llvm-capstone/clang/test/SemaCXX/delete-and-function-templates.cpp
Faisal Vali 81a88beec4 Fix PR28100 - Allow redeclarations of deleted explicit specializations.
See https://llvm.org/bugs/show_bug.cgi?id=28100.

In r266561 when I implemented allowing explicit specializations of function templates to override deleted status, I mistakenly assumed (and hence introduced a violable assertion) that when an explicit specialization was being declared, the corresponding specialization of the most specialized function template that it would get linked to would always be the one that was implicitly generated - and so if it was marked as 'deleted' it must have inherited it from the primary template and so should be safe to reset its deleted status, and set it to being an explicit specialization.  Obviously during redeclaration of a deleted explicit specialization, in order to avoid a recursive reset, we need to check that the previous specialization is not an explicit specialization (instead of assuming and asserting it) and that it hasn't been referenced, and so only then is it safe to reset its 'deleted' status.

All regression tests pass.

Thanks to Zhendong Su for reporting the bug and David Majnemer for tracking it to my commit r266561, and promptly bringing it to my attention.

llvm-svn: 272631
2016-06-14 03:23:15 +00:00

134 lines
4.2 KiB
C++

// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -emit-llvm-only %s
// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -fdelayed-template-parsing %s
// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -fms-extensions %s
// RUN: %clang_cc1 -std=c++11 -verify -fsyntax-only -fdelayed-template-parsing -fms-extensions %s
template<class T, class U> struct is_same { enum { value = false }; };
template<class T> struct is_same<T, T> { enum { value = true }; };
namespace test_sfinae_and_delete {
namespace ns1 {
template<class T> double f(T) = delete; //expected-note{{candidate}}
char f(...); //expected-note{{candidate}}
static_assert(is_same<decltype(f(3)),char>::value, ""); //expected-error{{call to deleted function}} expected-error{{static_assert failed}}
template<class T> decltype(f(T{})) g(T); // this one sfinae's out.
template<class T> int *g(T);
void foo() {
int *ip = g(3);
}
} //end ns1
namespace ns2 {
template<class T> double* f(T);
template<> double* f(double) = delete;
template<class T> decltype(f(T{})) g(T); // expected-note{{candidate}}
template<class T> int *g(T); //expected-note{{candidate}}
void foo() {
double *dp = g(3); //expected-error{{ambiguous}}
int *ip = g(3.14); // this is OK - because the explicit specialization is deleted and sfinae's out one of the template candidates
}
} // end ns2
namespace ns3 {
template<class T> double* f(T) = delete;
template<> double* f(double);
template<class T> decltype(f(T{})) g(T); // expected-note{{candidate}}
template<class T> int *g(T); //expected-note{{candidate}}
void foo() {
int *dp = g(3); // this is OK - because the non-double specializations are deleted and sfinae's out one of the template candidates
double *ip = g(3.14); //expected-error{{ambiguous}}
}
} // end ns3
} // end ns test_sfinae_and_delete
namespace test_explicit_specialization_of_member {
namespace ns1 {
template<class T> struct X {
int* f(T) = delete;
};
template<> int* X<int>::f(int) { }
template<class T> decltype(X<T>{}.f(T{})) g(T); // expected-note{{candidate}}
template<class T> int *g(T); //expected-note{{candidate}}
void foo() {
int *ip2 = g(3.14); // this is OK - because the non-int specializations are deleted and sfinae's out one of the template candidates
int *ip = g(3); //expected-error{{ambiguous}}
}
} // end ns1
namespace ns2 {
struct X {
template<class T> double* f(T) = delete;
};
template<> double* X::f(int);
template<class T> decltype(X{}.f(T{})) g(T); // expected-note{{candidate}}
template<class T> int *g(T); //expected-note{{candidate}}
void foo() {
int *ip2 = g(3.14); // this is OK - because the non-int specializations are deleted and sfinae's out one of the template candidates
int *ip = g(3); //expected-error{{ambiguous}}
}
} // end ns2
namespace ns3 {
template<class T> struct X {
template<class U> double *f1(U, T) = delete;
template<class U> double *f2(U, T) = delete;
};
template<> template<> double* X<int>::f1(int, int);
template<> template<class U> double* X<int>::f2(U, int);
template<class T, class U> decltype(X<T>{}.f1(U{}, T{})) g1(U, T); // expected-note{{candidate}}
template<class T, class U> int *g1(U, T); //expected-note{{candidate}}
template<class T, class U> decltype(X<T>{}.f2(U{}, T{})) g2(U, T); // expected-note2{{candidate}}
template<class T, class U> int *g2(U, T); //expected-note2{{candidate}}
void foo() {
int *ip2 = g1(3.14, 3); // this is OK - because the non-int specializations are deleted and sfinae's out one of the template candidates
int *ip = g1(3, 3); //expected-error{{ambiguous}}
{
int *ip3 = g2(3.14, 3); //expected-error{{ambiguous}}
int *ip4 = g2(3, 3); //expected-error{{ambiguous}}
}
{
int *ip3 = g2(3.14, 3.14);
int *ip4 = g2(3, 3.14);
}
}
} // end ns3
namespace ns4 {
template < typename T> T* foo (T);
template <> int* foo(int) = delete;
template <> int* foo(int); //expected-note{{candidate}}
int *IP = foo(2); //expected-error{{deleted}}
double *DP = foo(3.14);
} //end ns4
namespace ns5 {
template < typename T> T* foo (T);
template <> int* foo(int); //expected-note{{previous}}
template <> int* foo(int) = delete; //expected-error{{deleted definition must be first declaration}}
} //end ns5
} // end test_explicit_specializations_and_delete