Fix the build of develop: tests from #5997 and #5991 (#6019)

* Fix the build of develop: tests from #5997 and #5991

- unit-msgpack-cpp17: assign the result of json::parse in
  CHECK_THROWS_WITH_AS (GCC -Werror=unused-result)
- unit-json_view: failing_allocator::allocate is [[noreturn]]
  (clang -Wmissing-noreturn)
- unit-class_lexer: build the quoted string once
  (clang-tidy performance-inefficient-string-concatenation)
- unit-allocator: sweep_allocator provides pointer, reference and size
  typedefs, which GCC 4.8's std::map takes from the allocator
- unit-allocator: skip the "sax_parse into an existing value" sweep with
  iterator debugging, like the parser callback sweep: MSVC's std::vector
  default constructor is noexcept but allocates its debug proxy through
  the allocator, so a failing allocation in create<array_t>() terminates

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix the remaining CI failures of the tests from #5997 and #5991

- unit-custom-object-key-type: drop the redundant member initializer and
  return a braced init list (clang-tidy); direct-initialize the converted
  value, as copy-initialization makes GCC 4.8 instantiate the copy
  constructor, which needs a range constructor strict_object lacks
- unit-stream-bulk-scan: pick the claimed get area size by tag dispatch
  instead of a constant condition (MSVC C4127)
- unit-allocator: skip the parser callback and sax_parse sweeps with
  Clang 3.4 and 3.5, which leak memory when an element constructor throws
  inside a libstdc++ std::map copy or std::vector reallocation

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix the CI failures that the first failing TU of each job hid

- unit-stream-bulk-scan: compute the claimed size without a condition;
  the tag-dispatched template was unused with a 64-bit std::size_t
  (-Wunused-template)
- unit-json_view: give failing_allocator the typedefs, rebind and
  members that GCC 4.8's std::map takes from the allocator directly
- clang-tidy hits in the tests from #5997: raw string literals
  (unit-json_view), redundant c_str() and a NOLINT for &text[0]
  (unit-locale-cpp), reserve() before a loop (unit-ordered_json), and a
  NOLINT for a return that a braced list would turn into an array
  (unit-regression1)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Skip the 3 GiB get-area test with a 32-bit std::size_t in the preprocessor

The claimed size was a constant 0 on Win32, so `claimed == 0 || ...` was a
constant condition and MSVC reported C4127. Guard the section with
`#if SIZE_MAX > UINT32_MAX` instead, as unit-msgpack-custom-types.cpp does.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Silence modernize-use-transparent-functors for failing_map in unit-json_view

std::less<> needs C++14, and the test is also built as C++11.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

tests/src/unit-allocator.cpp

@@ -1038,6 +1038,14 @@ template<class T>
 struct sweep_allocator
 {
     using value_type = T;
+    // GCC 4.8's std::map takes these from the allocator instead of from
+    // std::allocator_traits
+    using pointer = T*;
+    using const_pointer = const T*;
+    using reference = T&;
+    using const_reference = const T&;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
 
     sweep_allocator() = default;
     template<class U> sweep_allocator(const sweep_allocator<U>& /*unused*/) noexcept {}
@@ -1155,9 +1163,14 @@ TEST_CASE("parse() survives a failing allocation at every point (#5985)")
 
     // With iterator debugging (MSVC STL debug builds, also used by clang-cl),
     // containers allocate a debug proxy through the allocator inside their
-    // noexcept move constructors, so failing that allocation terminates the
-    // program instead of throwing std::bad_alloc. Nothing to check there.
+    // noexcept default and move constructors, so failing that allocation
+    // terminates the program instead of throwing std::bad_alloc. Nothing to
+    // check there.
 #if !(defined(_ITERATOR_DEBUG_LEVEL) && _ITERATOR_DEBUG_LEVEL > 0)
+    // Clang 3.4 and 3.5 leak memory when an element constructor throws
+    // inside libstdc++'s containers (a std::map copy, a std::vector
+    // reallocation), without any json value involved.
+#if !(defined(__clang__) && !defined(__apple_build_version__) && __clang_major__ == 3 && __clang_minor__ < 6)
     SECTION("parser callback")
     {
         const auto keep_all = [](int /*depth*/, sweep_json::parse_event_t /*event*/, sweep_json& /*parsed*/) noexcept
@@ -1178,7 +1191,6 @@ TEST_CASE("parse() survives a failing allocation at every point (#5985)")
             return sweep_json::parse(text, drop_d);
         });
     }
-#endif
 
     SECTION("sax_parse into an existing value")
     {
@@ -1192,5 +1204,7 @@ TEST_CASE("parse() survives a failing allocation at every point (#5985)")
             return value;
         });
     }
+#endif
+#endif
 }
 #endif