mirror of
https://github.com/github/codeql.git
synced 2025-12-29 15:16:34 +01:00
f07a7bf8cf
Will need subsequent PRs fixing up test failures (due to deprecated methods moving around), but other than that everything should be straight-forward.
104 lines
2.7 KiB
Plaintext
104 lines
2.7 KiB
Plaintext
/**
|
|
* @name Redundant assignment
|
|
* @description Assigning a variable to itself is useless and very likely indicates an error in the code.
|
|
* @kind problem
|
|
* @tags reliability
|
|
* useless-code
|
|
* external/cwe/cwe-563
|
|
* @problem.severity error
|
|
* @sub-severity low
|
|
* @precision very-high
|
|
* @id py/redundant-assignment
|
|
*/
|
|
|
|
import python
|
|
|
|
predicate assignment(AssignStmt a, Expr left, Expr right) {
|
|
a.getATarget() = left and a.getValue() = right
|
|
}
|
|
|
|
predicate corresponding(Expr left, Expr right) {
|
|
assignment(_, left, right)
|
|
or
|
|
exists(Attribute la, Attribute ra |
|
|
corresponding(la, ra) and
|
|
left = la.getObject() and
|
|
right = ra.getObject()
|
|
)
|
|
}
|
|
|
|
predicate same_value(Expr left, Expr right) {
|
|
same_name(left, right)
|
|
or
|
|
same_attribute(left, right)
|
|
}
|
|
|
|
predicate maybe_defined_in_outer_scope(Name n) {
|
|
exists(SsaVariable v | v.getAUse().getNode() = n | v.maybeUndefined())
|
|
}
|
|
|
|
/*
|
|
* Protection against FPs in projects that offer compatibility between Python 2 and 3,
|
|
* since many of them make assignments such as
|
|
*
|
|
* if PY2:
|
|
* bytes = str
|
|
* else:
|
|
* bytes = bytes
|
|
*/
|
|
|
|
predicate isBuiltin(string name) { exists(Value v | v = Value::named(name) and v.isBuiltin()) }
|
|
|
|
predicate same_name(Name n1, Name n2) {
|
|
corresponding(n1, n2) and
|
|
n1.getVariable() = n2.getVariable() and
|
|
not isBuiltin(n1.getId()) and
|
|
not maybe_defined_in_outer_scope(n2)
|
|
}
|
|
|
|
ClassValue value_type(Attribute a) { a.getObject().pointsTo().getClass() = result }
|
|
|
|
predicate is_property_access(Attribute a) {
|
|
value_type(a).lookup(a.getName()) instanceof PropertyValue
|
|
}
|
|
|
|
predicate same_attribute(Attribute a1, Attribute a2) {
|
|
corresponding(a1, a2) and
|
|
a1.getName() = a2.getName() and
|
|
same_value(a1.getObject(), a2.getObject()) and
|
|
exists(value_type(a1)) and
|
|
not is_property_access(a1)
|
|
}
|
|
|
|
int pyflakes_commented_line(File file) {
|
|
exists(Comment c | c.getText().toLowerCase().matches("%pyflakes%") |
|
|
c.getLocation().hasLocationInfo(file.getAbsolutePath(), result, _, _, _)
|
|
)
|
|
}
|
|
|
|
predicate pyflakes_commented(AssignStmt assignment) {
|
|
exists(Location loc |
|
|
assignment.getLocation() = loc and
|
|
loc.getStartLine() = pyflakes_commented_line(loc.getFile())
|
|
)
|
|
}
|
|
|
|
predicate side_effecting_lhs(Attribute lhs) {
|
|
exists(ClassValue cls, ClassValue decl |
|
|
lhs.getObject().pointsTo().getClass() = cls and
|
|
decl = cls.getASuperType() and
|
|
not decl.isBuiltin()
|
|
|
|
|
decl.declaresAttribute("__setattr__")
|
|
)
|
|
}
|
|
|
|
from AssignStmt a, Expr left, Expr right
|
|
where
|
|
assignment(a, left, right) and
|
|
same_value(left, right) and
|
|
// some people use self-assignment to shut Pyflakes up, such as `ok = ok # Pyflakes`
|
|
not pyflakes_commented(a) and
|
|
not side_effecting_lhs(left)
|
|
select a, "This assignment assigns a variable to itself."
|