tokiwa-software
Inheritance using qualified names results in stack overflow/segfault
I want to fix the ambiguous naming in flang_dev/content/tutorial/examples/demo1_unit_types.fz by using qualified names.
demo1_unit_types is
Monoid1 (T type) ref is
zero T is abstract
add (a, b T) T is abstract
accum (T type, a array T, m demo1_unit_types.Monoid1 T) T is
for
res := m.zero, m.add res x
x in a
else
res
sum : Monoid1 i32 is
zero => 0
add (a, b i32) => a + b
product : Monoid1 i32 is
zero => 1
add (a, b i32) => a * b
i32array := [ 23, 345 , 3, 1, 3 ]
totalSum := accum i32 i32array sum
totalProduct := accum i32 i32array product
works, but once you change the Monoid1 into demo1_unit_types.Monoid1 in the inheritance of sum and product, there is a stack overflow in the interpreter and a segfault in the C backend-produced binary.
hm yes, I agree this can be intended behavior. But would this be different if one was using demo1_unit_types.this.Monoid1? This is what is suggested by the compiler, but when actually doing so, the parser complains about this in the function declaration and in inheritance, so
accum (T type, a array T, m demo1_unit_types.this.Monoid1 T) T is
...
and
sum : demo1_unit_types.this.Monoid1 i32 is
...
is not possible. Perhaps it should be, though?
With #1209, Monoid1 is now automatically expanded to demo1_unit_types.this.Monoid1, so the example give an error now
> ./build/bin/fz ex_1201.fz
/home/fridi/fuzion/work/ex_1201.fz:22:38: error 1: Incompatible types when passing argument in a call
totalSum := accum i32 i32array sum
-------------------------------------^
Actual type for argument #2 'm' does not match expected type.
In call to : 'demo1_unit_types.accum'
expected formal type: 'demo1_unit_types.Monoid1 i32'
actual type found : 'demo1_unit_types.this.type.ref sum'
assignable to : 'Any',
'demo1_unit_types.this.type.Monoid1 i32',
'demo1_unit_types.this.type.ref sum'
for value assigned : 'box(demo1_unit_types.this.sum)'
To solve this, you could change the type of the target 'm' to 'demo1_unit_types.this.type.ref sum' or convert the type of the assigned value to 'demo1_unit_types.Monoid1 i32'.
/home/fridi/fuzion/work/ex_1201.fz:23:38: error 2: Incompatible types when passing argument in a call
totalProduct := accum i32 i32array product
-------------------------------------^
Actual type for argument #2 'm' does not match expected type.
In call to : 'demo1_unit_types.accum'
expected formal type: 'demo1_unit_types.Monoid1 i32'
actual type found : 'demo1_unit_types.this.type.ref product'
assignable to : 'Any',
'demo1_unit_types.this.type.Monoid1 i32',
'demo1_unit_types.this.type.ref product'
for value assigned : 'box(demo1_unit_types.this.product)'
To solve this, you could change the type of the target 'm' to 'demo1_unit_types.this.type.ref product' or convert the type of the assigned value to 'demo1_unit_types.Monoid1 i32'.
2 errors.
fixing this by replacing m demo1_unit_types.Monoid1 T in the examples by m Monoid1 T
demo1_unit_types is
Monoid1 (T type) ref is
zero T is abstract
add (a, b T) T is abstract
accum (T type, a array T, m Monoid1 T) T is
for
res := m.zero, m.add res x
x in a
else
res
sum : Monoid1 i32 is
zero => 0
add (a, b i32) => a + b
product : Monoid1 i32 is
zero => 1
add (a, b i32) => a * b
i32array := [ 23, 345 , 3, 1, 3 ]
totalSum := accum i32 i32array sum
totalProduct := accum i32 i32array product
works:
> ./build/bin/fz ex_1201a.fz
>
Yes, this works. I changed this to Monoid1 because this is a temporary workaround. The problem reappears when it's called Monoid and you get an ambiguous name error. Which should be fixed by using demo1_unit_types.this.Monoid, but this does not work.
@fridis another ping because this is related to the examples in flang_dev.