1 // RUN: %clang_cc1 -emit-llvm -triple i686-pc-linux-gnu -std=c++1y -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NO-OPT
2 // RUN: %clang_cc1 -emit-llvm -triple i686-pc-linux-gnu -std=c++1y -O3 -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-OPT
3 // RUN: %clang_cc1 -emit-llvm -triple i686-pc-win32 -std=c++1y -o - %s | FileCheck %s --check-prefix=CHECK-MS
4 
5 // This check logically is attached to 'template int S<int>::i;' below.
6 // CHECK: @_ZN1SIiE1iE = weak_odr global i32
7 
8 // This check is logically attached to 'template int ExportedStaticLocal::f<int>()' below.
9 // CHECK-OPT: @_ZZN19ExportedStaticLocal1fIiEEvvE1i = linkonce_odr global
10 
11 template<typename T, typename U, typename Result>
12 struct plus {
13   Result operator()(const T& t, const U& u) const;
14 };
15 
16 template<typename T, typename U, typename Result>
17 Result plus<T, U, Result>::operator()(const T& t, const U& u) const {
18   return t + u;
19 }
20 
21 // CHECK-LABEL: define weak_odr noundef i32 @_ZNK4plusIillEclERKiRKl
22 template struct plus<int, long, long>;
23 
24 namespace EarlyInstantiation {
25   // Check that we emit definitions if we instantiate a function definition before
26   // it gets explicitly instantiatied.
27   template<typename T> struct S {
28     constexpr int constexpr_function() { return 0; }
29     auto deduced_return_type() { return 0; }
30   };
31 
32   // From an implicit instantiation.
33   constexpr int a = S<char>().constexpr_function();
34   int b = S<char>().deduced_return_type();
35 
36   // From an explicit instantiation declaration.
37   extern template struct S<int>;
38   constexpr int c = S<int>().constexpr_function();
39   int d = S<int>().deduced_return_type();
40 
41   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation1SIcE18constexpr_functionEv(
42   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation1SIcE19deduced_return_typeEv(
43   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation1SIiE18constexpr_functionEv(
44   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation1SIiE19deduced_return_typeEv(
45   template struct S<char>;
46   template struct S<int>;
47 
48   template<typename T> constexpr int constexpr_function() { return 0; }
49   template<typename T> auto deduced_return_type() { return 0; }
50 
51   // From an implicit instantiation.
52   constexpr int e = constexpr_function<char>();
53   int f = deduced_return_type<char>();
54 
55   // From an explicit instantiation declaration.
56   extern template int constexpr_function<int>();
57   extern template auto deduced_return_type<int>();
58   constexpr int g = constexpr_function<int>();
59   int h = deduced_return_type<int>();
60 
61   // The FIXMEs below are for PR19551.
62   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation18constexpr_functionIcEEiv(
63   // FIXME: define weak_odr noundef i32 @_ZN18EarlyInstantiation19deduced_return_typeIcEEiv(
64   // CHECK: define weak_odr noundef i32 @_ZN18EarlyInstantiation18constexpr_functionIiEEiv(
65   // FIXME: define weak_odr noundef i32 @_ZN18EarlyInstantiation19deduced_return_typeIiEEiv(
66   template int constexpr_function<char>();
67   // FIXME template auto deduced_return_type<char>();
68   template int constexpr_function<int>();
69   // FIXME template auto deduced_return_type<int>();
70 }
71 
72 namespace LateInstantiation {
73   // Check that we downgrade the linkage to available_externally if we see an
74   // explicit instantiation declaration after the function template is
75   // instantiated.
76   template<typename T> struct S { constexpr int f() { return 0; } };
77   template<typename T> constexpr int f() { return 0; }
78 
79   // Trigger eager instantiation of the function definitions.
80   int a, b = S<char>().f() + f<char>() + a;
81   int c, d = S<int>().f() + f<int>() + a;
82 
83   // Don't allow some of those definitions to be emitted.
84   extern template struct S<int>;
85   extern template int f<int>();
86 
87   // Check that we declare, define, or provide an available-externally
88   // definition as appropriate.
