[newlib] print formats for FAST and LEAST types

[Andre Vieira <Andre dot SimoesDiasVieira at arm dot com>]

Hello,

Kevin Bracey commented on Launchpad that he was having issues with a 
mismatch between <inttypes.h> and <stdint.h> when printing an 
int_fast32_t.  See 
https://answers.launchpad.net/gcc-arm-embedded/+question/269083

This is due to the fact that on targets where the size of âintâ and 
âlongâ are equal and 32 bits, the current header files will configure 
the type of int_fast32_t to be âintâ and PRIdFAST32 to be âldâ and make 
printf thus expect a âlongâ. The macroâs used in <stdint.h> come from 
âgcc/config/newlib-stdint.hâ.

This leads to a print format warning when -Wformat and we are exploring 
two possible ways of fixing it and would like your views on which path 
would be best to take.

Approach 1)
Change the print formats for FAST (and LEAST) to reflect the types used 
in âgcc/config/newlib-stdint.hâ. Less intrusive change. Though the fact 
that the approach for FASTNN and LEASTNN types is different from the one 
for INTNN types where âlongâ is chosen over âintâ if they are equally 
sized does make us feel slightly uneasy.

Approach 2)
Change âgcc/config/newlib-stdint.hâ such that for targets where the size 
of âintâ and âlongâ are the same,  âlongâ is used for FASTNN and LEASTNN 
types where âintâ was used previously. This would mimic the behavior of 
INTNN types, though it is more intrusive.

Kind Regards,

Andre Vieira