Mark stdlib modules with upper version bounds (#5394)

* Mark stdlib modules with upper version bounds

* Add minus to all versions and enforce in check_consistent

* Fix check_consistent and mypy_test to work with new VERSIONS format

tests/mypy_test.py

@@ -71,6 +71,9 @@ def match(fn, args, exclude_list):
     return True
 
 
+_VERSION_LINE_RE = re.compile(r"^([a-zA-Z_][a-zA-Z0-9_]*): ([23]\.\d{1,2})-([23]\.\d{1,2})?$")
+
+
 def parse_versions(fname):
     with open(fname) as f:
         data = f.read().splitlines()
@@ -79,13 +82,24 @@ def parse_versions(fname):
         # Allow having some comments or empty lines.
         if not line.strip() or line.startswith("#"):
             continue
-        mod, ver_str = line.split(": ")
-        assert ver_str.count(".") == 1
-        major, minor = ver_str.split(".")
-        result[mod] = (int(major), int(minor))
+        m = _VERSION_LINE_RE.match(line)
+        assert m, "invalid VERSIONS line :" + line
+        mod = m.group(1)
+        min_version = parse_version(m.group(2))
+        max_version = parse_version(m.group(3)) if m.group(3) else (99, 99)
+        result[mod] = min_version, max_version
     return result
 
 
+_VERSION_RE = re.compile(r"^([23])\.(\d+)$")
+
+
+def parse_version(v_str):
+    m = _VERSION_RE.match(v_str)
+    assert m, "invalid version :" + v_str
+    return int(m.group(1)), int(m.group(2))
+
+
 def is_supported(distribution, major):
     with open(os.path.join(THIRD_PARTY_NAMESPACE, distribution, "METADATA.toml")) as f:
         data = dict(toml.loads(f.read()))
@@ -202,9 +216,8 @@ def main():
                 if name == PY2_NAMESPACE or name == "VERSIONS":
                     continue
                 mod, _ = os.path.splitext(name)
-                if supported_versions[mod] > (major, minor):
-                    continue
-                add_files(files, seen, root, name, args, exclude_list)
+                if supported_versions[mod][0] <= (major, minor) <= supported_versions[mod][1]:
+                    add_files(files, seen, root, name, args, exclude_list)
 
         # Next add files for all third party distributions.
         for distribution in os.listdir(THIRD_PARTY_NAMESPACE):