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Java: Improve constant-loop-condition #5334

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Merged
merged 1 commit into from
Mar 5, 2021
Merged

Java: Improve constant-loop-condition #5334

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6 changes: 5 additions & 1 deletion java/ql/src/Likely Bugs/Termination/ConstantLoopCondition.ql
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,11 @@ where
) and
// And `cond` does not use method calls, field reads, or array reads.
not exists(MethodAccess ma | ma.getParent*() = cond) and
not exists(FieldRead fa | fa.getParent*() = cond) and
not exists(FieldRead fa |
// Ignore if field is final
not fa.getField().isFinal() and
fa.getParent*() = cond
) and
not exists(ArrayAccess aa | aa.getParent*() = cond)
select cond, "$@ might not terminate, as this loop condition is constant within the loop.", loop,
"Loop"
6 changes: 6 additions & 0 deletions java/ql/test/query-tests/ConstantLoopCondition/A.java
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
class A {
final boolean cond = otherCond();

boolean otherCond() { return 3 > 5; }

void f(int initx) {
Expand Down Expand Up @@ -30,5 +32,9 @@ void f(int initx) {
while(initx > 0) { // OK: loop used as an if-statement
break;
}

while (cond) { // BAD: read of final field
i++;
}
}
}
7 changes: 4 additions & 3 deletions java/ql/test/query-tests/ConstantLoopCondition/ConstantLoopCondition.expected
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@@ -1,3 +1,4 @@
| A.java:6:11:6:15 | !... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:6:5:6:16 | stmt | Loop |
| A.java:13:11:13:15 | ... > ... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:12:5:12:19 | stmt | Loop |
| A.java:27:20:27:32 | ... < ... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:27:5:27:38 | stmt | Loop |
| A.java:8:11:8:15 | !... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:8:5:8:16 | stmt | Loop |
| A.java:15:11:15:15 | ... > ... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:14:5:14:19 | stmt | Loop |
| A.java:29:20:29:32 | ... < ... | $@ might not terminate, as this loop condition is constant within the loop. | A.java:29:5:29:38 | stmt | Loop |
| A.java:36:12:36:15 | cond | $@ might not terminate, as this loop condition is constant within the loop. | A.java:36:5:36:16 | stmt | Loop |