feat universal: delete unsafe methods of zstring_view and StringLiteral

Tests: протестировано CI
commit_hash:eef2b763e273af79199c3ad02f663a1b0cedb2ba

Author: apolukhin

universal/include/userver/utils/string_literal.hpp

@@ -39,6 +39,9 @@ class StringLiteral : public zstring_view {
         // data()[size()] == '\0' is guaranteed by std::string_view that calls std::strlen(literal)
     }
 
+    void swap(zstring_view&) = delete;  // loses guarantee on lifetime because zstring_view may refer to non-literal
+    void swap(StringLiteral& other) noexcept { zstring_view::swap(other); }
+
     /// Constructs a StringLiteral from a pointer and size.
     /// @warning `str[len]` should be '\0' and `str` should point to compile time literal.
     static constexpr StringLiteral UnsafeMake(const char* str, std::size_t len) noexcept {

universal/include/userver/utils/zstring_view.hpp

@@ -34,6 +34,10 @@ class zstring_view : public std::string_view {  // NOLINT(readability-identifier
     zstring_view& operator=(std::string_view) = delete;
     zstring_view& operator=(const zstring_view&) = default;
 
+    void remove_suffix(std::size_t) = delete;  // zstring_view becomes not null-terminated after that function call
+    void swap(std::string_view&) = delete;     // zstring_view may become not null-terminated after that function call
+    void swap(zstring_view& other) noexcept { std::string_view::swap(other); }
+
     constexpr const char* c_str() const noexcept { return std::string_view::data(); }
 
     /// Constructs a zstring_view from a pointer and size.

universal/src/utils/string_literal_test.cpp

@@ -1,5 +1,9 @@
 #include <userver/utils/string_literal.hpp>
 
+#ifdef __cpp_concepts
+#include <concepts>
+#endif
+
 #include <type_traits>
 
 #include <gtest/gtest.h>
@@ -18,6 +22,16 @@ static_assert(!std::is_assignable_v<utils::StringLiteral, utils::zstring_view>);
 static_assert(std::is_assignable_v<std::string_view, utils::StringLiteral>);
 static_assert(std::is_assignable_v<utils::zstring_view, utils::StringLiteral>);
 
+#ifdef __cpp_concepts
+template <typename T>
+concept SuffixRemovable = requires(T t) { t.remove_suffix(10); };
+
+static_assert(std::swappable<utils::StringLiteral>);
+static_assert(!std::swappable_with<utils::StringLiteral, utils::zstring_view>);
+static_assert(!std::swappable_with<utils::StringLiteral, std::string_view>);
+static_assert(!SuffixRemovable<utils::StringLiteral>);
+#endif
+
 static constexpr utils::StringLiteral kLongString = "some long long long long long long long long long string";
 
 TEST(StringLiteral, UnsafeMake) {
@@ -44,4 +58,16 @@ TEST(StringLiteral, UnsafeMake) {
     static_assert(kLongString == utils::StringLiteral::UnsafeMake(kLongString.c_str(), kLongString.size()));
 }
 
+TEST(StringLiteral, Swap) {
+    constexpr utils::StringLiteral kShortString = "short";
+    constexpr utils::StringLiteral kLongString = "some long long long long long long long long long string";
+
+    auto v1 = kShortString;
+    auto v2 = kLongString;
+    v1.swap(v2);
+
+    EXPECT_EQ(v1, kLongString);
+    EXPECT_EQ(v2, kShortString);
+}
+
 USERVER_NAMESPACE_END

universal/src/utils/zstring_view_test.cpp

@@ -1,5 +1,9 @@
 #include <userver/utils/zstring_view.hpp>
 
+#ifdef __cpp_concepts
+#include <concepts>
+#endif
+
 #include <type_traits>
 
 #include <gtest/gtest.h>
@@ -15,6 +19,15 @@ static_assert(!std::is_assignable_v<utils::zstring_view, std::string_view>);
 
 static_assert(std::is_assignable_v<std::string_view, utils::zstring_view>);
 
+#ifdef __cpp_concepts
+template <typename T>
+concept SuffixRemovable = requires(T t) { t.remove_suffix(10); };
+
+static_assert(std::swappable<utils::zstring_view>);
+static_assert(!std::swappable_with<utils::zstring_view, std::string_view>);
+static_assert(!SuffixRemovable<utils::zstring_view>);
+#endif
+
 TEST(ZstringView, UnsafeMake) {
     static constexpr utils::zstring_view kShortString = "short";
     static constexpr utils::zstring_view kLongString = "some long long long long long long long long long string";
@@ -40,4 +53,15 @@ TEST(ZstringView, UnsafeMake) {
     static_assert(kLongString == utils::zstring_view::UnsafeMake(kLongString.c_str(), kLongString.size()));
 }
 
+TEST(ZstringView, Swap) {
+    constexpr utils::zstring_view kShortString = "short";
+    constexpr utils::zstring_view kLongString = "some long long long long long long long long long string";
+
+    auto v1 = kShortString;
+    auto v2 = kLongString;
+    v1.swap(v2);
+
+    EXPECT_EQ(v1, kLongString);
+    EXPECT_EQ(v2, kShortString);
+}
 USERVER_NAMESPACE_END