build: log build sources with -v (#9672)

With the changes I've been making to mypy's import handling, I think
this would be a useful thing to add preemptively.

Note that I would have found this very useful at points, and I think
others would too, eg #7672 and #8584

The existing logging ignores source_modules and source_text and won't
help with determining what mypy things the module name for a given file
is, which is useful for namespace package issues as in the complaint in #8584.

Co-authored-by: hauntsaninja <>

mypy/build.py

@@ -2541,37 +2541,25 @@ def skipping_ancestor(manager: BuildManager, id: str, path: str, ancestor_for: '
                           severity='note', only_once=True)
 
 
-def log_configuration(manager: BuildManager) -> None:
+def log_configuration(manager: BuildManager, sources: List[BuildSource]) -> None:
     """Output useful configuration information to LOG and TRACE"""
 
     manager.log()
     configuration_vars = [
         ("Mypy Version", __version__),
         ("Config File", (manager.options.config_file or "Default")),
-    ]
-
-    src_pth_str = "Source Path"
-    src_pths = list(manager.source_set.source_paths.copy())
-    src_pths.sort()
-
-    if len(src_pths) > 1:
-        src_pth_str += "s"
-        configuration_vars.append((src_pth_str, " ".join(src_pths)))
-    elif len(src_pths) == 1:
-        configuration_vars.append((src_pth_str, src_pths.pop()))
-    else:
-        configuration_vars.append((src_pth_str, "None"))
-
-    configuration_vars.extend([
         ("Configured Executable", manager.options.python_executable or "None"),
         ("Current Executable", sys.executable),
         ("Cache Dir", manager.options.cache_dir),
         ("Compiled", str(not __file__.endswith(".py"))),
-    ])
+    ]
 
     for conf_name, conf_value in configuration_vars:
         manager.log("{:24}{}".format(conf_name + ":", conf_value))
 
+    for source in sources:
+        manager.log("{:24}{}".format("Found source:", source))
+
     # Complete list of searched paths can get very long, put them under TRACE
     for path_type, paths in manager.search_paths._asdict().items():
         if not paths:
@@ -2591,7 +2579,7 @@ def dispatch(sources: List[BuildSource],
              manager: BuildManager,
              stdout: TextIO,
              ) -> Graph:
-    log_configuration(manager)
+    log_configuration(manager, sources)
 
     t0 = time.time()
     graph = load_graph(sources, manager)

mypy/modulefinder.py

@@ -85,7 +85,7 @@ def __init__(self, path: Optional[str], module: Optional[str],
         self.base_dir = base_dir  # Directory where the package is rooted (e.g. 'xxx/yyy')
 
     def __repr__(self) -> str:
-        return '<BuildSource path=%r module=%r has_text=%s base_dir=%s>' % (
+        return 'BuildSource(path=%r, module=%r, has_text=%s, base_dir=%r)' % (
             self.path,
             self.module,
             self.text is not None,