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From: Olaf Krzikalla <krzikalla@gmx.de>
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Subject: Two thoughts about attributes in the FCD
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Hi,

I have two issues regarding attributes:

1. The syntax does not allow the chaining of attribute-specifiers. That is,
you can write:

[[attribute1, attribute2]] for (;;) {}

but you can't write:

[[attribute1]] [[attribute2]] for (;;) {}

IMHO the second version should be allowed too and it should be semantically
equal to the first one. This allows for easier creation of
implementation-dependent constructs as follows:

#ifdef NEW_CPP
#define parfor [[some_parallel]] for
#else
#define parfor for
#endif

#ifdef EVEN_NEWER_CPP
#define parfor_aligned [[align(4)]] parfor
#else
#define parfor_aligned parfor
#endif

With the current syntax it would be difficult to define parfor_aligned on
top of parfor while keeping parfor indepedendent from parfor_aligned.


2. =A77.6.1.5 states, that attibute tokens not being specified behave
implementation-defined. Shouldn't we restrict this in a way, that attibutes
unknown to an particular implementation shall be ignored. Like: an
implementation is not allowed to refuse compilation only because a
syntactically correct attribute-token is unknown.
Maybe someone can rephrase this to standard speak.


Best regrads
Olaf Krzikalla


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