Fort - Features and Goals

End-user goals

Fast compiles and low memory use
Expressive diagnostics
Modern Fortran support

Utility and applications

Modular library based architecture
Support for building external tools via tooling API
Same ‘BSD’ license as LLVM

Development goals

Following LLVM best practices
Ease of maintenance
Support for all LLVM-supported platforms
Verbose diagnostics
Quick portability
Accepting contributions

Examples

For diagnostics, consider this program:

$ cat init.f90
module i
  integer x, y, z
  parameter (y = 1, x = 3 + y + z)
end module

Note that variable z does not have parameter attribute, and therefore is illegal in parameter initialization.

First, Flang:

$ flang -fsyntax-only init.f90
F90-S-0087-Non-constant expression where constant expression required (init.f90: 3)
  0 inform,   0 warnings,   1 severes, 0 fatal for i

That is literally all the output, at least from version that supports LLVM 5. Second, GNU Fortran:

$ gfortran -fsyntax-only init.f90
init.f90:3:29:

   parameter (y = 1, x = 3 + z)
                             1
Error: Parameter 'z' at (1) has not been declared or is a variable, which does not reduce to a constant expression

And finally the same with Fort:

$ fort -fsyntax-only init.f90
init.f90:3:21: error: parameter 'x' must be initialized by a constant expression
  parameter (y = 1, x = 3 + y + z)
                    ^
init.f90:3:33: note: this expression is not allowed in a constant expression
  parameter (y = 1, x = 3 + y + z)
                                ^