Don't check build for circular dependencies when cross compiling

conda_build/metadata.py

@@ -283,14 +283,20 @@ def _get_all_dependencies(metadata, envs=('host', 'build', 'run')):
     return reqs
 
 
-def check_circular_dependencies(render_order):
+def check_circular_dependencies(render_order, config=None):
+    if config and config.host_subdir != config.build_subdir:
+        # When cross compiling build dependencies are already built
+        # and cannot come from the recipe as subpackages
+        envs = ('host', 'run')
+    else:
+        envs = ('build', 'host', 'run')
     pairs = []
     for idx, m in enumerate(render_order.values()):
         for other_m in list(render_order.values())[idx + 1:]:
             if (any(m.name() == dep or dep.startswith(m.name() + ' ')
-                   for dep in _get_all_dependencies(other_m)) and
+                   for dep in _get_all_dependencies(other_m, envs=envs)) and
                 any(other_m.name() == dep or dep.startswith(other_m.name() + ' ')
-                   for dep in _get_all_dependencies(m))):
+                   for dep in _get_all_dependencies(m, envs=envs))):
                 pairs.append((m.name(), other_m.name()))
     if pairs:
         error = "Circular dependencies in recipe: \n"
@@ -2084,7 +2090,7 @@ def get_output_metadata_set(self, permit_undefined_jinja=False,
 
             # format here is {output_dict: metadata_object}
             render_order = toposort(out_metadata_map)
-            check_circular_dependencies(render_order)
+            check_circular_dependencies(render_order, config=self.config)
             conda_packages = OrderedDict()
             non_conda_packages = []
 

tests/test-recipes/split-packages/_circular_deps_cross/conda_build_config.yaml

@@ -0,0 +1,4 @@
+target_platform:
+  - linux-32
+cross_target_platform:
+  - linux-32

tests/test-recipes/split-packages/_circular_deps_cross/meta.yaml

@@ -0,0 +1,36 @@
+{% set name = "gcc_impl" %}
+{% set version = "7.5.0" %}
+
+package:
+  name: gcc_compilers
+  version: {{ version }}
+
+build:
+  number: 0
+
+outputs:
+  - name: gcc_impl_{{ cross_target_platform }}
+    requirements:
+      build:
+        - gcc_impl_{{ target_platform }}   # [build_platform != target_platform]
+        - gxx_impl_{{ target_platform }}   # [build_platform != target_platform]
+        - gcc_impl_{{ cross_target_platform }}   # [build_platform != target_platform]
+        - gxx_impl_{{ cross_target_platform }}   # [build_platform != target_platform]
+        - sysroot_{{ cross_target_platform }}
+      host:
+        - sysroot_{{ cross_target_platform }}
+      run:
+        - sysroot_{{ cross_target_platform }}
+
+  - name: gxx_impl_{{ cross_target_platform }}
+    requirements:
+      build:
+        - gcc_impl_{{ target_platform }}   # [build_platform != target_platform]
+        - gxx_impl_{{ target_platform }}   # [build_platform != target_platform]
+        - gcc_impl_{{ cross_target_platform }}   # [build_platform != target_platform]
+        - gxx_impl_{{ cross_target_platform }}   # [build_platform != target_platform]
+        - sysroot_{{ cross_target_platform }}
+      host:
+        - sysroot_{{ cross_target_platform }}
+      run:
+        - sysroot_{{ cross_target_platform }}

tests/test_subpackages.py

@@ -336,6 +336,12 @@ def test_inherit_build_number(testing_config):
         assert int(m.meta['build']['number']) == 1, "build number should have been inherited as '1'"
 
 
+def test_circular_deps_cross(testing_config):
+    recipe = os.path.join(subpackage_dir, '_circular_deps_cross')
+    # check that this does not raise an exception
+    ms = api.render(recipe, config=testing_config)
+
+
 @pytest.mark.slow
 def test_loops_do_not_remove_earlier_packages(testing_config):
     recipe = os.path.join(subpackage_dir, '_xgboost_example')