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Commit 56f8cf2

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hugues-affhugues-aff
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improve test coverage and documentation
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‎docs/source/command_line.rst

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@@ -212,6 +212,29 @@ imports.
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By default, mypy will suppress any error messages generated within :pep:`561`
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compliant packages. Adding this flag will disable this behavior.
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.. option:: --fast-module-lookup
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The default logic used to scan through search paths to resolve imports has a
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quadratic worse-case behavior in some cases, which is for instance triggered
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by a large number of folders sharing a top-level namespace as in:
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foo/
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company/
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foo/
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a.py
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bar/
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company/
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bar/
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b.py
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baz/
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company/
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baz/
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c.py
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...
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If you are in this situation, you can enable an experimental fast path by
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setting the :option:`--fast-module-lookup` option.
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.. _platform-configuration:
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‎docs/source/running_mypy.rst

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(However, if the files are in different directories, the one found
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in the earlier directory is used.)
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Other advice and best practices
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*******************************
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‎mypy/main.py

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group=code_group)
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add_invertible_flag(
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'--fast-module-lookup', default=False,
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help="Enable fast path for finding modules within input sources",
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help=argparse.SUPPRESS,
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group=code_group)
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code_group.add_argument(
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"--exclude",

‎mypy/modulefinder.py

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self.ns_ancestors.clear()
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def find_module_via_source_set(self, id: str) -> Optional[ModuleSearchResult]:
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"""Fast path to find modules by looking through the input sources
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This is only used when --fast-module-lookup is passed on the command line."""
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if not self.source_set:
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return None
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‎mypy/test/testcheck.py

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'check-multiple-inheritance.test',
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'check-super.test',
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'check-modules.test',
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'check-modules-fast.test',
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'check-typevar-values.test',
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'check-unsupported.test',
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'check-unreachable-code.test',

‎test-data/unit/check-modules-fast.test

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-- Type checker test cases dealing with module lookup edge cases
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-- to ensure that --fast-module-lookup matches regular lookup behavior
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[case testModuleLookup]
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# flags: --fast-module-lookup
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import m
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reveal_type(m.a) # N: Revealed type is "m.A"
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[file m.py]
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class A: pass
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a = A()
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[case testModuleLookupStub]
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# flags: --fast-module-lookup
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import m
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reveal_type(m.a) # N: Revealed type is "m.A"
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[file m.pyi]
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class A: pass
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a = A()
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[case testModuleLookupFromImport]
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# flags: --fast-module-lookup
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from m import a
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reveal_type(a) # N: Revealed type is "m.A"
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[file m.py]
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class A: pass
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a = A()
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[case testModuleLookupStubFromImport]
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# flags: --fast-module-lookup
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from m import a
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reveal_type(a) # N: Revealed type is "m.A"
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[file m.pyi]
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class A: pass
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a = A()
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[case testModuleLookupWeird]
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# flags: --fast-module-lookup
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from m import a
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reveal_type(a) # N: Revealed type is "builtins.object"
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reveal_type(a.b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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[file m/a.py]
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class B: pass
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b = B()
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[case testModuleLookupWeird2]
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# flags: --fast-module-lookup
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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[file m/a.py]
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class B: pass
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b = B()
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[case testModuleLookupWeird3]
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# flags: --fast-module-lookup
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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class B: pass
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a = B()
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[file m/a.py]
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class B: pass
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b = B()
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[case testModuleLookupWeird4]
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# flags: --fast-module-lookup
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import m.a
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m.a.b # E: "str" has no attribute "b"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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class B: pass
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a = 'foo'
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b = B()
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[file m/a.py]
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class C: pass
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b = C()
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[case testModuleLookupWeird5]
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# flags: --fast-module-lookup
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import m.a as ma
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reveal_type(ma.b) # N: Revealed type is "m.a.C"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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class B: pass
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a = 'foo'
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b = B()
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[file m/a.py]
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class C: pass
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b = C()
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[case testModuleLookupWeird6]
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# flags: --fast-module-lookup
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.C"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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class B: pass
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a = 'foo'
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b = B()
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[file m/a.py]
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class C: pass
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b = C()

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