On 2018-04-29 16:42, dd886k wrote:
Hello!
This is my first time posting, so do feel free to correct me and this post.
I started writing in D around Q2 2017 and recently been re-writing some
of my projects as betterC (entirely!).
I noticed something weird. It started with DMD 2.074.0 and it's still an
issue for me in DMD 2.079.1 (and any other compiler really).
Consider this piece:
```
import core.stdc.stdio;
extern(C) void main() {
printf("a");
}
```
It compiles and runs absolutely wonderful (OMF, MSCOFF, ELF, etc.). No
issues.
Now consider this piece:
```
import core.stdc.stdio;
extern(C) void main() {
putchar('a');
}
```
Oops, `Error 42: Symbol Undefined
__D4core4stdc5stdio7putcharFNbNiNeiZi`! To my surprise, `putchar` is
extern'd as D in druntime/src/core/stdc/stdio.d, and I find that _really
silly_.
Which means `putchar`, during linking, is affected for linking every
single C runtime out there, and the only reason I can think of is to
easily integrate it with D in general, which in my opinion, is not
necessarily needed since the D people (not meant as an insult) promotes
betterC as a stand-alone option.
On Windows, stdin, stdout, and stderr are affected when using -m32mscoff
and -m64 (and obviously, LDC) because under CRuntime_Microsoft, std* are
defined as `shared`.
I'm aware that an easy solution would be defining a version (D_betterC)
section.
Will I do a Pull Request? Unfortunately no, I fear I'll abandon mid-way
through. It's easier to advise the forums and let an actual professional
integrate the fix.
If you have other suggestions, I'm all ears.
Looks like "putchar" is inlined [1]. That means the "putchar" you're
referencing is not the one in the C standard library but it's
implemented in druntime. That means you need to link with
druntime/phobos, it's not enough to link with the C standard library.
I don't know why it was done this way. Perhaps it's just a macro on some
platforms.
[1]
https://github.com/dlang/druntime/blob/master/src/core/stdc/stdio.d#L1289
--
/Jacob Carlborg
