[Issue 21930] New: ICE (illegal instruction) with bad code

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21930

          Issue ID: 21930
           Summary: ICE (illegal instruction) with bad code
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: code.viator at gmail.com

dustmitted code

```
import std : enforce, getSymbolsByUDA, readText;
Token string;
alias C(X) = getSymbolsByUDA!(__traits(parent, X), X);
enum A;
struct U { static foreach (T; C!A) {} }
class R { this(string) { } }
@system main() { new R; }
```

output on dmd 2.096.1
```
app.d(2): Error: undefined identifier `Token`
app.d(7): Error: function `D main` must return `int` or `void`
fish: “dmd app.d” terminated by signal SIGILL (Illegal instruction)
```

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