contributing: Define the SPDX copyright header convention

COPYING

@@ -4,6 +4,15 @@ The Geographic Resources Analysis and Support System (GRASS)
 Geographic Information System (GIS) is Copyright by members
 of the GRASS Development Team.
 
+Copyright notices in individual source files use SPDX tags, for example:
+
+  SPDX-FileCopyrightText: 1999-2022 Jane Doe
+  SPDX-FileCopyrightText: Other GRASS authors
+  SPDX-License-Identifier: GPL-2.0-or-later
+
+Other GRASS authors denotes the authors of a file who are not named
+individually in it.
+
 This program is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the
 Free Software Foundation; either version 2 of the License, or (at your

doc/development/style_guide.md

@@ -768,12 +768,19 @@ Use the following header in your source code.
 #
 # PURPOSE:   Provide short description of module here...
 #
-# COPYRIGHT: (C) 2024 by John Doe and the GRASS Development Team
-#
+# SPDX-FileCopyrightText: 2024 John Doe
+# SPDX-FileCopyrightText: Other GRASS authors
 # SPDX-License-Identifier: GPL-2.0-or-later
 ##############################################################################
 ```
 
+Each copyright holder gets one `SPDX-FileCopyrightText` line carrying the years
+of their own contributions. Add a line for yourself when you make a substantial
+contribution, the same threshold as an `AUTHOR(S)` entry, and leave other
+people's lines alone. The line `SPDX-FileCopyrightText: Other GRASS authors`
+comes last and covers everyone not named individually; the `COPYING` file
+defines it. The `SPDX-License-Identifier` line follows all copyright lines.
+
 #### Use Standard Options in Interface
 
 GRASS tools must use the GRASS parser to handle its command line parameters. To
@@ -960,8 +967,7 @@ Please use the following docstring template:
 Classes:
  - example::ExampleClass
 
-(C) 2024 by the GRASS Development Team
-
+SPDX-FileCopyrightText: 2024 Other GRASS authors
 SPDX-License-Identifier: GPL-2.0-or-later
 
 @author First Author <first somewhere.com>
@@ -1078,8 +1084,8 @@ original work remains, it must be properly cited.
  * MODULE:       g.foo
  * AUTHOR(S):    John Doe <jdoe at somewhere org>
  * PURPOSE:      Provide short description of module here...
- * COPYRIGHT:    (C) 2010 by John Doe, and the GRASS Development Team
- *
+ * SPDX-FileCopyrightText: 2010 John Doe
+ * SPDX-FileCopyrightText: Other GRASS authors
  * SPDX-License-Identifier: GPL-2.0-or-later
  *
  *****************************************************************************/

general/g.parser/g.parser.html

@@ -565,17 +565,9 @@ <h3>Easy creation of a script</h3>
 # MODULE:       v.what.rast_wrapper
 # AUTHOR(S):    username
 # PURPOSE:      Wrapper for v.what.rast
-# COPYRIGHT:    (C) 2017 by username, and the GRASS Development Team
-#
-#  This program is free software; you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
+# SPDX-FileCopyrightText: 2017 username
+# SPDX-FileCopyrightText: Other GRASS authors
+# SPDX-License-Identifier: GPL-2.0-or-later
 #
 ############################################################################
 

general/g.parser/g.parser.md

@@ -556,17 +556,9 @@ v.what.rast --script
 # MODULE:       v.what.rast_wrapper
 # AUTHOR(S):    username
 # PURPOSE:      Wrapper for v.what.rast
-# COPYRIGHT:    (C) 2017 by username, and the GRASS Development Team
-#
-#  This program is free software; you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
+# SPDX-FileCopyrightText: 2017 username
+# SPDX-FileCopyrightText: Other GRASS authors
+# SPDX-License-Identifier: GPL-2.0-or-later
 #
 ############################################################################
 

general/g.parser/tests/g_parser_script_test.py

@@ -0,0 +1,63 @@
+"""Tests of the header emitted by g.parser --script
+
+The header is produced by G__script() in lib/gis/parser_script.c.
+"""
+
+import os
+import re
+
+import pytest
+
+import grass.script as gs
+from grass.tools import Tools
+
+TOOL = "v.what.rast"
+
+
+@pytest.fixture(scope="module")
+def session(tmp_path_factory):
