Note that a bareword before the -> is subject to interpretation as a function call if there is such a function:

$ perl -we'sub Foo { "Bar" }  Foo -> method'
Can't locate object method "method" via package "Bar" (perhaps you for
+got to load "Bar"?) at -e line 1.
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You can force its interpretation as a class name by saying Bar::->method (no, that doesn't call &Bar:: even if you go out of your way to define such an evilly named sub) or "Bar"->method.

In a module or in a program using other's modules, you should do this all the time. After all, your code may have done use Some::Module and established a contract with that module, but when you say Some::Module->classmethod you are implicitly making an assumtion about the module Some, which you have no arrangement with.