89   // CHECK: define linkonce_odr noundef i32 @_ZN17LateInstantiation1SIcE1fEv(
90   // CHECK: define linkonce_odr noundef i32 @_ZN17LateInstantiation1fIcEEiv(
91   // CHECK-NO-OPT: declare noundef i32 @_ZN17LateInstantiation1SIiE1fEv(
92   // CHECK-NO-OPT: declare noundef i32 @_ZN17LateInstantiation1fIiEEiv(
93   // CHECK-OPT: define available_externally noundef i32 @_ZN17LateInstantiation1SIiE1fEv(
94   // CHECK-OPT: define available_externally noundef i32 @_ZN17LateInstantiation1fIiEEiv(
95 }
96 
97 namespace PR21718 {
98 // The linkage of a used constexpr member function can change from linkonce_odr
99 // to weak_odr after explicit instantiation without errors about defining the
100 // same function twice.
101 template <typename T>
102 struct S {
103 // CHECK-LABEL: define weak_odr noundef i32 @_ZN7PR217181SIiE1fEv
104   __attribute__((used)) constexpr int f() { return 0; }
105 };
106 int g() { return S<int>().f(); }
107 template struct S<int>;
108 }
109 
110 namespace NestedClasses {
111   // Check how explicit instantiation of an outer class affects the inner class.
112   template <typename T> struct Outer {
113     struct Inner {
114       void f() {}
115     };
116   };
117 
118   // Explicit instantiation definition of Outer causes explicit instantiation
119   // definition of Inner.
120   template struct Outer<int>;
121   // CHECK: define weak_odr void @_ZN13NestedClasses5OuterIiE5Inner1fEv
122   // CHECK-MS: define weak_odr dso_local x86_thiscallcc void @"?f@Inner@?$Outer@H@NestedClasses@@QAEXXZ"
123 
124   // Explicit instantiation declaration of Outer causes explicit instantiation
125   // declaration of Inner, but not in MSVC mode.
126   extern template struct Outer<char>;
127   auto use = &Outer<char>::Inner::f;
128   // CHECK: {{declare|define available_externally}} void @_ZN13NestedClasses5OuterIcE5Inner1fEv
129   // CHECK-MS: define linkonce_odr dso_local x86_thiscallcc void @"?f@Inner@?$Outer@D@NestedClasses@@QAEXXZ"
130 }
131 
132 // Check that we emit definitions from explicit instantiations even when they
133 // occur prior to the definition itself.
134 template <typename T> struct S {
135   void f();
136   static void g();
137   static int i;
138   struct S2 {
139     void h();
140   };
141 };
142 
143 // CHECK-LABEL: define weak_odr void @_ZN1SIiE1fEv
144 template void S<int>::f();
145 
146 // CHECK-LABEL: define weak_odr void @_ZN1SIiE1gEv
147 template void S<int>::g();
148 
149 // See the check line at the top of the file.
150 template int S<int>::i;
151 
152 // CHECK-LABEL: define weak_odr void @_ZN1SIiE2S21hEv
153 template void S<int>::S2::h();
154 
155 template <typename T> void S<T>::f() {}
156 template <typename T> void S<T>::g() {}
157 template <typename T> int S<T>::i;
158 template <typename T> void S<T>::S2::h() {}
159 
160 namespace ExportedStaticLocal {
161 void sink(int&);
162 template <typename T>
163 inline void f() {
164   static int i;
165   sink(i);
166 }
167 // See the check line at the top of the file.
168 extern template void f<int>();
169 void use() {
170   f<int>();
171 }
172 }
173 
174 namespace DefaultedMembers {
175   struct B { B(); B(const B&); ~B(); };
176   template<typename T> struct A : B {
177     A() = default;
178     ~A() = default;
179   };
180   extern template struct A<int>;
181 
182   // CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiEC2Ev
183   // CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiED2Ev
184   A<int> ai;
185 
186   // CHECK-LABEL: define {{.*}} @_ZN16DefaultedMembers1AIiEC2ERKS1_
187   A<int> ai2(ai);
188 
189   // CHECK-NOT: @_ZN16DefaultedMembers1AIcE
190   template struct A<char>;
191 }
192