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[Reachability] count a labeled break only against the labeled statement #6200

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Merged
copybara-service merged 1 commit into from
Oct 13, 2026
Merged

[Reachability] count a labeled break only against the labeled statement #6200

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8 changes: 4 additions & 4 deletions check_api/src/main/java/com/google/errorprone/util/Reachability.java
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Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,8 @@ private boolean scan(Tree tree) {
/* A break statement cannot complete normally. */
@Override
public Boolean visitBreak(BreakTree tree, Void unused) {
breaks.add(skipLabel(requireNonNull(((JCTree.JCBreak) tree).target)));
// The target of a `break` with a label is the labeled statement
breaks.add(requireNonNull(((JCTree.JCBreak) tree).target));
return false;
}

Expand Down Expand Up @@ -218,9 +219,8 @@ public Boolean visitEmptyStatement(EmptyStatementTree tree, Void unused) {
public Boolean visitLabeledStatement(LabeledStatementTree tree, Void unused) {
// (1)
boolean completes = scan(tree.getStatement());
// (2) `visitBreak` records a `break` against the statement contained in its target (see
// `skipLabel`).
return completes || breaks.contains(tree.getStatement());
// (2)
return completes || breaks.contains(tree);
}

/* An expression statement can complete normally iff it is reachable. */
Expand Down
44 changes: 7 additions & 37 deletions check_api/src/test/java/com/google/errorprone/util/ReachabilityTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -158,16 +158,6 @@ void f(int x, Object o, Shape shape, Paint paint, Color color) {
*/
private CompilationTestHelper containedStatementCanCompleteNormallyTest(
boolean expected, String labeledStatement) {
return containedStatementCanCompleteNormallyTest(expected, expected, labeledStatement);
}

/**
* Like {@link #containedStatementCanCompleteNormallyTest(boolean, String)}, but documents a bug
* where {@link Reachability} disagrees with javac: {@code reachability} is what {@link
* Reachability} currently answers, and {@code javac} is what javac answers (the ground truth).
*/
private CompilationTestHelper containedStatementCanCompleteNormallyTest(
boolean reachability, boolean javac, String labeledStatement) {
String label = "l:\n";
checkArgument(labeledStatement.startsWith(label), labeledStatement);
String statement = labeledStatement.substring(label.length());
Expand All @@ -193,10 +183,10 @@ void javacAgrees(int x, Object o) {
}
"""
.formatted(
reachability,
expected,
labeledStatement,
statement,
javac ? "String s = \"\";" : "s.length();"));
expected ? "String s = \"\";" : "s.length();"));
}

@Test
Expand Down Expand Up @@ -615,11 +605,7 @@ public void breakExitsLabeledStatement_while() {
}
""";
canCompleteNormallyTest(/* expected= */ true, statement).doTest();
// BUG: Reachability credits `break l` to the statement contained in `l`, so it disagrees with
// javac, which says that statement can't complete normally.
containedStatementCanCompleteNormallyTest(
/* reachability= */ true, /* javac= */ false, statement)
.doTest();
containedStatementCanCompleteNormallyTest(/* expected= */ false, statement).doTest();
}

/**
Expand All @@ -636,11 +622,7 @@ public void breakExitsLabeledStatement_do() {
} while (true);
""";
canCompleteNormallyTest(/* expected= */ true, statement).doTest();
// BUG: Reachability credits `break l` to the statement contained in `l`, so it disagrees with
// javac, which says that statement can't complete normally.
containedStatementCanCompleteNormallyTest(
/* reachability= */ true, /* javac= */ false, statement)
.doTest();
containedStatementCanCompleteNormallyTest(/* expected= */ false, statement).doTest();
}

/**
Expand All @@ -657,11 +639,7 @@ public void breakExitsLabeledStatement_for() {
}
""";
canCompleteNormallyTest(/* expected= */ true, statement).doTest();
// BUG: Reachability credits `break l` to the statement contained in `l`, so it disagrees with
// javac, which says that statement can't complete normally.
containedStatementCanCompleteNormallyTest(
/* reachability= */ true, /* javac= */ false, statement)
.doTest();
containedStatementCanCompleteNormallyTest(/* expected= */ false, statement).doTest();
}

/**
Expand All @@ -681,11 +659,7 @@ public void breakExitsLabeledStatement_switch() {
}
""";
canCompleteNormallyTest(/* expected= */ true, statement).doTest();
// BUG: Reachability credits `break l` to the statement contained in `l`, so it disagrees with
// javac, which says that statement can't complete normally.
containedStatementCanCompleteNormallyTest(
/* reachability= */ true, /* javac= */ false, statement)
.doTest();
containedStatementCanCompleteNormallyTest(/* expected= */ false, statement).doTest();
}

/** Like {@link #breakExitsLabeledStatement_switch}, but with switch rules. */
Expand All @@ -703,11 +677,7 @@ public void breakExitsLabeledStatement_arrowSwitch() {
}
""";
canCompleteNormallyTest(/* expected= */ true, statement).doTest();
// BUG: Reachability credits `break l` to the statement contained in `l`, so it disagrees with
// javac, which says that statement can't complete normally.
containedStatementCanCompleteNormallyTest(
/* reachability= */ true, /* javac= */ false, statement)
.doTest();
containedStatementCanCompleteNormallyTest(/* expected= */ false, statement).doTest();
}

/**
Expand Down
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