[Bug d/95173] New: [D] ICE on some architecture targets when trying to use unknown attribute

[witold.baryluk+gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95173

            Bug ID: 95173
           Summary: [D] ICE on some architecture targets when trying to
                    use unknown attribute
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: witold.baryluk+gcc at gmail dot com
  Target Milestone: ---

https://explore.dgnu.org/z/bseyKQ


```
import gcc.attribute;

@attribute("foo")
void f() {}
```

This code crashes the compiler when compiling for alpha-linux-gnu, sparc64-elf,
hppa-linux-gnu, mmix-knuth-mmixware, pdp11-aout, lm32-elf and possibly more
with variations. (But sparc64-sun-solaris2.11 for examples works fine).

The code compiles correctly for known attributes.

Other targets do compile without a crash, just with a warning about unknown
attribute. That is correct behaviour.