https://issues.dlang.org/show_bug.cgi?id=24291

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
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                 CC|                            |bugzilla@digitalmars.com

--- Comment #1 from Walter Bright <bugzilla@digitalmars.com> ---
Can you please try reducing this to the offending few lines of code? I don't have src/core/vm.c, and probably not exactly the same .h files you're using, either.

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https://issues.dlang.org/show_bug.cgi?id=24291

anonymous4 <dfj1esp02@sneakemail.com> changed:

           What    |Removed                     |Added
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                URL|                            |https://forum.dlang.org/pos
                   |                            |t/woaixickqgqvfsazutex@foru
                   |                            |m.dlang.org

--- Comment #2 from anonymous4 <dfj1esp02@sneakemail.com> ---
>From forum discussion:
---
One Problem with Janet is that it uses computed gotos which is a
gcc extension
The code it complains about looks like:
```C
     /* opcode -> label lookup if using clang/GCC */
#ifdef JANET_USE_COMPUTED_GOTOS
     static void *op_lookup[255] = {
         &&label_JOP_NOOP,
         &&label_JOP_ERROR,
```

As you can see &&label is not valid C11.
Which is what the import C parser complains about.
---

Maybe something can be done there with that JANET_USE_COMPUTED_GOTOS define.

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https://issues.dlang.org/show_bug.cgi?id=24291

--- Comment #3 from anonymous4 <dfj1esp02@sneakemail.com> ---
clang provides __has_extension function for such checks, but doesn't document computed gotos.

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https://issues.dlang.org/show_bug.cgi?id=24291

--- Comment #4 from Walter Bright <bugzilla@digitalmars.com> ---
If you can post the definition of JANET_USE_COMPUTED_GOTOS we can see about making it evaluate to false.

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https://issues.dlang.org/show_bug.cgi?id=24291

Daniel <wyrlon@gmx.net> changed:

           What    |Removed                     |Added
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                 CC|                            |wyrlon@gmx.net

--- Comment #5 from Daniel <wyrlon@gmx.net> ---
#if defined(__GNUC__) && !defined(__EMSCRIPTEN__)
#define JANET_USE_COMPUTED_GOTOS
#endif

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https://issues.dlang.org/show_bug.cgi?id=24291

--- Comment #6 from anonymous4 <dfj1esp02@sneakemail.com> ---
Oh, __GNUC__ means gnu C dialect?

--- cjanet.c ---
#undef __GNUC__
#include "janet.c"
---
dmd -P-I. -c cjanet.c

Does this work?

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https://issues.dlang.org/show_bug.cgi?id=24291

--- Comment #7 from Walter Bright <bugzilla@digitalmars.com> ---
(In reply to Daniel from comment #5)
> #if defined(__GNUC__) && !defined(__EMSCRIPTEN__)
> #define JANET_USE_COMPUTED_GOTOS
> #endif

Unfortunately, if dmd #define'd __EMSCRIPTEN__ it would likely turn on some other nutburger extensions ImportC doesn't support. importc.h cannot #undef JANET_USE_COMPUTED_GOTOS because importc.h is #include'd first.

Turning off __GNUC__ will cause all kinds of other problems.

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https://issues.dlang.org/show_bug.cgi?id=24291

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Hardware|x86_64                      |All
            Summary|ImportC: cannot compile     |ImportC: support computed
                   |janet.c                     |goto
                 OS|Linux                       |All

--- Comment #8 from Walter Bright <bugzilla@digitalmars.com> ---
I'm going to leave this as an enhancement request for computed goto. If there are other ImportC problems with janet, please post a bugzilla issue about it!

https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html

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https://issues.dlang.org/show_bug.cgi?id=24291

--- Comment #9 from Walter Bright <bugzilla@digitalmars.com> ---
At least I can get you a better error message:

https://github.com/dlang/dmd/pull/15967

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