Re: [newlib] print formats for FAST and LEAST types

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

On 14/07/15 15:18, Corinna Vinschen wrote:
> On Jul 14 15:08, Andre Vieira wrote:
> > On 14/07/15 14:49, Corinna Vinschen wrote:
> > > On Jul 14 12:17, Andre Vieira wrote:
> > > > 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.
> > >
> > > Are you looking into an older version of newlib by any chance?  We
> > > added code to newlib's headers to check explicitely at runtime whether
> > > __INT32_TYPE__ is int or long, and set the PRIxxx32 macros accordingly.
> > >
> > > See https://sourceware.org/git/?p=newlib-cygwin.git;h=496380c
> > >
> > > I just checked this on 32 bit Cygwin:
> > >
> > >    $ gcc -E - <<EOF
> > >    #include <inttypes.h>
> > >    #include <stdint.h>
> > >    __INT_FAST32_TYPE__
> > >    PRIdFAST32
> > >    EOF
> > >    [...]
> > >    int
> > >    "d"
> > >
> > > If there's still anything wrong with that, feel free to send patches.
> > >
> > >
> > > Corinna
> >
> > Hi Corinna,
> >
> > I am on a newer version than the linked patch.
> >
> > However when I run your example I get int and "ld".
> > In your example, if you pass -dM, does it show INT32_EQ_LONG to be defined?
>
> No, it's undefined.  This is i686-pc-cygwin.  Please have a look at
> libc/include/sys/_intsup.h  and try to find out why this doesn't work
> for your target.
>
>
> Thanks,
> Corinna

Hi Corinna,

It doesn't work because PRIdFAST32 uses __PRI32(d) as a definition and 
in the patch you mentioned earlier __PRI32(d) is defined as "ld" if 
_INT32_EQ_LONG is defined.

However __INT_FAST32_TYPE__ is a builtin defined in '<GCC 
SRC>/gcc/c-family/c-common.c' using INT_FAST32_TYPE, which is defined in 
'<GCC SRC>/gcc/config/newlib-stdint.h' as:
#define INT_FAST32_TYPE (INT_TYPE_SIZE >= 32 ? "int" : INT_LEAST32_TYPE)

So if INT_TYPE_SIZE == LONG_TYPE_SIZE, int_fast32_t will be 'int' and 
PRIdFAST32 will yield "ld" and printf won't like that.

BR,
Andre