• kdevel (74/74) Apr 16 2020 Sorry for this lengthy post:
• Meta (7/7) Apr 16 2020 Unlike C/C++, char is not a numeric type in D; It's a UTF-8 code
• kdevel (51/53) Apr 17 2020 Thanks, it's a code /unit/. main reads now:
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (28/44) Apr 17 2020 The problem is, short/short gives an int answer:
• kdevel (25/39) Apr 17 2020 A curiosity. Usually you cast into the type on the left. But
• tsbockman (16/36) Apr 18 2020 The author of std.experimental.checkedint hasn't implemented the
• tsbockman (16/35) Apr 18 2020 The author of std.experimental.checkedint hasn't (yet) written
• kdevel (61/73) Apr 18 2020 The message suggests using -preview=intpromote. But it produces
• tsbockman (5/22) Apr 18 2020 I think that's a compiler bug, not a bug in my checkedint
• tsbockman (5/22) Apr 18 2020 This should be fixed now.

kdevel <kdevel vogtner.de> writes:

Sorry for this lengthy post:

```x.d
void foo (T) ()
{
    import std.experimental.checkedint;
    alias CT = Checked!(T, Throw);
    CT a = CT.min;
    CT x;
    --x;
    CT b = x;
    CT c = a / b;
}

void bar (T) ()
{
    import std.stdio;
    try foo!T ();
    catch (Exception e)
       writefln ("caught <%s>", e.msg);
}

void main ()
{
    bar!byte;
    bar!char;
    bar!ushort;
    bar!short;
    bar!uint;
    bar!int;
    bar!ulong;
    bar!long;
}
```

$ dmd x.d

[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(byte)0`, use
'-preview=intpromote' switch or `~cast(int)(cast(byte)0)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(byte, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!byte` error instantiating
x.d(22):        instantiated from here: `bar!byte`
x.d(4): Error: template instance 
`std.experimental.checkedint.Checked!(char, Throw)` does not 
match template declaration `Checked(T, Hook = Abort)`
   with `T = char,
        Hook = Throw`
   must satisfy one of the following constraints:
`       isIntegral!T
        is(T == Checked!(U, H), U, H)`
x.d(15): Error: template instance `x.foo!char` error instantiating
x.d(23):        instantiated from here: `bar!char`
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(ushort)0u`, use
'-preview=intpromote' switch or `~cast(int)(cast(ushort)0u)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(ushort, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!ushort` error 
instantiating
x.d(24):        instantiated from here: `bar!ushort`
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(short)0`, use
'-preview=intpromote' switch or `~cast(int)(cast(short)0)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(short, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!short` error 
instantiating
x.d(25):        instantiated from here: `bar!short`

$ dmd --version
DMD64 D Compiler v2.090.1
Copyright (C) 1999-2019 by The D Language Foundation, All Rights 
Reserved written by Walter Bright

Is Checked expected to work with the types byte, char, ushort and 
short? If so shall I file a bug report?

Meta <jared771 gmail.com> writes:

Unlike C/C++, char is not a numeric type in D; It's a UTF-8 code 
point:

import std.traits;

void main()
{
     pragma(msg, isNumeric!char); //Prints false
}

kdevel <kdevel vogtner.de> writes:

On Friday, 17 April 2020 at 04:29:06 UTC, Meta wrote:
 Unlike C/C++, char is not a numeric type in D; It's a UTF-8 
 code point:

Thanks, it's a code /unit/. main reads now:

void main ()
{
    bar!ubyte;
    bar!byte;
    bar!ushort;
    bar!short;
    bar!uint;
    bar!int;
    bar!ulong;
    bar!long;
}

and dmd complains:

