Export of internal Abseil changes

--
d74f30ef0da7139c30a24eb6c1776bc0c257e642 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 375779441

--
25e33cde30d78dbafcb81ee3ce77c3d70c74db5a by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 375520720

--
46857d17d4dbc6fbd13a27dd82e14ec814dd117a by Samuel Benzaquen <sbenza@google.com>:

Add an explicit template parameter barrier to absl::HashOf.

PiperOrigin-RevId: 375103300

--
cf2bf52b9a425b0360ed1f46778f0ef1326a3658 by Abseil Team <absl-team@google.com>:

Improve string_view API compliance with C++17 std::basic_string_view.

This adds missing overloads, default values, and constexpr specifiers.

PiperOrigin-RevId: 374885658

--
41e55166dc5bd3ed7bce567c400781585d55e1ce by Derek Mauro <dmauro@google.com>:

Update CI to GCC 11.1, Bazel 4.0.0, CMake 3.20.2, and
LLVM git:7bcc0a1e399d461af7ec013ff33bc330a2de6641

PiperOrigin-RevId: 374858288
GitOrigin-RevId: d74f30ef0da7139c30a24eb6c1776bc0c257e642
Change-Id: I657c815c83522b030495ff54ca327e7012ed151e

7 files changed, 182 insertions, 57 deletions

diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc
index bc320ff7..70f79dfc 100644
--- a/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -132,9 +132,8 @@ static uintptr_t GetFP(const void *vuc) {
     const uintptr_t bp = 0;
     const uintptr_t sp = 0;
 #endif
-    // Sanity-check that the base pointer is valid.  It should be as long as
-    // SHRINK_WRAP_FRAME_POINTER is not set, but it's possible that some code in
-    // the process is compiled with --copt=-fomit-frame-pointer or
+    // Sanity-check that the base pointer is valid. It's possible that some
+    // code in the process is compiled with --copt=-fomit-frame-pointer or
     // --copt=-momit-leaf-frame-pointer.
     //
     // TODO(bcmills): -momit-leaf-frame-pointer is currently the default
@@ -247,7 +246,7 @@ static void **NextStackFrame(void **old_fp, const void *uc) {
   // using an alternate signal stack.
   //
   // TODO(bcmills): The GetFP call should be completely unnecessary when
-  // SHRINK_WRAP_FRAME_POINTER is set (because we should be back in the thread's
+  // ENABLE_COMBINED_UNWINDER is set (because we should be back in the thread's
   // stack by this point), but it is empirically still needed (e.g. when the
   // stack includes a call to abort).  unw_get_reg returns UNW_EBADREG for some
   // frames.  Figure out why GetValidFrameAddr and/or libunwind isn't doing what
diff --git a/absl/hash/hash.h b/absl/hash/hash.h
index 69c44fde..8282ea53 100644
--- a/absl/hash/hash.h
+++ b/absl/hash/hash.h
@@ -230,7 +230,7 @@ using Hash = absl::hash_internal::Hash<T>;
 // The requirement that the arguments match in both type and value is critical.
 // It means that `a == b` does not necessarily imply `HashOf(a) == HashOf(b)` if
 // `a` and `b` have different types. For example, `HashOf(2) != HashOf(2.0)`.
-template <typename... Types>
+template <int&... ExplicitArgumentBarrier, typename... Types>
 size_t HashOf(const Types&... values) {
   auto tuple = std::tie(values...);
   return absl::Hash<decltype(tuple)>{}(tuple);
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index 02b7733d..b3ddebdd 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -995,4 +995,17 @@ TEST(HashOf, MatchesHashOfTupleForMultipleArguments) {
             absl::HashOf(std::make_tuple(hello, world)));
 }
 
+template <typename T>
+std::true_type HashOfExplicitParameter(decltype(absl::HashOf<T>(0))) {
+  return {};
+}
+template <typename T>
+std::false_type HashOfExplicitParameter(size_t) {
+  return {};
+}
+
+TEST(HashOf, CantPassExplicitTemplateParameters) {
+  EXPECT_FALSE(HashOfExplicitParameter<int>(0));
+}
+
 }  // namespace
diff --git a/absl/strings/string_view.cc b/absl/strings/string_view.cc
index c5f5de93..d596e08c 100644
--- a/absl/strings/string_view.cc
+++ b/absl/strings/string_view.cc
@@ -78,8 +78,8 @@ std::ostream& operator<<(std::ostream& o, string_view piece) {
   return o;
 }
 
