Help with Huffman

[narrow sandal]

I'm working on this GenerateLeafList method

    // Generate the leaf list for the Huffman algorithm (used in READ AND WRITE)
    //
    // Note:    Will cause leaks until ClearTree is implemented
    void GenerateLeafList() {
        // 1. Iterate through the frequency table and dynamically create a leaf node for each non-0
        // frequency. Add it to the mLeafList vector.
        mLeafList.clear();
        for (int i = 0; i < std::size(mFrequencyTable); i++)
        {
            if (mFrequencyTable[i] != 0 ) //&& mFrequencyTable[i] != 256
            {
                //Nodes should be dynamically alocated before put in leaf list
                HuffNode* newLeaf = new HuffNode(i, mFrequencyTable[i]);
                mLeafList.push_back(newLeaf);
            }
        }
    }

The error when I try to test is Exception thrown: read access violation.
_Pnext was 0x8. on the function

#if _ITERATOR_DEBUG_LEVEL == 2
    _CONSTEXPR20 void _Orphan_range_unlocked(pointer _First, pointer _Last) const {
        _Iterator_base12** _Pnext = &_Mypair._Myval2._Myproxy->_Myfirstiter;
        while (*_Pnext) {
            const auto _Pnextptr = static_cast<const_iterator&>(**_Pnext)._Ptr;
            if (_Pnextptr < _First || _Last < _Pnextptr) { // skip the iterator
                const auto _Temp = *_Pnext; // TRANSITION, VSO-1269037
                _Pnext           = &_Temp->_Mynextiter;
            } else { // orphan the iterator
                const auto _Temp = *_Pnext; // TRANSITION, VSO-1269037
                _Temp->_Myproxy  = nullptr;
                *_Pnext          = _Temp->_Mynextiter;
            }
        }
    }```

[rugged plover]

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[fast barn]

What is mFrequencyTable

mLeafList.clear(); is almost certainly a memory leak btw

You'll have to look at the stack to understand why something is going wrong in _Orphan_range_unlocked

The thing about memory errors / corruption is they tend to manifest far from their source

!wiki asan

[rugged plover]

How To Use Sanitizers

Sanitizers are tools which generate additional code in your program that can catch many common programming mistakes,
such as:

• accessing arrays out of bounds
• signed integer overflows
• race conditions

General Advice

Not all sanitizers can be combined, but when they can, use e.g.:
-fsanitize=address,undefined to combine them.
Always compile with debug info to get line numbers, variable names, etc.

GCC 4.8+

• -fsanitize=address
• -fsanitize=undefined
• -fsanitize=thread
• -g for debug info

clang 3.1+

• -fsanitize=address
• -fsanitize=undefined
• -fsanitize=thread
• -fsanitize=memory
• -g for debug info

MSVC 19.27+ and VS 2019 16.9+

• -fsanitize=address
• -Zi for debug info

Sample Program

int main(void) {
    int x;
    return x;
}

`-fsanitize=memory -g` Output

SUMMARY: MemorySanitizer: use-of-uninitialized-value /tmp/test.cpp:3:5 in main
Exiting
(3:5 is line and column of return)

Note: The sanitizer lists for GCC and clang are not exhaustive

[rugged plover]

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