> On Dec 31, 2016, at 4:41 PM, Richard Smith via cfe-commits > <cfe-commits@lists.llvm.org> wrote: > > Author: rsmith > Date: Sat Dec 31 15:41:23 2016 > New Revision: 290792 > > URL: http://llvm.org/viewvc/llvm-project?rev=290792&view=rev > Log: > [c++17] Implement P0522R0 as written. This allows a template template argument > to be specified for a template template parameter whenever the parameter is at > least as specialized as the argument (when there's an obvious and correct > mapping from uses of the parameter to uses of the argument). For example, a > template with more parameters can be passed to a template template parameter > with fewer, if those trailing parameters have default arguments. > > This is disabled by default, despite being a DR resolution, as it's fairly > broken in its current state: there are no partial ordering rules to cope with > template template parameters that have different parameter lists, meaning that > code that attempts to decompose template-ids based on arity can hit > unavoidable > ambiguity issues. > > The diagnostics produced on a non-matching argument are also pretty bad right > now, but I aim to improve them in a subsequent commit. > > Added: > cfe/trunk/test/SemaTemplate/temp_arg_template_cxx1z.cpp > Modified: > cfe/trunk/include/clang/Basic/LangOptions.def > cfe/trunk/include/clang/Driver/Options.td > cfe/trunk/include/clang/Sema/Sema.h > cfe/trunk/lib/Driver/Tools.cpp > cfe/trunk/lib/Frontend/CompilerInvocation.cpp > cfe/trunk/lib/Sema/SemaTemplate.cpp > cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp > cfe/trunk/test/SemaTemplate/temp_arg_template.cpp > cfe/trunk/www/cxx_status.html > > Modified: cfe/trunk/include/clang/Basic/LangOptions.def > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/LangOptions.def?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/include/clang/Basic/LangOptions.def (original) > +++ cfe/trunk/include/clang/Basic/LangOptions.def Sat Dec 31 15:41:23 2016 > @@ -134,6 +134,7 @@ LANGOPT(NoBuiltin , 1, 0, "disab > LANGOPT(NoMathBuiltin , 1, 0, "disable math builtin functions") > LANGOPT(GNUAsm , 1, 1, "GNU-style inline assembly") > LANGOPT(CoroutinesTS , 1, 0, "C++ coroutines TS") > +LANGOPT(RelaxedTemplateTemplateArgs, 1, 0, "C++17 relaxed matching of > tempalte template arguments") > > BENIGN_LANGOPT(ThreadsafeStatics , 1, 1, "thread-safe static initializers") > LANGOPT(POSIXThreads , 1, 0, "POSIX thread support") > > Modified: cfe/trunk/include/clang/Driver/Options.td > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/include/clang/Driver/Options.td (original) > +++ cfe/trunk/include/clang/Driver/Options.td Sat Dec 31 15:41:23 2016 > @@ -1088,6 +1088,11 @@ def fapplication_extension : Flag<["-"], > HelpText<"Restrict code to those available for App Extensions">; > def fno_application_extension : Flag<["-"], "fno-application-extension">, > Group<f_Group>; > +def frelaxed_template_template_args : Flag<["-"], > "frelaxed-template-template-args">, > + Flags<[CC1Option]>, HelpText<"Enable C++17 relaxed template template > argument matching">, > + Group<f_Group>; > +def fno_relaxed_template_template_args : Flag<["-"], > "fno-relaxed-template-template-args">, > + Group<f_Group>; > def fsized_deallocation : Flag<["-"], "fsized-deallocation">, > Flags<[CC1Option]>, > HelpText<"Enable C++14 sized global deallocation functions">, > Group<f_Group>; > def fno_sized_deallocation: Flag<["-"], "fno-sized-deallocation">, > Group<f_Group>; > > Modified: cfe/trunk/include/clang/Sema/Sema.h > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/include/clang/Sema/Sema.h (original) > +++ cfe/trunk/include/clang/Sema/Sema.h Sat Dec 31 15:41:23 2016 > @@ -6719,6 +6719,9 @@ public: > bool isMoreSpecializedThanPrimary(VarTemplatePartialSpecializationDecl *T, > sema::TemplateDeductionInfo &Info); > > + bool isTemplateTemplateParameterAtLeastAsSpecializedAs( > + TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc); > + > void MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs, > bool OnlyDeduced, > unsigned Depth, > > Modified: cfe/trunk/lib/Driver/Tools.