[flang] Missing diagnostic on deferred length parameter being used in type-spec of an ALLOCATE statement

[DanielCChen]

Consider the following code:

implicit none
character(:), allocatable  :: char
allocate (character(:)::char)
end

Flang doesn't diagnose the incorrect usage of the type-spec that has deferred length parameters.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following code: ``` implicit none character(:), allocatable :: char allocate (character(:)::char) end ```

Flang doesn't diagnose the incorrect usage of the type-spec that has deferred length parameters.

[eugeneepshteyn]

Indeed. Instead of the diagnostics, flang goes into lowering, which then goes into an infinite recursion and crashes.