Facebook, Inc.

Julien Marcel Verlaguet

Alok Menghrajani

Techniques provided implement automatic data type annotation in dynamically-typed source code. A codebase, which may comprise a plurality of source code files, is scanned at a global level. The resulting scanned data may describe characteristics of the codebase, including variable and function usage. Based on inferences drawn from the scanning, data types are determined for different variables, expressions, or functions to facilitate conversion from dynamically-typed source code to statically-typed source code. For example, if a function is called once with a parameter value of data type A (e.g., class A), and another time with a parameter value of data type B (e.g., class B), a conversion tool may annotate the parameter variable in the declaration of the function with a data type D (e.g., class d) when data type D is identified as a common ancestor (e.g., superclass) to both data type A and data type B.

Systems and methods for converting typed code

Disclosed is a method and system for detecting errors in source code of an application without executing the source code. Embodiments of the disclosed technique include detecting an error generating change at a specific location in source code of an application without executing the source code. The detection includes detecting an error in the changed portion of the source code as well dependencies of the changed portion of the source code. After the error detection, an error message containing information of the error is generated and stored in a storage unit. The information on the error includes (a) an indication of the change in source code, (b) the specific location, or (c) reason for the error. The types of error detected can include (i) a data type mismatch error, (ii) a syntax error, and (iii) other errors such as uninitialized variable access, null value or pointer dereference.

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Palo Alto, CA, United States of America

Julien Marcel Verlaguet