llvm/llvm-project
Specific structure name can cause shadowing of globally defined lambda, causing "struct::operator()" to be called instead of "lambda::operator()"
Aperta
#134.049 aperta il 2 apr 2025
c++clang:frontendgood first issuelambda
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Descrizione
Defining structure with naming convention used by the compiler for lambda expressions ("$_<num>") causes compiler to use structure's "operator()" instead of the one defined for a global lambda(s).
In the following code:
struct $_0
{
int c;
void operator()() const {std::cout << __func__ << " " << c <<" from struct\n";}
};
auto lambda = [](){std::cout << __func__ << " from lambda\n";};
int main()
{
lambda();
}
Call to "lambda()" invokes "$_0::operator()" instead of the expected lambda:
If the "$_0::operator()" makes use of any memory, then calls to lambdas result in memory access operations. "-fsanitize=address" allows for detection of them: godbolt example