Using Psalter

Psalm is good at finding potential issues in large codebases, but once found, it can be something of a gargantuan task to fix all the issues.

It comes with a tool, called Psalter, that helps you fix code.

You can either run it via its binary

vendor/bin/psalter [args]

or via Psalm's binary:

vendor/bin/psalm --alter [args]

Safety features

Updating code is inherently risky, doing so automatically is even more so. I've added a few features to make it a little more reassuring:

  • To see what changes Psalter will make ahead of time, you can run it with --dry-run.
  • You can target particular versions of PHP via --php-version, so that (for example) you don't add nullable typehints to PHP 7.0 code, or any typehints at all to PHP 5.6 code. --php-version defaults to your current version.
  • it has a --safe-types mode that will only update PHP 7 return typehints with information Psalm has gathered from non-docblock sources of type information (e.g. typehinted params, instanceof checks, other return typehints etc.)

Plugins

You can pass in your own manipulation plugins e.g.

vendor/bin/psalter --plugin=vendor/vimeo/psalm/examples/ClassUnqualifier.php --dry-run

The above example plugin converts all unnecessarily qualified classnames in your code to shorter aliased versions.

Supported fixes

This initial release provides support for the following alterations, corresponding to the names of issues Psalm finds:

MissingReturnType

Running vendor/bin/psalter --issues=MissingReturnType --php-version=7.0 on

function foo() {
  return "hello";
}

gives

function foo() : string {
  return "hello";
}

and running vendor/bin/psalter --issues=MissingReturnType --php-version=5.6 on

function foo() {
  return "hello";
}

gives

/**
 * @return string
 */
function foo() {
  return "hello";
}

MissingClosureReturnType

As above, except for closures

InvalidReturnType

Running vendor/bin/psalter --issues=InvalidReturnType on

/**
 * @return int
 */
function foo() {
  return "hello";
}

gives

/**
 * @return string
 */
function foo() {
  return "hello";
}

There's also support for return typehints, so running vendor/bin/psalter --issues=InvalidReturnType on

function foo() : int {
  return "hello";
}

gives

function foo() : string {
  return "hello";
}

InvalidNullableReturnType

Running vendor/bin/psalter --issues=InvalidNullableReturnType --php-version=7.1 on

function foo() : string {
  return rand(0, 1) ? "hello" : null;
}

gives

function foo() : ?string {
  return rand(0, 1) ? "hello" : null;
}

and running vendor/bin/psalter --issues=InvalidNullableReturnType --php-version=7.0 on

function foo() : string {
  return rand(0, 1) ? "hello" : null;
}

gives

/**
 * @return string|null
 */
function foo() {
  return rand(0, 1) ? "hello" : null;
}

InvalidFalsableReturnType

Running vendor/bin/psalter --issues=InvalidFalsableReturnType on

function foo() : string {
  return rand(0, 1) ? "hello" : false;
}

gives

/**
 * @return string|false
 */
function foo() {
  return rand(0, 1) ? "hello" : false;
}

MismatchingDocblockParamType

Given

class A {}
class B extends A {}
class C extends A {}
class D {}

running vendor/bin/psalter --issues=MismatchingDocblockParamType on

/**
 * @param B|C $first
 * @param D $second
 */
function foo(A $first, A $second) : void {}

gives

/**
 * @param B|C $first
 * @param A $second
 */
function foo(A $first, A $second) : void {}

MismatchingDocblockReturnType

Running vendor/bin/psalter --issues=MismatchingDocblockReturnType on

/**
 * @return int
 */
function foo() : string {
  return "hello";
}

gives

/**
 * @return string
 */
function foo() : string {
  return "hello";
}

LessSpecificReturnType

Running vendor/bin/psalter --issues=LessSpecificReturnType on

function foo() : ?string {
  return "hello";
}

gives

function foo() : string {
  return "hello";
}

PossiblyUndefinedVariable

Running vendor/bin/psalter --issues=PossiblyUndefinedVariable on

if (rand(0, 1)) {
  $a = 5;
}
echo $a;

gives

$a = null;
if (rand(0, 1)) {
  $a = 5;
}
echo $a;