Display both instances of duplicate modules in error message (#6772)

jxcl · Guido van Rossum · commit f210d6cb96d6 · 2019-05-06T11:01:46.000-05:00
Fixes #6741
diff --git a/mypy/build.py b/mypy/build.py
@@ -2569,7 +2569,10 @@ def load_graph(sources: List[BuildSource], manager: BuildManager,
             continue
         if st.id in graph:
             manager.errors.set_file(st.xpath, st.id)
-            manager.errors.report(-1, -1, "Duplicate module named '%s'" % st.id)
+            manager.errors.report(
+                -1, -1,
+                "Duplicate module named '%s' (also at '%s')" % (st.id, graph[st.id].xpath)
+            )
             manager.errors.raise_error()
         graph[st.id] = st
         new.append(st)
diff --git a/test-data/unit/cmdline.test b/test-data/unit/cmdline.test
@@ -106,7 +106,7 @@ mypy: can't decode file 'a.py': unknown encoding: uft-8
 [file two/mod/__init__.py]
 # type: ignore
 [out]
-two/mod/__init__.py: error: Duplicate module named 'mod'
+two/mod/__init__.py: error: Duplicate module named 'mod' (also at 'one/mod/__init__.py')
 == Return code: 2
 
 [case testFlagsFile]
