--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/SemaCXX/constexpr-string.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,650 @@
+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension
+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=gnu++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -DGNUMODE
+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-signed-char
+// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-wchar -DNO_PREDEFINED_WCHAR_T
+// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension
+// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=gnu++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -DGNUMODE
+// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-signed-char
+// RUN: %clang_cc1 %s -triple armebv7-unknown-linux -std=c++2a -fsyntax-only -verify -pedantic -Wno-vla-extension -fno-wchar -DNO_PREDEFINED_WCHAR_T
+
+# 9 "/usr/include/string.h" 1 3 4
+extern "C" {
+  typedef decltype(sizeof(int)) size_t;
+
+  extern size_t strlen(const char *p);
+
+  extern int strcmp(const char *s1, const char *s2);
+  extern int strncmp(const char *s1, const char *s2, size_t n);
+  extern int memcmp(const void *s1, const void *s2, size_t n);
+
+#ifdef GNUMODE
+  extern int bcmp(const void *s1, const void *s2, size_t n);
+#endif
+
+  extern char *strchr(const char *s, int c);
+  extern void *memchr(const void *s, int c, size_t n);
+
+  extern void *memcpy(void *d, const void *s, size_t n);
+  extern void *memmove(void *d, const void *s, size_t n);
+}
+# 25 "SemaCXX/constexpr-string.cpp" 2
+
+# 27 "/usr/include/wchar.h" 1 3 4
+extern "C" {
+#if NO_PREDEFINED_WCHAR_T
+  typedef decltype(L'0') wchar_t;
+#endif
+  extern size_t wcslen(const wchar_t *p);
+
+  extern int wcscmp(const wchar_t *s1, const wchar_t *s2);
+  extern int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n);
+  extern int wmemcmp(const wchar_t *s1, const wchar_t *s2, size_t n);
+
+  extern wchar_t *wcschr(const wchar_t *s, wchar_t c);
+  extern wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
+
+  extern wchar_t *wmemcpy(wchar_t *d, const wchar_t *s, size_t n);
+  extern wchar_t *wmemmove(wchar_t *d, const wchar_t *s, size_t n);
+}
+
+# 45 "SemaCXX/constexpr-string.cpp" 2
+namespace Strlen {
+  constexpr int n = __builtin_strlen("hello"); // ok
+  static_assert(n == 5);
+  constexpr int wn = __builtin_wcslen(L"hello"); // ok
+  static_assert(wn == 5);
+  constexpr int m = strlen("hello"); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strlen' cannot be used in a constant expression}}
+  constexpr int wm = wcslen(L"hello"); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wcslen' cannot be used in a constant expression}}
+
+  // Make sure we can evaluate a call to strlen.
+  int arr[3]; // expected-note 2{{here}}
+  int k = arr[strlen("hello")]; // expected-warning {{array index 5}}
+  int wk = arr[wcslen(L"hello")]; // expected-warning {{array index 5}}
+}
+
+namespace StrcmpEtc {
+  constexpr char kFoobar[6] = {'f','o','o','b','a','r'};
+  constexpr char kFoobazfoobar[12] = {'f','o','o','b','a','z','f','o','o','b','a','r'};
+
+  static_assert(__builtin_strcmp("abab", "abab") == 0);
+  static_assert(__builtin_strcmp("abab", "abba") == -1);
+  static_assert(__builtin_strcmp("abab", "abaa") == 1);
+  static_assert(__builtin_strcmp("ababa", "abab") == 1);
+  static_assert(__builtin_strcmp("abab", "ababa") == -1);
+  static_assert(__builtin_strcmp("a\203", "a") == 1);
+  static_assert(__builtin_strcmp("a\203", "a\003") == 1);
+  static_assert(__builtin_strcmp("abab\0banana", "abab") == 0);
+  static_assert(__builtin_strcmp("abab", "abab\0banana") == 0);
+  static_assert(__builtin_strcmp("abab\0banana", "abab\0canada") == 0);
+  static_assert(__builtin_strcmp(0, "abab") == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_strcmp("abab", 0) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+
+  static_assert(__builtin_strcmp(kFoobar, kFoobazfoobar) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_strcmp(kFoobar, kFoobazfoobar + 6) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_strncmp("abaa", "abba", 5) == -1);
+  static_assert(__builtin_strncmp("abaa", "abba", 4) == -1);
+  static_assert(__builtin_strncmp("abaa", "abba", 3) == -1);
+  static_assert(__builtin_strncmp("abaa", "abba", 2) == 0);
+  static_assert(__builtin_strncmp("abaa", "abba", 1) == 0);
+  static_assert(__builtin_strncmp("abaa", "abba", 0) == 0);
+  static_assert(__builtin_strncmp(0, 0, 0) == 0);
+  static_assert(__builtin_strncmp("abab\0banana", "abab\0canada", 100) == 0);
+
+  static_assert(__builtin_strncmp(kFoobar, kFoobazfoobar, 6) == -1);
+  static_assert(__builtin_strncmp(kFoobar, kFoobazfoobar, 7) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_strncmp(kFoobar, kFoobazfoobar + 6, 6) == 0);
+  static_assert(__builtin_strncmp(kFoobar, kFoobazfoobar + 6, 7) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_memcmp("abaa", "abba", 3) == -1);
+  static_assert(__builtin_memcmp("abaa", "abba", 2) == 0);
+  static_assert(__builtin_memcmp("a\203", "a", 2) == 1);
+  static_assert(__builtin_memcmp("a\203", "a\003", 2) == 1);
+  static_assert(__builtin_memcmp(0, 0, 0) == 0);
+  static_assert(__builtin_memcmp("abab\0banana", "abab\0banana", 100) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_memcmp("abab\0banana", "abab\0canada", 100) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_memcmp("abab\0banana", "abab\0canada", 7) == -1);
+  static_assert(__builtin_memcmp("abab\0banana", "abab\0canada", 6) == -1);
+  static_assert(__builtin_memcmp("abab\0banana", "abab\0canada", 5) == 0);
+
+  static_assert(__builtin_bcmp("abaa", "abba", 3) != 0);
+  static_assert(__builtin_bcmp("abaa", "abba", 2) == 0);
+  static_assert(__builtin_bcmp("a\203", "a", 2) != 0);
+  static_assert(__builtin_bcmp("a\203", "a\003", 2) != 0);
+  static_assert(__builtin_bcmp(0, 0, 0) == 0);
+  static_assert(__builtin_bcmp("abab\0banana", "abab\0banana", 100) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 100) != 0); // FIXME: Should we reject this?
+  static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 7) != 0);
+  static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 6) != 0);
+  static_assert(__builtin_bcmp("abab\0banana", "abab\0canada", 5) == 0);
+
+  extern struct Incomplete incomplete;
+  static_assert(__builtin_memcmp(&incomplete, "", 0u) == 0);
+  static_assert(__builtin_memcmp("", &incomplete, 0u) == 0);
+  static_assert(__builtin_memcmp(&incomplete, "", 1u) == 42); // expected-error {{not an integral constant}} expected-note {{read of incomplete type 'struct Incomplete'}}
+  static_assert(__builtin_memcmp("", &incomplete, 1u) == 42); // expected-error {{not an integral constant}} expected-note {{read of incomplete type 'struct Incomplete'}}
+
+  static_assert(__builtin_bcmp(&incomplete, "", 0u) == 0);
+  static_assert(__builtin_bcmp("", &incomplete, 0u) == 0);
+  static_assert(__builtin_bcmp(&incomplete, "", 1u) == 42); // expected-error {{not an integral constant}} expected-note {{read of incomplete type 'struct Incomplete'}}
+  static_assert(__builtin_bcmp("", &incomplete, 1u) == 42); // expected-error {{not an integral constant}} expected-note {{read of incomplete type 'struct Incomplete'}}
+
+  constexpr unsigned char ku00fe00[] = {0x00, 0xfe, 0x00};
+  constexpr unsigned char ku00feff[] = {0x00, 0xfe, 0xff};
+  constexpr signed char ks00fe00[] = {0, -2, 0};
+  constexpr signed char ks00feff[] = {0, -2, -1};
+  static_assert(__builtin_memcmp(ku00feff, ks00fe00, 2) == 0);
+  static_assert(__builtin_memcmp(ku00feff, ks00fe00, 99) == 1);
+  static_assert(__builtin_memcmp(ku00fe00, ks00feff, 99) == -1);
+  static_assert(__builtin_memcmp(ks00feff, ku00fe00, 2) == 0);
+  static_assert(__builtin_memcmp(ks00feff, ku00fe00, 99) == 1);
+  static_assert(__builtin_memcmp(ks00fe00, ku00feff, 99) == -1);
+  static_assert(__builtin_memcmp(ks00fe00, ks00feff, 2) == 0);
+  static_assert(__builtin_memcmp(ks00feff, ks00fe00, 99) == 1);
+  static_assert(__builtin_memcmp(ks00fe00, ks00feff, 99) == -1);
+
+  static_assert(__builtin_bcmp(ku00feff, ks00fe00, 2) == 0);
+  static_assert(__builtin_bcmp(ku00feff, ks00fe00, 99) != 0);
+  static_assert(__builtin_bcmp(ku00fe00, ks00feff, 99) != 0);
+  static_assert(__builtin_bcmp(ks00feff, ku00fe00, 2) == 0);
+  static_assert(__builtin_bcmp(ks00feff, ku00fe00, 99) != 0);
+  static_assert(__builtin_bcmp(ks00fe00, ku00feff, 99) != 0);
+  static_assert(__builtin_bcmp(ks00fe00, ks00feff, 2) == 0);
+  static_assert(__builtin_bcmp(ks00feff, ks00fe00, 99) != 0);
+  static_assert(__builtin_bcmp(ks00fe00, ks00feff, 99) != 0);
+
+  struct Bool3Tuple { bool bb[3]; };
+  constexpr Bool3Tuple kb000100 = {{false, true, false}};
+  static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00, kb000100.bb, 1) == 0);
+  static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00, kb000100.bb, 2) == 1);
+
+  static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00, kb000100.bb, 1) == 0);
+  static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00, kb000100.bb, 2) != 0);
+
+  constexpr long ksl[] = {0, -1};
+  constexpr unsigned int kui[] = {0, 0u - 1};
+  constexpr unsigned long long kull[] = {0, 0ull - 1};
+  constexpr const auto *kuSizeofLong(void) {
+    if constexpr(sizeof(long) == sizeof(int)) {
+      return kui;
+    } else if constexpr(sizeof(long) == sizeof(long long)) {
+      return kull;
+    } else {
+      return nullptr;
+    }
+  }
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) - 1) == 0);
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) + 0) == 0);
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) + 1) == 0);
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long) - 1) == 0);
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long) + 0) == 0);
+  static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long) + 1) == 42); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) - 1) == 0);
+  static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) + 0) == 0);
+  static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) + 1) == 42); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) - 1) == 0);
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 0) == 0);
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 1) == 0);
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) - 1) == 0);
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) + 0) == 0);
+  static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) + 1) == 42); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) - 1) == 0);
+  static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) + 0) == 0);
+  static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1, sizeof(long) + 1) == 42); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  constexpr int a = strcmp("hello", "world"); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strcmp' cannot be used in a constant expression}}
+  constexpr int b = strncmp("hello", "world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strncmp' cannot be used in a constant expression}}
+  constexpr int c = memcmp("hello", "world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'memcmp' cannot be used in a constant expression}}
+
+#ifdef GNUMODE
+  constexpr int d = bcmp("hello", "world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'bcmp' cannot be used in a constant expression}}
+#endif
+}
+
+namespace MultibyteElementTests {
+inline namespace Util {
+#define STR2(X) #X
+#define STR(X) STR2(X)
+constexpr const char ByteOrderString[] = STR(__BYTE_ORDER__);
+#undef STR
+#undef STR2
+constexpr bool LittleEndian{*ByteOrderString == '1'};
+
+constexpr size_t GoodFoldArraySize = 42, BadFoldArraySize = 43;
+struct NotBadFoldResult {};
+template <size_t> struct FoldResult;
+template <> struct FoldResult<GoodFoldArraySize> : NotBadFoldResult {};
+template <typename T, size_t N>
+FoldResult<N> *foldResultImpl(T (*ptrToConstantSizeArray)[N]);
+struct NotFolded : NotBadFoldResult {};
+NotFolded *foldResultImpl(bool anyPtr);
+template <auto Value> struct MetaValue;
+template <typename Callable, size_t N, auto ExpectedFoldResult>
+auto foldResult(const Callable &, MetaValue<N> *,
+                MetaValue<ExpectedFoldResult> *) {
+  int (*maybeVLAPtr)[Callable{}(N) == ExpectedFoldResult
+                         ? GoodFoldArraySize
+                         : BadFoldArraySize] = 0;
+  return foldResultImpl(maybeVLAPtr);
+}
+template <typename FoldResultKind, typename Callable, typename NWrap,
+          typename ExpectedWrap>
+constexpr bool checkFoldResult(const Callable &c, NWrap *n, ExpectedWrap *e) {
+  decltype(static_cast<FoldResultKind *>(foldResult(c, n, e))) *chk{};
+  return true;
+}
+template <size_t N> constexpr MetaValue<N> *withN() { return nullptr; }
+template <auto Expected> constexpr MetaValue<Expected> *withExpected() {
+  return nullptr;
+}
+} // namespace Util
+} // namespace MultibyteElementTests
+
+namespace MultibyteElementTests::Memcmp {
+#ifdef __SIZEOF_INT128__
+constexpr __int128 i128_ff_8_00_8 = -(__int128)1 - -1ull;
+constexpr __int128 i128_00_16 = 0;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memcmp(&i128_ff_8_00_8, &i128_00_16, n);
+    },
+    withN<1u>(), withExpected<LittleEndian ? 0 : 1>()));
+#endif
+
+constexpr const signed char ByteOrderStringReduced[] = {
+    ByteOrderString[0] - '0', ByteOrderString[1] - '0',
+    ByteOrderString[2] - '0', ByteOrderString[3] - '0',
+};
+constexpr signed int i04030201 = 0x04030201;
+constexpr unsigned int u04030201 = 0x04030201u;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memcmp(ByteOrderStringReduced, &i04030201, n);
+    },
+    withN<sizeof(int)>(), withExpected<0>()));
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memcmp(&u04030201, ByteOrderStringReduced, n);
+    },
+    withN<sizeof(int)>(), withExpected<0>()));
+
+constexpr unsigned int ui0000FEFF = 0x0000feffU;
+constexpr unsigned short usFEFF = 0xfeffU;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memcmp(&ui0000FEFF, &usFEFF, n);
+    },
+    withN<1u>(), withExpected<LittleEndian ? 0 : -1>()));
+
+constexpr unsigned int ui08038700 = 0x08038700u;
+constexpr unsigned int ui08048600 = 0x08048600u;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memcmp(&ui08038700, &ui08048600, n);
+    },
+    withN<sizeof(int)>(), withExpected<LittleEndian ? 1 : -1>()));
+}
+
+namespace WcscmpEtc {
+  constexpr wchar_t kFoobar[6] = {L'f',L'o',L'o',L'b',L'a',L'r'};
+  constexpr wchar_t kFoobazfoobar[12] = {L'f',L'o',L'o',L'b',L'a',L'z',L'f',L'o',L'o',L'b',L'a',L'r'};
+
+  static_assert(__builtin_wcscmp(L"abab", L"abab") == 0);
+  static_assert(__builtin_wcscmp(L"abab", L"abba") == -1);
+  static_assert(__builtin_wcscmp(L"abab", L"abaa") == 1);
+  static_assert(__builtin_wcscmp(L"ababa", L"abab") == 1);
+  static_assert(__builtin_wcscmp(L"abab", L"ababa") == -1);
+  static_assert(__builtin_wcscmp(L"abab\0banana", L"abab") == 0);
+  static_assert(__builtin_wcscmp(L"abab", L"abab\0banana") == 0);
+  static_assert(__builtin_wcscmp(L"abab\0banana", L"abab\0canada") == 0);
+#if __WCHAR_WIDTH__ == 32
+  static_assert(__builtin_wcscmp(L"a\x83838383", L"a") == (wchar_t)-1U >> 31);
+#endif
+  static_assert(__builtin_wcscmp(0, L"abab") == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_wcscmp(L"abab", 0) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+
+  static_assert(__builtin_wcscmp(kFoobar, kFoobazfoobar) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_wcscmp(kFoobar, kFoobazfoobar + 6) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 5) == -1);
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 4) == -1);
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 3) == -1);
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 2) == 0);
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 1) == 0);
+  static_assert(__builtin_wcsncmp(L"abaa", L"abba", 0) == 0);
+  static_assert(__builtin_wcsncmp(0, 0, 0) == 0);
+  static_assert(__builtin_wcsncmp(L"abab\0banana", L"abab\0canada", 100) == 0);
+#if __WCHAR_WIDTH__ == 32
+  static_assert(__builtin_wcsncmp(L"a\x83838383", L"aa", 2) ==
+                (wchar_t)-1U >> 31);
+#endif
+
+  static_assert(__builtin_wcsncmp(kFoobar, kFoobazfoobar, 6) == -1);
+  static_assert(__builtin_wcsncmp(kFoobar, kFoobazfoobar, 7) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_wcsncmp(kFoobar, kFoobazfoobar + 6, 6) == 0);
+  static_assert(__builtin_wcsncmp(kFoobar, kFoobazfoobar + 6, 7) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_wmemcmp(L"abaa", L"abba", 3) == -1);
+  static_assert(__builtin_wmemcmp(L"abaa", L"abba", 2) == 0);
+  static_assert(__builtin_wmemcmp(0, 0, 0) == 0);
+#if __WCHAR_WIDTH__ == 32
+  static_assert(__builtin_wmemcmp(L"a\x83838383", L"aa", 2) ==
+                (wchar_t)-1U >> 31);
+#endif
+  static_assert(__builtin_wmemcmp(L"abab\0banana", L"abab\0banana", 100) == 0); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_wmemcmp(L"abab\0banana", L"abab\0canada", 100) == -1); // FIXME: Should we reject this?
+  static_assert(__builtin_wmemcmp(L"abab\0banana", L"abab\0canada", 7) == -1);
+  static_assert(__builtin_wmemcmp(L"abab\0banana", L"abab\0canada", 6) == -1);
+  static_assert(__builtin_wmemcmp(L"abab\0banana", L"abab\0canada", 5) == 0);
+
+  constexpr int a = wcscmp(L"hello", L"world"); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wcscmp' cannot be used in a constant expression}}
+  constexpr int b = wcsncmp(L"hello", L"world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wcsncmp' cannot be used in a constant expression}}
+  constexpr int c = wmemcmp(L"hello", L"world", 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wmemcmp' cannot be used in a constant expression}}
+}
+
+namespace StrchrEtc {
+  constexpr const char *kStr = "abca\xff\0d";
+  constexpr char kFoo[] = {'f', 'o', 'o'};
+  static_assert(__builtin_strchr(kStr, 'a') == kStr);
+  static_assert(__builtin_strchr(kStr, 'b') == kStr + 1);
+  static_assert(__builtin_strchr(kStr, 'c') == kStr + 2);
+  static_assert(__builtin_strchr(kStr, 'd') == nullptr);
+  static_assert(__builtin_strchr(kStr, 'e') == nullptr);
+  static_assert(__builtin_strchr(kStr, '\0') == kStr + 5);
+  static_assert(__builtin_strchr(kStr, 'a' + 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, 'a' - 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, '\xff') == kStr + 4);
+  static_assert(__builtin_strchr(kStr, '\xff' + 256) == nullptr);
+  static_assert(__builtin_strchr(kStr, '\xff' - 256) == nullptr);
+  static_assert(__builtin_strchr(kFoo, 'o') == kFoo + 1);
+  static_assert(__builtin_strchr(kFoo, 'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_strchr(nullptr, 'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+
+  static_assert(__builtin_memchr(kStr, 'a', 0) == nullptr);
+  static_assert(__builtin_memchr(kStr, 'a', 1) == kStr);
+  static_assert(__builtin_memchr(kStr, '\0', 5) == nullptr);
+  static_assert(__builtin_memchr(kStr, '\0', 6) == kStr + 5);
+  static_assert(__builtin_memchr(kStr, '\xff', 8) == kStr + 4);
+  static_assert(__builtin_memchr(kStr, '\xff' + 256, 8) == kStr + 4);
+  static_assert(__builtin_memchr(kStr, '\xff' - 256, 8) == kStr + 4);
+  static_assert(__builtin_memchr(kFoo, 'x', 3) == nullptr);
+  static_assert(__builtin_memchr(kFoo, 'x', 4) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_memchr(nullptr, 'x', 3) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_memchr(nullptr, 'x', 0) == nullptr); // FIXME: Should we reject this?
+
+  extern struct Incomplete incomplete;
+  static_assert(__builtin_memchr(&incomplete, 0, 0u) == nullptr);
+  static_assert(__builtin_memchr(&incomplete, 0, 1u) == nullptr); // expected-error {{not an integral constant}} expected-note {{read of incomplete type 'struct Incomplete'}}
+
+  const unsigned char &u1 = 0xf0;
+  auto &&i1 = (const signed char []){-128}; // expected-warning {{compound literals are a C99-specific feature}}
+  static_assert(__builtin_memchr(&u1, -(0x0f + 1), 1) == &u1);
+  static_assert(__builtin_memchr(i1, 0x80, 1) == i1);
+
+  enum class E : unsigned char {};
+  struct EPair { E e, f; };
+  constexpr EPair ee{E{240}};
+  static_assert(__builtin_memchr(&ee.e, 240, 1) == &ee.e);
+
+  constexpr bool kBool[] = {false, true, false};
+  constexpr const bool *const kBoolPastTheEndPtr = kBool + 3;
+  static_assert(sizeof(bool) != 1u || __builtin_memchr(kBoolPastTheEndPtr - 3, 1, 99) == kBool + 1);
+  static_assert(sizeof(bool) != 1u || __builtin_memchr(kBool + 1, 0, 99) == kBoolPastTheEndPtr - 1);
+  static_assert(sizeof(bool) != 1u || __builtin_memchr(kBoolPastTheEndPtr - 3, -1, 3) == nullptr);
+  static_assert(sizeof(bool) != 1u || __builtin_memchr(kBoolPastTheEndPtr, 0, 1) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+
+  static_assert(__builtin_char_memchr(kStr, 'a', 0) == nullptr);
+  static_assert(__builtin_char_memchr(kStr, 'a', 1) == kStr);
+  static_assert(__builtin_char_memchr(kStr, '\0', 5) == nullptr);
+  static_assert(__builtin_char_memchr(kStr, '\0', 6) == kStr + 5);
+  static_assert(__builtin_char_memchr(kStr, '\xff', 8) == kStr + 4);
+  static_assert(__builtin_char_memchr(kStr, '\xff' + 256, 8) == kStr + 4);
+  static_assert(__builtin_char_memchr(kStr, '\xff' - 256, 8) == kStr + 4);
+  static_assert(__builtin_char_memchr(kFoo, 'x', 3) == nullptr);
+  static_assert(__builtin_char_memchr(kFoo, 'x', 4) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_char_memchr(nullptr, 'x', 3) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_char_memchr(nullptr, 'x', 0) == nullptr); // FIXME: Should we reject this?
+
+  static_assert(*__builtin_char_memchr(kStr, '\xff', 8) == '\xff');
+  constexpr bool char_memchr_mutable() {
+    char buffer[] = "mutable";
+    *__builtin_char_memchr(buffer, 't', 8) = 'r';
+    *__builtin_char_memchr(buffer, 'm', 8) = 'd';
+    return __builtin_strcmp(buffer, "durable") == 0;
+  }
+  static_assert(char_memchr_mutable());
+
+  constexpr bool a = !strchr("hello", 'h'); // expected-error {{constant expression}} expected-note {{non-constexpr function 'strchr' cannot be used in a constant expression}}
+  constexpr bool b = !memchr("hello", 'h', 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'memchr' cannot be used in a constant expression}}
+}
+
+namespace MultibyteElementTests::Memchr {
+constexpr unsigned int u04030201 = 0x04030201;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memchr(&u04030201, *ByteOrderString - '0', n);
+    },
+    withN<1u>(), withExpected<&u04030201>()));
+
+constexpr unsigned int uED = 0xEDU;
+static_assert(checkFoldResult<NotBadFoldResult>(
+    [](size_t n) constexpr {
+      return __builtin_memchr(&uED, 0xED, n);
+    },
+    withN<1u>(), withExpected<LittleEndian ? &uED : nullptr>()));
+}
+
+namespace WcschrEtc {
+  constexpr const wchar_t *kStr = L"abca\xffff\0dL";
+  constexpr wchar_t kFoo[] = {L'f', L'o', L'o'};
+  static_assert(__builtin_wcschr(kStr, L'a') == kStr);
+  static_assert(__builtin_wcschr(kStr, L'b') == kStr + 1);
+  static_assert(__builtin_wcschr(kStr, L'c') == kStr + 2);
+  static_assert(__builtin_wcschr(kStr, L'd') == nullptr);
+  static_assert(__builtin_wcschr(kStr, L'e') == nullptr);
+  static_assert(__builtin_wcschr(kStr, L'\0') == kStr + 5);
+  static_assert(__builtin_wcschr(kStr, L'a' + 256) == nullptr);
+  static_assert(__builtin_wcschr(kStr, L'a' - 256) == nullptr);
+  static_assert(__builtin_wcschr(kStr, L'\xffff') == kStr + 4);
+  static_assert(__builtin_wcschr(kFoo, L'o') == kFoo + 1);
+  static_assert(__builtin_wcschr(kFoo, L'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_wcschr(nullptr, L'x') == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+
+  static_assert(__builtin_wmemchr(kStr, L'a', 0) == nullptr);
+  static_assert(__builtin_wmemchr(kStr, L'a', 1) == kStr);
+  static_assert(__builtin_wmemchr(kStr, L'\0', 5) == nullptr);
+  static_assert(__builtin_wmemchr(kStr, L'\0', 6) == kStr + 5);
+  static_assert(__builtin_wmemchr(kStr, L'\xffff', 8) == kStr + 4);
+  static_assert(__builtin_wmemchr(kFoo, L'x', 3) == nullptr);
+  static_assert(__builtin_wmemchr(kFoo, L'x', 4) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced one-past-the-end}}
+  static_assert(__builtin_wmemchr(nullptr, L'x', 3) == nullptr); // expected-error {{not an integral constant}} expected-note {{dereferenced null}}
+  static_assert(__builtin_wmemchr(nullptr, L'x', 0) == nullptr); // FIXME: Should we reject this?
+
+  constexpr bool a = !wcschr(L"hello", L'h'); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wcschr' cannot be used in a constant expression}}
+  constexpr bool b = !wmemchr(L"hello", L'h', 3); // expected-error {{constant expression}} expected-note {{non-constexpr function 'wmemchr' cannot be used in a constant expression}}
+}
+
+namespace MemcpyEtc {
+  template<typename T>
+  constexpr T result(T (&arr)[4]) {
+    return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
+  }
+
+  constexpr int test_memcpy(int a, int b, int n) {
+    int arr[4] = {1, 2, 3, 4};
+    __builtin_memcpy(arr + a, arr + b, n);
+    // expected-note@-1 2{{overlapping memory regions}}
+    // expected-note@-2 {{size to copy (1) is not a multiple of size of element type 'int'}}
+    // expected-note@-3 {{source is not a contiguous array of at least 2 elements of type 'int'}}
+    // expected-note@-4 {{destination is not a contiguous array of at least 3 elements of type 'int'}}
+    return result(arr);
+  }
+  constexpr int test_memmove(int a, int b, int n) {
+    int arr[4] = {1, 2, 3, 4};
+    __builtin_memmove(arr + a, arr + b, n);
+    // expected-note@-1 {{size to copy (1) is not a multiple of size of element type 'int'}}
+    // expected-note@-2 {{source is not a contiguous array of at least 2 elements of type 'int'}}
+    // expected-note@-3 {{destination is not a contiguous array of at least 3 elements of type 'int'}}
+    return result(arr);
+  }
+  constexpr int test_wmemcpy(int a, int b, int n) {
+    wchar_t arr[4] = {1, 2, 3, 4};
+    __builtin_wmemcpy(arr + a, arr + b, n);
+    // expected-note@-1 2{{overlapping memory regions}}
+    // expected-note@-2 {{source is not a contiguous array of at least 2 elements of type 'wchar_t'}}
+    // expected-note@-3 {{destination is not a contiguous array of at least 3 elements of type 'wchar_t'}}
+    return result(arr);
+  }
+  constexpr int test_wmemmove(int a, int b, int n) {
+    wchar_t arr[4] = {1, 2, 3, 4};
+    __builtin_wmemmove(arr + a, arr + b, n);
+    // expected-note@-1 {{source is not a contiguous array of at least 2 elements of type 'wchar_t'}}
+    // expected-note@-2 {{destination is not a contiguous array of at least 3 elements of type 'wchar_t'}}
+    return result(arr);
+  }
+
+  static_assert(test_memcpy(1, 2, 4) == 1334);
+  static_assert(test_memcpy(2, 1, 4) == 1224);
+  static_assert(test_memcpy(0, 1, 8) == 2334); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memcpy(1, 0, 8) == 1124); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memcpy(1, 2, 1) == 1334); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memcpy(0, 3, 4) == 4234);
+  static_assert(test_memcpy(0, 3, 8) == 4234); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memcpy(2, 0, 12) == 4234); // expected-error {{constant}} expected-note {{in call}}
+
+  static_assert(test_memmove(1, 2, 4) == 1334);
+  static_assert(test_memmove(2, 1, 4) == 1224);
+  static_assert(test_memmove(0, 1, 8) == 2334);
+  static_assert(test_memmove(1, 0, 8) == 1124);
+  static_assert(test_memmove(1, 2, 1) == 1334); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memmove(0, 3, 4) == 4234);
+  static_assert(test_memmove(0, 3, 8) == 4234); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_memmove(2, 0, 12) == 4234); // expected-error {{constant}} expected-note {{in call}}
+
+  static_assert(test_wmemcpy(1, 2, 1) == 1334);
+  static_assert(test_wmemcpy(2, 1, 1) == 1224);
+  static_assert(test_wmemcpy(0, 1, 2) == 2334); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_wmemcpy(1, 0, 2) == 1124); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_wmemcpy(1, 2, 1) == 1334);
+  static_assert(test_wmemcpy(0, 3, 1) == 4234);
+  static_assert(test_wmemcpy(0, 3, 2) == 4234); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_wmemcpy(2, 0, 3) == 4234); // expected-error {{constant}} expected-note {{in call}}
+
+  static_assert(test_wmemmove(1, 2, 1) == 1334);
+  static_assert(test_wmemmove(2, 1, 1) == 1224);
+  static_assert(test_wmemmove(0, 1, 2) == 2334);
+  static_assert(test_wmemmove(1, 0, 2) == 1124);
+  static_assert(test_wmemmove(1, 2, 1) == 1334);
+  static_assert(test_wmemmove(0, 3, 1) == 4234);
+  static_assert(test_wmemmove(0, 3, 2) == 4234); // expected-error {{constant}} expected-note {{in call}}
+  static_assert(test_wmemmove(2, 0, 3) == 4234); // expected-error {{constant}} expected-note {{in call}}
+
+#define fold(x) (__builtin_constant_p(0) ? (x) : (x))
+
+  wchar_t global;
+  constexpr wchar_t *null = 0;
+  static_assert(__builtin_memcpy(&global, null, sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'memcpy' is nullptr}}
+  static_assert(__builtin_memmove(&global, null, sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'memmove' is nullptr}}
+  static_assert(__builtin_wmemcpy(&global, null, sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'wmemcpy' is nullptr}}
+  static_assert(__builtin_wmemmove(&global, null, sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'wmemmove' is nullptr}}
+  static_assert(__builtin_memcpy(null, &global, sizeof(wchar_t))); // expected-error {{}} expected-note {{destination of 'memcpy' is nullptr}}
+  static_assert(__builtin_memmove(null, &global, sizeof(wchar_t))); // expected-error {{}} expected-note {{destination of 'memmove' is nullptr}}
+  static_assert(__builtin_wmemcpy(null, &global, sizeof(wchar_t))); // expected-error {{}} expected-note {{destination of 'wmemcpy' is nullptr}}
+  static_assert(__builtin_wmemmove(null, &global, sizeof(wchar_t))); // expected-error {{}} expected-note {{destination of 'wmemmove' is nullptr}}
+  static_assert(__builtin_memcpy(&global, fold((wchar_t*)123), sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'memcpy' is (void *)123}}
+  static_assert(__builtin_memcpy(fold(reinterpret_cast<wchar_t*>(123)), &global, sizeof(wchar_t))); // expected-error {{}} expected-note {{destination of 'memcpy' is (void *)123}}
+  constexpr struct Incomplete *null_incomplete = 0;
+  static_assert(__builtin_memcpy(null_incomplete, null_incomplete, sizeof(wchar_t))); // expected-error {{}} expected-note {{source of 'memcpy' is nullptr}}
+
+  // Copying is permitted for any trivially-copyable type.
