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