Psalm uses an XML config file (by default, psalm.xml). A barebones example looks like this:
<?xml version="1.0"?>
<psalm>
<projectFiles>
<directory name="src" />
</projectFiles>
</psalm><psalm
totallyTyped="[bool]"
/>Enabling this will make Psalm very strict, such that it needs to be able to evaluate the type of every single statement, and emitting a bevy of Mixed* issues if the types cannot be determined. Defaults to false.
<psalm
resolveFromConfigFile="[bool]"
/>If this is enabled, relative directories mentioned in the config file will be resolved relative to the location of the config file. If it is disabled, or absent they will be resolved relative to the working directory of the Psalm process.
New versions of Psalm enable this option when generating config files. Older versions did not include it.
<psalm
useDocblockTypes="[bool]"
>Whether or not to use types as defined in docblocks. Defaults to true.
<psalm
useDocblockPropertyTypes="[bool]"
>If not using all docblock types, you can still use docblock property types. Defaults to false (though only relevant if useDocblockTypes is false.
<psalm
usePhpDocMethodsWithoutMagicCall="[bool]"
>The PHPDoc @method annotation normally only applies to classes with a __call method. Setting this to true allows you to use the @method annotation to override inherited method return types. Defaults to false.
<psalm
strictBinaryOperands="[bool]"
>If true we force strict typing on numerical and string operations (see #24). Defaults to false.
<psalm
requireVoidReturnType="[bool]"
>If false, Psalm will not complain when a function with no return types is missing an explicit @return annotation. Defaults to true.
<psalm
useAssertForType="[bool]"
>Some like to use assert for type checks. If true, Psalm will process assertions inside assert calls. Defaults to true.
<psalm
rememberPropertyAssignmentsAfterCall="[bool]"
>Setting this to false means that any function calls will cause Psalm to forget anything it knew about object properties within the scope of the function it's currently analysing. This duplicates functionality that Hack has. Defaults to true.
<psalm
allowPhpStormGenerics="[bool]"
>Allows you to specify whether or not to use the typed iterator docblock format supported by PHP Storm e.g. ArrayIterator|string[], which Psalm transforms to ArrayIterator<string>. Defaults to false.
<psalm
allowCoercionFromStringToClassConst="[bool]"
>When true, strings can be coerced to class-string, with Psalm emitting a TypeCoercion issue. If disabled, that issue changes to a more serious one. Defaults to false.
<psalm
allowStringToStandInForClass="[bool]"
>When true, strings can be used as classes, meaning $some_string::someMethod() is allowed. If false, only class constant strings (of the form Foo\Bar::class) can stand in for classes, otherwise an InvalidStringClass issue is emitted. Defaults to false.
<psalm
memoizeMethodCallResults="[bool]"
>When true, the results of method calls without arguments passed arguments are remembered between repeated calls of that method on a given object. Defaults to false.
<psalm
hoistConstants="[bool]"
>When true, constants defined in a function in a file are assumed to be available when requiring that file, and not just when calling that function. Defaults to false (i.e. constants defined in functions will only be available for use when that function is called)
<psalm
addParamDefaultToDocblockType="[bool]"
>Occasionally a param default will not match up with the docblock type. By default, Psalm emits an issue. Setting this flag to true causes it to expand the param type to include the param default. Defaults to false.
<psalm
checkForThrowsDocblock="[bool]"
>When true, Psalm will check that the developer has supplied @throws docblocks for every exception thrown in a given function or method. Defaults to false.
<psalm
checkForThrowsInGlobalScope="[bool]"
>When true, Psalm will check that the developer has caught every exception in global scope. Defaults to false.
<psalm
ignoreInternalFunctionFalseReturn="[bool]"
>When true, Psalm ignores possibly-false issues stemming from return values of internal functions (like preg_split) that may return false, but do so rarely). Defaults to true.
<psalm
ignoreInternalFunctionNullReturn="[bool]"
>When true, Psalm ignores possibly-null issues stemming from return values of internal array functions (like current) that may return null, but do so rarely. Defaults to true.
<psalm
findUnusedVariables="[bool]"
>When true, Psalm will attempt to find all unused variables, the equivalent of running with --find-unused-variables. Defaults to false.
<psalm
findUnusedCode="[bool]"
>When true, Psalm will attempt to find all unused code (including unused variables), the equivalent of running with --find-unused-code. Defaults to false.
<psalm
autoloader="[string]"
>if your application registers one or more custom autoloaders, and/or declares universal constants/functions, this autoloader script will be executed by Psalm before scanning starts. Psalm always registers composer's autoloader by default.
<psalm
throwExceptionOnError="[bool]"
>Useful in testing, things makes Psalm throw a regular-old exception when it encounters an error. Defaults to false.
<psalm
hideExternalErrors="[bool]"
>whether or not to show issues in files that are used by your project files, but which are not included in <projectFiles>. Defaults to false.
<psalm
cacheDirectory="[string]"
>The directory used to store Psalm's cache data - if you specify one (and it does not already exist), its parent directory must already exist, otherwise Psalm will throw an error.
<psalm
allowFileIncludes="[bool]"
>Whether or not to allow require/include calls in your PHP. Defaults to true.
<psalm
serializer="['igbinary'|'default']"
>Allows you to hard-code a serializer for Psalm to use when caching data. By default, Psalm uses ext-igbinary if the version is greater or equal to 2.0.5, otherwise it defaults to PHP's built-in serializer.
Contains a list of all the directories that Psalm should inspect. You can also specify a set of files and folders to ignore with the <ignoreFiles> directive, e.g.
<projectFiles>
<directory name="src" />
<ignoreFiles>
<directory name="src/Stubs" />
</ignoreFiles>
</projectFiles>Optional. A list of extensions to search over. See Checking non-PHP files to understand how to extend this.
Optional. A list of <plugin filename="path_to_plugin.php" /> entries. See the Plugins section for more information.
Optional. If you don't want Psalm to complain about every single issue it finds, the issueHandler tag allows you to configure that. Dealing with code issues tells you more.
Optional. Do you use mock classes in your tests? If you want Psalm to ignore them when checking files, include a fully-qualified path to the class with <class name="Your\Namespace\ClassName" />
Optional. If your codebase uses classes and functions that are not visible to Psalm via reflection (e.g. if there are internal packages that your codebase relies on that are not available on the machine running Psalm), you can use stub files. Used by PhpStorm (a popular IDE) and others, stubs provide a description of classes and functions without the implementations. You can find a list of stubs for common classes here. List out each file with <file name="path/to/file.php" />.
Optional. A list of exceptions to not report for checkForThrowsDocblock or checkForThrowsInGlobalScope. If an exception has onlyGlobalScope set to true, only checkForThrowsInGlobalScope is ignored for that exception, e.g.
<ignoreExceptions>
<class name="fully\qualified\path\Exc" onlyGlobalScope="true" />
</ignoreExceptions>