Memory leaks - Githubissues

vehlwn commented 5 years ago

I was playing with this version of your parser https://github.com/yhirose/cpp-peglib/blob/57f866c6ca77f5a5afe37f72942d5526c45d7e87/peglib.h and accidentally found unlimited memory consumption. Consider this example:

#include <cpp-peglib/peglib.h>
#include <iostream>
#include <cstdlib>

using namespace peg;
using namespace std;

int main(int , char** ) try
{
    do  
    {
        function<long (const Ast&)> eval = [&](const Ast& ast) {
            if (ast.name == "NUMBER") {
                return stol(ast.token);
            } else {
                const auto& nodes = ast.nodes;
                auto result = eval(*nodes[0]);
                for (auto i = 1u; i < nodes.size(); i += 2) {
                    auto num = eval(*nodes[i + 1]);
                    auto ope = nodes[i]->token[0];
                    switch (ope) {
                        case '+': result += num; break;
                        case '-': result -= num; break;
                        case '*': result *= num; break;
                        case '/': result /= num; break;
                    }
                }
                return result;
            }
        };

        parser parser(R"(
            EXPRESSION       <-  TERM (TERM_OPERATOR TERM)*
            TERM             <-  FACTOR (FACTOR_OPERATOR FACTOR)*
            FACTOR           <-  NUMBER / '(' EXPRESSION ')'
            TERM_OPERATOR    <-  < [-+] >
            FACTOR_OPERATOR  <-  < [/*] >
            NUMBER           <-  < [0-9]+ >
            %whitespace      <-  [ \t\r\n]*
        )");

        parser.enable_ast();
        parser.enable_packrat_parsing();

        auto expr = " 2+2*2 ";
        shared_ptr<Ast> ast;
        if (parser.parse(expr, ast)) {
            ast = AstOptimizer(true).optimize(ast);
            //cout << ast_to_s(ast);
            //cout << expr << " = " << eval(*ast) << endl;
        }
    }
    while(0);

    return 0;
}
catch(const std::exception &ex)
{
    std::cerr << "Error: " << ex.what() << "\n";
    return 1;
}

(Built with g++ (i686-posix-dwarf-rev0, Built by MinGW-W64 project) 8.1.0, Win7, 'g++ -std=c++17 -Wall -Wextra -Wpedantic -g -O0 -fno-inline -fno-omit-frame-pointer -ggdb -isystemK:/1/0/source/cpp-peglib main.cpp -o a.exe'.) If I make infinite loop while(1), process memory in a few minutes grows up to 200 MB and even more. Program with while(0) requires less than 1 MB. There is full output of 'drmemory -- a.exe' https://pastebin.com/raw/5qkLW8Zj. Its important parts:

Error #1: LEAK 172 direct bytes 0x020fbd20-0x020fbdcc + 540 indirect bytes
peglib.h:3269 _ZZN3peg6parser10enable_astINS_7AstBaseINS_9EmptyTypeEEEEERS0_vENKUlRKNS_14SemanticValuesEE_clES8_ 

Error #3: LEAK 8 direct bytes 0x021051d0-0x021051d8 + 344 indirect bytes
peglib.h:2942 peg::AstBase<>::AstBase

peglib.h:3269 in lambda: https://github.com/yhirose/cpp-peglib/blob/57f866c6ca77f5a5afe37f72942d5526c45d7e87/peglib.h#L3269

peglib.h:2942 in c-tor: https://github.com/yhirose/cpp-peglib/blob/57f866c6ca77f5a5afe37f72942d5526c45d7e87/peglib.h#L2942 Am I doing something wrong or is it error in your library? Could you fix it?