clang/test/SemaTemplate/deduction-guide.cpp

   1 // RUN: %clang_cc1 -std=c++2a -verify -ast-dump -ast-dump-decl-types -ast-dump-filter "deduction guide" %s | FileCheck %s --strict-whitespace
   2
   3 template<auto ...> struct X {};
   4 template<template<typename X, X> typename> struct Y {};
   5 template<typename ...> struct Z {};
   6
   7 template<typename T, typename ...Ts> struct A {
   8   template<Ts ...Ns, T *...Ps> A(X<Ps...>, Ts (*...qs)[Ns]);
   9 };
  10 int arr1[3], arr2[3];
  11 short arr3[4];
  12 A a(X<&arr1, &arr2>{}, &arr1, &arr2, &arr3);
  13 using AT = decltype(a);
  14 using AT = A<int[3], int, int, short>;
  15
  16 // CHECK-LABEL: Dumping <deduction guide for A>:
  17 // CHECK: FunctionTemplateDecl
  18 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 0 T
  19 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 1 ... Ts
  20 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'Ts...' depth 0 index 2 ... Ns
  21 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'T *' depth 0 index 3 ... Ps
  22 // CHECK: |-CXXDeductionGuideDecl
  23 // CHECK: | |-ParmVarDecl {{.*}} 'X<Ps...>'
  24 // CHECK: | `-ParmVarDecl {{.*}} 'Ts (*)[Ns]...' pack
  25 // CHECK: `-CXXDeductionGuideDecl
  26 // CHECK:   |-TemplateArgument type 'int[3]'
  27 // CHECK:   |-TemplateArgument pack
  28 // CHECK:   | |-TemplateArgument type 'int'
  29 // CHECK:   | |-TemplateArgument type 'int'
  30 // CHECK:   | `-TemplateArgument type 'short'
  31 // CHECK:   |-TemplateArgument pack
  32 // CHECK:   | |-TemplateArgument integral 3
  33 // CHECK:   | |-TemplateArgument integral 3
  34 // CHECK:   | `-TemplateArgument integral 4
  35 // CHECK:   |-TemplateArgument pack
  36 // CHECK:   | |-TemplateArgument decl
  37 // CHECK:   | | `-Var {{.*}} 'arr1' 'int[3]'
  38 // CHECK:   | `-TemplateArgument decl
  39 // CHECK:   |   `-Var {{.*}} 'arr2' 'int[3]'
  40 // CHECK:   |-ParmVarDecl {{.*}} 'X<&arr1, &arr2>'
  41 // CHECK:   |-ParmVarDecl {{.*}} 'int (*)[3]'
  42 // CHECK:   |-ParmVarDecl {{.*}} 'int (*)[3]'
  43 // CHECK:   `-ParmVarDecl {{.*}} 'short (*)[4]'
  44 // CHECK: FunctionProtoType {{.*}} 'auto (X<Ps...>, Ts (*)[Ns]...) -> A<T, Ts...>' dependent trailing_return
  45 // CHECK: |-InjectedClassNameType {{.*}} 'A<T, Ts...>' dependent
  46 // CHECK: |-ElaboratedType {{.*}} 'X<Ps...>' sugar dependent
  47 // CHECK: | `-TemplateSpecializationType {{.*}} 'X<Ps...>' dependent X
  48 // CHECK: |   `-TemplateArgument expr
  49 // CHECK: |     `-PackExpansionExpr {{.*}} 'T *'
  50 // CHECK: |       `-DeclRefExpr {{.*}} 'T *' NonTypeTemplateParm {{.*}} 'Ps' 'T *'
  51 // CHECK: `-PackExpansionType {{.*}} 'Ts (*)[Ns]...' dependent
  52 // CHECK:   `-PointerType {{.*}} 'Ts (*)[Ns]' dependent contains_unexpanded_pack
  53 // CHECK:     `-ParenType {{.*}} 'Ts[Ns]' sugar dependent contains_unexpanded_pack
  54 // CHECK:       `-DependentSizedArrayType {{.*}} 'Ts[Ns]' dependent contains_unexpanded_pack
  55 // CHECK:         |-TemplateTypeParmType {{.*}} 'Ts' dependent contains_unexpanded_pack depth 0 index 1 pack
  56 // CHECK:         | `-TemplateTypeParm {{.*}} 'Ts'
  57 // CHECK:         `-DeclRefExpr {{.*}} 'Ts' NonTypeTemplateParm {{.*}} 'Ns' 'Ts...'
