erik.pilkington created this revision.
erik.pilkington added a reviewer: rsmith.
Herald added a subscriber: dexonsmith.
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0961r1.html
I don't believe an actual defect report was filed for this, but the paper (in
the "wording" section) claims that we should back-port this to C++17 as if it
were a defect report. Besides that, this is pretty straightforward.
Thanks for taking a look!
Erik
Repository:
rC Clang
https://reviews.llvm.org/D50418
Files:
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/CXX/dcl.decl/dcl.decomp/p3.cpp
clang/www/cxx_status.html
Index: clang/www/cxx_status.html
===================================================================
--- clang/www/cxx_status.html
+++ clang/www/cxx_status.html
@@ -755,7 +755,7 @@
<tr>
<!-- from Jacksonville 2018 -->
<td><a href="http://wg21.link/p0961r1";>P0961R1</a> (<a href="#dr">DR</a>)</td>
- <td class="none" align="center">No</td>
+ <td class="none" align="center">SVN</td>
</tr>
<tr>
<!-- from Jacksonville 2018 -->
Index: clang/test/CXX/dcl.decl/dcl.decomp/p3.cpp
===================================================================
--- clang/test/CXX/dcl.decl/dcl.decomp/p3.cpp
+++ clang/test/CXX/dcl.decl/dcl.decomp/p3.cpp
@@ -36,7 +36,7 @@
auto [a0, a1, a2] = A(); // expected-error {{undeclared identifier 'get'}} expected-note {{in implicit initialization of binding declaration 'a0'}}
}
-template<int> float &get(A);
+template<int> float &get(A); // expected-note 2 {{no known conversion}}
void no_tuple_element_1() {
auto [a0, a1, a2] = A(); // expected-error-re {{'std::tuple_element<0U{{L*}}, A>::type' does not name a type}} expected-note {{in implicit}}
@@ -57,7 +57,7 @@
template<> struct std::tuple_element<1, A> { typedef float &type; };
template<> struct std::tuple_element<2, A> { typedef const float &type; };
-template<int N> auto get(B) -> int (&)[N + 1];
+template<int N> auto get(B) -> int (&)[N + 1]; // expected-note 2 {{no known conversion}}
template<int N> struct std::tuple_element<N, B> { typedef int type[N +1 ]; };
template<typename T> struct std::tuple_size<const T> : std::tuple_size<T> {};
@@ -138,19 +138,25 @@
return c;
}
-struct D { template<int> struct get {}; }; // expected-note {{declared here}}
+struct D {
+ // FIXME: Emit a note here explaining why this was ignored.
+ template<int> struct get {};
+};
template<> struct std::tuple_size<D> { static const int value = 1; };
template<> struct std::tuple_element<0, D> { typedef D::get<0> type; };
void member_get_class_template() {
- auto [d] = D(); // expected-error {{cannot refer to member 'get' in 'D' with '.'}} expected-note {{in implicit init}}
+ auto [d] = D(); // expected-error {{no matching function for call to 'get'}} expected-note {{in implicit init}}
}
-struct E { int get(); };
+struct E {
+ // FIXME: Emit a note here explaining why this was ignored.
+ int get();
+};
template<> struct std::tuple_size<E> { static const int value = 1; };
template<> struct std::tuple_element<0, E> { typedef int type; };
void member_get_non_template() {
// FIXME: This diagnostic is not very good.
- auto [e] = E(); // expected-error {{no member named 'get'}} expected-note {{in implicit init}}
+ auto [e] = E(); // expected-error {{no matching function for call to 'get'}} expected-note {{in implicit init}}
}
namespace ADL {
@@ -230,3 +236,35 @@
}
static_assert(g() == 4); // expected-error {{constant}} expected-note {{in call to 'g()'}}
}
+
+// P0961R1
+struct InvalidMemberGet {
+ int get();
+ template <class T> int get();
+ struct get {};
+};
+template <> struct std::tuple_size<InvalidMemberGet> { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, InvalidMemberGet> { typedef float type; };
+template <size_t> float get(InvalidMemberGet) { return 0; }
+int f() {
+ InvalidMemberGet img;
+ auto [x] = img;
+ typedef decltype(x) same_as_float;
+ typedef float same_as_float;
+}
+
+struct ValidMemberGet {
+ int get();
+ template <class T> int get() { return 0; }
+ template <size_t N> float get() { return 0; }
+};
+template <> struct std::tuple_size<ValidMemberGet> { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, ValidMemberGet> { typedef float type; };
+// Don't use this one; we should use the member get.
+template <size_t N> int get(ValidMemberGet) { static_assert(N && false, ""); }
+int f2() {
+ ValidMemberGet img;
+ auto [x] = img;
+ typedef decltype(x) same_as_float;
+ typedef float same_as_float;
+}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -1108,14 +1108,29 @@
// [dcl.decomp]p3:
// The unqualified-id get is looked up in the scope of E by class member
- // access lookup
+ // access lookup ...
LookupResult MemberGet(S, GetDN, Src->getLocation(), Sema::LookupMemberName);
bool UseMemberGet = false;
if (S.isCompleteType(Src->getLocation(), DecompType)) {
if (auto *RD = DecompType->getAsCXXRecordDecl())
S.LookupQualifiedName(MemberGet, RD);
+
+ // ... and if that finds at least one declaration that is a function
+ // template whose first template parameter is a non-type parameter ...
+ LookupResult::Filter Filter = MemberGet.makeFilter();
+ while (Filter.hasNext()) {
+ NamedDecl *ND = Filter.next();
+ if (auto *FTD = dyn_cast<FunctionTemplateDecl>(ND)) {
+ TemplateParameterList *TPL = FTD->getTemplateParameters();
+ if (TPL->size() != 0 && isa<NonTypeTemplateParmDecl>(TPL->getParam(0)))
+ continue;
+ }
+ Filter.erase();
+ }
+ Filter.done();
if (MemberGet.isAmbiguous())
return true;
+ // ... the initializer is e.get<i>().
UseMemberGet = !MemberGet.empty();
S.FilterAcceptableTemplateNames(MemberGet);
}
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