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/lib/Driver/Tools.cpp (original) > +++ cfe/trunk/lib/Driver/Tools.cpp Sat Dec 31 15:41:23 2016 > @@ -6020,6 +6020,13 @@ void Clang::ConstructJob(Compilation &C, > options::OPT_fno_assume_sane_operator_new)) > CmdArgs.push_back("-fno-assume-sane-operator-new"); > > + // -frelaxed-template-template-args is off by default, as it is a severe > + // breaking change until a corresponding change to template partial > ordering > + // is provided. > + if (Args.hasFlag(options::OPT_frelaxed_template_template_args, > + options::OPT_fno_relaxed_template_template_args, false)) > + CmdArgs.push_back("-frelaxed-template-template-args"); > + > // -fsized-deallocation is off by default, as it is an ABI-breaking change > for > // most platforms. > if (Args.hasFlag(options::OPT_fsized_deallocation, > > Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original) > +++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Sat Dec 31 15:41:23 2016 > @@ -1960,6 +1960,8 @@ static void ParseLangArgs(LangOptions &O > if (!Opts.NoBuiltin) > getAllNoBuiltinFuncValues(Args, Opts.NoBuiltinFuncs); > Opts.NoMathBuiltin = Args.hasArg(OPT_fno_math_builtin); > + Opts.RelaxedTemplateTemplateArgs = > + Args.hasArg(OPT_frelaxed_template_template_args); > Opts.SizedDeallocation = Args.hasArg(OPT_fsized_deallocation); > Opts.AlignedAllocation = > Args.hasFlag(OPT_faligned_allocation, OPT_fno_aligned_allocation, > > Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/lib/Sema/SemaTemplate.cpp (original) > +++ cfe/trunk/lib/Sema/SemaTemplate.cpp Sat Dec 31 15:41:23 2016 > @@ -5585,6 +5585,10 @@ ExprResult Sema::CheckTemplateArgument(N > return Arg; > } > > +static void DiagnoseTemplateParameterListArityMismatch( > + Sema &S, TemplateParameterList *New, TemplateParameterList *Old, > + Sema::TemplateParameterListEqualKind Kind, SourceLocation > TemplateArgLoc); > + > /// \brief Check a template argument against its corresponding > /// template template parameter. > /// > @@ -5601,6 +5605,9 @@ bool Sema::CheckTemplateArgument(Templat > return false; > } > > + if (Template->isInvalidDecl()) > + return true; > + > // C++0x [temp.arg.template]p1: > // A template-argument for a template template-parameter shall be > // the name of a class template or an alias template, expressed as an > @@ -5628,6 +5635,25 @@ bool Sema::CheckTemplateArgument(Templat > if (Param->isExpandedParameterPack()) > Params = Param->getExpansionTemplateParameters(ArgumentPackIndex); > > + // C++1z [temp.arg.template]p3: (DR 150) > + // A template-argument matches a template template-parameter P when P > + // is at least as specialized as the template-argument A. > + if (getLangOpts().RelaxedTemplateTemplateArgs) { > + // Quick check for the common case: > + // If P contains a parameter pack, then A [...] matches P if each of > A's > + // template parameters matches the corresponding template parameter in > + // the template-parameter-list of P. > + if (TemplateParameterListsAreEqual( > + Template->getTemplateParameters(), Params, false, > + TPL_TemplateTemplateArgumentMatch, Arg.getLocation())) > + return false; > + > + if (isTemplateTemplateParameterAtLeastAsSpecializedAs(Params, Template, > + Arg.getLocation())) > + return false; > + // FIXME: Produce better diagnostics for deduction failures. > + } > + > return !TemplateParameterListsAreEqual(Template->getTemplateParameters(), > Params, > true, > @@ -5839,7 +5865,7 @@ static bool MatchTemplateParameterKind(S > return false; > } > > - // Check that both are parameter packs are neither are parameter packs. > + // Check that both are parameter packs or neither are parameter packs. > // However, if we are matching a template template argument to a > // template template parameter, the template template parameter can have > // a parameter pack where the template template argument does not. > > Modified: cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp (original) > +++ cfe/trunk/lib/Sema/SemaTemplateDeduction.cpp Sat Dec 31 15:41:23 2016 > @@ -1898,11 +1898,11 @@ DeduceTemplateArguments(Sema &S, Templat > return NumberOfArgumentsMustMatch ? Sema::TDK_TooFewArguments > : Sema::TDK_Success; > > - if (Args[ArgIdx].isPackExpansion()) { > - // FIXME: We follow the logic of C++0x [temp.deduct.type]p22 here, > - // but applied to pack expansions that are template arguments. > + // C++1z [temp.deduct.type]p9: > + // During partial ordering, if Ai was originally a pack expansion > [and] > + // Pi is not a pack expansion, template argument deduction fails. > + if (Args[ArgIdx].isPackExpansion()) > return Sema::TDK_MiscellaneousDeductionFailure; > - } > > // Perform deduction for this Pi/Ai pair. > if (Sema::TemplateDeductionResult Result > @@ -1965,7 +1965,8 @@ DeduceTemplateArguments(Sema &S, > TemplateDeductionInfo &Info, > SmallVectorImpl<DeducedTemplateArgument> &Deduced) { > return DeduceTemplateArguments(S, TemplateParams, ParamList.asArray(), > - ArgList.asArray(), Info, Deduced, false); > + ArgList.asArray(), Info, Deduced, > + /*NumberOfArgumentsMustMatch*/false); > } > > /// \brief Determine whether two template arguments are the same. > @@ -4581,13 +4582,13 @@ UnresolvedSetIterator Sema::getMostSpeci > /// Determine whether one partial specialization, P1, is at least as > /// specialized than another, P2. > /// > -/// \tparam PartialSpecializationDecl The kind of P2, which must be a > -/// {Class,Var}Template{PartialSpecialization,}Decl. > +/// \tparam TemplateLikeDecl The kind of P2, which must be a > +/// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl. > /// \param T1 The injected-class-name of P1 (faked for a variable template). > /// \param T2 The injected-class-name of P2 (faked for a variable template). > -template<typename PartialSpecializationDecl> > +template<typename TemplateLikeDecl> > static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2, > - PartialSpecializationDecl *P2, > + TemplateLikeDecl *P2, > TemplateDeductionInfo &Info) { > // C++ [temp.class.order]p1: > // For two class template partial specializations, the first is at least > as > @@ -4729,6 +4730,72 @@ bool Sema::isMoreSpecializedThanPrimary( > return true; > } > > +bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs( > + TemplateParameterList *P, TemplateDecl *AArg, SourceLocation Loc) { > + // C++1z [temp.arg.template]p4: (DR 150) > + // A template template-parameter P is at least as specialized as a > + // template template-argument A if, given the following rewrite to two > + // function templates... > + > + // Rather than synthesize function templates, we merely perform the > + // equivalent partial ordering by performing deduction directly on > + // the template parameter lists of the template template parameters. > + // > + // Given an invented class template X with the template parameter list of > + // A (including default arguments): > + TemplateName X = Context.getCanonicalTemplateName(TemplateName(AArg)); > + TemplateParameterList *A = AArg->getTemplateParameters(); > + > + // - Each function template has a single function parameter whose type > is > + // a specialization of X with template arguments corresponding to the > + // template parameters from the respective function template > + SmallVector<TemplateArgument, 8> AArgs; > + Context.getInjectedTemplateArgs(A, AArgs); > + > + // Check P's arguments against A's parameter list. This will fill in > default > + // template arguments as needed. AArgs are already correct by construction. > + // We can't just use CheckTemplateIdType because that will expand alias > + // templates. > + SmallVector<TemplateArgument, 4> PArgs; > + { > + SFINAETrap Trap(*this); > + > + Context.getInjectedTemplateArgs(P, PArgs); > + TemplateArgumentListInfo PArgList(P->getLAngleLoc(), P->getRAngleLoc()); > + for (unsigned I = 0, N = P->size(); I != N; ++I) { > + // Unwrap packs that getInjectedTemplateArgs wrapped around pack > + // expansions, to form an "as written" argument list. > + TemplateArgument Arg = PArgs[I]; > + if (Arg.getKind() == TemplateArgument::Pack) { > + assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion()); > + Arg = *Arg.pack_begin(); > + } > + PArgList.addArgument(getTrivialTemplateArgumentLoc( > + Arg, QualType(), P->getParam(I)->getLocation())); > + } > + PArgs.clear(); > + > + // C++1z [temp.arg.template]p3: > + // If the rewrite produces an invalid type, then P is not at least as > + // specialized as A. > + if (CheckTemplateArgumentList(AArg, Loc, PArgList, false, PArgs) || > + Trap.hasErrorOccurred()) > + return false; > + } > + > + QualType AType = Context.getTemplateSpecializationType(X, AArgs); > + QualType PType = Context.getTemplateSpecializationType(X, PArgs); > + > + SmallVector<DeducedTemplateArgument, 4> Deduced; > + Deduced.resize(A->size());
