[rpms/dftd4] rawhide: Add the numerical hessian to dftd4_api

[Susi Lehtola <jussilehtola@fedoraproject.org>]

A new commit has been pushed.

Repo   : rpms/dftd4
Branch : rawhide
Commit : 6bf1f6e380fcb4daac5d37b23b2b60f10cb082e0
Author : Susi Lehtola <jussilehtola@fedoraproject.org>
Date   : 2026-07-29T11:56:45+00:00
Stats  : +25/-0 in 2 file(s)
URL    : https://src.fedoraproject.org/rpms/dftd4/c/6bf1f6e380fcb4daac5d37b23b2b60f10cb082e0?branch=rawhide

Log:
Add the numerical hessian to dftd4_api

---
diff --git a/dftd4-4.2.0-export-numerical-hessian.patch b/dftd4-4.2.0-export-numerical-hessian.patch
new file mode 100644
index 0000000..f853bf1
--- /dev/null
+++ b/dftd4-4.2.0-export-numerical-hessian.patch
@@ -0,0 +1,21 @@
+Export get_numerical_hessian_api from the dftd4_api module.
+
+The module defaults to PRIVATE, and get_numerical_hessian_api is the only
+bind(C) API routine that was never added to a public list. GCC used to emit
+the binding label as a global symbol anyway, but as of gcc 16.1.1-4 the
+unreferenced private module procedure gets dropped/localized during LTO, so
+libdftd4.so no longer exports dftd4_get_numerical_hessian and the C API
+tester fails to link:
+
+  undefined reference to `dftd4_get_numerical_hessian'
+
+--- a/src/dftd4/api.f90
++++ b/src/dftd4/api.f90
+@@ -55,6 +55,7 @@
+    public :: delete_param_api
+
+    public :: get_dispersion_api, get_pairwise_dispersion_api, get_properties_api
++   public :: get_numerical_hessian_api
+
+    !> Namespace for C routines
+    character(len=*), parameter :: namespace = "dftd4_"

diff --git a/dftd4.spec b/dftd4.spec
index 0e9a54b..ad2bdbf 100644
--- a/dftd4.spec
+++ b/dftd4.spec
@@ -5,6 +5,9 @@ Summary:        Generally Applicable Atomic-Charge Dependent London Dispersion C
 License:        LGPL-3.0-or-later
 URL:            https://dftd4.readthedocs.io/
 Source0:        https://github.com/dftd4/dftd4/archive/v%{version}/%{name}-%{version}.tar.gz
+# get_numerical_hessian_api is missing from the public list of the dftd4_api
+# module, so gcc >= 16.1.1-4 drops the dftd4_get_numerical_hessian symbol
+Patch0:         dftd4-4.2.0-export-numerical-hessian.patch
 
 BuildRequires:  meson
 BuildRequires:  gcc-gfortran
@@ -36,6 +39,7 @@ This package contains the Python 3 interface for dftd4.
 
 %prep
 %setup -q
+%patch -P 0 -p 1 -b .numhess
 
 %build
 %ifarch %{ix86}