String to ::class with leading backslash vs no leading backslash

[joshbmarshall]

Bug Report

Subject	Details
Rector version	v2.1.4

StringClassNameToClassConstantRector is replacing strings with leading backslashes, causing potential string mismatches.

I have a legacy application that stores the user's selection of a class in the database. At some point it was updated to use ::class which does not have leading backslashes, but some data remains with the leading backslash.

So e.g. the code:

if ($var == 'Foo\Bar' || $var == '\Foo\Bar') {}

gets replaced with:

if ($var == \Foo\Bar::class || $var == \Foo\Bar::class) {}

Minimal PHP Code Causing Issue

https://getrector.com/demo/3b6c7c8d-cf8f-464e-90d6-0e2bffe91f78

Expected Behaviour

I expect it not to change the comparison. Options might include leaving it unchanged or to have the leading slash when doing string comparisons?

if ($var == \Foo\Bar::class || $var == '\' . \Foo\Bar::class) {}

It might not just be for string comparisons. What if it was to output to the browser or was used as an api result, where it is actually being used as a string?

Note: I saw #9343 but I believe this is a slightly different issue - that one the outcome was to change the configuration, but I think that would only handle having one or the other but not both?

[samsonasik]

Here the history for the rule change:

• The rule was originally add \ prefix for original 1 - 1 comparison

• The feature removed at:

• [PHP 5.5] Remove extra preslash in class reference, as in practice removal manually rector-src#5338

• To cover that, the configurable was introduction

• [Php55] Make StringClassNameToClassConstantRector configurable to keep first pre-backslash string configurable rector-src#5354

• Then the feature removed:

• [cleanup] deprecate SHOULD_KEEP_PRE_SLASH, remove dont traverse const on StringClassNameToClassConstantRector rector-src#7704

[TomasVotruba]

@samsonasik I'll handle these reports.

@joshbmarshall Thanks for reporting. The reason is to avoid pre-empty pre-slashing every such class. In the end it end up the rule was adding \\ in many cases where simple transition is needed.

For your use case, skip this rule in rector.php, as your project uses hard coded string. If you ever move the class, it would also break as IDE moves it in your PHP codebase, but no in the database.

And ideally, not use the FQN class names in db and move to some stringy identifier instead. That way you'll be able to move classes independently on the db 👍