-string_view::size_type string_view::find(string_view s, size_type pos) const
-    noexcept {
+string_view::size_type string_view::find(string_view s,
+                                         size_type pos) const noexcept {
   if (empty() || pos > length_) {
     if (empty() && pos == 0 && s.empty()) return 0;
     return npos;
@@ -98,8 +98,8 @@ string_view::size_type string_view::find(char c, size_type pos) const noexcept {
   return result != nullptr ? result - ptr_ : npos;
 }
 
-string_view::size_type string_view::rfind(string_view s, size_type pos) const
-    noexcept {
+string_view::size_type string_view::rfind(string_view s,
+                                          size_type pos) const noexcept {
   if (length_ < s.length_) return npos;
   if (s.empty()) return std::min(length_, pos);
   const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_;
@@ -108,8 +108,8 @@ string_view::size_type string_view::rfind(string_view s, size_type pos) const
 }
 
 // Search range is [0..pos] inclusive.  If pos == npos, search everything.
-string_view::size_type string_view::rfind(char c, size_type pos) const
-    noexcept {
+string_view::size_type string_view::rfind(char c,
+                                          size_type pos) const noexcept {
   // Note: memrchr() is not available on Windows.
   if (empty()) return npos;
   for (size_type i = std::min(pos, length_ - 1);; --i) {
@@ -121,9 +121,8 @@ string_view::size_type string_view::rfind(char c, size_type pos) const
   return npos;
 }
 
-string_view::size_type string_view::find_first_of(string_view s,
-                                                  size_type pos) const
-    noexcept {
+string_view::size_type string_view::find_first_of(
+    string_view s, size_type pos) const noexcept {
   if (empty() || s.empty()) {
     return npos;
   }
@@ -138,9 +137,8 @@ string_view::size_type string_view::find_first_of(string_view s,
   return npos;
 }
 
-string_view::size_type string_view::find_first_not_of(string_view s,
-                                                      size_type pos) const
-    noexcept {
+string_view::size_type string_view::find_first_not_of(
+    string_view s, size_type pos) const noexcept {
   if (empty()) return npos;
   // Avoid the cost of LookupTable() for a single-character search.
   if (s.length_ == 1) return find_first_not_of(s.ptr_[0], pos);
@@ -153,9 +151,8 @@ string_view::size_type string_view::find_first_not_of(string_view s,
   return npos;
 }
 
-string_view::size_type string_view::find_first_not_of(char c,
-                                                      size_type pos) const
-    noexcept {
+string_view::size_type string_view::find_first_not_of(
+    char c, size_type pos) const noexcept {
   if (empty()) return npos;
   for (; pos < length_; ++pos) {
     if (ptr_[pos] != c) {
@@ -180,9 +177,8 @@ string_view::size_type string_view::find_last_of(string_view s,
   return npos;
 }
 
-string_view::size_type string_view::find_last_not_of(string_view s,
-                                                     size_type pos) const
-    noexcept {
+string_view::size_type string_view::find_last_not_of(
+    string_view s, size_type pos) const noexcept {
   if (empty()) return npos;
   size_type i = std::min(pos, length_ - 1);
   if (s.empty()) return i;
@@ -198,9 +194,8 @@ string_view::size_type string_view::find_last_not_of(string_view s,
   return npos;
 }
 
-string_view::size_type string_view::find_last_not_of(char c,
-                                                     size_type pos) const
-    noexcept {
+string_view::size_type string_view::find_last_not_of(
+    char c, size_type pos) const noexcept {
   if (empty()) return npos;
   size_type i = std::min(pos, length_ - 1);
   for (;; --i) {
diff --git a/absl/strings/string_view.h b/absl/strings/string_view.h
index 1f14a758..968549be 100644
--- a/absl/strings/string_view.h
+++ b/absl/strings/string_view.h
@@ -62,6 +62,12 @@ ABSL_NAMESPACE_END
 #define ABSL_INTERNAL_STRING_VIEW_MEMCMP memcmp
 #endif  // ABSL_HAVE_BUILTIN(__builtin_memcmp)
 
+#if defined(__cplusplus) && __cplusplus >= 201402L
+#define ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR constexpr
+#else
+#define ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 
@@ -265,9 +271,7 @@ class string_view {
   // string_view::size()
   //
   // Returns the number of characters in the `string_view`.
-  constexpr size_type size() const noexcept {
-    return length_;
-  }
+  constexpr size_type size() const noexcept { return length_; }
 
