From f9f16b9f74b767ca799a82f25be66a5fed25756d Mon Sep 17 00:00:00 2001 From: Harald Anlauf Date: Sun, 2 Mar 2025 22:20:28 +0100 Subject: Fortran: reject empty derived type with bind(C) attribute [PR101577] PR fortran/101577 gcc/fortran/ChangeLog: * symbol.cc (verify_bind_c_derived_type): Generate error message for derived type with no components in standard conformance mode, indicating that this is a GNU extension. gcc/testsuite/ChangeLog: * gfortran.dg/empty_derived_type.f90: Adjust dg-options. * gfortran.dg/empty_derived_type_2.f90: New test. --- gcc/fortran/symbol.cc | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) (limited to 'gcc/fortran') diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc index c689481..81aa81d 100644 --- a/gcc/fortran/symbol.cc +++ b/gcc/fortran/symbol.cc @@ -4624,12 +4624,29 @@ verify_bind_c_derived_type (gfc_symbol *derived_sym) entity may be defined by means of C and the Fortran entity is said to be interoperable with the C entity. There does not have to be such an interoperating C entity." + + However, later discussion on the J3 mailing list + (https://mailman.j3-fortran.org/pipermail/j3/2021-July/013190.html) + found this to be a defect, and Fortran 2018 added in section 18.3.4 + the following constraint: + "C1805: A derived type with the BIND attribute shall have at least one + component." + + We thus allow empty derived types only as GNU extension while giving a + warning by default, or reject empty types in standard conformance mode. */ if (curr_comp == NULL) { - gfc_warning (0, "Derived type %qs with BIND(C) attribute at %L is empty, " - "and may be inaccessible by the C companion processor", - derived_sym->name, &(derived_sym->declared_at)); + if (!gfc_notify_std (GFC_STD_GNU, "Derived type %qs with BIND(C) " + "attribute at %L has no components", + derived_sym->name, &(derived_sym->declared_at))) + return false; + else if (!pedantic) + /* Generally emit warning, but not twice if -pedantic is given. */ + gfc_warning (0, "Derived type %qs with BIND(C) attribute at %L " + "is empty, and may be inaccessible by the C " + "companion processor", + derived_sym->name, &(derived_sym->declared_at)); derived_sym->ts.is_c_interop = 1; derived_sym->attr.is_bind_c = 1; return true; -- cgit v1.1