Factor unrelated declarations out of tree.h (2/2)

[Andrew MacLeod]

On 11/15/2013 08:16 AM, Joseph S. Myers wrote:
> On Thu, 14 Nov 2013, Andrew MacLeod wrote:
>
>
>> btw, I ran tm.h through the include removal script for the c family front end
>> files... The attached patch compiles on x64 and removes 37 includes from the
>> front end files.... those are just the extraneous ones...   but it may be
>> helpful...
> When trimming tm.h includes you need to be careful about either the .c
> file itself, or headers it includes, referencing target macros in ways
> that don't cause build failures when they are missing (that is,
> #ifdef etc., rather than if ()).  And, I don't think it's helpful to
> remove tm.h includes from a file just because some other header implicitly
> includes it.  For example, in your patch. cp/class.c uses BITS_PER_UNIT,
> MAX_FIXED_MODE_SIZE, PCC_BITFIELD_TYPE_MATTERS, STRUCTURE_SIZE_BOUNDARY,
> TARGET_VTABLE_DATA_ENTRY_DISTANCE, TARGET_VTABLE_ENTRY_ALIGN and
> TARGET_VTABLE_USES_DESCRIPTORS; removing the tm.h include makes things
> look cleaner than they are.
Which is why I made the earlier point about flattening everything before 
it really means much in analysis terms... The patch was just meant to 
show that we can strip a lot of things out. .. when those other files 
are flattened, yeah, it may end up back.
>
> (Actually, the C++ front end can't really be usefully cleaned up regarding
> tm.h yet because cp-tree.h uses NO_DOLLAR_IN_LABEL and NO_DOT_IN_LABEL in
> #if conditionals.)
>
> Regarding the case of headers depending on tm.h in a nonobvious way (#if
> rather than anything that will clearly fail if tm.h isn't included): my
> inclination would be to put #error directives in such files so they fail
> immediately if tm.h hasn't been included first (TM_H isn't defined).
Ah yes, I just suggested this as a way to handle it as well in a 
different note.... certainly they all require manual inspection, and 
identifying all cases could be interesting, but is something we could 
start at least with the ones we know.

Andrew