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JS: recognize more conditionals in useless-conditional

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Asger F
2018-10-31 11:03:25 +00:00
parent 786377d8dc
commit 56707fc79a
3 changed files with 22 additions and 3 deletions
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9
javascript/ql/src/Statements/UselessConditional.ql
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@@ -120,9 +120,12 @@ predicate whitelist(Expr e) {
*/
predicate isConditional(ASTNode cond, Expr e) {
e = cond.(IfStmt).getCondition() or
e = cond.(WhileStmt).getExpr() or
e = cond.(ForStmt).getTest() or
e = cond.(ConditionalExpr).getCondition() or
e = cond.(LogAndExpr).getLeftOperand() or
e = cond.(LogOrExpr).getLeftOperand()
e = cond.(LogicalBinaryExpr).getLeftOperand() or
// Include `z` in `if (x && z)`.
isConditional(_, cond) and e = cond.(LogicalBinaryExpr).getRightOperand()
}
from ASTNode cond, DataFlow::AnalyzedNode op, boolean cv, ASTNode sel, string msg
@@ -132,7 +135,7 @@ where isConditional(cond, 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
if cond.(LogAndExpr).getLeftOperand() = op.asExpr() and cv = true and not op.asExpr().isPure() then
(sel = cond and msg = "This logical 'and' expression can be replaced with a comma expression.")
// otherwise we just report that `op` always evaluates to `cv`