Skip to content

Demonstrate bugs in PatternMatchingInstanceof with[] #5879

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
copybara-service merged 1 commit into from
Jun 16, 2026
+109 −0
Merged

Demonstrate bugs in PatternMatchingInstanceof with[] #5879

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
109 changes: 109 additions & 0 deletions core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1046,4 +1046,113 @@ void test(Object e) {
""")
.doTest();
}

@Test
public void castVariableReassigned_brokenRefactoring() {
// TODO: b/395603588 - This refactoring is broken because 's' is reassigned,
// but pattern variables are implicitly final. It should be expectUnchanged().
helper
.allowBreakingChanges()
.addInputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (o instanceof String) {
String s = (String) o;
s = "new value";
System.out.println(s);
}
}
}
""")
.addOutputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (o instanceof String s) {

s = "new value";
System.out.println(s);
}
}
}
""")
.doTest();
}

@Test
public void scopeExpansionClobbering_brokenRefactoring() {
// TODO: b/395603588 - This refactoring is broken because the pattern variable 's'
// scope expands and clashes with 'int s = 0'. It should be expectUnchanged().
helper
.allowBreakingChanges()
.addInputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (!(o instanceof String)) {
return;
}
{
String s = (String) o;
System.out.println(s);
}
int s = 0;
}
}
""")
.addOutputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (!(o instanceof String s)) {
return;
}
{
System.out.println(s);
}
int s = 0;
}
}
""")
.doTest();
}

@Test
public void patternVariableScopeDoesNotOverlapWithLaterDeclaration() {
helper
.addInputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (o instanceof String) {
String s = (String) o;
System.out.println(s);
}
int s = 0;
System.out.println(s);
}
}
""")
.addOutputLines(
"Test.java",
"""
class Test {
void test(Object o) {
if (o instanceof String s) {

System.out.println(s);
}
int s = 0;
System.out.println(s);
}
}
""")
.doTest();
}
}
Loading