[Issue 20532] [betterC] methods utilizing stdout cause a segfault

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20532

Dennis <dkorpel at live.nl> changed:

           What    |Removed                     |Added
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                 CC|                            |dkorpel at live.nl

--- Comment #1 from Dennis <dkorpel at live.nl> ---
The problem is that stdout in the Microsoft C runtime is a macro for
__acrt_iob_func(1), which in D is translated as a shared pointer that gets
initialized along with the D runtime: The function `rt.dmain2: rt_init` calls
`init_msvc` in rt/msvc.c where the pointers for stdin, stdout and stderr are
set.

If you have an extern(C) main() (with or without -betterC), the runtime won't
be initialized so you will be calling fprintf with a FILE* that is just null.
putchar is simply a function calling `putc(c,stdout)`, hence the same issue.

The annoying part is that people probably use the FILE pointers from
core.stdc.stdio precisely because their code is translated from C, where one
expects to require no runtime initialization. So the workaround "just
initialize them manually" doesn't help translated C programs from failing with
an unhelpful error code.

I guess the fix would be to make stdout, stderr and stdin functions instead of
globals in version (CRuntime_Microsoft), though that might break existing code
that takes the address of the global variables. I doubt many programs do that
however.

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