Looks like Deduced is unused here! > + > + // ... the function template corresponding to P is at least as > specialized > + // as the function template corresponding to A according to the partial > + // ordering rules for function templates. > + TemplateDeductionInfo Info(Loc, A->getDepth()); > + return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info); > +} > + > static void > MarkUsedTemplateParameters(ASTContext &Ctx, > const TemplateArgument &TemplateArg, > > Modified: cfe/trunk/test/SemaTemplate/temp_arg_template.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_template.cpp?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/test/SemaTemplate/temp_arg_template.cpp (original) > +++ cfe/trunk/test/SemaTemplate/temp_arg_template.cpp Sat Dec 31 15:41:23 2016 > @@ -6,11 +6,12 @@ template<template<typename T> class X> s > > template<template<typename T, int I> class X> struct B; // > expected-note{{previous template template parameter is here}} > > -template<template<int I> class X> struct C; // expected-note{{previous > non-type template parameter with type 'int' is here}} > +template<template<int I> class X> struct C; // expected-note 2{{previous > non-type template parameter with type 'int' is here}} > > template<class> struct X; // expected-note{{too few template parameters in > template template argument}} > template<int N> struct Y; // expected-note{{template parameter has a > different kind in template argument}} > template<long N> struct Ylong; // expected-note{{template non-type parameter > has a different type 'long' in template argument}} > +template<const int &N> struct Yref; // expected-note{{template non-type > parameter has a different type 'const int &' in template argument}} > > namespace N { > template<class> struct Z; > @@ -27,6 +28,7 @@ A<TooMany> *a5; // expected-error{{templ > B<X> *a6; // expected-error{{template template argument has different > template parameters than its corresponding template template parameter}} > C<Y> *a7; > C<Ylong> *a8; // expected-error{{template template argument has different > template parameters than its corresponding template template parameter}} > +C<Yref> *a9; // expected-error{{template template argument has different > template parameters than its corresponding template template parameter}} > > template<typename T> void f(int); > > > Added: cfe/trunk/test/SemaTemplate/temp_arg_template_cxx1z.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_template_cxx1z.cpp?rev=290792&view=auto > ============================================================================== > --- cfe/trunk/test/SemaTemplate/temp_arg_template_cxx1z.cpp (added) > +++ cfe/trunk/test/SemaTemplate/temp_arg_template_cxx1z.cpp Sat Dec 31 > 15:41:23 2016 > @@ -0,0 +1,102 @@ > +// RUN: %clang_cc1 -fsyntax-only -verify -std=c++1z > -frelaxed-template-template-args %s > + > +// expected-note@temp_arg_template_cxx1z.cpp:* 1+{{}} > + > +template<template<int> typename> struct Ti; > +template<template<int...> typename> struct TPi; > +template<template<int, int...> typename> struct TiPi; > +template<template<int..., int...> typename> struct TPiPi; // FIXME: Why is > this not ill-formed? > + > +template<typename T, template<T> typename> struct tT0; > +template<template<typename T, T> typename> struct Tt0; > + > +template<template<typename> typename> struct Tt; > +template<template<typename, typename...> typename> struct TtPt; > + > +template<int> struct i; > +template<int, int = 0> struct iDi; > +template<int, int> struct ii; > +template<int...> struct Pi; > +template<int, int, int...> struct iiPi; > + > +template<int, typename = int> struct iDt; > +template<int, typename> struct it; > + > +template<typename T, T v> struct t0; > + > +template<typename...