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
5namespace StdExample {
6
7constexpr int f(void *) { return 0; }
8constexpr int f(...) { return 1; }
9constexpr int g1() { return f(0); }
10constexpr int g2(int n) { return f(n); }
11constexpr int g3(int n) { return f(n*0); }
12
13namespace N {
14  constexpr int c = 5;
15  constexpr int h() { return c; }
16}
17constexpr int c = 0;
18constexpr int g4() { return N::h(); }
19
20static_assert(f(0) == 0, "");
21static_assert(f('0') == 1, "");
22static_assert(g1() == 0, "");
23static_assert(g2(0) == 1, "");
24static_assert(g2(1) == 1, "");
25static_assert(g3(0) == 1, "");
26static_assert(g3(1) == 1, "");
27static_assert(N::h() == 5, "");
28static_assert(g4() == 5, "");
29
30
31constexpr int f(bool b)
32  { return b ? throw 0 : 0; } // ok
33constexpr int f() { return throw 0, 0; } // expected-error {{constexpr function never produces a constant expression}} expected-note {{subexpression}}
34
35struct B {
36  constexpr B(int x) : i(0) { }
37  int i;
38};
39
40int global; // expected-note {{declared here}}
41
42struct D : B {
43  constexpr D() : B(global) { } // expected-error {{constexpr constructor never produces a constant expression}} expected-note {{read of non-const}}
44};
45
46}
47
48namespace PotentialConstant {
49
50constexpr 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
56int ng; // expected-note 6{{here}}
57constexpr int BinaryOp1(int n) { return n + ng; } // expected-error {{never produces}} expected-note {{read}}
58constexpr int BinaryOp2(int n) { return ng + n; } // expected-error {{never produces}} expected-note {{read}}
59
60double dg; // expected-note 2{{here}}
61constexpr double BinaryOp1(double d) { return d + dg; } // expected-error {{never produces}} expected-note {{read}}
62constexpr double BinaryOp2(double d) { return dg + d; } // expected-error {{never produces}} expected-note {{read}}
63
64constexpr int Add(int a, int b, int c) { return a + b + c; }
65constexpr int FunctionArgs(int a) { return Add(a, ng, a); } // expected-error {{never produces}} expected-note {{read}}
66
67struct S { int a; int b; int c[2]; };
68constexpr S InitList(int a) { return { a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
69constexpr S InitList1a(int a) { return S{ a, ng }; }; // expected-error {{never produces}} expected-note {{read}}
70constexpr S InitList2(int a) { return { a, a, { ng } }; }; // expected-error {{never produces}} expected-note {{read}}
71constexpr S InitList3(int a) { return a ? S{ a, a } : S{ a, ng }; }; // ok
72
73constexpr int LogicalAnd1(int n) { return n && (throw, 0); } // ok
74constexpr int LogicalAnd2(int n) { return 1 && (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
75
76constexpr int LogicalOr1(int n) { return n || (throw, 0); } // ok
77constexpr int LogicalOr2(int n) { return 0 || (throw, 0); } // expected-error {{never produces}} expected-note {{subexpression}}
78
79constexpr int Conditional1(bool b, int n) { return b ? n : ng; } // ok
80constexpr 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.
83constexpr 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}
86static_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.
90template<typename T> constexpr T cmin(T a, T b) {
91  return a < b ? a : b;
92}
93int n = cmin(3, 5); // ok
94
95struct X {
96  constexpr X() {}
97  bool operator<(X); // not constexpr
98};
99
100X x = cmin(X(), X()); // ok, not constexpr
101
102// Same with other temploids.
103template<typename T>
104struct Y {
105  constexpr Y() {}
106  constexpr int get() { return T(); }
107#if __cplusplus < 201402L
108  // expected-warning@-2 {{C++14}}
109#endif
110};
111struct Z { operator int(); };
112
113int y1 = Y<int>().get(); // ok
114int y2 = Y<Z>().get(); // ok
115
116}
117
118#ifndef NO_INVALID_CONSTEXPR
119namespace 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 {
128    static constexpr int f() { return n; }
129  };
130  template<typename T> struct B {
131    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
139constexpr void f() { throw; } // expected-error {{never produces}} expected-note {{subexpression}}
140#endif
141