[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(ubyte)0u`, use
'-preview=intpromote' switch or `~cast(int)(cast(ubyte)0u)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(ubyte, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!ubyte` error 
instantiating
x.d(22):        instantiated from here: `bar!ubyte`
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(byte)0`, use
'-preview=intpromote' switch or `~cast(int)(cast(byte)0)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(byte, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!byte` error instantiating
x.d(23):        instantiated from here: `bar!byte`
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(ushort)0u`, use
'-preview=intpromote' switch or `~cast(int)(cast(ushort)0u)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(ushort, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!ushort` error 
instantiating
x.d(24):        instantiated from here: `bar!ushort`
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(1410):
Deprecation: integral promotion not done for `~cast(short)0`, use
'-preview=intpromote' switch or `~cast(int)(cast(short)0)`
x.d(9): Error: template 
`std.experimental.checkedint.Checked!(short, 
Throw).Checked.__ctor` cannot deduce function from argument types 
`!()(Checked!(int, Throw))`, candidates are:
[...]linux/bin64/../../src/phobos/std/experimental/checkedint.d(331):       
`__ctor(U)(U rhs)`
x.d(15): Error: template instance `x.foo!short` error 
instantiating
x.d(25):        instantiated from here: `bar!short`

I tested some DMD versions down to 2.075 none of which compiled 
successfully.

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Friday, 17 April 2020 at 08:59:19 UTC, kdevel wrote:
 On Friday, 17 April 2020 at 04:29:06 UTC, Meta wrote:
 Unlike C/C++, char is not a numeric type in D; It's a UTF-8 
 code point:

 Thanks, it's a code /unit/. main reads now:

 void main ()
 {
    bar!ubyte;
    bar!byte;
    bar!ushort;
    bar!short;
    bar!uint;
    bar!int;
    bar!ulong;
    bar!long;
 }

 and dmd complains:


The problem is, short/short gives an int answer:

unittest {
     import std.experimental.checkedint;
     Checked!(short, Throw) a;
     pragma(msg, typeof(a/a));
}

So, in your code you get this situation:

unittest {
     import std.experimental.checkedint;
     Checked!(int, Throw) a;
     Checked!(short, Throw) b = a;
}

And assigning from an int to a short may discard data, so it's 
statically disallowed by Checked. This is a deliberate design 
choice, and the appropriate way to handle it is with a cast:

unittest {
     import std.experimental.checkedint;
     Checked!(int, Throw) a = 65535;
     Checked!(short, Throw) b = cast(short)a;
}

The above code will throw when casting (before the assignment), 
because 65535 can't fit in a short.

You also get a deprecation message, about an integral promotion 
not being performed. I believe the result is correct and the 
warning can be ignored.

--
   Simen

kdevel <kdevel vogtner.de> writes:

On Friday, 17 April 2020 at 12:59:20 UTC, Simen Kjærås wrote:

[Deleted text makes sense]

 And assigning from an int to a short may discard data, so it's 
 statically disallowed by Checked.
 This is a deliberate design choice, and the appropriate way to 
 handle it is with a cast:

 unittest {
     import std.experimental.checkedint;
     Checked!(int, Throw) a = 65535;
     Checked!(short, Throw) b = cast(short)a;
 }

A curiosity. Usually you cast into the type on the left. But

    Checked!(short, Throw) b = cast (Checked!(short, Throw)) a;

does not compile:

    Error: template std.experimental.checkedint.Checked!(int,
    Throw).Checked.opCast cannot deduce function from argument 
types
    !(Checked!(short, Throw))(), candidates are: [...]

One has to go over the underlying type?

 The above code will throw when casting (before the assignment), 
 because 65535 can't fit in a short.

It's remarkable that the cast to the /underlying type/ throws. I 
would have expected that

    cast(short) a

is equivalent to what actually must be written as

    cast(short) a.get

 You also get a deprecation message, about an integral promotion 
 not being performed. I believe the result is correct and the 
 warning can be ignored.

So the warning is a bug?

void foo (T) ()
{
    import std.experimental.checkedint;
    alias CT = Checked!(T, Throw);
    CT c = CT.min;
    CT b;
    --b;
    c /= b;
}

tsbockman <thomas.bockman gmail.com> writes:

On Friday, 17 April 2020 at 21:25:34 UTC, kdevel wrote:
 On Friday, 17 April 2020 at 12:59:20 UTC, Simen Kjærås wrote:
 A curiosity. Usually you cast into the type on the left. But

    Checked!(short, Throw) b = cast (Checked!(short, Throw)) a;

 does not compile:

    Error: template std.experimental.checkedint.Checked!(int,
    Throw).Checked.opCast cannot deduce function from argument 
 types
    !(Checked!(short, Throw))(), candidates are: [...]