+  struct Trivial { char k; short s; constexpr bool ok() { return k == 3 && s == 4; } };
+  constexpr bool test_trivial() {
+    Trivial arr[3] = {{1, 2}, {3, 4}, {5, 6}};
+    __builtin_memcpy(arr, arr+1, sizeof(Trivial));
+    __builtin_memmove(arr+1, arr, 2 * sizeof(Trivial));
+    return arr[0].ok() && arr[1].ok() && arr[2].ok();
+  }
+  static_assert(test_trivial());
+
+  // But not for a non-trivially-copyable type.
+  struct NonTrivial {
+    constexpr NonTrivial() : n(0) {}
+    constexpr NonTrivial(const NonTrivial &) : n(1) {}
+    int n;
+  };
+  constexpr bool test_nontrivial_memcpy() { // expected-error {{never produces a constant}}
+    NonTrivial arr[3] = {};
+    __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note 2{{non-trivially-copyable}}
+    return true;
+  }
+  static_assert(test_nontrivial_memcpy()); // expected-error {{constant}} expected-note {{in call}}
+  constexpr bool test_nontrivial_memmove() { // expected-error {{never produces a constant}}
+    NonTrivial arr[3] = {};
+    __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note 2{{non-trivially-copyable}}
+    return true;
+  }
+  static_assert(test_nontrivial_memmove()); // expected-error {{constant}} expected-note {{in call}}
+
+  // Type puns via constant evaluated memcpy are not supported yet.
+  constexpr float type_pun(const unsigned &n) {
+    float f = 0.0f;
+    __builtin_memcpy(&f, &n, 4); // expected-note {{cannot constant evaluate 'memcpy' from object of type 'const unsigned int' to object of type 'float'}}
+    return f;
+  }
+  static_assert(type_pun(0x3f800000) == 1.0f); // expected-error {{constant}} expected-note {{in call}}
+
+  // Make sure we're not confused by derived-to-base conversions.
+  struct Base { int a; };
+  struct Derived : Base { int b; };
+  constexpr int test_derived_to_base(int n) {
+    Derived arr[2] = {1, 2, 3, 4};
+    Base *p = &arr[0];
+    Base *q = &arr[1];
+    __builtin_memcpy(p, q, sizeof(Base) * n); // expected-note {{source is not a contiguous array of at least 2 elements of type 'MemcpyEtc::Base'}}
+    return arr[0].a * 1000 + arr[0].b * 100 + arr[1].a * 10 + arr[1].b;
+  }
+  static_assert(test_derived_to_base(0) == 1234);
+  static_assert(test_derived_to_base(1) == 3234);
+  // FIXME: We could consider making this work by stripping elements off both
+  // designators until we have a long enough matching size, if both designators
+  // point to the start of their respective final elements.
+  static_assert(test_derived_to_base(2) == 3434); // expected-error {{constant}} expected-note {{in call}}
+
+  // Check that when address-of an array is passed to a tested function the
+  // array can be fully copied.
+  constexpr int test_address_of_const_array_type() {
+    int arr[4] = {1, 2, 3, 4};
+    __builtin_memmove(&arr, &arr, sizeof(arr));
+    return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
+  }
+  static_assert(test_address_of_const_array_type() == 1234);
+
+  // Check that an incomplete array is rejected.
+  constexpr int test_incomplete_array_type() { // expected-error {{never produces a constant}}
+    extern int arr[];
+    __builtin_memmove(arr, arr, 4 * sizeof(arr[0]));
+    // expected-note@-1 2{{'memmove' not supported: source is not a contiguous array of at least 4 elements of type 'int'}}
+    return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
+  }
+  static_assert(test_incomplete_array_type() == 1234); // expected-error {{constant}} expected-note {{in call}}
+
+  // Check that a pointer to an incomplete array is rejected.
+  constexpr int test_address_of_incomplete_array_type() { // expected-error {{never produces a constant}}
+    extern int arr[];
+    __builtin_memmove(&arr, &arr, 4 * sizeof(arr[0]));
+    // expected-note@-1 2{{cannot constant evaluate 'memmove' between objects of incomplete type 'int []'}}
+    return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
+  }
+  static_assert(test_address_of_incomplete_array_type() == 1234); // expected-error {{constant}} expected-note {{in call}}
+
+  // Check that a pointer to an incomplete struct is rejected.
+  constexpr bool test_address_of_incomplete_struct_type() { // expected-error {{never produces a constant}}
+    struct Incomplete;
+    extern Incomplete x, y;
+    __builtin_memcpy(&x, &x, 4);
+    // expected-note@-1 2{{cannot constant evaluate 'memcpy' between objects of incomplete type 'Incomplete'}}
+    return true;
+  }
+  static_assert(test_address_of_incomplete_struct_type()); // expected-error {{constant}} expected-note {{in call}}
+}