Re: [PATCH] stdio: fix probe on mingw under gcc 5.1

[Assaf Gordon]

Hello,

I'm encountering a similar/related issue with PRIdMAX on mingw32-gcc 4.8.2.

In short, when using gnulib in my project and cross-compiling with mingw32-gcc 
4.8.2
somehow the PRIdMAX becomes "lld" instead of "I64d".

I was able to reproduce it with GNU Hello  (long details below).

perhaps I'm doing something incorrect and you might be able to suggest a fix?
An incorrect usage of gnulib's 'inttypes' or 'stdint' modules?

Thanks,
 - assaf

On 05/22/2015 08:08 AM, Eric Blake wrote:

/* Do this test only on MingW.  */
char PRIdMAX_is_I64d[sizeof PRIdMAX == sizeof "I64d" ? 1 : -1];

which will give us a compile-time failure if PRIdMAX is "lld".

I've tested it like so:

-1-
The system is Ubuntu 14.04.2, with mingw from the standard package.

    $ dpkg -l gcc-mingw-w64-x86-64
    ii  gcc-mingw-w64-x86-64 4.8.2-10ubuntu2 amd64           GNU C compiler for 
MinGW-w64 targeting Win64
    $ x86_64-w64-mingw32-gcc -v
    gcc version 4.8.2 (GCC)

-2-
Checking a simple C file without gnulib, PRIdMAX is correctly defined as "I64d":

    $ cat 1.c
    #include <stdint.h>
    #include <inttypes.h>
    int main(int argc, char* argv[])
    {
        char PRIdMAX_is_I64d[sizeof PRIdMAX == sizeof "I64d" ? 1 : -1];
        return 0;
    }

    $ x86_64-w64-mingw32-gcc -o 1 1.c
    # ( No compilation errors )

    $ x86_64-w64-mingw32-gcc -E 1.c  | tail -n5
    int main(int argc, char* argv[])
    {
     char PRIdMAX_is_I64d[sizeof "I64d" == sizeof "I64d" ? 1 : -1];
     return 0;
    }

-3-
Checking with gnulib's internal tests, PRIdMAX is still correct:

    # Create unit-tests for 'inttypes' module
    git clone git://git.sv.gnu.org/gnulib.git
    cd gnulib/
    ./gnulib-tool --create-testdir --dir foo inttypes
    cd foo

    # add the compile-time check
    sed -i '/return 0/ichar PRIdMAX_is_I64d[sizeof PRIdMAX == sizeof "I64d" ? 1 
: -1];' gltests/test-inttypes.c
    ./configure --host=x86_64-w64-mingw32
    make
    ## (no compilation errors)

    ## Verify the macro expansion:
    rm gltests/test-inttypes.o
    make CFLAGS="-E"
    grep PRI.MAX gltests/test-inttypes.o
    ==
       char PRIdMAX_is_I64d[sizeof "I64d" == sizeof "I64d" ? 1 : -1];
    ==


-4-
However,
Adding the same check to a 'real' project which uses gnulib (GNU Hello),
somehow PRIdMAX is reverted to "lld".
Perhaps some other headers are missing or additional gnulib modules are needed?

    git clone git://git.sv.gnu.org/hello.git
    cd hello

    # Needed as 'LC_MESSAGES' fails to compile with mingw32, not related to 
this issue
    sed -i '/setlocale/s/LC_MESSAGES/LC_ALL/' src/hello.c

    # Use gnulib modules inttypes and stdint
    sed -i '/gnulib_modules/ainttypes\nstdint' bootstrap.conf

    # Add #includes to the C file
    sed -i '/<config\.h>/a#include <stdint.h>\n#include <inttypes.h>' 
src/hello.c

    # Add the compile-type check for PRIdMAX
    sed -i '/Forward declarations/ichar PRIdMAX_is_I64d[sizeof PRIdMAX == sizeof 
"I64d" ? 1 : -1];' src/hello.c

    # Try to compile
    ./bootstrap
    ./configure --host=x86_64-w64-mingw32
    make

And it fails with:
    ...
    x86_64-w64-mingw32-gcc -DLOCALEDIR=\"/usr/local/share/locale\" 
-DHAVE_CONFIG_H -I.  -Ilib -I./lib -Isrc -I./src \
                           -g -O2 -MT src/hello.o -MD -MP -MF $depbase.Tpo -c -o 
src/hello.o src/hello.c &&\
                           mv -f $depbase.Tpo $depbase.Po
    src/hello.c:29:6: error: size of array 'PRIdMAX_is_I64d' is negative
    char PRIdMAX_is_I64d[sizeof PRIdMAX == sizeof "I64d" ? 1 : -1];
         ^
    make[2]: *** [src/hello.o] Error 1
    make[2]: Leaving directory `/tmp/j/hello'

Checking the macro expansion:

    rm -f src/hello.o
    make CFLAGS="-E"
    grep PRI.MAX src/hello.o
    ==
       char PRIdMAX_is_I64d[sizeof "lld" == sizeof "I64d" ? 1 : -1];
    ==

In my project I see the same error as with GNU Hello: PRIdMAX is incorrect, despite the 
underlying definition being "I64d".