 One has to go over the underlying type?

The author of std.experimental.checkedint hasn't implemented the 
overload of opCast required to make your code work. It's just a 
missing feature.

 The above code will throw when casting (before the 
 assignment), because 65535 can't fit in a short.

 It's remarkable that the cast to the /underlying type/ throws. 
 I would have expected that

    cast(short) a

 is equivalent to what actually must be written as

    cast(short) a.get

 You also get a deprecation message, about an integral 
 promotion not being performed. I believe the result is correct 
 and the warning can be ignored.

 So the warning is a bug?

The warning is caused by some (very annoying, but intentional) 
changes made to the compiler after std.experimental.checkedint 
was written. That module needs to be updated accordingly, but no 
one has done it yet.

Anyway, you might want to take a look at my checkedint package on 
Dub:

     https://code.dlang.org/packages/checkedint

In my opinion, the API is better - especially if you use 
SmartInt. (I submitted it for inclusion in the standard library 
originally, but Alexandrescu did not agree with my approach and 
so wrote his own version, which became 
std.experimental.checkedint.)

tsbockman <thomas.bockman gmail.com> writes:

On Friday, 17 April 2020 at 21:25:34 UTC, kdevel wrote:
 A curiosity. Usually you cast into the type on the left. But

    Checked!(short, Throw) b = cast (Checked!(short, Throw)) a;

 does not compile:

    Error: template std.experimental.checkedint.Checked!(int,
    Throw).Checked.opCast cannot deduce function from argument 
 types
    !(Checked!(short, Throw))(), candidates are: [...]

 One has to go over the underlying type?

The author of std.experimental.checkedint hasn't (yet) written 
the opCast overload required to make that code work. It's just a 
feature missing from the code for that specific module in the 
standard library, not a language issue.

 The above code will throw when casting (before the 
 assignment), because 65535 can't fit in a short.

 It's remarkable that the cast to the /underlying type/ throws. 
 I would have expected that

    cast(short) a

 is equivalent to what actually must be written as

    cast(short) a.get

 You also get a deprecation message, about an integral 
 promotion not being performed. I believe the result is correct 
 and the warning can be ignored.

 So the warning is a bug?

The deprecation message is a consequence of a (very annoying) 
language change made after std.experimental.checkedint was 
written. It's not really a bug, although someone should probably 
fix it anyway.

Anyway, you might want to give my checkedint package on DUB a 
try, instead:

     https://code.dlang.org/packages/checkedint

(It's the original candidate for std.experimental.checkedint. 
Alexandrescu didn't like it, so he rejected it and wrote his own. 
But, I still think mine has a better API, especially if you use 
the SmartInt types.)

kdevel <kdevel vogtner.de> writes:

On Saturday, 18 April 2020 at 08:39:52 UTC, tsbockman wrote:

[...]

 You also get a deprecation message, about an integral 
 promotion not being performed. I believe the result is 
 correct and the warning can be ignored.

 So the warning is a bug?

 The deprecation message is a consequence of a (very annoying) 
 language change made after std.experimental.checkedint was 
 written. It's not really a bug, although someone should 
 probably fix it anyway.

The message suggests using -preview=intpromote. But it produces 
another error:

```minusminus.d
void foo ()
{
    import std.experimental.checkedint;
    Checked!(short) b;
    --b;
}
```

$ dmd -preview=intpromote minusminus.d
[...]/linux/bin64/../../src/phobos/std/experimental/checkedint.d(727): Error:
cannot implicitly convert expression onOverflow(this.payload) of type int to
short
minusminus.d(5): Error: template instance 
std.experimental.checkedint.Checked!(short, 
Abort).Checked.opUnary!"--" error instantiating

 Anyway, you might want to give my checkedint package on DUB a 
 try, instead:

     https://code.dlang.org/packages/checkedint

Hm.

