1 // RUN: %clang_cc1 %s -Wno-uninitialized -std=c++1z -fsyntax-only -verify 2 3 const extern int arr[]; 4 constexpr auto p = arr; // ok f(int i)5constexpr int f(int i) {return p[i];} // expected-note {{read of dereferenced one-past-the-end pointer}} 6 7 constexpr int arr[] {1, 2, 3}; 8 constexpr auto p2 = arr + 2; // ok 9 constexpr int x = f(2); // ok 10 constexpr int y = f(3); // expected-error {{constant expression}} 11 // expected-note-re@-1 {{in call to 'f({{.*}})'}} 12 13 // FIXME: consider permitting this case 14 struct A {int m[];} a; 15 constexpr auto p3 = a.m; // expected-error {{constant expression}} expected-note {{without known bound}} 16 constexpr auto p4 = a.m + 1; // expected-error {{constant expression}} expected-note {{without known bound}} 17 g(int i)18void g(int i) { // expected-note 2{{declared here}} 19 int arr[i]; // expected-warning {{variable length arrays in C++ are a Clang extension}} \ 20 expected-note {{function parameter 'i' with unknown value cannot be used in a constant expression}} 21 constexpr auto *p = arr + 2; // expected-error {{constant expression}} expected-note {{without known bound}} 22 23 // FIXME: Give a better diagnostic here. The issue is that computing 24 // sizeof(*arr2) within the array indexing fails due to the VLA. 25 int arr2[2][i]; // expected-warning 2{{variable length arrays in C++ are a Clang extension}} \ 26 expected-note {{function parameter 'i' with unknown value cannot be used in a constant expression}} 27 constexpr int m = ((void)arr2[2], 0); // expected-error {{constant expression}} 28 } 29