[flang] Remove obsolete TODO

[unterumarmung]

Summary

As the comment tells, the TODO was added because
there was no conversion for abstract results in function types inside GlobalOps.
Since the conversion was added, this TODO is obsolete, so it is removed.

[unterumarmung]

I think there should be a test case that covers that code at least lowers from pre-fir-tree to FIR with some of operations that contain function type with abstract result in fir.global successfully. But I'm having a hard time coming up with the test case for the moment. Because I can imagine only 2 scenarios when we have the operations we need in fir.global:

1. Initialization of a procedure pointer with PARAMETER attribute. The procedure pointer are not supported yet, so it fails earlier than the deleted TODO.
2. I do not know how to describe it, just attach a code snippet below. The polymorphic types are not supported yet, so it fails earlier than the deleted TODO.

module a
    type f
    contains
        procedure foo
    end type f
contains
    function foo(obj) result(bar)
        class(f) :: obj
        character(len=:), allocatable :: bar
        if (.TRUE.) then
            bar = "true"
        else
            bar = "false"
        endif
    end function foo
end module a

Is there any other way to test it?

[unterumarmung]

Rebased

[jeanPerier]

In D130369#3672155, @unterumarmung wrote:

I think there should be a test case that covers that code at least lowers from pre-fir-tree to FIR with some of operations that contain function type with abstract result in fir.global successfully. But I'm having a hard time coming up [...]
Is there any other way to test it?

You can have a test that does not hit the polymorphic TODO if you go with something similar to your option 2., but with a procedure, nopass so that you do not need the class(f) argument.

[unterumarmung]

Rebased & added the test

[unterumarmung]

In D130369#3684206, @jeanPerier wrote:

In D130369#3672155, @unterumarmung wrote:

I think there should be a test case that covers that code at least lowers from pre-fir-tree to FIR with some of operations that contain function type with abstract result in fir.global successfully. But I'm having a hard time coming up [...]
Is there any other way to test it?

You can have a test that does not hit the polymorphic TODO if you go with something similar to your option 2., but with a procedure, nopass so that you do not need the class(f) argument.

Yes, this is a good idea, thank you! Totally forgot about nopass.
Added the test

[unterumarmung]

Rebase

[jeanPerier]

LGTM

[unterumarmung]

Rebased

[unterumarmung]

Rebased

[unterumarmung]

Update parent revision

flang/lib/Lower/ConvertExpr.cpp

if (Fortran::semantics::IsDummy(*symbol)) {
       if (fir::isCharacterProcedureTuple(funcPtr.getType(),
                                          /*acceptRawFunc=*/false))
         std::tie(funcPtr, funcPtrResultLength) =
             fir::factory::extractCharacterProcedureTuple(builder, loc, funcPtr);
     } else {
       std::string name = converter.mangleName(*symbol);
       mlir::func::FuncOp func =
           Fortran::lower::getOrDeclareFunction(name, proc, converter);
-      // Abstract results require later rewrite of the function type.
-      // This currently does not happen inside GloalOps, causing LLVM
-      // IR verification failure. This helper is only here to catch these
-      // cases and emit a TODOs for now.
-      if (inInitializer && fir::hasAbstractResult(func.getFunctionType()))
-        TODO(converter.genLocation(symbol->name()),
-             "static description of non trivial procedure bindings");
       funcPtr = builder.create<fir::AddrOfOp>(loc, func.getFunctionType(),
                                               builder.getSymbolRefAttr(name));
     }
     if (Fortran::lower::mustPassLengthWithDummyProcedure(proc, converter)) {
       // The result length, if available here, must be propagated along the
       // procedure address so that call sites where the result length is assumed
       // can retrieve the length.
       Fortran::evaluate::DynamicType resultType = proc.GetType().value();

flang/test/Fir/non-trivial-procedure-binding-description.f90

+! RUN: %flang_fc1 -emit-mlir %s -o - | FileCheck %s --check-prefix=BEFORE
+! RUN: %flang_fc1 -emit-mlir %s -o - | fir-opt --abstract-result-on-global-opt | FileCheck %s --check-prefix=AFTER
+module a
+  type f
+  contains
+! BEFORE: fir.address_of(@_QMaPfoo) : (!fir.ref<!fir.type<_QMaTf>>) -> !fir.box<!fir.heap<!fir.char<1,?>>>
+! AFTER: [[ADDRESS:%.*]] = fir.address_of(@_QMaPfoo) : (!fir.ref<!fir.box<!fir.heap<!fir.char<1,?>>>>, !fir.ref<!fir.type<_QMaTf>>) -> ()
+! AFTER: fir.convert [[ADDRESS]] : ((!fir.ref<!fir.box<!fir.heap<!fir.char<1,?>>>>, !fir.ref<!fir.type<_QMaTf>>) -> ()) -> ((!fir.ref<!fir.type<_QMaTf>>) -> !fir.box<!fir.heap<!fir.char<1,?>>>)
+! AFTER-NOT: fir.address_of(@_QMaPfoo) : (!fir.ref<!fir.type<_QMaTf>>) -> !fir.box<!fir.heap<!fir.char<1,?>>>
+    procedure, nopass :: foo
+  end type f
+contains
+  function foo(obj) result(bar)
+    type(f) :: obj
+    character(len=:), allocatable :: bar
+
+    if (.TRUE.) then
+      bar = "true"
+    else
+      bar = "false"
+    endif
+  end function foo
+end module a
+
+program main
+  use a
+
+  type(f) :: obj 
+  print *, obj%foo(obj)
+end program