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Avoid infinite recursion in getLifetimeVariable #1634

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Merged
danmar merged 2 commits into from
Jan 31, 2019
Merged

Avoid infinite recursion in getLifetimeVariable #1634

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a770ba4
Fix direct recursion
pfultz2 Jan 30, 2019
fc3c084
Limit depth of getLifetimeVariable
pfultz2 Jan 30, 2019
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12 changes: 8 additions & 4 deletions lib/valueflow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2662,11 +2662,13 @@ std::string lifetimeType(const Token *tok, const ValueFlow::Value *val)
return result;
}

const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPath &errorPath)
const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPath &errorPath, int depth)
{
if (!tok)
return nullptr;
const Variable *var = tok->variable();
if (depth < 0)
return var;
if (var && var->declarationId() == tok->varId()) {
if (var->isReference() || var->isRValueReference()) {
if (!var->declEndToken())
Expand All @@ -2680,7 +2682,7 @@ const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPat
if (vartok == tok)
return nullptr;
if (vartok)
return getLifetimeVariable(vartok, errorPath);
return getLifetimeVariable(vartok, errorPath, depth-1);
} else {
return nullptr;
}
Expand All @@ -2694,7 +2696,9 @@ const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPat
const Token *returnTok = findSimpleReturn(f);
if (!returnTok)
return nullptr;
const Variable *argvar = getLifetimeVariable(returnTok, errorPath);
if (returnTok == tok)
return var;
const Variable *argvar = getLifetimeVariable(returnTok, errorPath, depth-1);
if (!argvar)
return nullptr;
if (argvar->isArgument() && (argvar->isReference() || argvar->isRValueReference())) {
Expand All @@ -2704,7 +2708,7 @@ const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPat
const Token *argTok = getArguments(tok->previous()).at(n);
errorPath.emplace_back(returnTok, "Return reference.");
errorPath.emplace_back(tok->previous(), "Called function passing '" + argTok->str() + "'.");
return getLifetimeVariable(argTok, errorPath);
return getLifetimeVariable(argTok, errorPath, depth-1);
}
}
return var;
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2 changes: 1 addition & 1 deletion lib/valueflow.h
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Expand Up @@ -229,7 +229,7 @@ namespace ValueFlow {
std::string eitherTheConditionIsRedundant(const Token *condition);
}

const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPath &errorPath);
const Variable *getLifetimeVariable(const Token *tok, ValueFlow::Value::ErrorPath &errorPath, int depth=20);
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@amai2012 amai2012 Jan 30, 2019

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A bit off-topic: is there a specific reason why those functions are declared within this header but outside the namespace?


std::string lifetimeType(const Token *tok, const ValueFlow::Value *val);

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10 changes: 10 additions & 0 deletions test/testautovariables.cpp
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Expand Up @@ -112,6 +112,7 @@ class TestAutoVariables : public TestFixture {
TEST_CASE(returnReferenceCalculation);
TEST_CASE(returnReferenceLambda);
TEST_CASE(returnReferenceInnerScope);
TEST_CASE(returnReferenceRecursive);

TEST_CASE(danglingReference);

Expand Down Expand Up @@ -1246,6 +1247,15 @@ class TestAutoVariables : public TestFixture {
ASSERT_EQUALS("", errout.str());
}

void returnReferenceRecursive() {
check("int& f() { return f(); }");
ASSERT_EQUALS("", errout.str());

check("int& g(int& i) { return i; }\n"
"int& f() { return g(f()); }\n");
ASSERT_EQUALS("", errout.str());
}

void danglingReference() {
check("int f( int k )\n"
"{\n"
Expand Down