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Fix #13327 FN mismatchingContainers for struct member and c_str() #7024

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Merged
merged 6 commits into from
Dec 8, 2024
Merged

Fix #13327 FN mismatchingContainers for struct member and c_str() #7024

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1ebeaba
Update teststl.cpp
chrchr-github Nov 19, 2024
863b093
Update checkstl.cpp
chrchr-github Nov 19, 2024
413c4ce
Prune values
chrchr-github Dec 5, 2024
cf33a16
Format
chrchr-github Dec 5, 2024
5f090ba
irreflexive requirement
chrchr-github Dec 5, 2024
15d1f5b
Update checkstl.cpp
chrchr-github Dec 6, 2024
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5 changes: 5 additions & 0 deletions lib/checkstl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -741,6 +741,11 @@ static ValueFlow::Value getLifetimeIteratorValue(const Token* tok, MathLib::bigi
}
if (values.size() == 1)
return values.front();
it = std::find_if(values.cbegin(), values.cend(), [](const ValueFlow::Value& v) {
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This is problematic if there is divergent lifetimes, that is why we check the size is 1 or no duplicates for iterator kinds. Why is there multiple lifetimes? Do we have a lifetime for t.s.a and a both?

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@chrchr-github chrchr-github Dec 5, 2024 •
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This is problematic if there is divergent lifetimes, that is why we check the size is 1 or no duplicates for iterator kinds. Why is there multiple lifetimes? Do we have a lifetime for t.s.a and a both?

In the s.a example, the lifetime tokvalues are s and .. But I think it makes sense to choose the dot, unless there can be multiple dots.

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Its the . in s.a I assume? Ideally we should remove the lifetimes that refer to a sub expression of another lifetime from the vector. Something like this function could be called here(its not tested though):

std::vector<ValueFlow::Value> pruneLifetimes(std::vector<ValueFlow::Value> lifetimes)
{
    std::vector<ValueFlow::Value> result;
    auto start = lifetimes.begin();
    while(start != lifetimes.end())
    {
        const Token* tok1 = start->tokvalue;
        auto it = std::partition(start, lifetimes.end(), [&](const ValueFlow::Value& v) { 
            const Token* tok2 = v.tokvalue;
            return astHasToken(tok1, tok2) or astHasToken(tok2, tok1); 
        });
        auto root = std::min_element(start, it, [](const ValueFlow::Value& x, const ValueFlow::Value& y) {
            return astHasToken(x.tokvalue, y.tokvalue);
        });
        result.push_back(*root);
        start = it;
    }
    return result;
}

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Not entirely sure what it does, but it seems to work 👍

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@pfultz2 pfultz2 Dec 5, 2024 •
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First it groups the lifetimes together using std::partition with the lifetimes that refer to the same token or token of a subexpression. Then it finds the lifetime in that group that refers to the "highest" parent using std::min_element and adds that to the vector. Hopefully that makes sense.

return v.tokvalue->str() == ".";
});
if (it != values.cend())
return *it;
return ValueFlow::Value{};
}

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22 changes: 22 additions & 0 deletions test/teststl.cpp
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Expand Up @@ -70,6 +70,7 @@ class TestStl : public TestFixture {
TEST_CASE(iterator28); // #10450
TEST_CASE(iterator29);
TEST_CASE(iterator30);
TEST_CASE(iterator31);
TEST_CASE(iteratorExpression);
TEST_CASE(iteratorSameExpression);
TEST_CASE(mismatchingContainerIterator);
Expand Down Expand Up @@ -1900,6 +1901,27 @@ class TestStl : public TestFixture {
ASSERT_EQUALS("", errout_str());
}

void iterator31()
{
check("struct S {\n" // #13327
" std::string a;\n"
"};\n"
"struct T {\n"
" S s;\n"
"};\n"
"bool f(const S& s) {\n"
" std::string b;\n"
" return s.a.c_str() == b.c_str();\n"
"}\n"
"bool g(const T& t) {\n"
" std::string b;\n"
" return t.s.a.c_str() == b.c_str();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:9]: (error) Iterators of different containers 's.a' and 'b' are used together.\n"
"[test.cpp:13]: (error) Iterators of different containers 't.s.a' and 'b' are used together.\n",
errout_str());
}

void iteratorExpression() {
check("std::vector<int>& f();\n"
"std::vector<int>& g();\n"
Expand Down
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