  58
  59 template<typename T, T V> struct B {
  60   template<typename U, U W> B(X<W, V>);
  61 };
  62 B b(X<nullptr, 'x'>{});
  63 using BT = decltype(b);
  64 using BT = B<char, 'x'>;
  65
  66 // CHECK-LABEL: Dumping <deduction guide for B>:
  67 // CHECK: FunctionTemplateDecl
  68 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 0 T
  69 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'T' depth 0 index 1 V
  70 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 2 U
  71 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'type-parameter-0-2' depth 0 index 3 W
  72 // CHECK: |-CXXDeductionGuideDecl {{.*}} 'auto (X<W, V>) -> B<T, V>'
  73 // CHECK: | `-ParmVarDecl {{.*}} 'X<W, V>'
  74 // CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (X<nullptr, 'x'>) -> B<char, 'x'>'
  75 // CHECK:   |-TemplateArgument type 'char'
  76 // CHECK:   |-TemplateArgument integral 120
  77 // CHECK:   |-TemplateArgument type 'std::nullptr_t'
  78 // CHECK:   |-TemplateArgument nullptr
  79 // CHECK:   `-ParmVarDecl {{.*}} 'X<nullptr, 'x'>'
  80 // CHECK: FunctionProtoType {{.*}} 'auto (X<W, V>) -> B<T, V>' dependent trailing_return
  81 // CHECK: |-InjectedClassNameType {{.*}} 'B<T, V>' dependent
  82 // CHECK: `-TemplateSpecializationType {{.*}} 'X<W, V>' dependent X
  83 // CHECK:   |-TemplateArgument expr
  84 // CHECK:   | `-DeclRefExpr {{.*}} 'type-parameter-0-2' NonTypeTemplateParm {{.*}} 'W' 'type-parameter-0-2'
  85 // CHECK:   `-TemplateArgument expr
  86 // CHECK:     `-DeclRefExpr {{.*}} 'T' NonTypeTemplateParm {{.*}} 'V' 'T'
  87
  88 template<typename A> struct C {
  89   template<template<typename X, X> typename T, typename U, U V = 0> C(A, Y<T>, U);
  90 };
  91 C c(1, Y<B>{}, 2);
  92 using CT = decltype(c);
  93 using CT = C<int>;
  94
  95 // CHECK-LABEL: Dumping <deduction guide for C>:
  96 // CHECK: FunctionTemplateDecl
  97 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 0 A
  98 // CHECK: |-TemplateTemplateParmDecl {{.*}} depth 0 index 1 T
  99 // CHECK: | |-TemplateTypeParmDecl {{.*}} typename depth 1 index 0 X
 100 // CHECK: | `-NonTypeTemplateParmDecl {{.*}} 'X' depth 1 index 1
 101 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 2 U
 102 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'type-parameter-0-2' depth 0 index 3 V
 103 // CHECK: | `-TemplateArgument expr
 104 // CHECK: |   `-IntegerLiteral {{.*}} 'int' 0
 105 // CHECK: |-CXXDeductionGuideDecl {{.*}} 'auto (A, Y<>, type-parameter-0-2) -> C<A>'
 106 // CHECK: | |-ParmVarDecl {{.*}} 'A'
 107 // CHECK: | |-ParmVarDecl {{.*}} 'Y<>'
 108 // CHECK: | `-ParmVarDecl {{.*}} 'type-parameter-0-2'
 109 // CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (int, Y<B>, int) -> C<int>'
 110 // CHECK:  |-TemplateArgument type 'int'
 111 // CHECK:  |-TemplateArgument template B
 112 // CHECK:  |-TemplateArgument type 'int'
 113 // CHECK:  |-TemplateArgument integral 0
 114 // CHECK:  |-ParmVarDecl {{.*}} 'int'
 115 // CHECK:  |-ParmVarDecl {{.*}} 'Y<B>'
 116 // CHECK:  `-ParmVarDecl {{.*}} 'int'
 117 // CHECK: FunctionProtoType {{.*}} 'auto (A, Y<>, type-parameter-0-2) -> C<A>' dependent trailing_return cdecl
 118 // CHECK: |-InjectedClassNameType {{.*}} 'C<A>' dependent
 119 // CHECK: |-TemplateTypeParmType {{.*}} 'A' dependent depth 0 index 0
 120 // CHECK: | `-TemplateTypeParm {{.*}} 'A'
 121 // CHECK: |-ElaboratedType {{.*}} 'Y<>' sugar dependent
 122 // CHECK: | `-TemplateSpecializationType {{.*}} 'Y<>' dependent Y
 123 // CHECK: |   `-TemplateArgument template
 124 // CHECK: `-TemplateTypeParmType {{.*}} 'type-parameter-0-2' dependent depth 0 index 2
 125
 126 template<typename ...T> struct D { // expected-note {{candidate}}
 127   template<typename... U> using B = int(int (*...p)(T, U));
 128   template<typename U1, typename U2> D(B<U1, U2>*); // expected-note {{candidate}}
 129 };
 130 int f(int(int, int), int(int, int));
 131 // FIXME: We can't deduce this because we can't deduce through a
 132 // SubstTemplateTypeParmPackType.
