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-rw-r--r--absl/strings/string_view_test.cc25
1 files changed, 22 insertions, 3 deletions
diff --git a/absl/strings/string_view_test.cc b/absl/strings/string_view_test.cc
index 13fc214b841c..df307ac7cfab 100644
--- a/absl/strings/string_view_test.cc
+++ b/absl/strings/string_view_test.cc
@@ -796,11 +796,25 @@ TEST(StringViewTest, FrontBackSingleChar) {
   EXPECT_EQ(&c, &csp.back());
 }
 
+// `std::string_view::string_view(const char*)` calls
+// `std::char_traits<char>::length(const char*)` to get the std::string length. In
+// libc++, it doesn't allow `nullptr` in the constexpr context, with the error
+// "read of dereferenced null pointer is not allowed in a constant expression".
+// At run time, the behavior of `std::char_traits::length()` on `nullptr` is
+// undefined by the standard and usually results in crash with libc++. This
+// conforms to the standard, but `absl::string_view` implements a different
+// behavior for historical reasons. We work around tests that construct
+// `string_view` from `nullptr` when using libc++.
+#if !defined(ABSL_HAVE_STD_STRING_VIEW) || !defined(_LIBCPP_VERSION)
+#define ABSL_HAVE_STRING_VIEW_FROM_NULLPTR 1
+#endif  // !defined(ABSL_HAVE_STD_STRING_VIEW) || !defined(_LIBCPP_VERSION)
+
 TEST(StringViewTest, NULLInput) {
   absl::string_view s;
   EXPECT_EQ(s.data(), nullptr);
   EXPECT_EQ(s.size(), 0);
 
+#ifdef ABSL_HAVE_STRING_VIEW_FROM_NULLPTR
   s = absl::string_view(nullptr);
   EXPECT_EQ(s.data(), nullptr);
   EXPECT_EQ(s.size(), 0);
@@ -808,6 +822,7 @@ TEST(StringViewTest, NULLInput) {
   // .ToString() on a absl::string_view with nullptr should produce the empty
   // std::string.
   EXPECT_EQ("", std::string(s));
+#endif  // ABSL_HAVE_STRING_VIEW_FROM_NULLPTR
 }
 
 TEST(StringViewTest, Comparisons2) {
@@ -879,7 +894,9 @@ TEST(StringViewTest, NullSafeStringView) {
 
 TEST(StringViewTest, ConstexprCompiles) {
   constexpr absl::string_view sp;
+#ifdef ABSL_HAVE_STRING_VIEW_FROM_NULLPTR
   constexpr absl::string_view cstr(nullptr);
+#endif
   constexpr absl::string_view cstr_len("cstr", 4);
 
 #if defined(ABSL_HAVE_STD_STRING_VIEW)
@@ -923,10 +940,12 @@ TEST(StringViewTest, ConstexprCompiles) {
   constexpr absl::string_view::iterator const_end_empty = sp.end();
   EXPECT_EQ(const_begin_empty, const_end_empty);
 
+#ifdef ABSL_HAVE_STRING_VIEW_FROM_NULLPTR
   constexpr absl::string_view::iterator const_begin_nullptr = cstr.begin();
   constexpr absl::string_view::iterator const_end_nullptr = cstr.end();
   EXPECT_EQ(const_begin_nullptr, const_end_nullptr);
-#endif
+#endif  // ABSL_HAVE_STRING_VIEW_FROM_NULLPTR
+#endif  // !defined(__clang__) || ...
 
   constexpr absl::string_view::iterator const_begin = cstr_len.begin();
   constexpr absl::string_view::iterator const_end = cstr_len.end();
@@ -1042,11 +1061,11 @@ TEST(HugeStringView, TwoPointTwoGB) {
 }
 #endif  // THREAD_SANITIZER
 
-#ifndef NDEBUG
+#if !defined(NDEBUG) && !defined(ABSL_HAVE_STD_STRING_VIEW)
 TEST(NonNegativeLenTest, NonNegativeLen) {
   EXPECT_DEATH_IF_SUPPORTED(absl::string_view("xyz", -1), "len <= kMaxSize");
 }
-#endif  // NDEBUG
+#endif  // !defined(NDEBUG) && !defined(ABSL_HAVE_STD_STRING_VIEW)
 
 class StringViewStreamTest : public ::testing::Test {
  public: