https://issues.dlang.org/show_bug.cgi?id=23699

          Issue ID: 23699
           Summary: compilable/test22807.c:10:10: error: unknown type name
                    ‘OldFashionedHeader’
           Product: D
           Version: D2
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: ibuclaw@gdcproject.org

When compiling the test with `gcc -std=c11 -fsyntax-only`

compilable/test22807.c:10:10: error: unknown type name ‘OldFashionedHeader’
   10 | int peek(OldFashionedHeader *head){
      |          ^~~~~~~~~~~~~~~~~~


Test content:
```
struct OldFashionedHeader {
    int n; // number of entries in buff
    char buff[1];
};


int peek(OldFashionedHeader *head){
    if(head->n < 2)
        return 0;
    return head->buff[1]; // do not give array bounds error
}
```

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