on exe discovery ignore incorrect interpreters, also try in the… (#1573)

Signed-off-by: Bernat Gabor <[email protected]>

docs/changelog/1545.bugfix.rst

@@ -0,0 +1,6 @@
+Improve python discovery mechanism:
+
+- do not fail if there are executables that fail to query (e.g. for not having execute access to it) on the ``PATH``,
+- beside the prefix folder also try with the platform dependent binary folder within that,
+
+by :user:`gaborbernat`.

src/virtualenv/discovery/py_info.py

@@ -338,7 +338,9 @@ def discover_exe(self, prefix, exact=True):
             for name in possible_names:
                 exe_path = os.path.join(folder, name)
                 if os.path.exists(exe_path):
-                    info = self.from_exe(exe_path, resolve_to_host=False)
+                    info = self.from_exe(exe_path, resolve_to_host=False, raise_on_error=False)
+                    if info is None:  # ignore if for some reason we can't query
+                        continue
                     for item in ["implementation", "architecture", "version_info"]:
                         found = getattr(info, item)
                         searched = getattr(self, item)
@@ -411,6 +413,9 @@ def _find_possible_folders(self, inside_folder):
 
         # or at root level
         candidate_folder[inside_folder] = None
+        if self.executable.startswith(self.prefix):
+            binary_within = os.path.relpath(os.path.dirname(self.executable), self.prefix)
+            candidate_folder[os.path.join(inside_folder, binary_within)] = None
 
         return list(candidate_folder.keys())
 

tests/unit/discovery/py_info/test_py_info.py

@@ -205,7 +205,12 @@ def _make_py_info(of):
     target_py_info = _make_py_info(target)
     mocker.patch.object(target_py_info, "_find_possible_exe_names", return_value=names)
     mocker.patch.object(target_py_info, "_find_possible_folders", return_value=[str(tmp_path)])
-    mocker.patch.object(target_py_info, "from_exe", side_effect=lambda k, resolve_to_host: discovered_with_path[k])
+
+    # noinspection PyUnusedLocal
+    def func(k, resolve_to_host, raise_on_error):
+        return discovered_with_path[k]
+
+    mocker.patch.object(target_py_info, "from_exe", side_effect=func)
     target_py_info.real_prefix = str(tmp_path)
 
     target_py_info.system_executable = None