$ dub test
Generating test runner configuration 'checkedint-test-library' 
for 'library' (library).
Excluding package.d file from test due to 
https://issues.dlang.org/show_bug.cgi?id=11847
Performing "unittest" build using [...]/linux/bin64/dmd for 
x86_64.
checkedint ~master: building configuration 
"checkedint-test-library"...
Linking...
Running ./checkedint-test-library
source/checkedint/package.d(672): [unittest] unittest failure
core.exception.AssertError source/checkedint/package.d(672): 
unittest failure
----------------
??:? _d_unittestp [0x4c07b5]
source/checkedint/package.d:672 void 
checkedint.__unittest_L654_C5() [0x49959c]
??:? void checkedint.__modtest() [0x4bc4b2]
??:? int 
core.runtime.runModuleUnitTests().__foreachbody2(object.ModuleInfo*) [0x4da1ec]
??:? int object.ModuleInfo.opApply(scope int 
delegate(object.ModuleInfo*)).__lambda2(immutable(object.ModuleInfo*))
[0x4bedb7]
??:? int rt.minfo.moduleinfos_apply(scope int 
delegate(immutable(object.ModuleInfo*))).__foreachbody2(ref 
rt.sections_elf_shared.DSO) [0x4c581f]
??:? int rt.sections_elf_shared.DSO.opApply(scope int 
delegate(ref rt.sections_elf_shared.DSO)) [0x4c5d8c]
??:? int rt.minfo.moduleinfos_apply(scope int 
delegate(immutable(object.ModuleInfo*))) [0x4c57ad]
??:? int object.ModuleInfo.opApply(scope int 
delegate(object.ModuleInfo*)) [0x4bed89]
??:? runModuleUnitTests [0x4da029]
??:? void rt.dmain2._d_run_main2(char[][], ulong, extern (C) int 
function(char[][])*).runAll() [0x4c226c]
??:? void rt.dmain2._d_run_main2(char[][], ulong, extern (C) int 
function(char[][])*).tryExec(scope void delegate()) [0x4c21f8]
??:? _d_run_main2 [0x4c2161]
??:? _d_run_main [0x4c1f1d]
[...]/linux/bin64/../../src/druntime/import/core/internal/entrypoint.d:34 main
[0x48c241]
??:? __libc_start_main [0x7ffff700e585]
1/3 unittests FAILED
Program exited with code 1

tsbockman <thomas.bockman gmail.com> writes:

On Saturday, 18 April 2020 at 15:20:42 UTC, kdevel wrote:
 On Saturday, 18 April 2020 at 08:39:52 UTC, tsbockman wrote:
     https://code.dlang.org/packages/checkedint

 Hm.

 $ dub test
 Generating test runner configuration 'checkedint-test-library' 
 for 'library' (library).
 Excluding package.d file from test due to 
 https://issues.dlang.org/show_bug.cgi?id=11847
 Performing "unittest" build using [...]/linux/bin64/dmd for 
 x86_64.
 checkedint ~master: building configuration 
 "checkedint-test-library"...
 Linking...
 Running ./checkedint-test-library
 source/checkedint/package.d(672): [unittest] unittest failure
 core.exception.AssertError source/checkedint/package.d(672): 
 unittest failure

I think that's a compiler bug, not a bug in my checkedint 
package, as the unit tests pass on earlier D compiler versions 
(including GDC 2.075). Regardless, I'll try to track it down and 
either fix it or file a compiler bug report for it today.

tsbockman <thomas.bockman gmail.com> writes:

On Saturday, 18 April 2020 at 15:20:42 UTC, kdevel wrote:
 On Saturday, 18 April 2020 at 08:39:52 UTC, tsbockman wrote:
     https://code.dlang.org/packages/checkedint

 Hm.

 $ dub test
 Generating test runner configuration 'checkedint-test-library' 
 for 'library' (library).
 Excluding package.d file from test due to 
 https://issues.dlang.org/show_bug.cgi?id=11847
 Performing "unittest" build using [...]/linux/bin64/dmd for 
 x86_64.
 checkedint ~master: building configuration 
 "checkedint-test-library"...
 Linking...
 Running ./checkedint-test-library
 source/checkedint/package.d(672): [unittest] unittest failure
 core.exception.AssertError source/checkedint/package.d(672): 
 unittest failure

This should be fixed now.

(It actually appears there was a bug in two of my unit tests 
*and* in *old* versions of the compiler, where the compiler bug 
allowed my bad unit tests to wrongly pass. Weird...)