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Fix FP with side-effect in toplevel condition

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This commit is contained in:
Clément Fournier
2020-06-22 18:00:17 +02:00
parent c837e244e9
commit 1d022d3d91
2 changed files with 56 additions and 26 deletions
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33
pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/UnusedAssignmentRule.java
View File

@ -343,7 +343,7 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
AlgoState thenState = before.fork();
AlgoState elseState = elseBranch != null ? before.fork() : before;
linkConditional(before, condition, thenState, elseState);
linkConditional(before, condition, thenState, elseState, true);
thenState = acceptOpt(thenBranch, thenState);
elseState = acceptOpt(elseBranch, elseState);
@ -351,17 +351,22 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
return elseState.absorb(thenState);
}
private AlgoState linkConditional(AlgoState prev, JavaNode condition, AlgoState thenState, AlgoState elseState) {
private AlgoState linkConditional(AlgoState before, JavaNode condition, AlgoState thenState, AlgoState elseState, boolean isTopLevel) {
if (condition instanceof ASTConditionalOrExpression) {
return visitShortcutOrExpr(condition, prev, thenState, elseState);
return visitShortcutOrExpr(condition, before, thenState, elseState);
} else if (condition instanceof ASTConditionalAndExpression) {
// To mimic a shortcut AND expr, swap the thenState and the elseState
// See explanations in method
return visitShortcutOrExpr(condition, prev, elseState, thenState);
return visitShortcutOrExpr(condition, before, elseState, thenState);
} else if (condition instanceof ASTExpression && condition.getNumChildren() == 1) {
return linkConditional(prev, condition.getChild(0), thenState, elseState);
return linkConditional(before, condition.getChild(0), thenState, elseState, isTopLevel);
} else {
return acceptOpt(condition, prev);
AlgoState state = acceptOpt(condition, before);
if (isTopLevel) {
thenState.absorb(state);
elseState.absorb(state);
}
return state;
}
// TODO parenthesized expression
}
@ -391,7 +396,7 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
AlgoState cur = before;
do {
JavaNode cond = iterator.next();
cur = linkConditional(cur, cond, thenState, elseState);
cur = linkConditional(cur, cond, thenState, elseState, false);
thenState.absorb(cur);
} while (iterator.hasNext());
@ -674,7 +679,7 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
JavaNode rhs = node.getChild(2);
result = acceptOpt(rhs, result);
VariableNameDeclaration lhsVar = getLhsVar(node.getChild(0), true);
VariableNameDeclaration lhsVar = getVarFromExpression(node.getChild(0), true);
if (lhsVar != null) {
// in that case lhs is a normal variable (array access not supported)
@ -709,7 +714,7 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
}
private AlgoState checkIncOrDecrement(JavaNode unary, AlgoState data) {
VariableNameDeclaration var = getLhsVar(unary.getChild(0), true);
VariableNameDeclaration var = getVarFromExpression(unary.getChild(0), true);
if (var != null) {
data.use(var);
data.assign(var, unary);
@ -721,19 +726,19 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
@Override
public Object visit(ASTPrimaryExpression node, Object data) {
super.visit(node, data); // visit subexpressions
AlgoState state = (AlgoState) visit((JavaNode) node, data); // visit subexpressions
VariableNameDeclaration var = getLhsVar(node, false);
VariableNameDeclaration var = getVarFromExpression(node, false);
if (var != null) {
((AlgoState) data).use(var);
state.use(var);
}
return data;
return state;
}
/**
* Get the variable accessed from a primary.
*/
private VariableNameDeclaration getLhsVar(JavaNode primary, boolean inLhs) {
private VariableNameDeclaration getVarFromExpression(JavaNode primary, boolean inLhs) {
if (primary instanceof ASTPrimaryExpression) {
ASTPrimaryPrefix prefix = (ASTPrimaryPrefix) primary.getChild(0);

29
pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/UnusedAssignment.xml
View File

@ -2124,7 +2124,7 @@ class Foo {
<message>The initializer for variable 'i' is never used (overwritten on line 7)</message>
</expected-messages>
<code><![CDATA[
class Foo {
class Foo {
void main(int[] bufline, int start, int bufsize) {
@ -2139,10 +2139,35 @@ class Foo {
log(j);
}
}
}
}
]]></code>
</test-code>
<test-code>
<description>FP with argument</description>
<expected-problems>1</expected-problems>
<expected-messages>
<message>The initializer for variable 'i' is never used (overwritten on line 7)</message>
</expected-messages>
<code><![CDATA[
class Foo {
static String replaceBackslash(String str) {
int i = 0, len = str.length();
char c;
StringBuffer b = new StringBuffer();
for (i = 0; i < len; i++)
if ((c = str.charAt(i)) == '\\')
b.append("\\\\");
else
b.append(c);
return b.toString();
}
}
]]></code>
</test-code>
</test-data>