[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
This revision was automatically updated to reflect the committed changes.
Closed by commit rL339375: [Sema] P0961R1: Relaxing the structured bindings
customization point finding… (authored by epilk, committed by ).
Herald added a subscriber: llvm-commits.
Changed prior to commit:
https://reviews.llvm.org/D50418?vs=159629=159989#toc
Repository:
rL LLVM
https://reviews.llvm.org/D50418
Files:
cfe/trunk/lib/Sema/SemaDeclCXX.cpp
cfe/trunk/test/CXX/dcl.decl/dcl.decomp/p3.cpp
cfe/trunk/www/cxx_status.html
Index: cfe/trunk/www/cxx_status.html
===
--- cfe/trunk/www/cxx_status.html
+++ cfe/trunk/www/cxx_status.html
@@ -755,7 +755,7 @@
http://wg21.link/p0961r1;>P0961R1 (DR)
-No
+SVN
Index: cfe/trunk/test/CXX/dcl.decl/dcl.decomp/p3.cpp
===
--- cfe/trunk/test/CXX/dcl.decl/dcl.decomp/p3.cpp
+++ cfe/trunk/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 float (A);
+template float (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 };
template<> struct std::tuple_element<2, A> { typedef const float };
-template auto get(B) -> int (&)[N + 1];
+template auto get(B) -> int (&)[N + 1]; // expected-note 2 {{no known conversion}}
template struct std::tuple_element { typedef int type[N +1 ]; };
template struct std::tuple_size : std::tuple_size {};
@@ -138,19 +138,25 @@
return c;
}
-struct D { template struct get {}; }; // expected-note {{declared here}}
+struct D {
+ // FIXME: Emit a note here explaining why this was ignored.
+ template struct get {};
+};
template<> struct std::tuple_size { 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 { 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 +236,62 @@
}
static_assert(g() == 4); // expected-error {{constant}} expected-note {{in call to 'g()'}}
}
+
+// P0961R1
+struct InvalidMemberGet {
+ int get();
+ template int get();
+ struct get {};
+};
+template <> struct std::tuple_size { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, InvalidMemberGet> { typedef float type; };
+template 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 int get() { return 0; }
+ template float get() { return 0; }
+};
+template <> struct std::tuple_size { 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 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;
+}
+
+struct Base1 {
+ int get(); // expected-note{{member found by ambiguous name lookup}}
+};
+struct Base2 {
+ template int get(); // expected-note{{member found by ambiguous name lookup}}
+};
+struct Derived : Base1, Base2 {};
+
+template <> struct std::tuple_size { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, Derived> { typedef int type; };
+
+auto [x] = Derived(); // expected-error{{member 'get' found in multiple base classes of different types}}
+
+struct Base {
+ template int get();
+};
+struct UsingGet : Base {
+ using Base::get;
+};
+
+template <> struct std::tuple_size {
+ static constexpr size_t value = 1;
+};
+template <> struct std::tuple_element<0, UsingGet> { typedef int type; };
+
+auto [y] = UsingGet();
Index:
[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
rsmith accepted this revision.
rsmith added a comment.
This revision is now accepted and ready to land.
LGTM with a small bugfix.
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:1122
+for (Decl *D : MemberGet) {
+ if (FunctionTemplateDecl *FTD = dyn_cast(D)) {
+TemplateParameterList *TPL = FTD->getTemplateParameters();
You should use `D->getUnderlyingDecl()` rather than just `D` here, otherwise
you'll reject this:
```
struct A {
template void get();
};
struct B : A {
using A::get;
};
```
... because `D` will be a `UsingShadowDecl` not a `FunctionTemplateDecl`.
(Please also add a corresponding testcase.)
https://reviews.llvm.org/D50418
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[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
erik.pilkington added inline comments.
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:1118-1130
+// ... 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(ND)) {
+TemplateParameterList *TPL = FTD->getTemplateParameters();
rsmith wrote:
> This should be done by walking the lookup results, not by filtering them.