   // string_view::length()
   //
@@ -334,7 +338,7 @@ class string_view {
   //
   // Removes the first `n` characters from the `string_view`. Note that the
   // underlying string is not changed, only the view.
-  void remove_prefix(size_type n) {
+  ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void remove_prefix(size_type n) {
     ABSL_HARDENING_ASSERT(n <= length_);
     ptr_ += n;
     length_ -= n;
@@ -344,7 +348,7 @@ class string_view {
   //
   // Removes the last `n` characters from the `string_view`. Note that the
   // underlying string is not changed, only the view.
-  void remove_suffix(size_type n) {
+  ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void remove_suffix(size_type n) {
     ABSL_HARDENING_ASSERT(n <= length_);
     length_ -= n;
   }
@@ -352,7 +356,7 @@ class string_view {
   // string_view::swap()
   //
   // Swaps this `string_view` with another `string_view`.
-  void swap(string_view& s) noexcept {
+  ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR void swap(string_view& s) noexcept {
     auto t = *this;
     *this = s;
     s = t;
@@ -389,7 +393,7 @@ class string_view {
   // `n`) as another string_view. This function throws `std::out_of_bounds` if
   // `pos > size`.
   // Use absl::ClippedSubstr if you need a truncating substr operation.
-  constexpr string_view substr(size_type pos, size_type n = npos) const {
+  constexpr string_view substr(size_type pos = 0, size_type n = npos) const {
     return ABSL_PREDICT_FALSE(pos > length_)
                ? (base_internal::ThrowStdOutOfRange(
                       "absl::string_view::substr"),
@@ -413,31 +417,31 @@ class string_view {
 
   // Overload of `string_view::compare()` for comparing a substring of the
   // 'string_view` and another `absl::string_view`.
-  int compare(size_type pos1, size_type count1, string_view v) const {
+  constexpr int compare(size_type pos1, size_type count1, string_view v) const {
     return substr(pos1, count1).compare(v);
   }
 
   // Overload of `string_view::compare()` for comparing a substring of the
   // `string_view` and a substring of another `absl::string_view`.
-  int compare(size_type pos1, size_type count1, string_view v, size_type pos2,
-              size_type count2) const {
+  constexpr int compare(size_type pos1, size_type count1, string_view v,
+                        size_type pos2, size_type count2) const {
     return substr(pos1, count1).compare(v.substr(pos2, count2));
   }
 
   // Overload of `string_view::compare()` for comparing a `string_view` and a
-  // a different  C-style string `s`.
-  int compare(const char* s) const { return compare(string_view(s)); }
+  // a different C-style string `s`.
+  constexpr int compare(const char* s) const { return compare(string_view(s)); }
 
   // Overload of `string_view::compare()` for comparing a substring of the
   // `string_view` and a different string C-style string `s`.
-  int compare(size_type pos1, size_type count1, const char* s) const {
+  constexpr int compare(size_type pos1, size_type count1, const char* s) const {
     return substr(pos1, count1).compare(string_view(s));
   }
 
   // Overload of `string_view::compare()` for comparing a substring of the
   // `string_view` and a substring of a different C-style string `s`.
-  int compare(size_type pos1, size_type count1, const char* s,
-              size_type count2) const {
+  constexpr int compare(size_type pos1, size_type count1, const char* s,
+                        size_type count2) const {
     return substr(pos1, count1).compare(string_view(s, count2));
   }
 
@@ -454,48 +458,92 @@ class string_view {
   // within the `string_view`.
   size_type find(char c, size_type pos = 0) const noexcept;
 
+  // Overload of `string_view::find()` for finding a substring of a different
+  // C-style string `s` within the `string_view`.
+  size_type find(const char* s, size_type pos, size_type count) const {
+    return find(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::find()` for finding a different C-style string
+  // `s` within the `string_view`.
+  size_type find(const char* s, size_type pos = 0) const {
+    return find(string_view(s), pos);
+  }
+
   // string_view::rfind()
   //
   // Finds the last occurrence of a substring `s` within the `string_view`,
   // returning the position of the first character's match, or `npos` if no
   // match was found.
-  size_type rfind(string_view s, size_type pos = npos) const
-      noexcept;
+  size_type rfind(string_view s, size_type pos = npos) const noexcept;
 
   // Overload of `string_view::rfind()` for finding the last given character `c`
   // within the `string_view`.
   size_type rfind(char c, size_type pos = npos) const noexcept;
 
+  // Overload of `string_view::rfind()` for finding a substring of a different
+  // C-style string `s` within the `string_view`.
+  size_type rfind(const char* s, size_type pos, size_type count) const {
+    return rfind(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::rfind()` for finding a different C-style string
+  // `s` within the `string_view`.
+  size_type rfind(const char* s, size_type pos = npos) const {
+    return rfind(string_view(s), pos);
+  }
+
   // string_view::find_first_of()
   //
   // Finds the first occurrence of any of the characters in `s` within the
   // `string_view`, returning the start position of the match, or `npos` if no
   // match was found.
-  size_type find_first_of(string_view s, size_type pos = 0) const
-      noexcept;
+  size_type find_first_of(string_view s, size_type pos = 0) const noexcept;
 
