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ShadowGlobal.ql
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76 lines (69 loc) · 2.41 KB
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/**
* @name Global shadowed by local variable
* @description Defining a local variable with the same name as a global variable
* makes the global variable unusable within the current scope and makes the code
* more difficult to read.
* @kind problem
* @tags quality
* maintainability
* readability
* correctness
* @problem.severity recommendation
* @sub-severity low
* @precision medium
* @id py/local-shadows-global
*/
import python
private import LegacyPointsTo
import Shadowing
import semmle.python.types.Builtins
predicate shadows(Name d, GlobalVariable g, Function scope, int line) {
g.getScope() = scope.getScope() and
d.getScope() = scope and
exists(LocalVariable l |
d.defines(l) and
l.getId() = g.getId()
) and
not exists(Import il, Import ig, Name gd | il.contains(d) and gd.defines(g) and ig.contains(gd)) and
not exists(Assign a | a.getATarget() = d and a.getValue() = g.getAnAccess()) and
not exists(Builtin::builtin(g.getId())) and
d.getLocation().getStartLine() = line and
exists(Name defn | defn.defines(g) | not exists(If i | i.isNameEqMain() | i.contains(defn))) and
not optimizing_parameter(d)
}
/* pytest dynamically populates its namespace so, we cannot look directly for the pytest.fixture function */
AttrNode pytest_fixture_attr() {
exists(ModuleValue pytest |
result.getObject("fixture").(ControlFlowNodeWithPointsTo).pointsTo(pytest)
)
}
Value pytest_fixture() {
exists(CallNode call |
call.getFunction() = pytest_fixture_attr()
or
call.getFunction().(CallNode).getFunction() = pytest_fixture_attr()
|
call.(ControlFlowNodeWithPointsTo).pointsTo(result)
)
}
/* pytest fixtures require that the parameter name is also a global */
predicate assigned_pytest_fixture(GlobalVariable v) {
exists(NameNode def |
def.defines(v) and
def.(DefinitionNode).getValue().(ControlFlowNodeWithPointsTo).pointsTo(pytest_fixture())
)
}
predicate first_shadowing_definition(Name d, GlobalVariable g) {
exists(int first, Scope scope |
shadows(d, g, scope, first) and
first = min(int line | shadows(_, g, scope, line))
)
}
from Name d, GlobalVariable g, Name def
where
first_shadowing_definition(d, g) and
not exists(Name n | n.deletes(g)) and
def.defines(g) and
not assigned_pytest_fixture(g) and
not g.getId() = "_"
select d, "Local variable '" + g.getId() + "' shadows a $@.", def, "global variable"