https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109548
Bug ID: 109548
Summary: Detect c_str() dangling problems
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: paul.f.fee at gmail dot com
Target Milestone: ---
Thanks to bug 106393, G++ 13 can now catch simple dangling references, such as:
const int& f(const int& i) { return i; }
const int& i = f(10);
However, more complex examples do not trigger warnings:
#include <string>
std::string foo();
auto ptr = foo().c_str();
ASAN can detect stack-use-after-scope at runtime. Clang can catch the issue at
build time.
$ clang++ -c small.cpp
small.cpp:3:12: warning: object backing the pointer will be destroyed at the
end of the full-expression [-Wdangling-gsl]
auto ptr = foo().c_str();
^~~~~
1 warning generated.
Another example:
std::stringstream ss;
ss << "foo";
auto ptr = ss.str().c_str();
We're warned against this in the notes on cppreference.com, however it would be
better if GCC could detect such issues and warn during compilation.
https://en.cppreference.com/w/cpp/io/basic_stringstream/str
