.pyc files can be moved, so use __file__ to correctly find the source file.

3 files changed, 19 insertions, 4 deletions

diff --git a/coverage/collector.py b/coverage/collector.py
index b6ca19bd..f290b85b 100644
--- a/coverage/collector.py
+++ b/coverage/collector.py
@@ -24,7 +24,7 @@ except ImportError:
                 filename = frame.f_code.co_filename
                 tracename = self.should_trace_cache.get(filename)
                 if tracename is None:
-                    tracename = self.should_trace(filename)
+                    tracename = self.should_trace(filename, frame)
                     self.should_trace_cache[filename] = tracename
                 if tracename:
                     # We need to trace.  Push the current filename on the stack
diff --git a/coverage/control.py b/coverage/control.py
index 529f5252..ab9112ef 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -33,7 +33,7 @@ class coverage:
         import atexit
         atexit.register(self.save)
 
-    def _should_trace(self, filename):
+    def _should_trace(self, filename, frame):
         """Decide whether to trace execution in `filename`
         
         Returns a canonicalized filename if it should be traced, False if it
@@ -44,8 +44,23 @@ class coverage:
             # There's no point in ever tracing string executions, we can't do
             # anything with the data later anyway.
             return False
-        
+
+        # Compiled Python files have two filenames: frame.f_code.co_filename is
+        # the filename where the .pyc was originally compiled.  The second name
+        # is __file__, which is where the .pyc was actually loaded from.  Since
+        # .pyc files can be moved after compilation (for example, by being
+        # installed), we look for __file__ in the frame and prefer it to the
+        # co_filename value.
+        dunder_file = frame.f_globals.get('__file__')
+        if dunder_file:
+            filename = dunder_file
+            if not filename.endswith(".py"):
+                filename = filename[:-1]
+
         canonical = self.file_locator.canonical_filename(filename)
+        
+        # If we aren't supposed to trace the stdlib, then check if this is in
+        # the stdlib and skip it if so.
         if not self.cover_stdlib:
             if canonical.startswith(self.sysprefix):
                 return False
diff --git a/coverage/tracer.c b/coverage/tracer.c
index 2831264a..bfb27614 100644
--- a/coverage/tracer.c
+++ b/coverage/tracer.c
@@ -80,7 +80,7 @@ Tracer_trace(Tracer *self, PyFrameObject *frame, int what, PyObject *arg)
         tracename = PyDict_GetItem(self->should_trace_cache, filename);

         if (tracename == NULL) {

             // We've never considered this file before.  Ask should_trace about it.

-            PyObject * args = Py_BuildValue("(O)", filename);

+            PyObject * args = Py_BuildValue("(OO)", filename, frame);

             tracename = PyObject_Call(self->should_trace, args, NULL);

             Py_DECREF(args);

             if (tracename == NULL) {