hohn/codeql
1
0
Fork 0
mirror of https://github.com/github/codeql.git synced 2026-04-30 19:26:02 +02:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #380 from asger-semmle/generalize-useless-conditional

Browse Source 
Approved by esben-semmle
This commit is contained in:
semmle-qlci
2018-10-31 07:31:06 +00:00
committed by GitHub
parent dc3c5a684c 1568d5dadd
commit 28f3b686a7
4 changed files with 24 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
change-notes/1.19/analysis-javascript.md
View File

@@ -39,6 +39,7 @@
| User-controlled bypass of security check | Fewer results | This rule no longer flags conditions that guard early returns. The precision of this rule has been revised to "medium". Results are no longer shown on LGTM by default. |
| Whitespace contradicts operator precedence | Fewer false-positive results | This rule no longer flags operators with asymmetric whitespace. |
| Unused import | Fewer false-positive results | This rule no longer flags imports used by the `transform-react-jsx` Babel plugin. |
| Useless conditional | More true-positive results | This rule now flags useless conditions in more cases. |
## Changes to QL libraries

18
javascript/ql/src/Statements/UselessConditional.ql
View File

@@ -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 (

5
javascript/ql/test/query-tests/Statements/UselessConditional/UselessConditional.expected
View File

@@ -1,4 +1,4 @@
| UselessConditional.js:5:7:5:12 | !lines | This expression always evaluates to false. |
| UselessConditional.js:5:8:5:12 | lines | Variable 'lines' always evaluates to true here. |
| UselessConditional.js:12:34:12:79 | (v = ne ... k] = v) | This logical 'and' expression can be replaced with a comma expression. |
| UselessConditional.js:17:9:17:9 | a | Variable 'a' always evaluates to false here. |
| UselessConditional.js:18:9:18:9 | b | Variable 'b' always evaluates to false here. |
@@ -15,7 +15,8 @@
| UselessConditional.js:65:5:65:5 | x | Variable 'x' always evaluates to true here. |
| UselessConditional.js:76:13:76:13 | x | Variable 'x' always evaluates to true here. |
| UselessConditional.js:82:13:82:13 | x | Variable 'x' always evaluates to true here. |
| UselessConditional.js:89:10:89:16 | x, true | This expression always evaluates to true. |
| UselessConditional.js:94:16:94:16 | x | Variable 'x' always evaluates to false here. |
| UselessConditional.js:101:18:101:18 | x | Variable 'x' always evaluates to false here. |
| UselessConditionalGood.js:58:12:58:13 | x2 | Variable 'x2' always evaluates to false here. |
| UselessConditionalGood.js:69:12:69:13 | xy | Variable 'xy' always evaluates to false here. |
| UselessConditionalGood.js:85:12:85:13 | xy | Variable 'xy' always evaluates to false here. |

13
javascript/ql/test/query-tests/Statements/UselessConditional/UselessConditional.js
View File

@@ -89,4 +89,17 @@ async function awaitFlow(){
if ((x, true));
});
(function (x, y) {
if (!x) {
while (x) { // NOT OK
f();
}
while (true) { // OK
break;
}
if (true && true) {} // OK
if (y && x) {} // NOT OK
}
});
// semmle-extractor-options: --experimental