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IDEA-206567 Warn about double bitwise complement (~) operation

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This commit is contained in:
Tagir Valeev
2019-02-08 14:05:27 +07:00
parent 3635a36bef
commit c44ec9e596
2 changed files with 41 additions and 18 deletions
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plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bitwise/PointlessBitwiseExpressionInspection.java
+34 -18
View File
@@ -78,13 +78,15 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
if (expression instanceof PsiPolyadicExpression) {
return calculateReplacementExpression((PsiPolyadicExpression)expression, ct);
}
if (expression instanceof PsiPrefixExpression) {
PsiPrefixExpression prefixExpression = (PsiPrefixExpression)expression;
if (prefixExpression.getOperationTokenType().equals(TILDE)) {
PsiExpression decremented = extractDecrementedValue(prefixExpression.getOperand());
if (decremented != null) {
return "-" + ct.text(decremented, ParenthesesUtils.PREFIX_PRECEDENCE);
}
PsiExpression complemented = unwrapComplement(expression);
if (complemented != null) {
PsiExpression decremented = extractDecrementedValue(complemented);
if (decremented != null) {
return "-" + ct.text(decremented, ParenthesesUtils.PREFIX_PRECEDENCE);
}
PsiExpression twiceComplemented = unwrapComplement(complemented);
if (twiceComplemented != null) {
return ct.text(twiceComplemented);
}
}
return "";
@@ -133,8 +135,8 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
}
}
else {
PsiExpression left = unwrapNegation(previousOperand);
PsiExpression right = unwrapNegation(operand);
PsiExpression left = optionallyUnwrapComplement(previousOperand);
PsiExpression right = optionallyUnwrapComplement(operand);
if (EquivalenceChecker.getCanonicalPsiEquivalence().expressionsAreEquivalent(left, right)) {
if (tokenType.equals(AND)) {
return getText(expression, previousOperand, operand, PsiType.LONG.equals(expression.getType()) ? "0L" : "0", ct);
@@ -231,8 +233,16 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
@Override
public void visitPrefixExpression(PsiPrefixExpression expression) {
super.visitPrefixExpression(expression);
if (expression.getOperationTokenType().equals(TILDE) && extractDecrementedValue(expression.getOperand()) != null) {
PsiExpression complemented = unwrapComplement(expression);
if (complemented == null) return;
if (extractDecrementedValue(complemented) != null) {
registerError(expression, expression);
} else {
PsiExpression twiceComplemented = unwrapComplement(complemented);
if (twiceComplemented != null && unwrapComplement(twiceComplemented) == null) {
// In case of triple or more complements report innermost only to avoid overlapping reports
registerError(expression, expression);
}
}
}
@@ -277,7 +287,7 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
PsiExpression previousExpression = null;
for (PsiExpression operand : operands) {
if (isZero(operand) || isAllOnes(operand) ||
(areEquivalentModuloNegation(previousExpression, operand) && !SideEffectChecker.mayHaveSideEffects(operand))) {
(areEquivalentModuloComplement(previousExpression, operand) && !SideEffectChecker.mayHaveSideEffects(operand))) {
return true;
}
previousExpression = operand;
@@ -285,8 +295,9 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
return false;
}
private boolean areEquivalentModuloNegation(PsiExpression op1, PsiExpression op2) {
return EquivalenceChecker.getCanonicalPsiEquivalence().expressionsAreEquivalent(unwrapNegation(op1), unwrapNegation(op2));
private boolean areEquivalentModuloComplement(PsiExpression op1, PsiExpression op2) {
return EquivalenceChecker.getCanonicalPsiEquivalence().expressionsAreEquivalent(
optionallyUnwrapComplement(op1), optionallyUnwrapComplement(op2));
}
private boolean shiftExpressionIsPointless(PsiExpression[] operands) {
@@ -299,12 +310,17 @@ public class PointlessBitwiseExpressionInspection extends BaseInspection {
}
}
private static PsiExpression unwrapNegation(PsiExpression op) {
PsiExpression deparenthesized = PsiUtil.skipParenthesizedExprDown(op);
if (deparenthesized instanceof PsiPrefixExpression && ((PsiPrefixExpression)deparenthesized).getOperationTokenType().equals(TILDE)) {
return ((PsiPrefixExpression)deparenthesized).getOperand();
private static PsiExpression optionallyUnwrapComplement(PsiExpression op) {
PsiExpression unwrapped = unwrapComplement(op);
return unwrapped == null ? op : unwrapped;
}
private static PsiExpression unwrapComplement(PsiExpression op) {
op = PsiUtil.skipParenthesizedExprDown(op);
if (op instanceof PsiPrefixExpression && ((PsiPrefixExpression)op).getOperationTokenType().equals(TILDE)) {
return ((PsiPrefixExpression)op).getOperand();
}
return op;
return null;
}
private boolean isZero(PsiExpression expression) {
plugins/InspectionGadgets/test/com/siyeh/igtest/bitwise/pointless_bitwise_expression/PointlessBitwiseExpression.java
+7
View File
@@ -93,4 +93,11 @@ public class PointlessBitwiseExpression {
int r8 = <warning descr="'x | ~x' can be replaced with '-1'">x | ~x</warning>;
long r9 = <warning descr="'y ^ ~y' can be replaced with '-1L'">y ^ ~y</warning>;
}
void testDoubleTilde(int x, long y) {
int r1 = <warning descr="'~~x' can be replaced with 'x'">~~x</warning>;
long r2 = ~<warning descr="'~~y' can be replaced with 'y'">~~y</warning>;
int r3 = <warning descr="'~(~(x))' can be replaced with '(x)'">~(~(x))</warning>;
long r4 = ~(~(<warning descr="'~(~y)' can be replaced with 'y'">~(~y)</warning>));
}
}