Hi,

I created a Dub project containing two files: app.d and zstd_binding.c

$ cat source/zstd_binding.c

#include <zstd.h>
#include <zstd_errors.h>

#include <stdio.h>

void relatedCode(void)
{
	printf("Hallo! This is some output from C code!\n");
}

and

$ cat source/app.d
import std.conv;
import std.stdio;

import zstd_binding;

void main()
{
	auto versionNr = ZSTD_versionNumber();
	auto versionStr = ZSTD_versionString();
	writefln("Version Info: Numeric %d String %s", versionNr, versionStr.to!string);

	/** more code stripped */

	relatedCode(); // The linker can't find it....
}

Accessing ZSTD works perfect. For linking you must give "-lzstd". So far, so good. The problem started, when I try to access the relatedCode() C function. There is simply no code generated for this C function. I need to compile the C separately into an object file and pass it as extra linker argument.

I expected that ImportC also allows to import C functions and creates the required code on the fly.

Is this a bug? What's wrong?

On Friday, 28 October 2022 at 17:45:59 UTC, Carsten Schlote wrote:

Are you using DMD?

On Friday, 28 October 2022 at 17:56:57 UTC, Imperatorn wrote:

I'm using

$ dub --version
DUB version 1.29.2, built on Sep 29 2022
$ dmd-beta --version
DMD64 D Compiler v2.101.0-beta.1-36-ga2865d74fb
Copyright (C) 1999-2022 by The D Language Foundation, All Rights Reserved written by Walter Bright

On 10/28/22 1:45 PM, Carsten Schlote wrote:

$ cat source/zstd_binding.c

#include <zstd.h>
#include <zstd_errors.h>

#include <stdio.h>

void relatedCode(void)
{
     printf("Hallo! This is some output from C code!\n");
}

$ cat source/app.d
import std.conv;
import std.stdio;

import zstd_binding;

void main()
{
     auto versionNr = ZSTD_versionNumber();
     auto versionStr = ZSTD_versionString();
     writefln("Version Info: Numeric %d String %s", versionNr, versionStr.to!string);

     /** more code stripped */

     relatedCode(); // The linker can't find it....
}

Are you passing the c file to the compiler? Also, you must be using dmd for ImportC currently.

What is your build line?

-Steve

On Friday, 28 October 2022 at 18:31:25 UTC, Steven Schveighoffer wrote:

$ cat dub.json
{
	"authors": [
		"Carsten Schlote"
	],
	"copyright": "Copyright © 2022, Carsten Schlote",
	"description": "A minimal D application.",
	"license": "proprietary",
	"name": "importc-app",
	"lflags": [ "-lzstd", "zstd_binding.o" ],
	"preBuildCommands": [ "gcc -g -O0 -c -o zstd_binding.o source/zstd_binding.c"]

$ dub build --compiler=dmd-beta -v
Using dub registry url 'https://code.dlang.org/'
Refreshing local packages (refresh existing: true)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Note: Failed to determine version of package importc-app at .. Assuming ~master.
Refreshing local packages (refresh existing: false)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Refreshing local packages (refresh existing: false)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Generating using build
Configuring dependent importc-app, deps:
Performing "debug" build using dmd-beta for x86_64.
Target '/home2/cschlote/build/dlang/importc-tests/dubbed/.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app' doesn't exist, need rebuild.
importc-app ~master: building configuration "application"...
Running pre-build commands...
Running gcc -g -O0 -c -o zstd_binding.o source/zstd_binding.c
dmd-beta -c -of.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app.o -debug -g -w -version=Have_importc_app -Isource/ source/app.d -vcolumns
Linking...
dmd-beta -of.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app .dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app.o -L--no-as-needed -L-lzstd -Lzstd_binding.o -g
Copying target from /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app to /home2/cschlote/build/dlang/importc-tests/dubbed

Without the preBuildCommands and without passing the resulting object file to the linker, the relatedCode() doesn't exist. And linking is failing.

On Friday, 28 October 2022 at 18:43:21 UTC, Carsten Schlote wrote:

$ cat dub.json
{
	"authors": [
		"Carsten Schlote"
	],
	"copyright": "Copyright © 2022, Carsten Schlote",
	"description": "A minimal D application.",
	"license": "proprietary",
	"name": "importc-app",
	"lflags": [ "-lzstd", "zstd_binding.o" ],
	"preBuildCommands": [ "gcc -g -O0 -c -o zstd_binding.o source/zstd_binding.c"]

Like schveiguy said, what's your build line? dmd should pick up the file if the import has the same name as the file.

On Friday, 28 October 2022 at 18:56:03 UTC, Imperatorn wrote:

What do you mean with 'buildline'? The project is build with dub. See previous posts with outputs from commandline.

DMD does find and import the C file. But it doesn't create code for relatedCode() in the C file. The only way to fix this, is to compile it with a C compiler and use the object as additional linker output.

IMHO this is a bug.

On 10/28/22 2:43 PM, Carsten Schlote wrote:

$ cat dub.json
{
     "authors": [
         "Carsten Schlote"
     ],
     "copyright": "Copyright © 2022, Carsten Schlote",
     "description": "A minimal D application.",
     "license": "proprietary",
     "name": "importc-app",
     "lflags": [ "-lzstd", "zstd_binding.o" ],
     "preBuildCommands": [ "gcc -g -O0 -c -o zstd_binding.o source/zstd_binding.c"]

$ dub build --compiler=dmd-beta -v
Using dub registry url 'https://code.dlang.org/'
Refreshing local packages (refresh existing: true)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Note: Failed to determine version of package importc-app at .. Assuming ~master.
Refreshing local packages (refresh existing: false)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Refreshing local packages (refresh existing: false)...
Looking for local package map at /var/lib/dub/packages/local-packages.json
Looking for local package map at /home/cschlote/.dub/packages/local-packages.json
Looking for local package map at /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/packages/local-packages.json
Generating using build
Configuring dependent importc-app, deps:
Performing "debug" build using dmd-beta for x86_64.
Target '/home2/cschlote/build/dlang/importc-tests/dubbed/.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app' doesn't exist, need rebuild.
importc-app ~master: building configuration "application"...
Running pre-build commands...
Running gcc -g -O0 -c -o zstd_binding.o source/zstd_binding.c
dmd-beta -c -of.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app.o -debug -g -w -version=Have_importc_app -Isource/ source/app.d -vcolumns
Linking...
dmd-beta -of.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app .dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app.o -L--no-as-needed -L-lzstd -Lzstd_binding.o -g
Copying target from /home2/cschlote/build/dlang/importc-tests/dubbed/.dub/build/application-debug-linux.posix-x86_64-dmd_v2.101.0-beta.1-36-ga2865d74fb-9DB8925B9A720899BDD003C68BC85F85/importc-app to /home2/cschlote/build/dlang/importc-tests/dubbed

By default dub does not build C files (as evidenced by your command line). It may not even let you I don't know, but try:

  "sourceFiles" : ["source/zstdc_binding.c"]

-Steve

On Friday, 28 October 2022 at 19:04:21 UTC, Carsten Schlote wrote:

Have you read this?

https://dlang.org/spec/importc.html

On Friday, 28 October 2022 at 19:08:47 UTC, Steven Schveighoffer wrote:

  "sourceFiles" : ["source/zstdc_binding.c"]

Ok, this works. So Dub is not picking any C files by default. Thanks for the hint.

I will spent some time to prepare a fix for Dub, so that C files (only '.c' files, no headers) in detected/configured source directories are picked up as well.