99 lines
4 KiB
C++
99 lines
4 KiB
C++
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// RUN: %clang_cc1 -std=c++20 -verify -fconstexpr-steps=1024 -Wvla %s
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namespace std {
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using size_t = decltype(sizeof(0));
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}
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void *operator new(std::size_t, void *p) { return p; }
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namespace std {
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template<typename T> struct allocator {
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constexpr T *allocate(size_t N) {
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return (T*)operator new(sizeof(T) * N); // #alloc
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}
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constexpr void deallocate(void *p) {
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operator delete(p);
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}
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};
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template<typename T, typename ...Args>
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constexpr void construct_at(void *p, Args &&...args) { // #construct
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new (p) T((Args&&)args...);
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}
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}
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namespace GH63562 {
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template <typename T>
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struct S {
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constexpr S(unsigned long long N)
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: data(nullptr){
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data = alloc.allocate(N); // #call
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for(std::size_t i = 0; i < N; i ++)
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std::construct_at<T>(data + i, i); // #construct_call
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}
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constexpr T operator[](std::size_t i) const {
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return data[i];
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}
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constexpr ~S() {
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alloc.deallocate(data);
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}
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std::allocator<T> alloc;
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T* data;
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};
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// Only run these tests on 64 bits platforms
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#if __LP64__
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constexpr std::size_t s = S<std::size_t>(~0UL)[42]; // expected-error {{constexpr variable 's' must be initialized by a constant expression}} \
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// expected-note-re@#call {{in call to 'this->alloc.allocate({{.*}})'}} \
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// expected-note-re@#alloc {{cannot allocate array; evaluated array bound {{.*}} is too large}} \
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// expected-note-re {{in call to 'S({{.*}})'}}
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#endif
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// Check that we do not try to fold very large arrays
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std::size_t s2 = S<std::size_t>(~0UL)[42];
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std::size_t s3 = S<std::size_t>(~0ULL)[42];
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// We can allocate and initialize a small array
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constexpr std::size_t ssmall = S<std::size_t>(100)[42];
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// We can allocate this array but we hikt the number of steps
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constexpr std::size_t s4 = S<std::size_t>(1024)[42]; // expected-error {{constexpr variable 's4' must be initialized by a constant expression}} \
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// expected-note@#construct {{constexpr evaluation hit maximum step limit; possible infinite loop?}} \
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// expected-note@#construct_call {{in call}} \
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// expected-note {{in call}}
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constexpr std::size_t s5 = S<std::size_t>(1025)[42]; // expected-error{{constexpr variable 's5' must be initialized by a constant expression}} \
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// expected-note@#alloc {{cannot allocate array; evaluated array bound 1025 exceeds the limit (1024); use '-fconstexpr-steps' to increase this limit}} \
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// expected-note@#call {{in call to 'this->alloc.allocate(1025)'}} \
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// expected-note {{in call}}
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// Check we do not perform constant initialization in the presence
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// of very large arrays (this used to crash)
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template <auto N>
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constexpr int stack_array() {
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[[maybe_unused]] char BIG[N] = {1}; // expected-note 3{{cannot allocate array; evaluated array bound 1025 exceeds the limit (1024); use '-fconstexpr-steps' to increase this limit}}
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return BIG[N-1];
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}
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int a = stack_array<~0U>();
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int c = stack_array<1024>();
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int d = stack_array<1025>();
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constexpr int e = stack_array<1024>();
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constexpr int f = stack_array<1025>(); // expected-error {{constexpr variable 'f' must be initialized by a constant expression}} \
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// expected-note {{in call}}
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void ohno() {
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int bar[stack_array<1024>()];
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int foo[stack_array<1025>()]; // expected-warning {{variable length arrays in C++ are a Clang extension}} \
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// expected-note {{in call to 'stack_array<1025>()'}}
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constexpr int foo[stack_array<1025>()]; // expected-warning {{variable length arrays in C++ are a Clang extension}} \
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// expected-error {{constexpr variable cannot have non-literal type 'const int[stack_array<1025>()]'}} \
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// expected-note {{in call to 'stack_array<1025>()'}}
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}
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}
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