> Testcase:
>
> ```
> struct A {
> int get();
> };
> struct B {
> template int get();
> };
> struct C : A, B {};
> // plus specializations of tuple_size and tuple_element
> auto [x] = C();
> ```
>
> This should be ill-formed due to ambiguity when looking up `C::get`. We
> should not resolve the ambiguity by selecting `B::get`.
Ah, I see. In the new patch we finish the class member access lookup, then we
check this condition separately. I added this test to the patch. Thanks!
https://reviews.llvm.org/D50418
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[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
erik.pilkington updated this revision to Diff 159629.
erik.pilkington added a comment.
Address review comments.
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 @@
http://wg21.link/p0961r1;>P0961R1 (DR)
-No
+SVN
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 float (A);
+template float (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 };
template<> struct std::tuple_element<2, A> { typedef const float };
-template auto get(B) -> int (&)[N + 1];
+template auto get(B) -> int (&)[N + 1]; // expected-note 2 {{no known conversion}}
template struct std::tuple_element { typedef int type[N +1 ]; };
template struct std::tuple_size : std::tuple_size {};
@@ -138,19 +138,25 @@
return c;
}
-struct D { template struct get {}; }; // expected-note {{declared here}}
+struct D {
+ // FIXME: Emit a note here explaining why this was ignored.
+ template struct get {};
+};
template<> struct std::tuple_size { 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 { 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 +236,48 @@
}
static_assert(g() == 4); // expected-error {{constant}} expected-note {{in call to 'g()'}}
}
+
+// P0961R1
+struct InvalidMemberGet {
+ int get();
+ template int get();
+ struct get {};
+};
+template <> struct std::tuple_size { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, InvalidMemberGet> { typedef float type; };
+template 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 int get() { return 0; }
+ template float get() { return 0; }
+};
+template <> struct std::tuple_size { 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 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;
+}
+
+struct Base1 {
+ int get(); // expected-note{{member found by ambiguous name lookup}}
+};
+struct Base2 {
+ template int get(); // expected-note{{member found by ambiguous name lookup}}
+};
+struct Derived : Base1, Base2 {};
+
+template <> struct std::tuple_size { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, Derived> { typedef int type; };
+
+auto [x] = Derived(); // expected-error{{member 'get' found in multiple base classes of different types}}
Index: clang/lib/Sema/SemaDeclCXX.cpp
===
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -1108,15 +1108,26 @@
// [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())
[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
rsmith added inline comments.
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:1118-1130
+// ... 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(ND)) {
+TemplateParameterList *TPL = FTD->getTemplateParameters();
This should be done by walking the lookup results, not by filtering them.
Testcase:
```
struct A {
int get();
};
struct B {
template int get();
};
struct C : A, B {};
// plus specializations of tuple_size and tuple_element
auto [x] = C();
```
This should be ill-formed due to ambiguity when looking up `C::get`. We should
not resolve the ambiguity by selecting `B::get`.
Repository:
rC Clang
https://reviews.llvm.org/D50418
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[PATCH] D50418: [Sema] Support for P0961R1: Relaxing the structured bindings customization point finding rules
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 @@
http://wg21.link/p0961r1;>P0961R1 (DR)
-No
+SVN
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 float (A);
+template float (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 };
template<> struct std::tuple_element<2, A> { typedef const float };
-template auto get(B) -> int (&)[N + 1];
+template auto get(B) -> int (&)[N + 1]; // expected-note 2 {{no known conversion}}
template struct std::tuple_element { typedef int type[N +1 ]; };
template struct std::tuple_size : std::tuple_size {};
@@ -138,19 +138,25 @@
return c;
}
-struct D { template struct get {}; }; // expected-note {{declared here}}
+struct D {
+ // FIXME: Emit a note here explaining why this was ignored.
+ template struct get {};
+};
template<> struct std::tuple_size { 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 { 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 int get();
+ struct get {};
+};
+template <> struct std::tuple_size { static constexpr size_t value = 1; };
+template <> struct std::tuple_element<0, InvalidMemberGet> { typedef float type; };
+template 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 int get() { return 0; }
+ template float get() { return 0; }
+};
+template <> struct std::tuple_size { 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 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
