[Issue 24042] New: ImportC: Error: no definition for static 'function'

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24042

          Issue ID: 24042
           Summary: ImportC: Error: no definition for static 'function'
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: ibuclaw at gdcproject.org

```
// cfile.c
static int staticfunc() { return 0; }

// dmodule.d
import cfile;
int main() { return staticfunc(); }
```

Compiler IMO correctly issues an error
---
Error: no definition for static staticfunc
---
However, besides the obvious lack of source file/line information, it looks
like the error occurs (in the back-end) because the symbol is missing from
compilation, rather than just disallowing the referencing of C static symbols
from D.

Even if both D and C sources are compiled in the same CU, I find it
questionable to allow referencing C static symbols from D. But that can be
debated out here.

For reference, this is where in dmd backend the error comes from.
```
// In backend/cgen.d
if (f.sym.Sseg == UNKNOWN)
{
    printf("Error: no definition for static %s\n", prettyident(f.sym));
        // no definition found for static
    err_exit(); // BUG: do better
}
```

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