[PATCH] Add save_expr langhook (PR c/68513)

[Joseph Myers]

On Sat, 28 Nov 2015, Richard Biener wrote:

> Different approach: after the FE folds (unexpectedly?), scan the result 
> for SAVE_EXPRs and if found, drop the folding.

Or, if conversions are going to fold from language-independent code (which 
is the underlying problem here - a conversion without folding would be 
preferred once the fallout from that can be resolved), make the front end 
fold with c_fully_fold before doing the conversion, and wrap the result of 
the conversion in a C_MAYBE_CONST_EXPR with c_wrap_maybe_const in the same 
way as done in other places that fold early (if either c_fully_fold 
indicates it can't occur in a constant expression, or the result of 
folding / conversion is not an INTEGER_CST).

-- 
Joseph S. Myers
joseph@codesourcery.com