Substate instantiation issues in gcc/clang

[tralamazza]

Expected Behavior

• Composite state machines should not require a dummy member variable
• Code compiles in both Gcc and Clang.

Actual Behavior

!Expected Behavior

Steps to Reproduce the Problem

1. https://cpp.godbolt.org/z/MqW1dM6GM

[Line 42] There are 2 sub state machines, one Good another Bad. Good always works and the only difference between them is a member variable.

[Line 16] If Bad defines a default ctor then the error goes away (only in Clang).

[Line 31] If the guard in the Composite state machine uses a copy argument instead of a reference (const or not) then the error also disappears.

Specifications

• Version: master
• Platform: godbolt (linux)
• Subsystem:

[tralamazza]

should this requirement be in the docs? @kris-jusiak