Fix: Build environments not activated

conda_build/build.py

@@ -2584,8 +2584,11 @@ def construct_metadata_for_test(recipedir_or_package, config):
 
 
 def write_build_scripts(m, script, build_file):
-    with utils.path_prepended(m.config.host_prefix):
-        with utils.path_prepended(m.config.build_prefix):
+    # TODO: Prepending the prefixes here should probably be guarded by
+    #         if not m.activate_build_script:
+    #       Leaving it as is, for now, since we need a quick, non-disruptive patch release.
+    with utils.path_prepended(m.config.host_prefix, False):
+        with utils.path_prepended(m.config.build_prefix, False):
             env = environ.get_dict(m=m)
     env["CONDA_BUILD_STATE"] = "BUILD"
 

conda_build/environ.py

@@ -663,7 +663,6 @@ def system_vars(env_dict, m, prefix):
     return os_vars(m, prefix)
 
 
-@lru_cache(maxsize=None)
 def os_vars(m, prefix):
     d = dict()
     # note the dictionary is passed in here - variables are set in that dict if they are non-null

conda_build/metadata.py

@@ -1046,6 +1046,8 @@ def stringify_numbers():
 
 
 class MetaData:
+    __hash__ = None  # declare as non-hashable to avoid its use with memoization
+
     def __init__(self, path, config=None, variant=None):
 
         self.undefined_jinja_vars = []

conda_build/utils.py

@@ -950,11 +950,10 @@ def get_build_folders(croot):
 
 
 def prepend_bin_path(env, prefix, prepend_prefix=False):
-    # bin_dirname takes care of bin on *nix, Scripts on win
-    env['PATH'] = join(prefix, bin_dirname) + os.pathsep + env['PATH']
+    env['PATH'] = join(prefix, "bin") + os.pathsep + env['PATH']
     if sys.platform == "win32":
         env['PATH'] = join(prefix, "Library", "mingw-w64", "bin") + os.pathsep + \
-                      join(prefix, "Library", "usr", "bin") + os.pathsep + os.pathsep + \
+                      join(prefix, "Library", "usr", "bin") + os.pathsep + \
                       join(prefix, "Library", "bin") + os.pathsep + \
                       join(prefix, "Scripts") + os.pathsep + \
                       env['PATH']
@@ -985,9 +984,10 @@ def sys_path_prepended(prefix):
 
 
 @contextlib.contextmanager
-def path_prepended(prefix):
+def path_prepended(prefix, prepend_prefix=True):
+    # FIXME: Unclear why prepend_prefix=True for all platforms.
     old_path = os.environ['PATH']
-    os.environ['PATH'] = prepend_bin_path(os.environ.copy(), prefix, True)['PATH']
+    os.environ['PATH'] = prepend_bin_path(os.environ.copy(), prefix, prepend_prefix)['PATH']
     try:
         yield
     finally:

conda_build/windows.py

@@ -250,6 +250,9 @@ def write_build_scripts(m, env, bld_bat):
 
 
 def build(m, bld_bat, stats, provision_only=False):
+    # TODO: Prepending the prefixes here should probably be guarded by
+    #         if not m.activate_build_script:
+    #       Leaving it as is, for now, since we need a quick, non-disruptive patch release.
     with path_prepended(m.config.host_prefix):
         with path_prepended(m.config.build_prefix):
             env = environ.get_dict(m=m)

news/4665-fix-activation-path

@@ -0,0 +1,20 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Fix build/host environment activation broken in >=3.23.0,<=3.23.2
+* Add PREFIX/bin to PATH on Windows and remove PREFIX root from PATH on Unix
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>

tests/test_api_build.py

@@ -36,7 +36,7 @@
 from conda_build.render import finalize_metadata
 from conda_build.utils import (copy_into, on_win, check_call_env, convert_path_for_cygwin_or_msys2,
                                package_has_file, check_output_env, get_conda_operation_locks, rm_rf,
-                               walk, env_var, FileNotFoundError)
+                               prepend_bin_path, walk, env_var, FileNotFoundError)
 from conda_build.os_utils.external import find_executable
 from conda_build.exceptions import (DependencyNeedsBuildingError, CondaBuildException,
                                     OverLinkingError, OverDependingError)
@@ -1652,3 +1652,41 @@ def assert_keyword(keyword):
         assert_keyword('<hidden>')
     finally:
         os.environ.pop(token)
+
+
+@pytest.mark.slow
+def test_activated_prefixes_in_actual_path(testing_config, testing_metadata):
+    """
+    Check if build and host env are properly added to PATH in the correct order.
+    Do this in an actual build and not just in a unit test to avoid regression.
+    Currently only tests for single non-"outputs" recipe with build/host split
+    and proper env activation (Metadata.is_cross and Config.activate both True).
+    """
+    file = "env-path-dump"
+    testing_metadata.config.activate = True
+    meta = testing_metadata.meta
+    meta["requirements"]["host"] = []
+    meta["build"]["script"] = [
+        f"echo %PATH%>%PREFIX%/{file}" if on_win else f"echo $PATH>$PREFIX/{file}"
+    ]
+    outputs = api.build(testing_metadata)
+    env = {"PATH": ""}
+    # We get the PATH entries twice: (which we should fix at some point)
+    #   1. from the environment activation hooks,
+    #   2. also beforehand from utils.path_prepended at the top of
+    #      - build.write_build_scripts on Unix
+    #      - windows.build on Windows
+    #        And apparently here the previously added build env gets deactivated
+    #        from the activation hook, hence only host is on PATH twice.
+    prepend_bin_path(env, testing_metadata.config.host_prefix)
+    if not on_win:
+        prepend_bin_path(env, testing_metadata.config.build_prefix)
+    prepend_bin_path(env, testing_metadata.config.host_prefix)
+    prepend_bin_path(env, testing_metadata.config.build_prefix)
+    expected_paths = [path for path in env["PATH"].split(os.pathsep) if path]
+    actual_paths = [
+        path
+        for path in package_has_file(outputs[0], file).strip().split(os.pathsep)
+        if path in expected_paths
+    ]
+    assert actual_paths == expected_paths