• Zans (14/14) Apr 25 2019 import std.stdio;
• Patrick Schluter (9/23) Apr 25 2019 The issue here is not Windows vs Linux but 32 bits vs 64 bits.
• Mike Parker (21/35) Apr 25 2019 DMD defaults to 64-bit output on 64-Bit Linux but always to
• Ron Tarrant (3/4) Apr 26 2019 Not trying to be a but it also works with -m64 on
• Mike Parker (3/7) Apr 26 2019 Yes, thanks. That's a typo. -m32, where size_t is uint, is the

Zans <dlafotok inbox.lv> writes:

import std.stdio;

void main()
{
     char[] mychars;
     mychars ~= 'a';
     long index = 0L;
     writeln(mychars[index]);
}

Why would the code above compile perfectly on Linux (Ubuntu 
16.04), however it would produce the following error on Windows 
10:

source\app.d(8,21): Error: cannot implicitly convert expression 
index of type long to uint

On both operating systems DMD version is 2.085.0.

Patrick Schluter <Patrick.Schluter bbox.fr> writes:

On Thursday, 25 April 2019 at 20:18:28 UTC, Zans wrote:
 import std.stdio;

 void main()
 {
     char[] mychars;
     mychars ~= 'a';
     long index = 0L;
     writeln(mychars[index]);
 }

 Why would the code above compile perfectly on Linux (Ubuntu 
 16.04), however it would produce the following error on Windows 
 10:

 source\app.d(8,21): Error: cannot implicitly convert expression 
 index of type long to uint

 On both operating systems DMD version is 2.085.0.

The issue here is not Windows vs Linux but 32 bits vs 64 bits.
On 32 bits architectures size_t is defined as uint, long being 64 
bits long, conversion from long to uint is a truncating cast 
which are not allowed implicitely in D.
It is unfortunate that the D compiler on Windows is still 
delivered by default as a 32 bits binary and generating 32 bits 
code. I think the next release will start to deliver the compiler 
as 64 bits binary and generating 64 bits code.

Mike Parker <aldacron gmail.com> writes:

On Thursday, 25 April 2019 at 20:18:28 UTC, Zans wrote:
 import std.stdio;

 void main()
 {
     char[] mychars;
     mychars ~= 'a';
     long index = 0L;
     writeln(mychars[index]);
 }

 Why would the code above compile perfectly on Linux (Ubuntu 
 16.04), however it would produce the following error on Windows 
 10:

 source\app.d(8,21): Error: cannot implicitly convert expression 
 index of type long to uint

 On both operating systems DMD version is 2.085.0.

DMD defaults to 64-bit output on 64-Bit Linux but always to 
32-bit output on Windows, If you compile with -m32 on Windows the 
error goes away. Reasons::

* Array indices are default typed as size_t, which is uint in 
32-bit and ulong in 64. long is not implicitly convertible to 
uint.

* On Linux, both 64- and 32-bit builds of DMD are available and 
the output for each defaults to the same. Only the 32-bit build 
is distributed on Windows.

* Historically, compiling 64-bit binaries on Windows required a 
separate installation of the Microsoft Build Tools ( or Visual 
Studio) and/or the Windows SDK. If 64-bit output were the 
default, DMD would not work out of the box. Recently, DMD has 
been shipping with the lld linker and some MinGW-based Windows 
libraries so that the additional installation is not required and 
64-bit compiles can work out of the box, but it’s still 
considered experimental.

When out-of-the-box 64-bit compilation is solid and 64-bit builds 
are distributed on Windows, the default behavior should be the 
same as on Linux.

Ron Tarrant <rontarrant gmail.com> writes:

On Thursday, 25 April 2019 at 20:38:31 UTC, Mike Parker wrote:
 If you compile with -m32 on Windows the error goes away.

Not trying to be a <clever donkey> but it also works with -m64 on 
Windows.

Mike Parker <aldacron gmail.com> writes:

On Friday, 26 April 2019 at 15:48:51 UTC, Ron Tarrant wrote:
 On Thursday, 25 April 2019 at 20:38:31 UTC, Mike Parker wrote:
 If you compile with -m32 on Windows the error goes away.

 Not trying to be a <clever donkey> but it also works with -m64 
 on Windows.

Yes, thanks. That's a typo. -m32, where size_t is uint, is the 
default. In -m64, size_t is ulong.