> struct Pt; > + > +namespace IntParam { > + using ok = Pt<Ti<i>, > + Ti<iDi>, > + Ti<Pi>, > + Ti<iDt>>; > + using err1 = Ti<ii>; // expected-error {{different template parameters}} > + using err2 = Ti<iiPi>; // expected-error {{different template parameters}} > + using err3 = Ti<t0>; // expected-error {{different template parameters}} > + using err4 = Ti<it>; // expected-error {{different template parameters}} > +} > + > +// These are accepted by the backwards-compatibility "parameter pack in > +// parameter matches any number of parameters in arguments" rule. > +namespace IntPackParam { > + using ok = TPi<Pi>; > + using ok_compat = Pt<TPi<i>, TPi<iDi>, TPi<ii>, TPi<iiPi>>; > + using err1 = TPi<t0>; // expected-error {{different template parameters}} > + using err2 = TPi<iDt>; // expected-error {{different template parameters}} > + using err3 = TPi<it>; // expected-error {{different template parameters}} > +} > + > +namespace IntAndPackParam { > + using ok = TiPi<Pi>; > + using ok_compat = Pt<TiPi<ii>, TiPi<iDi>, TiPi<iiPi>>; > + using err = TiPi<iDi>; > +} > + > +namespace DependentType { > + using ok = Pt<tT0<int, i>, tT0<int, iDi>>; > + using err1 = tT0<int, ii>; // expected-error {{different template > parameters}} > + using err2 = tT0<short, i>; // FIXME: should this be OK? > + using err2a = tT0<long long, i>; // FIXME: should this be OK (if long long > is larger than int)? > + using err2b = tT0<void*, i>; // expected-error {{different template > parameters}} > + using err3 = tT0<short, t0>; // expected-error {{different template > parameters}} > + > + using ok2 = Tt0<t0>; > + using err4 = Tt0<it>; // expected-error {{different template parameters}} > +} > + > +namespace Auto { > + template<template<int> typename T> struct TInt {}; > + template<template<int*> typename T> struct TIntPtr {}; > + template<template<auto> typename T> struct TAuto {}; > + template<template<auto*> typename T> struct TAutoPtr {}; > + template<auto> struct Auto; > + template<auto*> struct AutoPtr; > + template<int> struct Int; > + template<int*> struct IntPtr; > + > + TInt<Auto> ia; > + TInt<AutoPtr> iap; // FIXME: ill-formed > + TInt<Int> ii; > + TInt<IntPtr> iip; // expected-error {{different template parameters}} > + > + TIntPtr<Auto> ipa; > + TIntPtr<AutoPtr> ipap; > + TIntPtr<Int> ipi; // expected-error {{different template parameters}} > + TIntPtr<IntPtr> ipip; > + > + TAuto<Auto> aa; > + TAuto<AutoPtr> aap; // FIXME: ill-formed > + TAuto<Int> ai; // FIXME: ill-formed > + TAuto<IntPtr> aip; // FIXME: ill-formed > + > + TAutoPtr<Auto> apa; > + TAutoPtr<AutoPtr> apap; > + TAutoPtr<Int> api; // FIXME: ill-formed > + TAutoPtr<IntPtr> apip; // FIXME: ill-formed > + > + int n; > + template<auto A, decltype(A) B = &n> struct SubstFailure; > + TInt<SubstFailure> isf; // expected-error {{different template parameters}} > + TIntPtr<SubstFailure> ipsf; // expected-error {{different template > parameters}} > +} > > Modified: cfe/trunk/www/cxx_status.html > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_status.html?rev=290792&r1=290791&r2=290792&view=diff > ============================================================================== > --- cfe/trunk/www/cxx_status.html (original) > +++ cfe/trunk/www/cxx_status.html Sat Dec 31 15:41:23 2016 > @@ -733,7 +733,7 @@ as the draft C++1z standard evolves. > <tr> > <td>Matching template template parameters to compatible arguments</td> > <td><a href="http://wg21.link/p0522r0";>P0522R0</a></td> > - <td class="none" align="center">No <a href="#p0522">(12)</a></td> > + <td class="partial" align="center">Partial <a > href="#p0522">(12)</a></td> > </tr> > <tr> > <td>Removing deprecated dynamic exception specifications</td> > @@ -763,8 +763,12 @@ left to right in the callee. As a result > functions using expression syntax are no longer guaranteed to be destroyed in > reverse construction order in that ABI. > </span><br> > -<span id="p0522">(12): This is the resolution to a Defect Report, so will be > -applied to all language versions. > +<span id="p0522">(12): Despite being the the resolution to a Defect Report, > this > +feature is disabled by default in all language versions, and can be enabled > +explicitly with the flag <tt>-frelaxed-template-template-args</tt>. The > change > +to the standard lacks a corresponding change for template partial ordering, > +resulting in ambiguity errors for reasonable and previously-valid code. This > +issue is expected to be rectified soon. > </span> > </p> > </details> > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
