Fix warnings from Clang 10 and GCC 9

Makefile

@@ -102,7 +102,8 @@ doctest:
 # -Wno-switch-enum -Wno-covered-switch-default: pedantic/contradicting warnings about switches
 # -Wno-weak-vtables: exception class is defined inline, but has virtual method
 pedantic_clang:
-	$(MAKE) json_unit CXX=c++ CXXFLAGS=" \
+	rm -fr build_pedantic
+	CXXFLAGS=" \
 		-std=c++11 -Wno-c++98-compat -Wno-c++98-compat-pedantic \
 		-Werror \
 		-Weverything \
@@ -115,11 +116,13 @@ pedantic_clang:
 		-Wno-padded \
 		-Wno-range-loop-analysis \
 		-Wno-switch-enum -Wno-covered-switch-default \
-		-Wno-weak-vtables"
+		-Wno-weak-vtables" cmake -S . -B build_pedantic -GNinja -DCMAKE_BUILD_TYPE=Debug -DJSON_MultipleHeaders=ON
+	cmake --build build_pedantic
 
 # calling GCC with most warnings
 pedantic_gcc:
-	$(MAKE) json_unit CXX=/usr/local/bin/g++-9 CXXFLAGS=" \
+	rm -fr build_pedantic
+	CXXFLAGS=" \
 		-std=c++11 \
 		-Waddress \
 		-Waddress-of-packed-member \
@@ -233,7 +236,7 @@ pedantic_gcc:
 		-Wno-system-headers \
 		-Wno-templates \
 		-Wno-undef \
-		-Wnoexcept \
+		-Wno-noexcept \
 		-Wnoexcept-type \
 		-Wnon-template-friend \
 		-Wnon-virtual-dtor \
@@ -340,7 +343,8 @@ pedantic_gcc:
 		-Wvolatile-register-var \
 		-Wwrite-strings \
 		-Wzero-as-null-pointer-constant \
-		"
+		" cmake -S . -B build_pedantic -GNinja -DCMAKE_BUILD_TYPE=Debug -DJSON_MultipleHeaders=ON
+	cmake --build build_pedantic
 
 ##########################################################################
 # benchmarks

include/nlohmann/detail/input/binary_reader.hpp

@@ -32,7 +32,7 @@ namespace detail
 
 @note from https://stackoverflow.com/a/1001328/266378
 */
-static bool little_endianess(int num = 1) noexcept
+static inline bool little_endianess(int num = 1) noexcept
 {
     return *reinterpret_cast<char*>(&num) == 1;
 }

include/nlohmann/detail/output/binary_writer.hpp

@@ -194,9 +194,9 @@ class binary_writer
                 }
                 else
                 {
-                    if (j.m_value.number_float >= std::numeric_limits<float>::lowest() and
-                            j.m_value.number_float <= std::numeric_limits<float>::max() and
-                            static_cast<double>(static_cast<float>(j.m_value.number_float)) == j.m_value.number_float)
+                    if (static_cast<double>(j.m_value.number_float) >= static_cast<double>(std::numeric_limits<float>::lowest()) and
+                            static_cast<double>(j.m_value.number_float) <= static_cast<double>(std::numeric_limits<float>::max()) and
+                            static_cast<double>(static_cast<float>(j.m_value.number_float)) == static_cast<double>(j.m_value.number_float))
                     {
                         oa->write_character(get_cbor_float_prefix(static_cast<float>(j.m_value.number_float)));
                         write_number(static_cast<float>(j.m_value.number_float));