   // Overload of `string_view::find_first_of()` for finding a character `c`
   // within the `string_view`.
-  size_type find_first_of(char c, size_type pos = 0) const
-      noexcept {
+  size_type find_first_of(char c, size_type pos = 0) const noexcept {
     return find(c, pos);
   }
 
+  // Overload of `string_view::find_first_of()` for finding a substring of a
+  // different C-style string `s` within the `string_view`.
+  size_type find_first_of(const char* s, size_type pos,
+                                    size_type count) const {
+    return find_first_of(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::find_first_of()` for finding a different C-style
+  // string `s` within the `string_view`.
+  size_type find_first_of(const char* s, size_type pos = 0) const {
+    return find_first_of(string_view(s), pos);
+  }
+
   // string_view::find_last_of()
   //
   // Finds the last occurrence of any of the characters in `s` within the
   // `string_view`, returning the start position of the match, or `npos` if no
   // match was found.
-  size_type find_last_of(string_view s, size_type pos = npos) const
-      noexcept;
+  size_type find_last_of(string_view s, size_type pos = npos) const noexcept;
 
   // Overload of `string_view::find_last_of()` for finding a character `c`
   // within the `string_view`.
-  size_type find_last_of(char c, size_type pos = npos) const
-      noexcept {
+  size_type find_last_of(char c, size_type pos = npos) const noexcept {
     return rfind(c, pos);
   }
 
+  // Overload of `string_view::find_last_of()` for finding a substring of a
+  // different C-style string `s` within the `string_view`.
+  size_type find_last_of(const char* s, size_type pos, size_type count) const {
+    return find_last_of(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::find_last_of()` for finding a different C-style
+  // string `s` within the `string_view`.
+  size_type find_last_of(const char* s, size_type pos = npos) const {
+    return find_last_of(string_view(s), pos);
+  }
+
   // string_view::find_first_not_of()
   //
   // Finds the first occurrence of any of the characters not in `s` within the
@@ -507,18 +555,43 @@ class string_view {
   // that is not `c` within the `string_view`.
   size_type find_first_not_of(char c, size_type pos = 0) const noexcept;
 
+  // Overload of `string_view::find_first_not_of()` for finding a substring of a
+  // different C-style string `s` within the `string_view`.
+  size_type find_first_not_of(const char* s, size_type pos,
+                              size_type count) const {
+    return find_first_not_of(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::find_first_not_of()` for finding a different
+  // C-style string `s` within the `string_view`.
+  size_type find_first_not_of(const char* s, size_type pos = 0) const {
+    return find_first_not_of(string_view(s), pos);
+  }
+
   // string_view::find_last_not_of()
   //
   // Finds the last occurrence of any of the characters not in `s` within the
   // `string_view`, returning the start position of the last non-match, or
   // `npos` if no non-match was found.
   size_type find_last_not_of(string_view s,
-                                          size_type pos = npos) const noexcept;
+                             size_type pos = npos) const noexcept;
 
   // Overload of `string_view::find_last_not_of()` for finding a character
   // that is not `c` within the `string_view`.
-  size_type find_last_not_of(char c, size_type pos = npos) const
-      noexcept;
+  size_type find_last_not_of(char c, size_type pos = npos) const noexcept;
+
+  // Overload of `string_view::find_last_not_of()` for finding a substring of a
+  // different C-style string `s` within the `string_view`.
+  size_type find_last_not_of(const char* s, size_type pos,
+                             size_type count) const {
+    return find_last_not_of(string_view(s, count), pos);
+  }
+
+  // Overload of `string_view::find_last_not_of()` for finding a different
+  // C-style string `s` within the `string_view`.
+  size_type find_last_not_of(const char* s, size_type pos = npos) const {
+    return find_last_not_of(string_view(s), pos);
+  }
 
  private:
   static constexpr size_type kMaxSize =
@@ -596,6 +669,7 @@ std::ostream& operator<<(std::ostream& o, string_view piece);
 ABSL_NAMESPACE_END
 }  // namespace absl
 
+#undef ABSL_INTERNAL_STRING_VIEW_CXX14_CONSTEXPR
 #undef ABSL_INTERNAL_STRING_VIEW_MEMCMP
 
 #endif  // ABSL_USES_STD_STRING_VIEW
diff --git a/absl/strings/string_view_test.cc b/absl/strings/string_view_test.cc
index 643af8f8..2c13dd1c 100644
--- a/absl/strings/string_view_test.cc
+++ b/absl/strings/string_view_test.cc
@@ -449,6 +449,24 @@ TEST(StringViewTest, STL2) {
   EXPECT_EQ(d.find('x', 4), absl::string_view::npos);
   EXPECT_EQ(e.find('x', 7), absl::string_view::npos);
 