+    """Set up a GRASS session for the tests."""
+    tmp_path = tmp_path_factory.mktemp("grass_session")
+    project = "test_project"
+    gs.create_project(tmp_path, project)
+    with gs.setup.init(tmp_path / project, env=os.environ.copy()) as session:
+        yield session
+
+
+@pytest.fixture(scope="module")
+def script(session):
+    """Return the script generated by TOOL --script."""
+    tools = Tools(session=session)
+    return tools.run_cmd([TOOL, "--script"]).stdout
+
+
+def test_script_header_has_no_obsolete_license_text(script):
+    """The generated header carries no COPYRIGHT field and no GPL paragraph."""
+    for obsolete in ("COPYRIGHT:", "free software", "GNU General Public License"):
+        assert obsolete not in script, (
+            f"Generated script still contains obsolete license text: {obsolete!r}"
+        )
+
+
+def test_script_header_has_one_holder_per_line(script):
+    """Each copyright line names one holder, and the collective one comes last."""
+    lines = script.splitlines()
+    copyright_lines = [
+        i for i, line in enumerate(lines) if "SPDX-FileCopyrightText:" in line
+    ]
+    identifiers = [
+        i for i, line in enumerate(lines) if "SPDX-License-Identifier:" in line
+    ]
+
+    assert len(identifiers) == 1, "Expected exactly one SPDX-License-Identifier line."
+    assert copyright_lines, "Expected at least one SPDX-FileCopyrightText line."
+    assert max(copyright_lines) < identifiers[0], (
+        "All SPDX-FileCopyrightText lines must precede SPDX-License-Identifier."
+    )
+    assert (
+        lines[max(copyright_lines)] == "# SPDX-FileCopyrightText: Other GRASS authors"
+    ), "The last copyright line must be the collective line."
+    for i in copyright_lines:
+        assert not re.search(r",\s+and\s|\sand\sthe\s", lines[i]), (
+            f"Copyright line names more than one holder: {lines[i]!r}"
+        )

lib/gis/parser_script.c

@@ -3,10 +3,8 @@
 
    \brief GIS Library - Argument parsing functions (script)
 
-   (C) 2001-2009, 2011 by the GRASS Development Team
-
-   This program is free software under the GNU General Public License
-   (>=v2). Read the file COPYING that comes with GRASS for details.
+   SPDX-FileCopyrightText: 2001-2009, 2011 Other GRASS authors
+   SPDX-License-Identifier: GPL-2.0-or-later
 
    \author Original author CERL
    \author Soeren Gebbert added Dec. 2009 WPS process_description document
@@ -33,28 +31,10 @@ void G__script(void)
     fprintf(fp, "# MODULE:       %s_wrapper\n", G_program_name());
     fprintf(fp, "# AUTHOR(S):    %s\n", G_whoami());
     fprintf(fp, "# PURPOSE:      Wrapper for %s\n", G_program_name());
-    fprintf(fp,
-            "# COPYRIGHT:    (C) %s by %s, and the GRASS Development Team\n",
-            GRASS_VERSION_DATE, G_whoami());
-    fprintf(fp, "#\n");
-    fprintf(fp, "#  This program is free software; you can redistribute it "
-                "and/or modify\n");
-    fprintf(fp, "#  it under the terms of the GNU General Public License as "
-                "published by\n");
-    fprintf(fp, "#  the Free Software Foundation; either version 2 of the "
-                "License, or\n");
-    fprintf(fp, "#  (at your option) any later version.\n");
-    fprintf(fp, "#\n");
-    fprintf(
-        fp,
-        "#  This program is distributed in the hope that it will be useful,\n");
-    fprintf(
-        fp,
-        "#  but WITHOUT ANY WARRANTY; without even the implied warranty of\n");
-    fprintf(
-        fp,
-        "#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n");
-    fprintf(fp, "#  GNU General Public License for more details.\n");
+    fprintf(fp, "# SPDX-FileCopyrightText: %s %s\n", GRASS_VERSION_DATE,
+            G_whoami());
+    fprintf(fp, "# SPDX-FileCopyrightText: Other GRASS authors\n");
+    fprintf(fp, "# SPDX-License-Identifier: GPL-2.0-or-later\n");
     fprintf(fp, "#\n");
     fprintf(fp, "##############################################################"
                 "##############\n\n");