Hello,

I'm working on a C++ project requiring an XML parser. I decided to make it in D so I could easily parse at run-time or compile-time as I wish.

As our project uses a gcc tool-chain, I naturally use GDC (GCC 9.4.0).

But I have a few problems with D, linking with it, trying to use better-C and CTFE, etc.

Here's a reduced sample of one of my problems:

parser.d

extern(C) int* ct_parse()
{
    int* a = new int(42);
    return a;
}

main.cpp

extern "C" const int* ct_parse();

int main(int argc, char ** argv)
{
    return *ct_parse();
}

Compiling/linking using the following command-lines:

gcc -c parser.d -o parser.o
gcc -std=c++17 -c main.cpp -o main.o
gcc main.o parser.o -lstdc++ -lgphobos -lgdruntime -o test

It seg-faults...

Here's the output of gdb:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff777858a in gc_qalloc () from /usr/lib/x86_64-linux-gnu/libgdruntime.so.76

Does anyone have any idea what's going on?

(if I just compile a single D file with "int main() { int* a = new int(42); return *a; }", it works as intended.)

On Tuesday, 26 April 2022 at 10:23:15 UTC, Claude wrote:

Hello,

<%--SNIP--%>

The new keyword requests the druntime GC to allocate memory, however you haven't initialized the D run-time in your program.

main.cpp

extern "C" int rt_init();
extern "C" const int* ct_parse();

int main(int argc, char ** argv)
{
    rt_init();
    return *ct_parse();
}

On Tuesday, 26 April 2022 at 10:23:15 UTC, Claude wrote:

Just to make it clear, it seg-faults at run-time (not at compilation or link time) when I launch the executable "test".

On Tuesday, 26 April 2022 at 10:29:39 UTC, Iain Buclaw wrote:

extern "C" int rt_init();
extern "C" const int* ct_parse();

int main(int argc, char ** argv)
{
    rt_init();
    return *ct_parse();
}

Ok, thanks!
I should have suspected something like this.

PS :
I use

ldc2 --gcc=cc ,
cc -v : clang version 11.0.1

On Tuesday, 26 April 2022 at 12:49:21 UTC, Alain De Vos wrote:

ldc2 --gcc=cc ,
cc -v : clang version 11.0.1

We only have gcc in our toolchain (we target an ARM-based embedded system).

I also encountered problems while I was trying to use CTFE only functions (using betterC so I don't have to link phobos/D-runtime).

However, if those functions use the GC for instance (like appending a dynamic-array), it will require me to link D-runtime, whereas I only use them at compile-time. So I'm a bit confused... I'll try and get more information and reduce a code sample.

On Tuesday, 26 April 2022 at 13:36:19 UTC, Claude wrote:

dont't use new if you mean using betterC, new is based on GC. with betterC, you should using malloc/free

reference info: https://dlang.org/spec/cpp_interface.html#memory-allocation