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Don't crash on 'arrow' switches in FallThrough #2124

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merged 1 commit into from Jan 19, 2021
Merged

Don't crash on 'arrow' switches in FallThrough #2124

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6 changes: 4 additions & 2 deletions core/src/main/java/com/google/errorprone/bugpatterns/FallThrough.java
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Expand Up @@ -35,6 +35,7 @@
import com.sun.source.tree.SwitchTree;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.util.Position;
import java.util.List;
import java.util.regex.Pattern;

/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
Expand All @@ -57,13 +58,14 @@ public Description matchSwitch(SwitchTree tree, VisitorState state) {
break;
}
CaseTree next = it.peek();
if (caseTree.getStatements().isEmpty()) {
List<? extends StatementTree> statements = caseTree.getStatements();
if (statements == null || statements.isEmpty()) {
continue;
}
// We only care whether the last statement completes; javac would have already
// reported an error if that statement wasn't reachable, and the answer is
// independent of any preceding statements.
boolean completes = Reachability.canCompleteNormally(getLast(caseTree.getStatements()));
boolean completes = Reachability.canCompleteNormally(getLast(statements));
int endPos = caseEndPosition(state, caseTree);
if (endPos == Position.NOPOS) {
break;
Expand Down
22 changes: 22 additions & 0 deletions core/src/test/java/com/google/errorprone/bugpatterns/FallThroughTest.java
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Expand Up @@ -16,7 +16,10 @@

package com.google.errorprone.bugpatterns;

import static org.junit.Assume.assumeTrue;

import com.google.errorprone.CompilationTestHelper;
import com.google.errorprone.util.RuntimeVersion;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;
Expand Down Expand Up @@ -95,4 +98,23 @@ public void emptyBlock() {
"}")
.doTest();
}

@Test
public void arrowSwitch() {
assumeTrue(RuntimeVersion.isAtLeast14());
testHelper
.addSourceLines(
"Test.java",
"class Test {",
" enum Case { ONE, TWO }",
" void m(Case c) {",
" switch (c) {",
" case ONE -> {}",
" case TWO -> {}",
" default -> {}",
" }",
" }",
"}")
.doTest();
}
}