Initialization problem in while true loop #1727
Comments
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javac compiler has special handling for class B {
}
public class Bug {
private B foo(int x, int y) {
B b;
while (x==y) {// This line is not always true
B op = getB();
if (op == null) {
b = new B();
break;
}else{
b = op;
break;
}
}
return b;
}
private B getB() {return new B();}
}And after I ran: This makes sense, because if But if we change |
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Thanks for filing this :) I just encountered the same thing, and once I minimized it, I was able to find this existing issue. Here's what I ended up with: $ cat AssignAndBreak.java
class AssignAndBreak {
void foo() {
Object e;
while (true) {
e = "";
break;
}
e.toString();
}
}FYI, we saw it in our |
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Sorry, I forgot to add: I had hoped that switching to |
This PR fixes both issue #3249 and issue #1727, by adapting the CFG in the following way: If the loop condition is checked to be a constant true (according to the same logic in javac flow analysis), then the loop condition does not have an else-branch, i.e. the block holding the loop condition is directly followed by the one holding the loop entry, instead of followed by a conditional block. Fixes #1727 and Fixes #3249`
Testcase(please remove txt file extension after download):
Bug.java.txt
Command I used:
javac -processor nullness testinput/typecheck/Bug.java -version -verbose -AprintErrorStack -AprintAllQualifiersConsole Output:
Expected: no errors
Actual: return type incompatible on line 22.
Reasoning:
while(true)loop is guaranteed to be executed and both branches(if&else) initializes b to be a@NonNullvalue. So at line 22,b's type should be@Initialized @NonNull.The text was updated successfully, but these errors were encountered: