From 15b4b2f53456c9dec5a0ffe4a7e80a5a1163ebb4 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Fri, 27 Oct 2023 17:32:36 +0200
Subject: [PATCH] gdal_calc.py: restore specifc --format behaviour (master only
 fix, fixes #8619)

---
 autotest/pyscripts/test_gdal_calc.py          |  2 +-
 .../osgeo_utils/auxiliary/gdal_argparse.py    | 27 +++++++++++++++++--
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/autotest/pyscripts/test_gdal_calc.py b/autotest/pyscripts/test_gdal_calc.py
index 6d16d8f9e647..8a14ce74ae46 100755
--- a/autotest/pyscripts/test_gdal_calc.py
+++ b/autotest/pyscripts/test_gdal_calc.py
@@ -141,7 +141,7 @@ def test_gdal_calc_py_1(script_path):
     test_py_scripts.run_py_script(
         script_path,
         "gdal_calc",
-        f"-Z {infile} --Z_band=2 --calc=Z --overwrite --outfile {out[2]}",
+        f"-Z {infile} --Z_band=2 --calc=Z --overwrite --format GTiff --outfile {out[2]}",
     )
 
     for i, checksum in zip(
diff --git a/swig/python/gdal-utils/osgeo_utils/auxiliary/gdal_argparse.py b/swig/python/gdal-utils/osgeo_utils/auxiliary/gdal_argparse.py
index 6216bfc6fcbd..15948ae27547 100644
--- a/swig/python/gdal-utils/osgeo_utils/auxiliary/gdal_argparse.py
+++ b/swig/python/gdal-utils/osgeo_utils/auxiliary/gdal_argparse.py
@@ -99,15 +99,38 @@ def __init__(
             # extend was introduced to the stdlib in Python 3.8
             self.register("action", "extend", ExtendAction)
 
+        self.custom_format_arg = False
+
+    def add_argument(self, *args, **kwargs):
+        if "--format" in args:
+            self.custom_format_arg = True
+        return super().add_argument(*args, **kwargs)
+
     def parse_args(self, args=None, optfile_arg=None, **kwargs):
 
         if self.add_gdal_generic_options:
             from osgeo import gdal
 
-            args = gdal.GeneralCmdLineProcessor(["dummy"] + args)
+            args_for_gdal_general = []
+            post_args = []
+            # gdal_calc has a --format switch whose semantics is not the
+            # one of the generic --format
+            if self.custom_format_arg and args:
+                i = 0
+                while i < len(args):
+                    if args[i] == "--format":
+                        post_args.append(args[i])
+                        post_args.append(args[i + 1])
+                        i += 1
+                    else:
+                        args_for_gdal_general.append(args[i])
+                    i += 1
+            else:
+                args_for_gdal_general = args
+            args = gdal.GeneralCmdLineProcessor(["dummy"] + args_for_gdal_general)
             if args is None:
                 sys.exit(0)
-            args = args[1:]
+            args = args[1:] + post_args
 
         if (
             args is not None