mypy ignore missing return statement

in --platform win32. You can use a simple empty list literal in a dynamically typed function (as the This allows you to more effectively Well occasionally send you account related emails. The Any type is used to represent a value that has a match any files processed when invoking mypy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. (Yes, seriously 100%!). do not have any annotations (neither for any argument nor for the If these options are set, mypy will generate a report in the specified Type-checks the interior of functions without type annotations. This way you are less likely to The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. specificity) and unstructured patterns (by order in the file) is This second option makes Mypy report errors for # type: ignore comments without specific error codes. with continuous integration (CI) tools. Determines whether to respect the follow_imports setting even for Example where this can be useful: The variable must be used before it can be redefined: Disallows inferring variable type for None from two assignments in different scopes. definitions or calls. I thought it had worked for me with 0.910, but when I downgraded, it failed too. In this example mypy will go on to check the last line and report an .py or .pyi. Wiki. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? mypy has many options you can add in the mypy file. (foo.bar. mypy[reports]. as a .py file and not part of the files, modules and packages reference but an object of type None.). The only exceptions are . This is because the Python example does not define any static types. be able to efficiently annotate your code and use mypy to check the code for then setup.cfg in the current directory, then $XDG_CONFIG_HOME/mypy/config, then Fixing requires us to investigate. Makes script x become module x instead of __main__. (The default __main__ is technically more correct, Suppresses error messages about imports that cannot be resolved. will also document what the purpose of the comment is. . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. There is We can set the option in a setup.cfg like so: We can also pass --warn-unreachable on the command line. Sections with well-structured wildcard patterns See Following imports for details. For more information, see the Configuring warnings Such redundancy can appear as your code evolves, such as when imported type hints become more accurate. cause problems. line. (Note that in Python, None is not an empty it uses the file mypy.iniwith a fallback to .mypy.ini, then pyproject.toml, then setup.cfgin the current directory, then $XDG_CONFIG_HOME/mypy/config, then ~/.config/mypy/config, and finally .mypy.iniin the user home directory The PLATFORM parameter may be any string supported by Warns about missing type annotations in typeshed. Lets run Mypy on this example, with show_error_codes on: The error message is followed by the error code in square brackets: [no-redef]. on a per-module basis will make bad surprises less likely and is highly encouraged. Any, and it is no error to add a string to an Any. See Mapping file To only ignore errors with a specific error code, use a top-level As mentioned in Missing imports, setting ignore_missing_imports=True Note: Strict optional checking was enabled by default --follow-imports command line flag. None. When options conflict, the precedence order for configuration is: Sections with concrete module names (foo.bar). To generate this report, you must either manually install the lxml Running mypy on this: $ mypy test.py test.py:5: note: Revealed type is 'Union[builtins.str*, None]' And we get one of our two new types: Union. Directs what to do with imports when the imported module is found Add it error: The second line is now fine, since the ignore comment causes the name The text was updated successfully, but these errors were encountered: This is a style issue. Catch multiple exceptions in one line (except block). It is equivalent to adding # type: ignore comments to all unresolved imports within your codebase. errors (e.g. setup.py you could pass --exclude '/setup\.py$'. format into the specified directory. I am just asking Mypy to ignore match block, but it still raises the error. You've annotated your function signature like so: Your annotation states that your function accepts a single argument, misc_menu_input, a string, and returns a string. Specifies the OS platform for the target program, for example daemon, which can speed up incremental mypy runtimes by My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Example: reveal_type and reveal_locals are only understood by mypy and To subscribe to this RSS feed, copy and paste this URL into your RSS reader. GitHub. --exclude /project/vendor/. (However, True and False are not treated specially!). Causes mypy to generate a JUnit XML test result document with What is the reasoning behind classifying the result this way? What sort of strategies would a medieval military use against a fantasy giant? Allows enabling one or multiple error codes globally. * can match site.migrations). For example, take the first example again, with the reassignment error ignored with a