Change `--strict to --strict-markers`, preserving the old one

Fix #5023

src/_pytest/main.py

@@ -47,11 +47,6 @@ def pytest_addoption(parser):
         type="args",
         default=[],
     )
-    # parser.addini("dirpatterns",
-    #    "patterns specifying possible locations of test files",
-    #    type="linelist", default=["**/test_*.txt",
-    #            "**/test_*.py", "**/*_test.py"]
-    # )
     group = parser.getgroup("general", "running and selection options")
     group._addoption(
         "-x",
@@ -71,9 +66,10 @@ def pytest_addoption(parser):
         help="exit after first num failures or errors.",
     )
     group._addoption(
+        "--strict-markers",
         "--strict",
         action="store_true",
-        help="marks not registered in configuration file raise errors.",
+        help="markers not registered in the `markers` section of the configuration file raise errors.",
     )
     group._addoption(
         "-c",

src/_pytest/mark/structures.py

@@ -311,8 +311,11 @@ class MarkGenerator(object):
             # If the name is not in the set of known marks after updating,
             # then it really is time to issue a warning or an error.
             if name not in self._markers:
-                if self._config.option.strict:
-                    fail("{!r} is not a registered marker".format(name), pytrace=False)
+                if self._config.option.strict_markers:
+                    fail(
+                        "{!r} not found in `markers` configuration option".format(name),
+                        pytrace=False,
+                    )
                 else:
                     warnings.warn(
                         "Unknown pytest.mark.%s - is this a typo?  You can register "