 133 D d = f; // expected-error {{no viable}}
 134 using DT = decltype(d);
 135 using DT = D<int, int>;
 136
 137 // CHECK-LABEL: Dumping <deduction guide for D>:
 138 // CHECK: FunctionTemplateDecl
 139 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 0 ... T
 140 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 1 U1
 141 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 2 U2
 142 // CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (B<type-parameter-0-1, type-parameter-0-2> *) -> D<T...>'
 143 // CHECK:   `-ParmVarDecl {{.*}} 'B<type-parameter-0-1, type-parameter-0-2> *'
 144 // CHECK: FunctionProtoType {{.*}} 'auto (B<type-parameter-0-1, type-parameter-0-2> *) -> D<T...>' dependent trailing_return
 145 // CHECK: |-InjectedClassNameType {{.*}} 'D<T...>' dependent
 146 // CHECK: `-PointerType {{.*}} 'B<type-parameter-0-1, type-parameter-0-2> *' dependent
 147 // CHECK:   `-TemplateSpecializationType {{.*}} 'B<type-parameter-0-1, type-parameter-0-2>' sugar dependent alias B
 148 // CHECK:     |-TemplateArgument type 'type-parameter-0-1'
 149 // CHECK:     |-TemplateArgument type 'type-parameter-0-2'
 150 // CHECK:     `-FunctionProtoType {{.*}} 'int (int (*)(T, U)...)' dependent cdecl
 151 // CHECK:       |-BuiltinType {{.*}} 'int'
 152 // CHECK:       `-PackExpansionType {{.*}} 'int (*)(T, U)...' dependent expansions 2
 153 // CHECK:         `-PointerType {{.*}} 'int (*)(T, U)' dependent contains_unexpanded_pack
 154 // CHECK:           `-ParenType {{.*}} 'int (T, U)' sugar dependent contains_unexpanded_pack
 155 // CHECK:             `-FunctionProtoType {{.*}} 'int (T, U)' dependent contains_unexpanded_pack cdecl
 156 // CHECK:               |-BuiltinType {{.*}} 'int'
 157 // CHECK:               |-TemplateTypeParmType {{.*}} 'T' dependent contains_unexpanded_pack depth 0 index 0 pack
 158 // CHECK:               | `-TemplateTypeParm {{.*}} 'T'
 159 // CHECK:               `-SubstTemplateTypeParmPackType {{.*}} 'U' dependent contains_unexpanded_pack typename depth 1 index 0 ... U
 160 // CHECK:                 |-TypeAliasTemplate {{.*}} 'B'
 161 // CHECK:                 `-TemplateArgument pack
 162 // CHECK:                   |-TemplateArgument type 'type-parameter-0-1'
 163 // CHECK-NOT: Subst
 164 // CHECK:                   | `-TemplateTypeParmType
 165 // CHECK:                   `-TemplateArgument type 'type-parameter-0-2'
 166 // CHECK-NOT: Subst
 167 // CHECK:                     `-TemplateTypeParmType
 168
 169 template<int ...N> struct E { // expected-note {{candidate}}
 170   template<int ...M> using B = Z<X<N, M>...>;
 171   template<int M1, int M2> E(B<M1, M2>); // expected-note {{candidate}}
 172 };
 173 // FIXME: We can't deduce this because we can't deduce through a
 174 // SubstNonTypeTemplateParmPackExpr.
