opend's commands: build, dmd, ldc2...

[programandala-net]

I've been learning D and I mainly use the dmd compiler, but I've been trying
also OpenD in order to cross-compile for Windows some programs, on Debian. The
opend install xpack-win64 command makes things much simpler than configuring
the ldc2 compiler.

The issue is I don't understand the relation between OpenD, as a modified,
improved variant of the D language, and its dmd and ldc2 commands, which
are mutually exclusive with build, run and publish:

`opend command_or_filename [args...]` where commands include:
     help  Displays this information
      run  Does a debug build and immediately runs the program
     test  Builds the code and runs its unittests
 testOnly  Builds the code and runs unittests but only for files explicitly listed, not auto-imported files
    check  Performs quick syntax and semantic tests, without performing code generation
    build  Does a debug build with the given arguments
  publish  Does a release build with the given arguments
      dmd  Forwards arguments directly to the OpenD dmd driver
    ldmd2  Forwards arguments directly to the OpenD ldmd2 driver
     ldc2  Forwards arguments directly to the OpenD ldc2 driver
  install  Installs optional components or updates to opend
anyfile.d  Compiles the given file

In other words, what is the difference between the following commands?:

opend build x.d
opend dmd x.d
opend ldc2 x.d
opend x.d

Are opend dmd, opend ldc2 just command-line wrappers, just like ldmd2 is
a simple wrapper to the ldc2 compiler?

In fact, during my tries I got compilation errors with some of those commands,
what made me think opend x.d, opend build x.d and opend dmd x.d are
equivalent under the hood.

I simplified my tries to the minimum in order to isolate the problem. Finally
I got this simple code snippet:

// write.d
import std.stdio : writeln;
void main()
{
    writeln("x");
}

The compilation fails with three commands:

dmd write.d           # ok
ldc2 write.d          # ok
opend write.d         # XXX FAILS
opend build write.d   # XXX FAILS
opend publish write.d # ok
opend dmd write.d     # XXX FAILS
opend ldc2 write.d    # ok

The error is identical is the three cases:

/usr/include/dmd/phobos/std/stdio.d(4161): Error: none of the overloads of template `std.stdio.File.LockingTextWriter.put` are callable using argument types `!()(string)`
/usr/include/dmd/phobos/std/stdio.d(3107):        Candidates are: `put(A)(scope A writeme)`
  with `A = string`
  must satisfy one of the following constraints:
`       isSomeChar!(ElementType!A)
       is(ElementType!A : const(ubyte))`
/usr/include/dmd/phobos/std/stdio.d(3137):                        `put(C)(scope C c)`
  with `C = string`
  must satisfy one of the following constraints:
`       isSomeChar!C
       is(C : const(ubyte))`
/usr/include/dmd/phobos/std/stdio.d(3159): Error: none of the overloads of template `std.utf.decodeFront` are callable using argument types `!()(char[])`
/usr/include/dmd/phobos/std/utf.d(1245):        Candidates are: `decodeFront(Flag useReplacementDchar = No.useReplacementDchar, S)(ref S str, out size_t numCodeUnits)`
/usr/include/dmd/phobos/std/utf.d(1285):                        `decodeFront(Flag useReplacementDchar = No.useReplacementDchar, S)(ref scope S str, out size_t numCodeUnits)`
/usr/include/dmd/phobos/std/utf.d(1314):                        `decodeFront(Flag useReplacementDchar = No.useReplacementDchar, S)(ref S str)`
  with `useReplacementDchar = Flag.no,
       S = char[]`
  must satisfy the following constraint:
`       isInputRange!S`
/usr/include/dmd/druntime/import/core/lifetime.d(2742): Error: unrecognized trait `isCOMClass`
/usr/include/dmd/phobos/std/utf.d(2311): Error: template instance `core.lifetime._d_newclassT!(UTFException)` error instantiating
/usr/include/dmd/phobos/std/utf.d(2514):        instantiated from here: `_utfException!Flag.no`
/usr/include/dmd/phobos/std/stdio.d(3161):        instantiated from here: `encode!Flag.no`
/usr/include/dmd/phobos/std/stdio.d(4163):        instantiated from here: `put!char`
write.d(8):        instantiated from here: `writeln!string`

I use Debian 12.12, amd64; I updated OpenD on 2025-09-10; besides I have these versions
of dmd and ldc2:

> dmd --version
DMD64 D Compiler v2.111.0
Copyright (C) 1999-2025 by The D Language Foundation, All Rights Reserved written by Walter Bright

> ldc2 --version
LDC - the LLVM D compiler (1.41.0):
  based on DMD v2.111.0 and LLVM 20.1.5
  built with LDC - the LLVM D compiler (1.41.0)
  Default target: x86_64-unknown-linux-gnu
  Host CPU: skylake

Probably I am missing something. Any enlighten will be appreciated.

