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fix #13227: False positive: legacy uninitvar #6936

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merged 1 commit into from
Oct 19, 2024
Merged

fix #13227: False positive: legacy uninitvar #6936

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34 changes: 27 additions & 7 deletions lib/checkuninitvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -916,7 +916,7 @@ bool CheckUninitVar::checkIfForWhileHead(const Token *startparentheses, const Va
}

/** recursively check loop, return error token */
const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Variable& var, const Alloc alloc, const std::string &membervar, bool &bailout) const
const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Variable& var, const Alloc alloc, const std::string &membervar, bool &bailout, bool &alwaysReturns) const
{
assert(start->str() == "{");

Expand All @@ -941,9 +941,10 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
if (!Token::simpleMatch(top->previous(), "for (") || !Token::simpleMatch(top->link(), ") {"))
continue;
const Token *bodyStart = top->link()->next();
const Token *errorToken1 = checkLoopBodyRecursive(bodyStart, var, alloc, membervar, bailout);
const Token *errorToken1 = checkLoopBodyRecursive(bodyStart, var, alloc, membervar, bailout, alwaysReturns);
if (!errorToken)
errorToken = errorToken1;
bailout |= alwaysReturns;
if (bailout)
return nullptr;
}
Expand All @@ -962,11 +963,12 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
return nullptr;
}

const Token *errorToken1 = checkLoopBodyRecursive(tok, var, alloc, membervar, bailout);
bool alwaysReturnsUnused;
const Token *errorToken1 = checkLoopBodyRecursive(tok, var, alloc, membervar, bailout, alwaysReturnsUnused);
tok = tok->link();
if (Token::simpleMatch(tok, "} else {")) {
const Token *elseBody = tok->tokAt(2);
const Token *errorToken2 = checkLoopBodyRecursive(elseBody, var, alloc, membervar, bailout);
const Token *errorToken2 = checkLoopBodyRecursive(elseBody, var, alloc, membervar, bailout, alwaysReturnsUnused);
tok = elseBody->link();
if (errorToken1 && errorToken2)
return errorToken1;
Expand All @@ -979,6 +981,23 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
errorToken = errorToken1;
}

if (Token::simpleMatch(tok, "return")) {
bool returnWithoutVar = true;
while (tok && !Token::simpleMatch(tok, ";")) {
if (tok->isVariable() && tok->variable() == &var) {
returnWithoutVar = false;
break;
}
tok = tok->next();
}
if (returnWithoutVar) {
alwaysReturns = true;
return nullptr;
}
}
if (!tok)
break;

if (tok->varId() != var.declarationId())
continue;

Expand Down Expand Up @@ -1068,17 +1087,18 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
bool CheckUninitVar::checkLoopBody(const Token *tok, const Variable& var, const Alloc alloc, const std::string &membervar, const bool suppressErrors)
{
bool bailout = false;
const Token *errorToken = checkLoopBodyRecursive(tok, var, alloc, membervar, bailout);
bool alwaysReturns = false;
const Token *errorToken = checkLoopBodyRecursive(tok, var, alloc, membervar, bailout, alwaysReturns);

if (!suppressErrors && !bailout && errorToken) {
if (!suppressErrors && !bailout && !alwaysReturns && errorToken) {
if (membervar.empty())
uninitvarError(errorToken, errorToken->expressionString(), alloc);
else
uninitStructMemberError(errorToken, errorToken->expressionString() + "." + membervar);
return true;
}

return bailout;
return bailout || alwaysReturns;
}

void CheckUninitVar::checkRhs(const Token *tok, const Variable &var, Alloc alloc, nonneg int number_of_if, const std::string &membervar)
Expand Down
2 changes: 1 addition & 1 deletion lib/checkuninitvar.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ class CPPCHECKLIB CheckUninitVar : public Check {
const Token* checkExpr(const Token* tok, const Variable& var, Alloc alloc, bool known, bool* bailout = nullptr) const;
bool checkIfForWhileHead(const Token *startparentheses, const Variable& var, bool suppressErrors, bool isuninit, Alloc alloc, const std::string &membervar);
bool checkLoopBody(const Token *tok, const Variable& var, Alloc alloc, const std::string &membervar, bool suppressErrors);
const Token* checkLoopBodyRecursive(const Token *start, const Variable& var, Alloc alloc, const std::string &membervar, bool &bailout) const;
const Token* checkLoopBodyRecursive(const Token *start, const Variable& var, Alloc alloc, const std::string &membervar, bool &bailout, bool &alwaysReturns) const;
void checkRhs(const Token *tok, const Variable &var, Alloc alloc, nonneg int number_of_if, const std::string &membervar);
static int isFunctionParUsage(const Token *vartok, const Library &library, bool pointer, Alloc alloc, int indirect = 0);
int isFunctionParUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect = 0) const;
Expand Down
17 changes: 17 additions & 0 deletions test/testuninitvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ class TestUninitVar : public TestFixture {
TEST_CASE(uninitvar3); // #3844
TEST_CASE(uninitvar4); // #3869 (reference)
TEST_CASE(uninitvar5); // #3861
TEST_CASE(uninitvar6); // #13227
TEST_CASE(uninitvar2_func); // function calls
TEST_CASE(uninitvar2_value); // value flow
TEST_CASE(valueFlowUninit2_value);
Expand Down Expand Up @@ -3071,6 +3072,22 @@ class TestUninitVar : public TestFixture {
ASSERT_EQUALS("[test.cpp:3]: (error) Uninitialized variable: c\n", errout_str());
}

// #13227
void uninitvar6() {
checkUninitVar("int foo(int x) {\n"
" int i;\n"
" if (x == 1) {\n"
" i = 3;\n"
" } else {\n"
" do {\n"
" return 2;\n"
" } while (0);\n"
" }\n"
" return i;\n"
"}\n");
ASSERT_EQUALS("", errout_str());
}

void uninitvar8() {
const char code[] = "struct Fred {\n"
" void Sync(dsmp_t& type, int& len, int limit = 123);\n"
Expand Down
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