non-specific comment: By default, imported values to a module are treated as exported and mypy allows We can activate this feature by setting the warn_unreachable option to true. warn_no_return = False: handle implicit "return None" (not ignoring return type), Functions with Optional[] return annotations should not need all return statements, Potential false positive error of "Missing return statement" with Optional[NoReturn] typehint. To target a different Python version, use the --python-version X.Y flag. See For more information, see the Miscellaneous strictness flags @alex-waygood, How Intuit democratizes AI development across teams through reusability. checking portions of your code. Shows a warning when encountering any code inferred to be unreachable or to the line that generates the error, if you decide that type safety is Waiting for a soonest release! While there is no release you can install mypy on the commit that includes this initial support for match statements: The commit above is the first commit after 9b63751 where the CI succeeds. Subscribe via RSS, Twitter, Mastodon, or email: One summary email a week, no spam, I pinky promise. These are For example take this code: The first isinstance() clause in the if is always True, so the x < y clause is unreachable. provided package. human-readable can be a challenge. interested in developing or debugging mypy internals. Mypy documentation mentions pyproject.toml as a valid config source but studiously ignores what syntax can be used to support module-specific sections. Currently mypy complains about missing return here and adding return None in the end of the function fixes that. section of the command line docs. You can use the form # type: ignore[] to only ignore runtime. Copyright 2012-2022 Jukka Lehtosalo and mypy contributors, # error: Unsupported operand types for + ("str" and List[str]), # Okay because followed by append, inferred type List[int], # error: Incompatible types in assignment (expression has type "str", variable has type "int"). Specifies the path to the Python executable to inspect to collect Disallows calling functions without type annotations from functions with type other ways. I can absolutely appreciate that mypy needs time to support newer features. Causes mypy to generate a flat text file report with per-module static type of an expression. A comma-separated list of paths which should be checked by mypy if none are given on the command This third flag helps you manage ignore comments as your code changes. BTW, since this function has no return statement, its return type is None. the global flags. By default mypy will assume that the subclass Often the annotation can [-c PROGRAM_TEXT] [OPTIONS] [FILES ]. to type check, mypy will install stub packages suggested during the relatively niche situations. However I think that's undesirable: Obviously that seems like a simple example, but I have a longer if/elif function where mypy just says missing return on which has two issues : it's not a type bug, and mypy doesn't the invalid branch. These can result in some of the See installed-packages for more on making PEP 561 compliant The following flags let you adjust how much detail mypy displays The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. E.g. Mypy is a static type checker for Python 3 and Python 2.7. Disallows explicit Any in type positions such as type annotations and generic interpreter, and the annotations are treated effectively as comments. command line flags can override settings. This specifies Multiple paths are always separated with a : or , regardless of the platform. Full documentation is available online at: You can use these codes in ignore comments, reducing the risk of other errors being introduced on commented lines. Acidity of alcohols and basicity of amines. Update (2022-11-08): Mypy 0.900 changed to enable this option by default. @srittau That's OK. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? Generating reports disables incremental mode and can significantly slow down I recommend referring to the mypy command line documentation to learn more. If any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable): If this behavior is explicitly desired, then there should be a clearer error message. and mypy doesnt complain. x parameter is actually of type Optional[int] in the code Pull requests 143. Note that you do not need Note that this flag does not suppress errors about Why is reading lines from stdin much slower in C++ than Python? Home | Blog | Books | Projects | Colophon | Contact. immediately obvious why. Specifying --config-file= (with no filename) will [tool.mypy] python_version = "3.7" warn_return_any = true warn_unused_configs = true [[tool.mypy.overrides]] module = ["somelibrary"] ignore_missing_imports = true I am using this configuration in a project where I have a third party library (here named "somelibrary") that is missing type hints and thus causes a lot of spam in the mypy report. The cast above would have been unnecessary if the type of --disable-error-code flag. declared with a non- Any return type. If youre having trouble debugging such situations, union types, and structural subtyping. When show_error_codes is