[adamdruppe]

Looks like it is using the Phobos from your upstream D install instead of from the opend dmd install.... probably loading a global /etc/dmd.conf put there by upstream... i need to remove it reading that, i forgot you can even do a global file like that, and now it conflicts with the different versions. publish and ldc2 works because they use the ldc driver which doesn't open that global file, but the others use the dmd driver which does. So I need to fix that.

Note that opend --target=windows write.d will always use the ldc driver so that should be working for you too.

So note that the commands are really shortcuts for each other:

opend write.d # XXX FAILS

This is short for opend build write.d, which is itself a shortcut:

opend build write.d # XXX FAILS

This is short for opend dmd -i -g write.d (or when cross-compiling or on a arm Mac, it instead uses opend ldmd2 -i -g write.d since the dmd driver doesn't support those cases) The -i and -g switches enable including imported modules automatically and debug info.

opend publish write.d # ok

This is short for opend ldmd2 -i -O2 write.d

again it brings in referenced modules automatically but also turns on the optimizer.

(ldmd2 translates command line args from common dmd style to ldc-specific style, then calls ldc)

opend dmd write.d # XXX FAILS

This just forwards the arguments directly to the dmd that comes with opend. It will bypass any other dmd you have installed, specifically asking for the opend one (which you can also run directly but you gotta specify the path). It adds no additional arguments to the compiler, just what you pass.

opend ldc2 write.d # ok

And ditto for the ldc2 that comes with opend. (and there's also opend ldmd2 which goes to opend's ldmd2 version which then calls out to ldc`.

So if you do like opend dmd you should see the opend build date at the top.

But what's happening with your error

[programandala-net]

Adam D. Ruppe escribió/skribis/wrote/scrit (2025-09-13T10:57:40-0700):

Looks like it is using the Phobos from your upstream D install instead of from the opend dmd install.... probably loading a global /etc/dmd.conf put there by upstream...

i see, this is my /etc/dmd.conf: ``` ; ; dmd.conf file for dmd ; ; dmd will look for dmd.conf in the following sequence of directories: ; - current working directory ; - directory specified by the HOME environment variable ; - directory dmd resides in ; - /etc directory ; ; Names enclosed by %% are searched for in the existing environment and inserted ; ; The special name ***@***.***% is replaced with the path to this file ; [Environment32] DFLAGS=-I/usr/include/dmd/phobos -I/usr/include/dmd/druntime/import -L-L/usr/lib/i386-linux-gnu -L--export-dynamic -fPIC [Environment64] DFLAGS=-I/usr/include/dmd/phobos -I/usr/include/dmd/druntime/import -L-L/usr/lib/x86_64-linux-gnu -L--export-dynamic -fPIC ```

i need to remove it reading that, i forgot you can even do a global file like that, and now it conflicts with the different versions. `publish` and `ldc2` works because they use the ldc driver which doesn't open that global file, but the others use the dmd driver which does. So I need to fix that.

understood.

Note that `opend --target=windows write.d` will always use the ldc driver so that should be working for you too.

yes. i did not mention that because cross-compilation always worked fine with `opend ldc2`.

So note that the commands are really shortcuts for each other:

thank you for the explanation. now i understand the full picture. those details about the shortcuts would be helpful in the help text or some readme.

So if you do like `opend dmd` you should see the opend build date at the top.

```

opend dmd

DMD64 OpenD Compiler v2.107.0-beta.1 Sun Sep 7 17:48:14 2025 Copyright (C) 1999-2024 by The D Language Foundation, All Rights Reserved written by Walter Bright ```

…

-- Marcos Cruz http://programandala.net