[flang] Default initialization failure

[DanielCChen]

Consider the following code:

   type Base
      integer :: i /-1/
   end type

   type, extends(Base) :: Child
      integer :: j /-3/
   end type

   type(Child) :: c1 = Child(1000)
   print*, c1%i
   print*, c1%j
end

Flang complains:

./t.f:10:24: error: Structure constructor lacks a value for component 'j'
     type(Child) :: c1 = Child(1000)
                         ^^^^^
./t.f:7:18: Declaration of 'j'
        integer :: j /-3/
                   ^

It works if I use integer :: i = -1 instead.
It also works if I use "empty" constructor as type(child) :: c1

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following code: ```

type Base
integer :: i /-1/
end type

type, extends(Base) :: Child
integer :: j /-3/
end type

type(Child) :: c1 = Child(1000)
print*, c1%i
print*, c1%j
end

Flang complains:

./t.f:10:24: error: Structure constructor lacks a value for component 'j'
type(Child) :: c1 = Child(1000)
^^^^^
./t.f:7:18: Declaration of 'j'
integer :: j /-3/
^

It works if I use `integer :: i = -1` instead. 
It also works if I use "empty" constructor as `type(child) :: c1`
</details>

[akuhlens]

This isn't conforming fortran and I don't know of a compiler besides xlf that supports this syntax for default initialization of components. I think the issue here is that we don't outright reject this syntax.

[kkwli]

For the initialization with /.../ syntax, I think it is an extension in flang too.

Initialization in type declaration statements using /values/

https://flang.llvm.org/docs/Extensions.html

[akuhlens]

Yep! I was wrong. Looks like the issue is deeper than I initially thought.