 175 E e = Z<X<1, 2>, X<3, 4>>(); // expected-error {{no viable}}
 176 using ET = decltype(e);
 177 using ET = E<1, 3>;
 178
 179 // CHECK-LABEL: Dumping <deduction guide for E>:
 180 // CHECK: FunctionTemplateDecl
 181 // CHECK: |-NonTypeTemplateParmDecl [[N:0x[0-9a-f]*]] {{.*}} 'int' depth 0 index 0 ... N
 182 // CHECK: |-NonTypeTemplateParmDecl [[M1:0x[0-9a-f]*]] {{.*}} 'int' depth 0 index 1 M1
 183 // CHECK: |-NonTypeTemplateParmDecl [[M2:0x[0-9a-f]*]] {{.*}} 'int' depth 0 index 2 M2
 184 // CHECK: `-CXXDeductionGuideDecl {{.*}} 'auto (B<M1, M2>) -> E<N...>'
 185 // CHECK:   `-ParmVarDecl {{.*}} 'B<M1, M2>':'Z<X<N, M>...>'
 186 // CHECK: FunctionProtoType {{.*}} 'auto (B<M1, M2>) -> E<N...>' dependent trailing_return
 187 // CHECK: |-InjectedClassNameType {{.*}} 'E<N...>' dependent
 188 // CHECK: `-TemplateSpecializationType {{.*}} 'B<M1, M2>' sugar dependent alias B
 189 // CHECK:   |-TemplateArgument expr
 190 // CHECK:   | `-DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'M1' 'int'
 191 // CHECK:   |-TemplateArgument expr
 192 // CHECK:   | `-DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'M2' 'int'
 193 // CHECK:   `-TemplateSpecializationType {{.*}} 'Z<X<N, M>...>' dependent Z
 194 // CHECK:     `-TemplateArgument type 'X<N, M>...'
 195 // CHECK:       `-PackExpansionType {{.*}} 'X<N, M>...' dependent expansions 2
 196 // CHECK:         `-TemplateSpecializationType {{.*}} 'X<N, M>' dependent contains_unexpanded_pack X
 197 // CHECK:           |-TemplateArgument expr
 198 // CHECK-NOT: Subst
 199 // CHECK:           | `-DeclRefExpr {{.*}} 'int' NonTypeTemplateParm [[N]] 'N' 'int'
 200 // CHECK:           `-TemplateArgument expr
 201 // CHECK:             `-SubstNonTypeTemplateParmPackExpr {{.*}} 'int'
 202 // CHECK:               |-NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 1 index 0 ... M
 203 // CHECK:               `-TemplateArgument pack
 204 // CHECK:                 |-TemplateArgument expr
 205 // CHECK-NOT: Subst
 206 // CHECK:                 | `-DeclRefExpr {{.*}} 'int' NonTypeTemplateParm [[M1]] 'M1' 'int'
 207 // CHECK:                 `-TemplateArgument expr
 208 // CHECK-NOT: Subst
 209 // CHECK:                   `-DeclRefExpr {{.*}} 'int' NonTypeTemplateParm [[M2]] 'M2' 'int'
 210
 211 template <char = 'x'> struct F;
 212
 213 template <char> struct F {
 214   template <typename U>
 215   requires(false) F(U);
 216   template <typename U>
 217   requires(true) F(U);
 218 };
 219
 220 F s(0);
 221
 222 // CHECK-LABEL: Dumping <deduction guide for F>:
 223 // CHECK: FunctionTemplateDecl
 224 // CHECK: |-NonTypeTemplateParmDecl {{.*}} 'char' depth 0 index 0
 225 // CHECK:   `-TemplateArgument expr
 226 // CHECK: |   |-inherited from NonTypeTemplateParm {{.*}} '' 'char'
 227 // CHECK: |   `-CharacterLiteral {{.*}} 'char' 120
 228 // CHECK: |-TemplateTypeParmDecl {{.*}} typename depth 0 index 1 U
 229 // CHECK: |-ParenExpr {{.*}} 'bool'
 230 // CHECK: | `-CXXBoolLiteralExpr {{.*}} 'bool' false
 231 // CHECK: |-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for F> 'auto (type-parameter-0-1) -> F<>'
 232 // CHECK: | `-ParmVarDecl {{.*}} 'type-parameter-0-1'
 233 // CHECK: `-CXXDeductionGuideDecl {{.*}} implicit <deduction guide for F> 'auto (int) -> F<>'
 234 // CHECK:   |-TemplateArgument integral 120
 235 // CHECK:   |-TemplateArgument type 'int'
 236 // CHECK:   | `-BuiltinType {{.*}} 'int'
 237 // CHECK:   `-ParmVarDecl {{.*}} 'int'
 238 // CHECK: FunctionProtoType {{.*}} 'auto (type-parameter-0-1) -> F<>' dependent trailing_return cdecl
 239 // CHECK: |-InjectedClassNameType {{.*}} 'F<>' dependent
 240 // CHECK: | `-CXXRecord {{.*}} 'F'
 241 // CHECK: `-TemplateTypeParmType {{.*}} 'type-parameter-0-1' dependent depth 0 index 1