From f7dd4ed84fd996cb8d9f113a9817b878e9dd773e Mon Sep 17 00:00:00 2001
From: danpetry <dpetry@anaconda.com>
Date: Thu, 2 Nov 2023 13:57:57 -0500
Subject: [PATCH] Avoid clobbering variants from higher priority cbc.yaml
 (#5039)

* Add record of previously checked config entries, to avoid clobbering by lower priority entries.
* Add test for clobbering.

---------

Co-authored-by: Ken Odegard <kodegard@anaconda.com>
Co-authored-by: Jean-Christophe Morin <38703886+JeanChristopheMorinPerso@users.noreply.github.com>
---
 conda_build/variants.py                |  7 ++++-
 news/5039-dont-clobber-multiple-config | 19 ++++++++++++
 tests/test_variants.py                 | 43 ++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 news/5039-dont-clobber-multiple-config

diff --git a/conda_build/variants.py b/conda_build/variants.py
index d7c6841238..319ace7fea 100644
--- a/conda_build/variants.py
+++ b/conda_build/variants.py
@@ -679,9 +679,13 @@ def filter_combined_spec_to_used_keys(combined_spec, specs):
 
     # TODO: act here?
     combined_spec = explode_variants(combined_spec)
+    # seen_keys makes sure that a setting from a lower-priority spec doesn't clobber
+    # the same setting that has been redefined in a higher-priority spec.
+    seen_keys = set()
+    # The specs are checked from high to low priority order.
     for source, source_specs in reversed(specs.items()):
         for k, vs in source_specs.items():
-            if k not in extend_keys:
+            if k not in extend_keys and k not in seen_keys:
                 # when filtering ends up killing off all variants, we just ignore that.  Generally,
                 #    this arises when a later variant config overrides, rather than selects a
                 #    subspace of earlier configs
@@ -689,6 +693,7 @@ def filter_combined_spec_to_used_keys(combined_spec, specs):
                     filter_by_key_value(combined_spec, k, vs, source_name=source)
                     or combined_spec
                 )
+                seen_keys.add(k)
     return combined_spec
 
 
diff --git a/news/5039-dont-clobber-multiple-config b/news/5039-dont-clobber-multiple-config
new file mode 100644
index 0000000000..630868093d
--- /dev/null
+++ b/news/5039-dont-clobber-multiple-config
@@ -0,0 +1,19 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Avoid clobbering of variants in high priority cbc.yaml entries when they aren't present in lower priority cbc.yamls. (#5039)
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>
diff --git a/tests/test_variants.py b/tests/test_variants.py
index 3e7ba621a5..819f39d793 100644
--- a/tests/test_variants.py
+++ b/tests/test_variants.py
@@ -16,6 +16,7 @@
 from conda_build.variants import (
     combine_specs,
     dict_of_lists_to_list_of_dicts,
+    filter_combined_spec_to_used_keys,
     get_package_variants,
     validate_spec,
 )
@@ -657,3 +658,45 @@ def test_variant_subkeys_retained():
     m.final = False
     outputs = m.get_output_metadata_set(permit_unsatisfiable_variants=False)
     get_all_replacements(outputs[0][1].config.variant)
+
+
+@pytest.mark.parametrize(
+    "internal_defaults, low_prio_config, high_prio_config, expected",
+    [
+        pytest.param(
+            {"pkg_1": "1.0"},
+            {"pkg_1": "1.1"},
+            {"pkg_1": ["1.1", "1.2"], "pkg_2": ["1.1"]},
+            [{"pkg_1": "1.1", "pkg_2": "1.1"}, {"pkg_1": "1.2", "pkg_2": "1.1"}],
+            id="basic",
+        ),
+        pytest.param(
+            {"pkg_1": "1.0"},
+            {"pkg_1": "1.1"},
+            {
+                "pkg_1": ["1.1", "1.2"],
+                "pkg_2": ["1.1", "1.2"],
+                "zip_keys": [["pkg_1", "pkg_2"]],
+            },
+            [
+                {"pkg_1": "1.1", "pkg_2": "1.1", "zip_keys": [["pkg_1", "pkg_2"]]},
+                {"pkg_1": "1.2", "pkg_2": "1.2", "zip_keys": [["pkg_1", "pkg_2"]]},
+            ],
+            id="zip_keys",
+        ),
+    ],
+)
+def test_zip_key_filtering(
+    internal_defaults, low_prio_config, high_prio_config, expected
+):
+    combined_spec = {
+        **low_prio_config,
+        **high_prio_config,
+    }
+    specs = {
+        "internal_defaults": internal_defaults,
+        "low_prio_config": low_prio_config,
+        "high_prio_config": high_prio_config,
+    }
+
+    assert filter_combined_spec_to_used_keys(combined_spec, specs=specs) == expected