Cross-module exception issue with pre-compiler define _HAS_EXCEPTIONS=0 used in an application #4668
Description
Hi @obiltschnig
I encountered a very subtle issue. It is about Poco::Exception in PocoFoundation64.dll. In Visual Studio 2019/2022 release_shared x64.
It is very hard to reproduce. Due to the large amount of code, I can't paste it all here, so I’ve only extracted a small portion.
// This is a small portion I extracted from a large amount of code.
int main() {
std::uint64_t val = 0x1122334455667788;
try {
throw Poco::Exception("error");
// If I do not use Poco::XXXXXXException, everything works fine.
// throw std::exception("error"); // It's OK !!!
} catch (const Poco::Exception& e) {
}
std::cout << val; // Now the val is 0x1122334400000000 !!!
// It's Very Strange !!! It lost low 32 bit.
return 0;
}It took me two days to find the real reason.
auto m = sizeof(Poco::Exception);
auto n = sizeof(std::exception);
// m=72, n=24: In PocoFoundation64.dll
// m=64, n=16: In my EXEIt was all caused by _HAS_EXCEPTIONS=0 in my EXE compile options. This macro will change the class size and implementation of std::exception.
// By: _HAS_EXCEPTIONS=1 (default in visual studio)
// sizeof(std::exception) == 24
namespace std {
class exception {
public:
virtual ~exception() {}
private:
char const* _What;
bool _DoFree;
}
}
// By: _HAS_EXCEPTIONS=0
// sizeof(std::exception) == 16
namespace std {
class exception {
public:
virtual ~exception() {}
protected:
const char* _Ptr;
}
}I think it's necessary to add some tips in POCO documentation to avoid users wasting unnecessary time on this issue.
See alse: nodejs/node-addon-api#85
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