psalm/docs/dealing_with_code_issues.md

Dealing with code issues

Code issues in Psalm fall into three categories:

error

this will cause Psalm to print a message, and to ultimately terminate with a non-zero exist status

info

this will cause Psalm to print a message

suppress

this will cause Psalm to ignore the code issue entirely

The third category, suppress, is the one you will probably be most interested in, especially when introducing Psalm to a large codebase.

Suppressing issues

There are two ways to suppress an issue – via the Psalm config or via a function docblock.

Config suppression

You can use the <issueHandlers> tag in the config file to influence how issues are treated.

<issueHandlers>
  <MissingPropertyType errorLevel="suppress" />

  <InvalidReturnType>
    <errorLevel type="suppress">
      <directory name="some_bad_directory" /> <!-- all InvalidReturnType issues in this directory are suppressed -->
      <file name="some_bad_file.php" />  <!-- all InvalidReturnType issues in this file are suppressed -->
    </errorLevel>
  </InvalidReturnType>
</issueHandlers>

Docblock suppression

You can also use @psalm-suppress IssueName on a function's docblock to suppress Psalm issues e.g.

/**
 * @psalm-suppress InvalidReturnType
 */
function (int $a) : string {
  return $a;
}

You can also suppress issues at the line level e.g.

/**
 * @psalm-suppress InvalidReturnType
 */
function (int $a) : string {
  /**
   * @psalm-suppress InvalidReturnStatement
   */
  return $a;
}