My code is this

struct ConstValueIndex
{
    ushort const_value_index;
}

struct EnumConstValue
{
    ushort type_name_index;
    ushort const_name_index;
}

struct ClassInfoIndex
{
    ushort class_info_index;
}

struct AnnotationValue
{
    Annotation annotation_value;
}

struct ArrayValue
{
    ElementValue[] values;
}

alias ElementValue = SumType!(
    ConstValueIndex,
    EnumConstValue,
    ClassInfoIndex,
    AnnotationValue,
    ArrayValue,
);

It results in quite a cryptic error

Error: unknown, please file report on issues.dlang.org
/usr/include/dlang/dmd/std/meta.d(632,42): Error: template instance `std.sumtype.matchImpl!(Flag.yes, destroyIfOwner).matchImpl!(SumType!(ConstValueIndex, EnumConstValue, ClassInfoIndex, AnnotationValue, ArrayValue)).matchImpl.valueTypes!4LU.fun!0LU` error instantiating
/usr/include/dlang/dmd/std/sumtype.d(1931,32):        instantiated from here: `Map!(getType, 0LU)`
/usr/include/dlang/dmd/std/sumtype.d(1967,51):        instantiated from here: `valueTypes!4LU`
/usr/include/dlang/dmd/std/sumtype.d(1649,52):        instantiated from here: `matchImpl!(SumType!(ConstValueIndex, EnumConstValue, ClassInfoIndex, AnnotationValue, ArrayValue))`
/usr/include/dlang/dmd/std/sumtype.d(752,17):        instantiated from here: `match!(SumType!(ConstValueIndex, EnumConstValue, ClassInfoIndex, AnnotationValue, ArrayValue))`
source/parser/definitions/attributes.d(262,22):        instantiated from here: `SumType!(ConstValueIndex, EnumConstValue, ClassInfoIndex, AnnotationValue, ArrayValue)`
/usr/include/dlang/dmd/std/sumtype.d(1985,13):        while evaluating: `static assert((__error)(hid))`
Error /usr/bin/dmd failed with exit code 1.

(I tried all three compilers, happens in all)

Should I make an issue for this as it suggests?

On Tuesday, 30 May 2023 at 08:42:38 UTC, Gimbles wrote:

struct ConstValueIndex
{
    ushort const_value_index;
}

[...]

https://gist.github.com/run-dlang/5dd783c750f04329405af1b1e4a83cde

Here's the full source

On Tuesday, 30 May 2023 at 08:42:38 UTC, Gimbles wrote:

100% yes. This an "Internal Compiler Error" (ICE), meaning the compiler has crashed.
Open a ticket here : https://issues.dlang.org/show_bug.cgi?id=23935

with a title like "ICE caused by std.sumtype", and paste the test case.

On Tuesday, 30 May 2023 at 08:47:16 UTC, user456 wrote:

Alright, thanks! Opening a ticket :)

On Tuesday, 30 May 2023 at 08:54:33 UTC, Gimbles wrote:

https://issues.dlang.org/show_bug.cgi?id=23945

For reference ^^^