[PATCH 2/2] Profile2: use an implicit initializer for a struct array

[Thiago Macieira]

Em seg 10 mar 2014, às 09:24:08, Dirk Hohndel escreveu:
> I'll ask our resident compiler and language standards guru (Thiago) to
> chime in here. I thought that the ISO standard requires the initializer
> to be non-empty and that the '{}' initializer was a gcc-ism.

I've just taken a quick look at the C99 standard. In 6.7.8 Initialization, the 
grammar does not allow empty braces:

Syntax
 initializer:
	assignment-expression
	{ initializer-list }
	{ initializer-list , }
 initializer-list:
	designation_opt initializer
	initializer-list , designation_opt initializer
 designation:
	designator-list =
 designator-list:
	designator
	designator-list designator
 designator:
	[ constant-expression ]
	. identifier

So if you open a brace, you must have at least one assignment-expression.

[The C99 standard is not public, but the committee draft for C11 is:
 http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
 section 6.7.9, page 139]


HOWEVER, this file is not C. It's C++ and C++11 does allow for {}. See 8.5 
Initializers [dcl.init], with the syntax:

initializer:
	brace-or-equal-initializer
	( expression-list )
brace-or-equal-initializer:
	= initializer-clause
	braced-init-list
braced-init-list:
	{ initializer-list ,opt }
	{}

So the {} is explicitly allowed in C++11.

[The C++11 final draft is not publicly available, but the editor revised 
version is: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf, 
search for [dcl.init]; or see 
https://github.com/cplusplus/draft/blob/master/source/declarators.tex#L2372]
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
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