Fix transitive subpackage dependency resolution

conda_build/build.py

@@ -2433,7 +2433,7 @@ def build(
                     exclude_pattern = re.compile(
                         r"|".join(rf"(?:^{exc}(?:\s|$|\Z))" for exc in excludes)
                     )
-            add_upstream_pins(m, False, exclude_pattern)
+            add_upstream_pins(m, False, exclude_pattern, [])
 
         create_build_envs(top_level_pkg, notest)
 

conda_build/render.py

@@ -130,6 +130,7 @@ def get_env_dependencies(
     exclude_pattern=None,
     permit_unsatisfiable_variants=False,
     merge_build_host_on_same_platform=True,
+    extra_specs=None,
 ):
     specs = m.get_depends_top_and_out(env)
     # replace x.x with our variant's numpy version, or else conda tries to literally go get x.x
@@ -148,6 +149,8 @@ def get_env_dependencies(
     )
 
     dependencies = set(dependencies)
+    if extra_specs:
+        dependencies |= set(extra_specs)
     unsat = None
     random_string = "".join(
         random.choice(string.ascii_uppercase + string.digits) for _ in range(10)
@@ -183,7 +186,7 @@ def get_env_dependencies(
     specs = [package_record_to_requirement(prec) for prec in precs]
     return (
         utils.ensure_list(
-            (specs + subpackages + pass_through_deps)
+            (specs + subpackages + pass_through_deps + (extra_specs or []))
             or m.get_value(f"requirements/{env}", [])
         ),
         precs,
@@ -439,13 +442,15 @@ def _read_upstream_pin_files(
     env,
     permit_unsatisfiable_variants,
     exclude_pattern,
+    extra_specs,
 ):
     deps, precs, unsat = get_env_dependencies(
         m,
         env,
         m.config.variant,
         exclude_pattern,
         permit_unsatisfiable_variants=permit_unsatisfiable_variants,
+        extra_specs=extra_specs,
     )
     # extend host deps with strong build run exports.  This is important for things like
     #    vc feature activation to work correctly in the host env.
@@ -457,12 +462,18 @@ def _read_upstream_pin_files(
     )
 
 
-def add_upstream_pins(m: MetaData, permit_unsatisfiable_variants, exclude_pattern):
+def add_upstream_pins(
+    m: MetaData, permit_unsatisfiable_variants, exclude_pattern, extra_specs
+):
     """Applies run_exports from any build deps to host and run sections"""
     # if we have host deps, they're more important than the build deps.
     requirements = m.get_section("requirements")
     build_deps, build_unsat, extra_run_specs_from_build = _read_upstream_pin_files(
-        m, "build", permit_unsatisfiable_variants, exclude_pattern
+        m,
+        "build",
+        permit_unsatisfiable_variants,
+        exclude_pattern,
+        [] if m.is_cross else extra_specs,
     )
 
     # is there a 'host' section?
@@ -488,7 +499,7 @@ def add_upstream_pins(m: MetaData, permit_unsatisfiable_variants, exclude_patter
         host_reqs.extend(extra_run_specs_from_build.get("strong", []))
 
         host_deps, host_unsat, extra_run_specs_from_host = _read_upstream_pin_files(
-            m, "host", permit_unsatisfiable_variants, exclude_pattern
+            m, "host", permit_unsatisfiable_variants, exclude_pattern, extra_specs
         )
         if m.noarch or m.noarch_python:
             extra_run_specs = set(extra_run_specs_from_host.get("noarch", []))
@@ -645,9 +656,40 @@ def finalize_metadata(
             utils.insert_variant_versions(requirements, m.config.variant, "build")
             utils.insert_variant_versions(requirements, m.config.variant, "host")
 
+        host_requirements = requirements.get("host" if m.is_cross else "build", [])
+        host_requirement_names = [req.split(" ")[0] for req in host_requirements]
+        extra_specs = []
+        if output and output_excludes and not is_top_level and host_requirement_names:
+            reqs = {}
+
+            # we first make a mapping of output -> requirements
+            for (name, _), (_, other_meta) in m.other_outputs.items():
+                if name == m.name():
+                    continue
+                other_meta_reqs = other_meta.meta.get("requirements", {}).get("run", [])
+                reqs[name] = set(other_meta_reqs)
+
+            seen = set()
+            # for each subpackage that is a dependency we add its dependencies
+            # and transitive dependencies if the dependency of the subpackage
+            # is a subpackage.
+            to_process = set(
+                name for (name, _) in m.other_outputs if name in host_requirement_names
+            )
+            while to_process:
+                name = to_process.pop()
+                if name == m.name():
+                    continue
+                for req in reqs[name]:
+                    req_name = req.split(" ")[0]
+                    if req_name not in reqs:
+                        extra_specs.append(req)
+                    elif req_name not in seen:
+                        to_process.add(req_name)
+
         m = parent_metadata.get_output_metadata(m.get_rendered_output(m.name()))
         build_unsat, host_unsat = add_upstream_pins(
-            m, permit_unsatisfiable_variants, exclude_pattern
+            m, permit_unsatisfiable_variants, exclude_pattern, extra_specs
         )
         # getting this AFTER add_upstream_pins is important, because that function adds deps
         #     to the metadata.
@@ -675,6 +717,7 @@ def finalize_metadata(
             m.config.variant,
             exclude_pattern=exclude_pattern,
             permit_unsatisfiable_variants=permit_unsatisfiable_variants,
+            extra_specs=extra_specs,
         )
         full_build_dep_versions = {
             dep.split()[0]: " ".join(dep.split()[1:]) for dep in full_build_deps

news/5603-transitive-subpackage.rst

@@ -0,0 +1,19 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Fixes transitive subpackage dependency resolution issue #3308. (#5603)
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>

tests/test-recipes/metadata/transitive_subpackage/conda_build_config.yaml

@@ -0,0 +1,4 @@
+openssl:
+  - 1.0.2
+python:
+  - 3.6

tests/test-recipes/metadata/transitive_subpackage/meta.yaml

@@ -0,0 +1,15 @@
+package:
+  name: foo_split
+  version: 1.0.0
+
+outputs:
+  - name: libfoo
+    requirements:
+      host:
+        - openssl
+
+  - name: foo
+    requirements:
+      host:
+        - python
+        - {{ pin_subpackage('libfoo', exact=True) }}

tests/test_api_render.py

@@ -122,6 +122,16 @@ def test_pin_compatible_semver(testing_config):
     assert "zlib >=1.2.11,<2.0a0" in metadata.get_value("requirements/run")
 
 
+def test_transitive_subpackage_dependency(testing_config):
+    recipe_dir = os.path.join(metadata_dir, "transitive_subpackage")
+    metadata = api.render(recipe_dir, config=testing_config)[1][0]
+    assert not metadata.get_value("requirements/run")
+    assert any(
+        req.startswith("openssl 1.0.2")
+        for req in metadata.get_value("requirements/host")
+    )
+
+
 @pytest.mark.slow
 @pytest.mark.xfail(on_win, reason="Defaults channel has conflicting vc packages")
 def test_resolved_packages_recipe(testing_config):