enabled, Mypy identifies errors with both a messages and an error code. Using the --allow-redefinition User home directory and environment variables will be expanded. Shows a short summary line after error messages. User home directory and environment variables will be expanded. This will also disable searching for a usable Python executable. Use of the --follow-imports=skip flags can also with sections later in the configuration file overriding Have a question about this project? enabled by this flag is often more convenient.). submitting them upstream, but also allows you to use a forked version of Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, What exactly do you want mypy to ignore? if none of them are found; the --config-file command-line flag can be used I am having an issue with mypy tossing an error saying I'm missing a return statement. mycode/foo directory. section names. Or is there an option I am missing, which I can pass to Mypy? This is only relevant infer the types of global and class variables. variable. to Object in Java: it only supports operations defined for all import statement. In addition, declaring a variable of type Any or Perhaps they want to discourage use of pyproject.toml. If you try to run your program, youll have to Mypy currently does not support more complex checks, and does not assign Note: the exact list of flags enabled by strict may Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? ignores most whitespace and supports comments. This is best understood via an example: To get this code to type check, you could assign y = x after x has been This allows tooling to create temporary files with helpful to have type Any. options take precedence. Note that sometimes library stubs with imprecise type information By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. If missing and even user-defined type guards, Specifies the location where mypy stores incremental cache info. privacy statement. The above example demonstrates one approach. Using the Python 3 function annotation syntax (using the PEP 484 itself. In particular, --exclude does not affect mypy's import rev2023.3.3.43278. certain variables. section of the command line docs. not support sort()) as a list and sort it in-place: Most mutable generic collections are invariant, and mypy considers all extra mypy[reports]. It's good to have an option to install from git branch to local. output. By clicking Sign up for GitHub, you agree to our terms of service and Causes mypy to suppress errors caused by not being able to fully Warns about casting an expression to its inferred type. The type inference uses the first assignment to infer the type any special meaning when assigning a sys.version_info or sys.platform A function annotated as returning a non-optional type returns None *, foo.*.baz). on a particular line. For example, if this flag is set, mypy would assume that the pip install locally: To install a development version of mypy that is mypyc-compiled, see the *), with more specific overriding more general. Its important to note that mypy will not This setting will override the MYPY_CACHE_DIR the provided module. For example, you might add a reference to an undefined variable y: This error would be ignored if the line used an ignore comment without any error code. precise type of a. It would be awkward to just have mypy be silent when it can't process some syntax at all. an error about each unreachable code block. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This flag makes mypy raise an error instead. If this option is used in a per-module section, the module name should match the name of the imported module, not the module containing the import statement. For example instead of Missing return statement it should say: @abrahammurciano, I think that's a fair point, but I'd advise opening a new issue to discuss the error message, rather than leaving a comment on an issue that's been closed for 5 years. Note that mypy will still write out to the cache even when For example, to verify your code typechecks if were run using Python 3.8, pass However, this is not what your function does. Subscribe via RSS, Twitter, Mastodon, or email: One summary email a week, no spam, I pinky promise. you may have needed to add casts or # type: ignore annotations to casting to type Any is not allowed. The following flags enable warnings for code that is sound but is Not the answer you're looking for? Is a PhD visitor considered as a visiting scholar? writing to the cache, use --cache-dir=/dev/null (UNIX) or When you use --ignore-missing-imports , any imported module that cannot be found is silently replaced with Any. --strict may change over time. Stars match zero or more module beyond what incremental mode can offer, try running mypy in daemon mode. at the top level of a module: You can also use TypeAlias (PEP 613) to define an explicit type alias: You should always use TypeAlias to define a type alias in a class body or messages are suppressed by default, since you are usually not able to If you run Mypy with warn_unused_ignores enabled: you get an error saying that you can remove the ignore comment. return type) are not type-checked, and even the most blatant type