gfortran compiles the following source without error: subroutine foo(bar) implicit none (external) call bar(1) end subroutine foo However my understanding is that it should reject it, because "bar" is an implicit dummy procedure, which is forbidden by "implicit none (external)". Note that this is not the same issue as Bug 100972, which was not about dummy procedures.
Confirmed. 8.7 IMPLICIT statement ... An IMPLICIT NONE statement can indicate ..., or that external and dummy procedures need to be explicitly given the EXTERNAL attribute. 'bar' is clearly a dummy procedure, so 'externa bar' is required.
This patch catches the need for an external attribute. diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc index 6e42397c2ea..1e19712b413 100644 --- a/gcc/fortran/resolve.cc +++ b/gcc/fortran/resolve.cc @@ -3818,6 +3818,16 @@ resolve_call (gfc_code *c) /* Resume assumed_size checking. */ need_full_assumed_size--; + /* If 'implicit none (external)' and the symbol is a dummy argument, + check for an 'external' attribute. */ + if (csym->ns->has_implicit_none_export + && csym->attr.external == 0 && csym->attr.dummy == 1) + { + gfc_error ("Dummy procedure %qs at %C requires an EXTERNAL attribute", + csym->name); + return false; + } + /* If external, check for usage. */ if (csym && is_external_proc (csym)) resolve_global_procedure (csym, &c->loc, 1); A dejagnu-ified testcase. ! { dg-do compile } subroutine foo(bar) implicit none (external) call bar(1) ! { dg-error "requires an EXTERNAL attribute" } end subroutine foo