Fix PR18498: Support explicit template arguments with variadic generic lambdas

http://llvm.org/bugs/show_bug.cgi?id=18498

This code was resulting in a crash:

auto L = [](auto ... v) { };
L.operator()<int>(3);

The reason is that the partially-substituted-pack is incorrectly retained within the current-instantiation-scope during template-argument-finalization, and because lambda's are local, there parent instantiation scopes are merged, which leads to the expansion-pattern being retained in the finalized specialization.

This patch ensures that once we have finalized deduction of a parameter-pack, we remove the partially-substituted-pack so that it doesn't cause CheckParameterPacksForExpansion to incorrectly inform the caller that it needs to retain the expansion pattern.


Thanks to Richard Smith for the review!

http://reviews.llvm.org/D2135

llvm-svn: 209992
This commit is contained in:
Faisal Vali 2014-06-01 16:11:54 +00:00
parent d6f11a70ab
commit 3628cb9cb6
2 changed files with 111 additions and 1 deletions

View File

@ -2816,9 +2816,19 @@ Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
// argument, because it was explicitly-specified. Just record the
// presence of this argument.
Builder.push_back(Deduced[I]);
// We may have had explicitly-specified template arguments for a
// template parameter pack (that may or may not have been extended
// via additional deduced arguments).
if (Param->isParameterPack() && CurrentInstantiationScope) {
if (CurrentInstantiationScope->getPartiallySubstitutedPack() ==
Param) {
// Forget the partially-substituted pack; its substitution is now
// complete.
CurrentInstantiationScope->ResetPartiallySubstitutedPack();
}
}
continue;
}
// We have deduced this argument, so it still needs to be
// checked and converted.

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@ -0,0 +1,100 @@
// RUN: %clang_cc1 -std=c++1y -verify -fsyntax-only -fblocks %s
// RUN: %clang_cc1 -std=c++1y -verify -fsyntax-only -fblocks -fdelayed-template-parsing %s -DDELAYED_TEMPLATE_PARSING
// RUN: %clang_cc1 -std=c++1y -verify -fsyntax-only -fblocks -fms-extensions %s -DMS_EXTENSIONS
// RUN: %clang_cc1 -std=c++1y -verify -fsyntax-only -fblocks -fdelayed-template-parsing -fms-extensions %s -DMS_EXTENSIONS -DDELAYED_TEMPLATE_PARSING
namespace explicit_argument_variadics {
template<class ... Ts> void print(Ts ... ) { }
struct X { };
struct Y { };
struct Z { };
int test() {
{
auto L = [](auto ... as) { };
L.operator()<bool>(true);
}
{
auto L = [](auto a) { };
L.operator()<bool>(false);
}
{
auto L = [](auto a, auto b) { };
L.operator()<bool>(false, 'a');
}
{
auto L = [](auto a, auto b) { };
L.operator()<bool, char>(false, 'a');
}
{
auto L = [](auto a, auto b, auto ... cs) { };
L.operator()<bool, char>(false, 'a');
L.operator()<bool, char, const char*>(false, 'a', "jim");
}
{
auto L = [](auto ... As) {
};
L.operator()<bool, double>(false, 3.14, "abc");
}
{
auto L = [](auto A, auto B, auto ... As) {
};
L.operator()<bool>(false, 3.14, "abc");
L.operator()<bool, char>(false, 3.14, "abc"); //expected-warning{{implicit conversion}}
L.operator()<X, Y, bool, Z>(X{}, Y{}, 3.14, Z{}, X{}); //expected-warning{{implicit conversion}}
}
{
auto L = [](auto ... As) {
print("\nL::As = ", As ...);
return [](decltype(As) ... as, auto ... Bs) {
print("\nL::Inner::as = ", as ...);
print("\nL::Inner::Bs = ", Bs ...);
return 4;
};
};
auto M = L.operator()<bool, double>(false, 3.14, "abc");
M(false, 6.26, "jim", true);
M.operator()<bool>(true, 6.26, "jim", false, 3.14);
}
{
auto L = [](auto A, auto ... As) {
print("\nL::As = ", As ...);
return [](decltype(As) ... as, decltype(A) a, auto ... Bs) {
print("\nL::Inner::as = ", as ...);
print("\nL::Inner::Bs = ", Bs ...);
return 4;
};
};
auto M = L.operator()<bool, double>(false, 3.14, "abc");
M(6.26, "jim", true);
M.operator()<X>(6.26, "jim", false, X{}, Y{}, Z{});
}
return 0;
}
int run = test();
} // end ns explicit_argument_extension
#ifdef PR18499_FIXED
namespace variadic_expansion {
void f(int &, char &);
template <typename ... T> void g(T &... t) {
f([&a(t)]()->decltype(auto) {
return a;
}() ...);
f([&a(f([&b(t)]()->decltype(auto) { return b; }()...), t)]()->decltype(auto) {
return a;
}()...);
}
void h(int i, char c) { g(i, c); }
}
#endif