Author: rsmith
Date: Tue Dec 27 00:14:37 2016
New Revision: 290586
URL: http://llvm.org/viewvc/llvm-project?rev=290586&view=rev
Log:
Work around a standard defect: template argument deduction for non-type
template parameters of reference type basically doesn't work, because we're
always deducing from an argument expression of non-reference type, so the type
of the deduced expression never matches. Instead, compare the type of an
expression naming the parameter to the type of the argument.
Modified:
cfe/trunk/lib/Sema/SemaTemplate.cpp
cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp
cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=290586&r1=290585&r2=290586&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplate.cpp Tue Dec 27 00:14:37 2016
@@ -5040,7 +5040,8 @@ ExprResult Sema::CheckTemplateArgument(N
"non-type template parameter type cannot be qualified");
if (CTAK == CTAK_Deduced &&
- !Context.hasSameUnqualifiedType(ParamType, Arg->getType())) {
+ !Context.hasSameType(ParamType.getNonLValueExprType(Context),
+ Arg->getType().getNonLValueExprType(Context))) {
// C++ [temp.deduct.type]p17: (DR1770)
// If P has a form that contains <i>, and if the type of i differs from
// the type of the corresponding template parameter of the template named
@@ -5048,6 +5049,11 @@ ExprResult Sema::CheckTemplateArgument(N
//
// Note that CTAK will be CTAK_DeducedFromArrayBound if the form was [i]
// rather than <i>.
+ //
+ // FIXME: We interpret the 'i' here as referring to the expression
+ // denoting the non-type template parameter rather than the parameter
+ // itself, and so strip off references before comparing types. It's
+ // not clear how this is supposed to work for references.
Diag(StartLoc, diag::err_deduced_non_type_template_arg_type_mismatch)
<< Arg->getType().getUnqualifiedType()
<< ParamType.getUnqualifiedType();
Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=290586&r1=290585&r2=290586&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Tue Dec 27 00:14:37 2016
@@ -327,13 +327,18 @@ static Sema::TemplateDeductionResult Ded
}
Deduced[NTTP->getIndex()] = Result;
- return S.getLangOpts().CPlusPlus1z
- ? DeduceTemplateArgumentsByTypeMatch(
- S, TemplateParams, NTTP->getType(), ValueType, Info,
Deduced,
- TDF_ParamWithReferenceType | TDF_SkipNonDependent,
- /*PartialOrdering=*/false,
- /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound())
- : Sema::TDK_Success;
+ if (!S.getLangOpts().CPlusPlus1z)
+ return Sema::TDK_Success;
+
+ // FIXME: It's not clear how deduction of a parameter of reference
+ // type from an argument (of non-reference type) should be performed.
+ // For now, we just remove reference types from both sides and let
+ // the final check for matching types sort out the mess.
+ return DeduceTemplateArgumentsByTypeMatch(
+ S, TemplateParams, NTTP->getType().getNonReferenceType(),
+ ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
+ /*PartialOrdering=*/false,
+ /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
}
/// \brief Deduce the value of the given non-type template parameter
Modified: cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp?rev=290586&r1=290585&r2=290586&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp (original)
+++ cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp Tue Dec 27 00:14:37 2016
@@ -374,3 +374,28 @@ namespace partial_order_different_types
template<typename T, typename U, U V> struct A<0, 0, T, U, V> {}; //
expected-note {{matches}}
A<0, 0, int, int, 0> a; // expected-error {{ambiguous partial
specializations}}
}
+
+namespace partial_order_references {
+ // FIXME: The standard does not appear to consider the second specialization
+ // to be more more specialized than the first! The problem is that deducing
+ // an 'int&' parameter from an argument 'R' results in a type mismatch,
+ // because the parameter has a reference type and the argument is an
+ // expression and thus does not have reference type. We resolve this by
+ // matching the type of an expression corresponding to the parameter rather
+ // than matching the parameter itself.
+ template <int, int, int &> struct A {};
+ template <int N, int &R> struct A<N, 0, R> {};
+ template <int &R> struct A<0, 0, R> {};
+ int N;
+ A<0, 0, N> a;
+
+ // FIXME: These should both be rejected as they are not more specialized than
+ // the primary template (they can never be used due to the type mismatch).
+ template<int, int &R> struct B; // expected-note {{template}}
+ template<const int &R> struct B<0, R> {};
+ B<0, N> b; // expected-error {{undefined}}
+
+ template<int, const int &R> struct C; // expected-note {{template}}
+ template<int &R> struct C<0, R> {};
+ C<0, N> c; // expected-error {{undefined}}
+}
Modified: cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp?rev=290586&r1=290585&r2=290586&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp (original)
+++ cfe/trunk/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp Tue Dec 27 00:14:37
2016
@@ -278,6 +278,12 @@ namespace Auto {
using R1 = fn_result_type<foo>::type;
using R1 = double;
+
+ template<int, auto &f> struct fn_result_type_partial_order;
+ template<auto &f> struct fn_result_type_partial_order<0, f>;
+ template<class R, class... Args, R (& f)(Args...)>
+ struct fn_result_type_partial_order<0, f> {};
+ fn_result_type_partial_order<0, foo> frtpo;
}
namespace Variadic {
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