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JS: use guard nodes instead of synactic isConditional check

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Asger F
2018-10-29 14:33:45 +00:00
parent 336f605153
commit 7e5e5aea11
2 changed files with 8 additions and 12 deletions
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18
javascript/ql/src/Statements/UselessConditional.ql
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@@ -115,25 +115,21 @@ predicate whitelist(Expr e) {
}
/**
* Holds if `e` is part of a conditional node `cond` that evaluates
* `e` and checks its value for truthiness.
* Gets the `&&` expression that defines this guard node, if any.
*/
predicate isConditional(ASTNode cond, Expr e) {
e = cond.(IfStmt).getCondition() or
e = cond.(ConditionalExpr).getCondition() or
e = cond.(LogAndExpr).getLeftOperand() or
e = cond.(LogOrExpr).getLeftOperand()
LogAndExpr getLogAndExpr(ConditionGuardNode guard) {
result.getLeftOperand().stripParens() = guard.getTest()
}
from ASTNode cond, DataFlow::AnalyzedNode op, boolean cv, ASTNode sel, string msg
where isConditional(cond, op.asExpr()) and
from ConditionGuardNode guard, DataFlow::AnalyzedNode op, boolean cv, ASTNode sel, string msg
where guard.getTest() = op.asExpr() and
cv = op.getTheBooleanValue()and
not whitelist(op.asExpr()) and
// if `cond` is of the form `<non-trivial truthy expr> && <something>`,
// we suggest replacing it with `<non-trivial truthy expr>, <something>`
if cond instanceof LogAndExpr and cv = true and not op.asExpr().isPure() then
(sel = cond and msg = "This logical 'and' expression can be replaced with a comma expression.")
if exists(getLogAndExpr(guard)) and cv = true and not op.asExpr().isPure() then
(sel = getLogAndExpr(guard) and msg = "This logical 'and' expression can be replaced with a comma expression.")
// otherwise we just report that `op` always evaluates to `cv`
else (