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Fix #11139, #11817 FP unreadVariable #5221

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Merged
orbitcowboy merged 2 commits into from
Jul 7, 2023
Merged

Fix #11139, #11817 FP unreadVariable #5221

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9213ce8
Fix #11139 False positive: unreadVariable for aliased data
chrchr-github Jul 6, 2023
9fc9754
Fix #11817 FP unreadVariable with reference and else if
chrchr-github Jul 6, 2023
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6 changes: 6 additions & 0 deletions lib/fwdanalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -364,6 +364,8 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
const Result &result1 = checkRecursive(expr, tok->tokAt(2), tok->linkAt(1), exprVarIds, local, inInnerClass, depth);
if (result1.type == Result::Type::READ || result1.type == Result::Type::BAILOUT)
return result1;
if (mWhat == What::UnusedValue && result1.type == Result::Type::WRITE && expr->variable() && expr->variable()->isReference())
return result1;
if (mWhat == What::ValueFlow && result1.type == Result::Type::WRITE)
mValueFlowKnown = false;
if (mWhat == What::Reassign && result1.type == Result::Type::BREAK) {
Expand Down Expand Up @@ -530,6 +532,10 @@ bool FwdAnalysis::possiblyAliased(const Token *expr, const Token *startToken) co
addrOf = tok->astOperand1();
else if (Token::simpleMatch(tok, "std :: ref ("))
addrOf = tok->tokAt(3)->astOperand2();
else if (tok->valueType() && tok->valueType()->pointer &&
(Token::Match(tok, "%var% = %var% ;") || Token::Match(tok, "%var% {|( %var% }|)")) &&
Token::Match(expr->previous(), "%varid% [", tok->tokAt(2)->varId()))
addrOf = tok->tokAt(2);
else
continue;

Expand Down
32 changes: 32 additions & 0 deletions test/testunusedvar.cpp
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Expand Up @@ -165,6 +165,8 @@ class TestUnusedVar : public TestFixture {
TEST_CASE(localvaralias19); // ticket #9828
TEST_CASE(localvaralias20); // ticket #10966
TEST_CASE(localvaralias21);
TEST_CASE(localvaralias22);
TEST_CASE(localvaralias23);
TEST_CASE(localvarasm);
TEST_CASE(localvarstatic);
TEST_CASE(localvarextern);
Expand Down Expand Up @@ -5037,6 +5039,36 @@ class TestUnusedVar : public TestFixture {
ASSERT_EQUALS("", errout.str());
}

void localvaralias22() { // #11139
functionVariableUsage("int f() {\n"
" int x[1], *p = x;\n"
" x[0] = 42;\n"
" return *p;\n"
"}\n"
"int g() {\n"
" int x[1], *p{ x };\n"
" x[0] = 42;\n"
" return *p;\n"
"}\n"
"int h() {\n"
" int x[1], *p(x);\n"
" x[0] = 42;\n"
" return *p;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}

void localvaralias23() { // #11817
functionVariableUsage("void f(int& r, bool a, bool b) {\n"
" int& e = r;\n"
" if (a)\n"
" e = 42;\n"
" else if (b)\n"
" e = 1;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}

void localvarasm() {

functionVariableUsage("void foo(int &b)\n"
Expand Down