[Bug c++/90396] New: error while using sizeof in [[assert]]: internal compiler error: in gimplify_expr, at gimplify.c:13199

[moussu.robin at pm dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90396

            Bug ID: 90396
           Summary: error while using sizeof in [[assert]]: internal
                    compiler error: in gimplify_expr, at gimplify.c:13199
           Product: gcc
           Version: 9.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: moussu.robin at pm dot me
  Target Milestone: ---

Test it directly on https://godbolt.org/z/IsXG2E

Version of the compiler: 9.0.1 (contracts branch)

The following line doesn't compile:
```
[[assert: sizeof(decltype([]{})) == sizeof(nullptr)]];
```

<source>:5:15: internal compiler error: in gimplify_expr, at gimplify.c:13199
    5 |     [[assert: sizeof(decltype([]{})) == sizeof(nullptr)]];
      |               ^~~~~~~~~~~~~~~~~~~~~~