[llvm] [Dexter] Add basic structured script parsing (PR #193710)

[Stephen Tozer via llvm-commits]

================
@@ -110,6 +110,49 @@ def get_required_attr(config, attr_name):
     config.available_features.add("llvm-ar")
 
 
+def check_dexter_requirements():
+    # Determine whether Dexter's dependencies are available, and disable Dexter tests if not.
+    dexter_requirements_path = os.path.join(
+        config.cross_project_tests_src_root,
+        "debuginfo-tests",
+        "dexter",
+        "requirements.txt",
+    )
+    if not os.path.isfile(dexter_requirements_path):
+        print(
+            f"Couldn't find Dexter requirements path at existed path: {dexter_requirements_path}"
+        )
+        return False
+    with open(dexter_requirements_path) as req:
+        requirements_list = [
+            req_str
+            for req_line in req
+            if (req_str := req_line.strip()) and not req_str.startswith("#")
+        ]
+    try:
+        from packaging.requirements import Requirement
+        from importlib.metadata import version
+    except Exception as e:
----------------
SLTozer wrote:

Correct, there's no risk here as I understand it - `packaging` doesn't invoke `pip` for anything AFAIUI, it's just for processing package requirements, and happens to be where some of the `distutils` utilities for inspecting available (i.e. installed, on-disk) packages ended up.

https://github.com/llvm/llvm-project/pull/193710