# Contributing to QL

We welcome contributions to our standard library and standard checks. Got an idea for a new check, or how to improve an existing query? Then please go ahead and open a pull request!

Before we accept your pull request, we require that you have agreed to our Contributor License Agreement, this is not something that you need to do before you submit your pull request, but until you've done so, we will be unable to accept your contribution.

## Adding a new query

If you have an idea for a query that you would like to share with other Semmle users, please open a pull request to add it to this repository. 
Follow the steps below to help other users understand what your query does, and to ensure that your query is consistent with the other Semmle queries.

1. **Consult the QL documentation for query writers**

   There is lots of useful documentation to help you write QL, ranging from information about query file structure to language-specific tutorials. For more information on the documentation available, see [Writing QL queries](https://help.semmle.com/QL/learn-ql/writing-queries/writing-queries.html) on [help.semmle.com](https://help.semmle.com).

2. **Format your QL correctly**

   All of Semmle's standard QL queries and libraries are uniformly formatted for clarity and consistency, so we strongly recommend that all QL contributions follow the same formatting guidelines. If you use QL for Eclipse, you can auto-format your query in the [QL editor](https://help.semmle.com/ql-for-eclipse/Content/WebHelp/ql-editor.html). For more information, see the [QL style guide](https://github.com/Semmle/ql/blob/master/docs/ql-style-guide.md).

3. **Make sure your query has the correct metadata**

   Query metadata is used by Semmle's analysis to identify your query and make sure the query results are displayed properly. 
   The most important metadata to include are the `@name`, `@description`, and the `@kind`.
   Other metadata properties (`@precision`, `@severity`, and `@tags`) are usually added after the query has been reviewed by Semmle staff.
   For more information on writing query metadata, see the [Query metadata style guide](https://github.com/Semmle/ql/blob/master/docs/query-metadata-style-guide.md).

4. **Make sure the `select` statement is compatible with the query type**

   The `select` statement of your query must be compatible with the query type (determined by the `@kind` metadata property) for alert or path results to be displayed correctly in LGTM and QL for Eclipse.
   For more information on `select` statement format, see [Introduction to query files](https://help.semmle.com/QL/learn-ql/writing-queries/introduction-to-queries.html#select-clause) on help.semmle.com.

5. **Save your query in a `.ql` file in correct language directory in this repository**

   There are five language-specific directories in this repository:
   
     * C/C++: `ql/cpp/ql/src`
     * C#: `ql/csharp/ql/src`
     * Java: `ql/java/ql/src`
     * JavaScript: `ql/javascript/ql/src`
     * Python: `ql/python/ql/src`

   Each language-specific directory contains further subdirectories that group queries based on their `@tags` properties or purpose. Select the appropriate subdirectory for your new query, or create a new one if necessary. 

6. **Write a query help file**

   Query help files explain the purpose of your query to other users. Write your query help in a `.qhelp` file and save it in the same directory as your new query. 
   For more information on writing query help, see the [Query help style guide](https://github.com/Semmle/ql/blob/master/docs/query-help-style-guide.md).

## Using your personal data

If you contribute to this project, we will record your name and email
address (as provided by you with your contributions) as part of the code
repositories, which might be made public. We might also use this information
to contact you in relation to your contributions, as well as in the
normal course of software development. We also store records of your
CLA agreements. Under GDPR legislation, we do this
on the basis of our legitimate interest in creating the QL product.

Please do get in touch (privacy@semmle.com) if you have any questions about
this or our data protection policies.

## Contributor License Agreement

This Contributor License Agreement (“Agreement”) is entered into between Semmle Limited (“Semmle,” “we” or “us” etc.), and You (as defined and further identified below).

Accordingly, You hereby agree to the following terms for Your present and future Contributions submitted to Semmle:

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   * "Contribution(s)" shall mean the code, documentation or other original works of authorship, including any modifications or additions to an existing work, submitted by You to Semmle for inclusion in, or documentation of, any of the products or projects owned or managed by Semmle (the "Work(s)").  For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to Semmle or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, Semmle for the purpose of discussing and/or improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by You as "Not a Contribution."

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7. **Inclusion of Code**. We determine the code that is in our Works. You understand that the decision to include the Contribution in any project or source repository is entirely that of Semmle, and this agreement does not guarantee that the Contributions will be included in any product.

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