I've been wanting to put together a programming to teach D. The raspberry pi seemed like a good computer to use so everyone could be guaranteed to have a computer to practice on. I've had some trouble, however, getting a test project to compile, and the first culprit lives in std.format.

I tried both LDC and GDC by using `sudo apt install ldc` and `sudo apt install gdc`

compiling my test file with ldc gives these errors

/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(620): Error: can only * a pointer, not a 'int'
/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(631): Error: can only * a pointer, not a 'int'
/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(620): Error: using * on an array is no longer supported; use *(_param_2).ptr instead
/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(631): Error: using * on an array is no longer supported; use *(_param_2).ptr instead
/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(633): Error: template instance std.format.formattedRead!(char[], char, string) error instantiating
diceware.d(26):        instantiated from here: formattedRead!(char[], char, int, string)
diceware.d(39): Error: template std.format.formattedRead cannot deduce function from argument types !()(string, string, int), candidates are:
/usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(588):        std.format.formattedRead(R, Char, S...)(ref R r, const(Char)[] fmt, S args)

compiling with gdc gives these errors:

/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:618:26: error: can only * a pointer, not a 'int'
         alias A = typeof(*args[0]);
                          ^
/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:629:13: error: can only * a pointer, not a 'int'
             *args[0] = unformatValue!(A)(r, spec);
             ^
/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:618:26: error: using * on an array is no longer supported; use *(_param_2).ptr instead
         alias A = typeof(*args[0]);
                          ^
/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:629:13: error: using * on an array is no longer supported; use *(_param_2).ptr instead
             *args[0] = unformatValue!(A)(r, spec);
             ^
/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:631:33: error: template instance std.format.formattedRead!(char[], char, string) error instantiating
         return 1 + formattedRead(r, spec.trailing, args[1 .. $]);
                                 ^
/home/pi/diceware/diceware.d:26:22: note: instantiated from here: formattedRead!(char[], char, int, string)
         formattedRead(line, "%d\t%s", dummy, word);
                      ^
/home/pi/diceware/diceware.d:39:18: error: template std.format.formattedRead cannot deduce function from argument types !()(string, string, int), candidates are:
     formattedRead(readln.strip, "%d", num_words);
                  ^
/usr/lib/gcc/arm-linux-gnueabihf/6/include/d/std/format.d:586:6: note: std.format.formattedRead(R, Char, S...)(ref R r, const(Char)[] fmt, S args)
 uint formattedRead(R, Char, S...)(ref R r, const(Char)[] fmt, S args)

You can find my test file and a text file that makes the program work at https://github.com/d-us-vb/diceware. It compiles without warning on my (x86) laptop.

Looking at format.d on the RPi and on my laptop, I noticed that the desktop version of phobos doesn't have those places of trying to dereference an array element, so I tried replacing format.d on my raspberry pi with the format.d I have on my laptop. This produced some other errors, which I won't bother posting yet.

What can I do to fix this and get the most recent version of phobos that will compile?

On Saturday, 8 August 2020 at 17:00:17 UTC, Jeremiah Glover wrote:
> I've been wanting to put together a programming to teach D. The raspberry pi seemed like a good computer to use so everyone could be guaranteed to have a computer to practice on. I've had some trouble, however, getting a test project to compile, and the first culprit lives in std.format.
>
> I tried both LDC and GDC by using `sudo apt install ldc` and `sudo apt install gdc`
>
> compiling my test file with ldc gives these errors
>
> /usr/lib/ldc/arm-linux-gnueabihf/include/d/std/format.d(620): Error: can only * a pointer, not a 'int'

> You can find my test file and a text file that makes the program work at https://github.com/d-us-vb/diceware.

Seems to work fine with LDC 1.22:
https://d.godbolt.org/z/c14b1E

Perhaps the version of LDC and GDC that you are using is very old?

-Johan

On 8/8/20 1:00 PM, Jeremiah Glover wrote:

> What can I do to fix this and get the most recent version of phobos that will compile?

You are using an old version of the compiler. formattedRead used to accept only pointers, not by ref.

See https://github.com/dlang/phobos/pull/5009

Try doing:
formattedRead(line, "%d\t%s", &dummy, &word);

Figure out which version of the compiler you have, and then use the docs for that version by downloading the compiler and using the local html documentation.

Alternatively, see if you can find a newer compiler that suports ARM.

-Steve