Merge pull request #5003 from blueyed/off

Fix off-by-one error with lineno in mark collection error

src/_pytest/_code/source.py

@@ -203,7 +203,9 @@ def compile_(source, filename=None, mode="exec", flags=0, dont_inherit=0):
 
 def getfslineno(obj):
     """ Return source location (path, lineno) for the given object.
-    If the source cannot be determined return ("", -1)
+    If the source cannot be determined return ("", -1).
+
+    The line number is 0-based.
     """
     from .code import Code
 

src/_pytest/mark/structures.py

@@ -44,7 +44,7 @@ def get_empty_parameterset_mark(config, argnames, func):
         f_name = func.__name__
         _, lineno = getfslineno(func)
         raise Collector.CollectError(
-            "Empty parameter set in '%s' at line %d" % (f_name, lineno)
+            "Empty parameter set in '%s' at line %d" % (f_name, lineno + 1)
         )
     else:
         raise LookupError(requested_mark)