+  EXPECT_EQ(a.find(b.data(), 1, 0), 1);
+  EXPECT_EQ(a.find(c.data(), 9, 0), 9);
+  EXPECT_EQ(a.find(c.data(), absl::string_view::npos, 0),
+            absl::string_view::npos);
+  EXPECT_EQ(b.find(c.data(), absl::string_view::npos, 0),
+            absl::string_view::npos);
+  // empty string nonsense
+  EXPECT_EQ(d.find(b.data(), 4, 0), absl::string_view::npos);
+  EXPECT_EQ(e.find(b.data(), 7, 0), absl::string_view::npos);
+
+  EXPECT_EQ(a.find(b.data(), 1), absl::string_view::npos);
+  EXPECT_EQ(a.find(c.data(), 9), 23);
+  EXPECT_EQ(a.find(c.data(), absl::string_view::npos), absl::string_view::npos);
+  EXPECT_EQ(b.find(c.data(), absl::string_view::npos), absl::string_view::npos);
+  // empty string nonsense
+  EXPECT_EQ(d.find(b.data(), 4), absl::string_view::npos);
+  EXPECT_EQ(e.find(b.data(), 7), absl::string_view::npos);
+
   EXPECT_EQ(a.rfind(b), 0);
   EXPECT_EQ(a.rfind(b, 1), 0);
   EXPECT_EQ(a.rfind(c), 23);
@@ -490,6 +508,14 @@ TEST(StringViewTest, STL2) {
   EXPECT_EQ(e.rfind('o'), absl::string_view::npos);
   EXPECT_EQ(d.rfind('o', 4), absl::string_view::npos);
   EXPECT_EQ(e.rfind('o', 7), absl::string_view::npos);
+
+  EXPECT_EQ(a.rfind(b.data(), 1, 0), 1);
+  EXPECT_EQ(a.rfind(c.data(), 22, 0), 22);
+  EXPECT_EQ(a.rfind(c.data(), 1, 0), 1);
+  EXPECT_EQ(a.rfind(c.data(), 0, 0), 0);
+  EXPECT_EQ(b.rfind(c.data(), 0, 0), 0);
+  EXPECT_EQ(d.rfind(b.data(), 4, 0), 0);
+  EXPECT_EQ(e.rfind(b.data(), 7, 0), 0);
 }
 
 // Continued from STL2
@@ -678,6 +704,7 @@ TEST(StringViewTest, STL2Substr) {
   EXPECT_EQ(a.substr(23, 3), c);
   EXPECT_EQ(a.substr(23, 99), c);
   EXPECT_EQ(a.substr(0), a);
+  EXPECT_EQ(a.substr(), a);
   EXPECT_EQ(a.substr(3, 2), "de");
   // empty string nonsense
   EXPECT_EQ(d.substr(0, 99), e);
@@ -1087,7 +1114,24 @@ TEST(StringViewTest, ConstexprCompiles) {
   EXPECT_EQ(sp_npos, -1);
 }
 
-TEST(StringViewTest, ConstexprSubstr) {
+constexpr char ConstexprMethodsHelper() {
+#if defined(__cplusplus) && __cplusplus >= 201402L
+  absl::string_view str("123", 3);
+  str.remove_prefix(1);
+  str.remove_suffix(1);
+  absl::string_view bar;
+  str.swap(bar);
+  return bar.front();
+#else
+  return '2';
+#endif
+}
+
+TEST(StringViewTest, ConstexprMethods) {
+  // remove_prefix, remove_suffix, swap
+  static_assert(ConstexprMethodsHelper() == '2', "");
+
+  // substr
   constexpr absl::string_view foobar("foobar", 6);
   constexpr absl::string_view foo = foobar.substr(0, 3);
   constexpr absl::string_view bar = foobar.substr(3);
diff --git a/ci/linux_docker_containers.sh b/ci/linux_docker_containers.sh
index 1c29d9a1..e7eef0fc 100644
--- a/ci/linux_docker_containers.sh
+++ b/ci/linux_docker_containers.sh
@@ -16,6 +16,6 @@
 # Test scripts should source this file to get the identifiers.
 
 readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20201026"
-readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
-readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
+readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20210519"
+readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20210519"
 readonly LINUX_GCC_FLOOR_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-floor:20201015"