Internal error if trying to assign a unit var of unit type with struct init

[bbannier]

If I try to assign to a unit var which is of unit type with struct init syntax I hit an internal error.

$ spicy-config --version
1.6.0-dev.55 (851ec8b9)

$ cat bla.spicy
module bla;

type X = unit {
	x: uint8;
};

public type Y = unit {
	var x: X;
	y: uint8 { self.x = [$x = $$]; }
};

$ spicyc -j bla.spicy
[internal-error] bla.spicy:9:22: ctor spicy::ctor::Unit failed to compile

--- Aborting
# 0   libhilti.dylib                      0x000000010f1103a6 _ZN5hilti2rt9BacktraceC1Ev + 166
# 1   libhilti.dylib                      0x000000010eae29db _ZN5hilti4util20abort_with_backtraceEv + 139
# 2   libhilti.dylib                      0x000000010eadbf67 _ZN5hilti6Logger13internalErrorERKNSt3__112basic_stringIcNS1_11char_traitsIcEENS1_9allocatorIcEEEERKNS_8LocationE + 55
# 3   libhilti.dylib                      0x000000010eb185c5 _ZN5hilti6Logger13internalErrorINS_4ctor6detail4CtorELPv0EEEvNSt3__112basic_stringIcNS6_11char_traitsIcEENS6_9allocatorIcEEEERKT_ + 149
# 4   libhilti.dylib                      0x000000010eb1842c _ZN5hilti6detail7CodeGen7compileERKNS_4ctor6detail4CtorEb + 700
# 5   libhilti.dylib                      0x000000010eb2762f _ZN5hilti6detail7visitor11do_dispatchINS0_3cxx10ExpressionENS_10expression6detail10ExpressionEN12_GLOBAL__N_17VisitorENS1_8IteratorINS_4NodeELNS1_5OrderE0ELb0EEEEENSt3__111conditionalIXsr3stdE9is_void_vIT_EEbNSE_8optionalISG_EEE4typeERT0_RT1_RNT2_8PositionERb + 879
# 6   libhilti.dylib                      0x000000010eb262b4 _ZN5hilti6detail7CodeGen7compileERKNS_10expression6detail10ExpressionEb + 2196
# 7   libhilti.dylib                      0x000000010eb28b19 _ZN12_GLOBAL__N_17VisitorclERKN5hilti10expression7CoercedE + 57
# 8   libhilti.dylib                      0x000000010eb275f8 _ZN5hilti6detail7visitor11do_dispatchINS0_3cxx10ExpressionENS_10expression6detail10ExpressionEN12_GLOBAL__N_17VisitorENS1_8IteratorINS_4NodeELNS1_5OrderE0ELb0EEEEENSt3__111conditionalIXsr3stdE9is_void_vIT_EEbNSE_8optionalISG_EEE4typeERT0_RT1_RNT2_8PositionERb + 824
# 9   libhilti.dylib                      0x000000010eb262b4 _ZN5hilti6detail7CodeGen7compileERKNS_10expression6detail10ExpressionEb + 2196
# 10  libhilti.dylib                      0x000000010eb27e4a _ZN12_GLOBAL__N_17VisitorclERKN5hilti10expression6AssignE + 90
# 11  libhilti.dylib                      0x000000010eb275b0 _ZN5hilti6detail7visitor11do_dispatchINS0_3cxx10ExpressionENS_10expression6detail10ExpressionEN12_GLOBAL__N_17VisitorENS1_8IteratorINS_4NodeELNS1_5OrderE0ELb0EEEEENSt3__111conditionalIXsr3stdE9is_void_vIT_EEbNSE_8optionalISG_EEE4typeERT0_RT1_RNT2_8PositionERb + 752
# 12  libhilti.dylib                      0x000000010eb262b4 _ZN5hilti6detail7CodeGen7compileERKNS_10expression6detail10ExpressionEb + 2196
# 13  libhilti.dylib                      0x000000010eb53ebf _ZN5hilti6detail7visitor11do_dispatchIvNS_9statement6detail9StatementEN12_GLOBAL__N_17VisitorENS1_8IteratorINS_4NodeELNS1_5OrderE0ELb0EEEEENSt3__111conditionalIXsr3stdE9is_void_vIT_EEbNSC_8optionalISE_EEE4typeERT0_RT1_RNT2_8PositionERb + 6879
# 14  libhilti.dylib                      0x000000010eb4e290 _ZN5hilti6detail7visitor7VisitorIvN12_GLOBAL__N_17VisitorENS_4NodeELNS1_5OrderE0EE8dispatchERKS5_ + 2928
# 15  libhilti.dylib                      0x000000010eb5718a _ZN12_GLOBAL__N_17VisitorclERKN5hilti9statement5BlockE + 1066
# 16  libhilti.dylib                      0x000000010eb537aa _ZN5hilti6detail7visitor11do_dispatchIvNS_9statement6detail9StatementEN12_GLOBAL__N_17VisitorENS1_8IteratorINS_4NodeELNS1_5OrderE0ELb0EEEEENSt3__111conditionalIXsr3stdE9is_void_vIT_EEbNSC_8optionalISE_EEE4typeERT0_RT1_RNT2_8PositionERb + 5066
# 17  libhilti.dylib                      0x000000010eb4e290 _ZN5hilti6detail7visitor7VisitorIvN12_GLOBAL__N_17VisitorENS_4NodeELNS1_5OrderE0EE8dispatchERKS5_ + 2928
# 18  libhilti.dylib                      0x000000010eb4d2f1 _ZN5hilti6detail7CodeGen7compileERKNS_9statement6detail9StatementEPNS0_3cxx5BlockE + 465
# 19  libhilti.dylib                      0x000000010eaf183b _ZN12_GLOBAL__N_17VisitorclERKN5hilti11declaration8FunctionENS1_7visitor8PositionIRNS1_4NodeEEE + 2571
# 20  libhilti.dylib                      0x000000010eaea817 _ZN5hilti6detail7visitor7VisitorIvN12_GLOBAL__N_17VisitorENS_4NodeELNS1_5OrderE0EE8dispatchERKS5_ + 1671
# 21  libhilti.dylib                      0x000000010eae976b _ZN5hilti6detail7CodeGen13compileModuleERNS_4NodeEPNS_4UnitEb + 523
# 22  libhilti.dylib                      0x000000010ec8147d _ZN5hilti4Unit7codegenEv + 957
# 23  libhilti.dylib                      0x000000010ec2e44f _ZN5hilti6Driver13_codegenUnitsEv + 1087
# 24  libhilti.dylib                      0x000000010ec2fa35 _ZN5hilti6Driver12compileUnitsEv + 2453
# 25  libhilti.dylib                      0x000000010ec3034d _ZN5hilti6Driver7compileEv + 45
# 26  libhilti.dylib                      0x000000010ec2fec9 _ZN5hilti6Driver3runEv + 185
# 27  spicyc                              0x000000010cc5de97 main + 311
# 28  dyld                                0x00000001176ac52e start + 462

[bbannier]

Looks like this never worked. We added support for initializing units with struct init syntax in ea85cd7 (#1145); before that this code was rejected, after that commit we trigger the interal error.