[cfe-dev] Feature proposal: Compile Configuration Disclosure

[James Widman]

On Mar 5, 2010, at 7:09 PM, James Widman wrote:

> 
> On Mar 3, 2010, at 7:05 PM, Douglas Gregor wrote:
> 
>> On Mar 3, 2010, at 2:44 PM, James Widman wrote:
>> 
>>> List of Needs:
>>> --------------
>>> 
>>>  - The complete set of predefined macro definitions;
>>> 
>>>  - The ordered sequence of directory pathnames used for header-searching in #include "" and #include <>;
>>> 
>>>  - The ordered sequence of implicit #include directives;
>> 
>> The ordering between predefined macro defs and implicit includes (e.g., based on -include on the command line) can matter.
> 
> So bullet points 1 & 3 boil down to something simpler (or at least more general):
> 
>    - The sequence of preprocessing directives implicitly processed (in effect) at the outset of each translation unit

Incidentally, GCC does not seem to care about the order of -D and -include options; e.g. for a.h with:

#ifdef Bar
#error Bar defined!
#endif

... and the invocation:

g++ -DFoo -include a.h -DBar empty.cpp 

... GCC hits the #error.  (Ditto for clang.)

However, the updated (merged) bullet point still makes more sense: if anyone decides to start caring about the order of these things, the updated bullet point would cover it.  And it's just clearer that way.  So if/when GCC implements this, their disclosure file should contain:

#define Foo 1
#define Bar 1
#include "./a.h"

James Widman  
-- 
Gimpel Software 
http://gimpel.com