1 // RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify -std=c++11 -fcxx-exceptions %s
2 // RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -verify -std=c++14 -fcxx-exceptions %s
3 // RUN: %clang_cc1 -fsyntax-only -triple x86_64-unknown-unknown -std=c++11 -fcxx-exceptions -Wno-invalid-constexpr %s -DNO_INVALID_CONSTEXPR
4
5 namespace StdExample {
6
f(void *)7 constexpr int f(void *) { return 0; }
f(...)8 constexpr int f(...) { return 1; }
g1()9 constexpr int g1() { return f(0); }
g2(int n)10 constexpr int g2(int n) { return f(n); }
g3(int n)11 constexpr int g3(int n) { return f(n*0); }
12
13 namespace N {
14 constexpr int c = 5;
h()15 constexpr int h() { return c; }
16 }
17 constexpr int c = 0;
g4()18 constexpr int g4() { return N::h(); }
19
20 static_assert(f(0) == 0, "");
21 static_assert(f('0') == 1, "");
22 static_assert(g1() == 0, "");
23 static_assert(g2(0) == 1, "");
24 static_assert(g2(1) == 1, "");
25 static_assert(g3(0) == 1, "");
26 static_assert(g3(1) == 1, "");
27 static_assert(N::h() == 5, "");
28 static_assert(g4() == 5, "");
29
30
f(bool b)31 constexpr int f(bool b)
32 { return b ? throw 0 : 0; } // ok
f()33 constexpr int f() { return throw 0, 0; } // expected-error {{constexpr function never produces a constant expression}} expected-note {{subexpression}}
34
35 struct B {
BStdExample::B36 constexpr B(int x) : i(0) { }
37 int i;
38 };
39
40 int global; // expected-note {{declared here}}
41
42 struct D : B {
DStdExample::D43 constexpr D() : B(global) { } // expected-error {{constexpr constructor never produces a constant expression}} expected-note {{read of non-const}}
44 };
45
46 }
47
48 namespace PotentialConstant {
49
Comma(int n)50 constexpr int Comma(int n) { return // expected-error {{constexpr function never produces a constant expression}}
51 (void)(n * 2),
52 throw 0, // expected-note {{subexpression}}
53 0;
54 }
55
56 int ng; // expected-note 6{{here}}
BinaryOp1(int n)57 constexpr int BinaryOp1(int n) { return n + ng; } // expected-error {{never produces}} expected-note {{read}}
BinaryOp2(int n)58 constexpr int BinaryOp2(int n) { return ng + n; } // expected-error {{never produces}} expected-note {{read}}
59
60 double dg; // expected-note 2{{here}}
BinaryOp1(double d)61 constexpr double BinaryOp1(double d) { return d + dg; } // expected-error {{never produces}} expected-note {{read}}
BinaryOp2(double d)62 constexpr double BinaryOp2(double d) { return dg + d; } // expected-error {{never produces}} expected-note {{read}}
63
Add(int a,int b,int c)64 constexpr int Add(int a, int b, int c) { return a + b + c; }
FunctionArgs(int a)65 constexpr int FunctionArgs(int a) { return Add(a, ng, a); } // expected-error {{never produces}} expected-note {{read}}
66
67 struct S { int a; int b; int c[2]; };
InitList(int a)68 constexpr S InitList(int a) { return { a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
InitList1a(int a)69 constexpr S InitList1a(int a) { return S{ a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
InitList2(int a)70 constexpr S InitList2(int a) { return { a, a, { ng } }; }; // expected-error {{never produces}} expected-note {{read}}
InitList3(int a)71 constexpr S InitList3(int a) { return a ? S{ a, a } : S{ a, ng }; }; // ok
72
LogicalAnd1(int n)73 constexpr int LogicalAnd1(int n) { return n && (throw, 0); } // ok
LogicalAnd2(int n)74 constexpr int LogicalAnd2(int n) { return 1 && (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
75
LogicalOr1(int n)76 constexpr int LogicalOr1(int n) { return n || (throw, 0); } // ok
LogicalOr2(int n)77 constexpr int LogicalOr2(int n) { return 0 || (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
78
Conditional1(bool b,int n)79 constexpr int Conditional1(bool b, int n) { return b ? n : ng; } // ok
Conditional2(bool b,int n)80 constexpr int Conditional2(bool b, int n) { return b ? n * ng : n + ng; } // expected-error {{never produces}} expected-note {{both arms of conditional operator are unable to produce a constant expression}}
81
82 // __builtin_constant_p ? : is magical, and is always a potential constant.
BcpCall(int n)83 constexpr bool BcpCall(int n) {
84 return __builtin_constant_p((int*)n != &n) ? (int*)n != &n : (int*)n != &n; // expected-warning 3 {{cast to 'int *' from smaller integer type 'int'}}
85 }
86 static_assert(BcpCall(0), "");
87
88 // DR1311: A function template which can produce a constant expression, but
89 // for which a particular specialization cannot, is ok.
cmin(T a,T b)90 template<typename T> constexpr T cmin(T a, T b) {
91 return a < b ? a : b;
92 }
93 int n = cmin(3, 5); // ok
94
95 struct X {
XPotentialConstant::X96 constexpr X() {}
97 bool operator<(X); // not constexpr
98 };
99
100 X x = cmin(X(), X()); // ok, not constexpr
101
102 // Same with other temploids.
103 template<typename T>
104 struct Y {
YPotentialConstant::Y105 constexpr Y() {}
getPotentialConstant::Y106 constexpr int get() { return T(); }
107 #if __cplusplus < 201402L
108 // expected-warning@-2 {{C++14}}
109 #endif
110 };
111 struct Z { operator int(); };
112
113 int y1 = Y<int>().get(); // ok
114 int y2 = Y<Z>().get(); // ok
115
116 }
117
118 #ifndef NO_INVALID_CONSTEXPR
119 namespace PR14550 {
120 // As an "extension", we allow functions which can't produce constant
121 // expressions to be declared constexpr in system headers (libstdc++
122 // marks some functions as constexpr which use builtins which we don't
123 // support constant folding). Ensure that we don't mark those functions
124 // as invalid after suppressing the diagnostic.
125 # 126 "p5.cpp" 1 3
126 int n;
127 struct A {
fPR14550::A128 static constexpr int f() { return n; }
129 };
130 template<typename T> struct B {
BPR14550::B131 B() { g(T::f()); } // expected-error {{undeclared identifier 'g'}}
132 };
133 # 134 "p5.cpp" 2
134 template class B<A>; // expected-note {{here}}
135 }
136 #endif
137
138 #if __cplusplus >= 201402L
f()139 constexpr void f() { throw; } // expected-error {{never produces}} expected-note {{subexpression}}
140 #endif
141