phanalist

E0048: Unbounded Direct Recursion

E0048 reports direct recursion that reuses unchanged arguments and does not reassign the corresponding parameters. These calls are strong candidates for infinite recursion.

What it checks

• A function calling itself with the same parameter variables
• A method calling $this->sameMethod() with the same parameter variables
• A static method calling self::sameMethod(), static::sameMethod(), or ClassName::sameMethod() with the same parameter variables
• Zero-argument functions and methods that call themselves

A recursive call is accepted when it changes an argument, for example countdown($number - 1), or when the function mutates the parameter before the call. Mutations include direct assignment, ++/--, array element writes, property writes on parameter objects, unset(), foreach targets, and builtins that mutate an argument such as array_pop(), array_shift(), sort(), or preg_match().

Recursion is also accepted when the function mutates object or static state, calls another method on $this before recursing, or places the recursive call in a closure that shadows a parameter name. A fully qualified call such as \getenv() is treated as the global function, not as a recursive call to a namespaced getenv() function.

Model limits

E0048 is a local, conservative heuristic:

• Mutual recursion between two functions or methods is not reported.
• Recursion that changes global, static, or object state is not reported.
• Recursion through a closure parameter that shadows a function parameter is not reported.
• A base case is not required for a finding; the rule reports the unchanged recursive call and asks the author to make termination explicit.
• Recursive calls through variables, first-class callables, or dynamic method names are not reported.
• Argument identity is syntactic. countdown($number + 0) is treated as changed, and countdown($number) is treated as unchanged.
• Variadic parameter lists are skipped.

Configuration

E0048 has no configuration options and is enabled by default.

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