45 AM Sebastian Huber <sebastian.hu...@embedded-brains.de <mailto:sebastian.hu...@embedded-brains.de>> wrote:This addresses compiler warnings like this: warning: array subscript 0 is outside the bounds of an interior zero-length array 'abc[0]' [-Wzero-length-bounds] --- cpukit/include/rtems/score/basedefs.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/cpukit/include/rtems/score/basedefs.h b/cpukit/include/rtems/score/basedefs.h index a934507d80..5a7e4e4f31 100644 --- a/cpukit/include/rtems/score/basedefs.h +++ b/cpukit/include/rtems/score/basedefs.h @@ -430,7 +430,11 @@ * doesn't allow flexible array members. Use the GNU extension which is also * supported by other compilers. */ -#define RTEMS_ZERO_LENGTH_ARRAY 0 +#if __STDC_VERSION__ >= 199409L + #define RTEMS_ZERO_LENGTH_ARRAY +#else + #define RTEMS_ZERO_LENGTH_ARRAY 0 +#endifI'm not disagreeing with this change since it moves to the C99 feature rather than a GNU extension but any use of it violates a rule in various safety standards. Googlerandomly found the CodeSonar manual which cites: * MISRA C:2004, 8.12 - When an array is declared with external linkage, its size shall be stated explicitly or defined implicitly by initialisation * MISRA C++:2008, 3-1-3 - When an array is declared, its size shall either be stated explicitly or defined implicitly by initialization * MISRA C:2012, 8.11 - When an array with external linkage is declared, its size should be explicitely specified * MISRA C:2012, 9.5 - Where designated initializers are used to initialize an array object the size of the array shall be specified explicitly * CERT, ARR02-C. <https://www.securecoding.cert.org/confluence/x/HQEOAQ> - Explicitly specify array bounds, even if implicitly defined by an initializer https://rules.sonarsource.com/c/RSPEC-834 We should definitely limit the use of this.
Yes, dynamically sized arrays should be used with care. I added the RTEMS_ZERO_LENGTH_ARRAY some time ago to find them more easily in the code base.
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