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StrictUnusedVariable maintains side effects #870

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merged 3 commits into from
Sep 20, 2019
Merged

StrictUnusedVariable maintains side effects #870

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9a76d24
StrictUnusedVariable maintains side effects
Sep 19, 2019
b5fa311
Fix broken test
dansanduleac Sep 20, 2019
1ea49a1
Add generated changelog entries
dansanduleac Sep 20, 2019
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23 changes: 3 additions & 20 deletions ...line-error-prone/src/main/java/com/palantir/baseline/errorprone/StrictUnusedVariable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -409,10 +409,7 @@ private static ImmutableList<SuggestedFix> buildUnusedVarFixes(
return ImmutableList.of();
}
ElementKind varKind = varSymbol.getKind();
boolean encounteredSideEffects = false;
SuggestedFix.Builder fix = SuggestedFix.builder().setShortDescription("remove unused variable");
SuggestedFix.Builder removeSideEffectsFix =
SuggestedFix.builder().setShortDescription("remove unused variable and any side effects");
for (TreePath usagePath : usagePaths) {
StatementTree statement = (StatementTree) usagePath.getLeaf();
if (statement.getKind() == Tree.Kind.VARIABLE) {
Expand All @@ -422,37 +419,29 @@ private static ImmutableList<SuggestedFix> buildUnusedVarFixes(
VariableTree variableTree = (VariableTree) statement;
ExpressionTree initializer = variableTree.getInitializer();
if (hasSideEffect(initializer) && TOP_LEVEL_EXPRESSIONS.contains(initializer.getKind())) {
encounteredSideEffects = true;
if (varKind == ElementKind.FIELD) {
String newContent =
String.format(
"%s{ %s; }",
varSymbol.isStatic() ? "static " : "", state.getSourceForNode(initializer));
fix.merge(SuggestedFixes.replaceIncludingComments(usagePath, newContent, state));
removeSideEffectsFix.replace(statement, "");
} else {
fix.replace(statement, String.format("%s;", state.getSourceForNode(initializer)));
removeSideEffectsFix.replace(statement, "");
}
} else if (isEnhancedForLoopVar(usagePath)) {
String modifiers =
nullToEmpty(
variableTree.getModifiers() == null
? null
: state.getSourceForNode(variableTree.getModifiers()));
String newContent =
String.format(
"%s%s unused",
modifiers.isEmpty() ? "" : (modifiers + " "), variableTree.getType());
String newContent = String.format(
"%s%s unused", modifiers.isEmpty() ? "" : (modifiers + " "), variableTree.getType());
// The new content for the second fix should be identical to the content for the first
// fix in this case because we can't just remove the enhanced for loop variable.
fix.replace(variableTree, newContent);
removeSideEffectsFix.replace(variableTree, newContent);
} else {
String replacement = needsBlock(usagePath) ? "{}" : "";
fix.merge(SuggestedFixes.replaceIncludingComments(usagePath, replacement, state));
removeSideEffectsFix.merge(
SuggestedFixes.replaceIncludingComments(usagePath, replacement, state));
}
continue;
} else if (statement.getKind() == Tree.Kind.EXPRESSION_STATEMENT) {
Expand All @@ -468,26 +457,20 @@ private static ImmutableList<SuggestedFix> buildUnusedVarFixes(
((JCTree.JCAssignOp) tree).getExpression().getStartPosition(),
"");
fix.merge(replacement);
removeSideEffectsFix.merge(replacement);
continue;
}
} else if (tree instanceof AssignmentTree) {
if (hasSideEffect(((AssignmentTree) tree).getExpression())) {
encounteredSideEffects = true;
fix.replace(
tree.getStartPosition(), ((JCTree.JCAssign) tree).getExpression().getStartPosition(), "");
removeSideEffectsFix.replace(statement, "");
continue;
}
}
}
String replacement = needsBlock(usagePath) ? "{}" : "";
fix.replace(statement, replacement);
removeSideEffectsFix.replace(statement, replacement);
}
return encounteredSideEffects
? ImmutableList.of(removeSideEffectsFix.build(), fix.build())
: ImmutableList.of(fix.build());
return ImmutableList.of(fix.build());
}

private static ImmutableList<SuggestedFix> buildUnusedParameterFixes(
Expand Down
24 changes: 24 additions & 0 deletions ...-error-prone/src/test/java/com/palantir/baseline/errorprone/StrictUnusedVariableTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -145,6 +145,30 @@ public void fails_suppressed_but_used_variables() {
"}").doTest();
}

@Test
public void side_effects_are_preserved() {
refactoringTestHelper
.addInputLines(
"Test.java",
"class Test {",
" private static int _field = 1;",
" public static void privateMethod() {",
" Object foo = someMethod();",
" }",
" private static Object someMethod() { return null; }",
"}")
.addOutputLines(
"Test.java",
"class Test {",
" private static int _field = 1;",
" public static void privateMethod() {",
" someMethod();",
" }",
" private static Object someMethod() { return null; }",
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"}")
.doTest(TestMode.TEXT_MATCH);
}

@Test
public void fixes_suppressed_but_used_variables() {
refactoringTestHelper
Expand Down
6 changes: 6 additions & 0 deletions changelog/@unreleased/pr-870.v2.yml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
type: fix
fix:
description: When removing unused variables, `StrictUnusedVariable` will preserve
side effects
links:
- https://github.com/palantir/gradle-baseline/pull/870