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From: "josopait at goopax dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/65786] New: Wrong code when using decltype to specify the return type Date: Thu, 16 Apr 2015 08:27:00 -0000 [thread overview] Message-ID: <bug-65786-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65786 Bug ID: 65786 Summary: Wrong code when using decltype to specify the return type Product: gcc Version: 4.9.2 Status: UNCONFIRMED Severity: critical Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: josopait at goopax dot com In the program below, the assignment of the return value is messed up. While the C++-14 style of fully automatic type deduction works fine, the mymax11 function call produces some random numbers. The output is: 1 2 -2100190336 or similar. The last line is different for every program execution. I am using gcc 4.9.2 on x86_64 Linux. I don't get this bug if I use -m32. #include <iostream> using namespace std; struct testclass { int data; inline operator const int&() const { return data; } testclass& operator = (const int& in) { data = in; return *this; } }; template <typename A, typename B> auto mymax14(const A& a, const B& b) { return std::max((int)a, (int)b); } template <typename A, typename B> auto mymax11(const A& a, const B& b) -> decltype(std::max((int)a, (int)b)) { return std::max((int)a, (int)b); } int main() { testclass d; d = 1; cout << d.data << endl; // ok, d.data==1 d = mymax14(d, 2); cout << d.data << endl; // ok, d.data==2 d = mymax11(d, 2); cout << d.data << endl; // bad: d.data == some random number. return 0; }
next reply other threads:[~2015-04-16 8:27 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-04-16 8:27 josopait at goopax dot com [this message] 2015-04-16 8:40 ` [Bug c++/65786] " pinskia at gcc dot gnu.org 2015-04-16 9:31 ` redi at gcc dot gnu.org 2015-04-16 9:35 ` josopait at goopax dot com 2015-04-16 9:53 ` glisse at gcc dot gnu.org
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