On 02/12/2017 01:27 AM, Gerald Pfeifer wrote:
On Tue, 7 Feb 2017, Martin Sebor wrote:
The attached documentation-only patch clarifies the description
of the -dM option to mention that __FILE__ (and other predefined
macros) do no appear on the list generated by the option.
+The predefined macros @code{__FILE__}, @code{__LINE__}, @code{__DATE__},
+and @code{__TIME__} are excluded from this list because their replacements
+may change from one line of output to the next.
Is this ("their replacements may change") truefor __FILE__ as well?
In any case, this may be too nit-picking, and the patch looks fine
to me.
Thanks. __FILE__ too can change between different lines of output:
by means of a #line directive.
I actually think it would be preferable if GCC printed the value of
__FILE__ and all the other macros, including the four mentioned here.
But since in response to the bug report Andrew implied that not
printing them is intentional I figured I'd just update the docs
and resolve this old bug (raised in 2009).
That said, I find the argument that these four are special because
their value can change from line to line a weak one given that the
definition of any predefined macro can change (simply by undefining
and redefining it something else).
Is there a better argument for not printing __FILE__ et al? Do we
want to document this or change GCC to print all macros?
Martin