single_include/nlohmann/json.hpp

@@ -5596,7 +5596,7 @@ namespace detail
 
 @note from https://stackoverflow.com/a/1001328/266378
 */
-static bool little_endianess(int num = 1) noexcept
+static inline bool little_endianess(int num = 1) noexcept
 {
     return *reinterpret_cast<char*>(&num) == 1;
 }
@@ -12188,9 +12188,9 @@ class binary_writer
                 }
                 else
                 {
-                    if (j.m_value.number_float >= std::numeric_limits<float>::lowest() and
-                            j.m_value.number_float <= std::numeric_limits<float>::max() and
-                            static_cast<double>(static_cast<float>(j.m_value.number_float)) == j.m_value.number_float)
+                    if (static_cast<double>(j.m_value.number_float) >= static_cast<double>(std::numeric_limits<float>::lowest()) and
+                            static_cast<double>(j.m_value.number_float) <= static_cast<double>(std::numeric_limits<float>::max()) and
+                            static_cast<double>(static_cast<float>(j.m_value.number_float)) == static_cast<double>(j.m_value.number_float))
                     {
                         oa->write_character(get_cbor_float_prefix(static_cast<float>(j.m_value.number_float)));
                         write_number(static_cast<float>(j.m_value.number_float));

test/src/unit-cbor.cpp

@@ -939,7 +939,7 @@ TEST_CASE("CBOR")
                 }
                 SECTION("-3.40282e+38(lowest float)")
                 {
-                    double v = std::numeric_limits<float>::lowest();
+                    double v = static_cast<double>(std::numeric_limits<float>::lowest());
                     json j = v;
                     std::vector<uint8_t> expected =
                     {
@@ -953,7 +953,7 @@ TEST_CASE("CBOR")
                 }
                 SECTION("1 + 3.40282e+38(more than max float)")
                 {
-                    double v = std::numeric_limits<float>::max() + 0.1e+34;
+                    double v = static_cast<double>(std::numeric_limits<float>::max()) + 0.1e+34;
                     json j = v;
                     std::vector<uint8_t> expected =
                     {
@@ -968,7 +968,7 @@ TEST_CASE("CBOR")
                 }
                 SECTION("-1 - 3.40282e+38(less than lowest float)")
                 {
-                    double v = std::numeric_limits<float>::lowest() - 1;
+                    double v = static_cast<double>(std::numeric_limits<float>::lowest()) - 1.0;
                     json j = v;
                     std::vector<uint8_t> expected =
                     {
@@ -1582,7 +1582,7 @@ TEST_CASE("CBOR")
                 auto j = json::from_cbor(input);
                 CHECK(j.is_binary());
                 auto k = json::binary_array({0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0x99});
-                CAPTURE(j.dump(0, ' ', false, json::error_handler_t::strict, true));
+                CAPTURE(j.dump(0, ' ', false, json::error_handler_t::strict, true))
                 CHECK(j == k);
             }
 

test/src/unit-noexcept.cpp

@@ -46,7 +46,12 @@ void to_json(json&, pod) noexcept;
 void to_json(json&, pod_bis);
 void from_json(const json&, pod) noexcept;
 void from_json(const json&, pod_bis);
-static json* j;
+void to_json(json&, pod) noexcept {}
+void to_json(json&, pod_bis) {}
+void from_json(const json&, pod) noexcept {}
+void from_json(const json&, pod_bis) {}
+
+static json* j = nullptr;
 
 static_assert(noexcept(json{}), "");
 static_assert(noexcept(nlohmann::to_json(*j, 2)), "");
@@ -79,4 +84,14 @@ TEST_CASE("runtime checks")
         CHECK(std::is_nothrow_copy_constructible<json::out_of_range>::value == std::is_nothrow_copy_constructible<std::runtime_error>::value);
         CHECK(std::is_nothrow_copy_constructible<json::other_error>::value == std::is_nothrow_copy_constructible<std::runtime_error>::value);
     }
+
+    SECTION("silence -Wunneeded-internal-declaration errors")
+    {
+        j = nullptr;
+        json j2;
+        to_json(j2, pod());
+        to_json(j2, pod_bis());
+        from_json(j2, pod());
+        from_json(j2, pod_bis());
+    }
 }

test/src/unit-udt.cpp

@@ -120,6 +120,8 @@ static void to_json(BasicJsonType& j, country c)
         case country::russia:
             j = u8"Российская Федерация";
             return;
+        default:
+            break;
     }
 }
 
@@ -803,7 +805,9 @@ class Evil
   public:
     Evil() = default;
     template <typename T>
-    Evil(T) {}
+    Evil(T t) : m_i(sizeof(t)) {}
+
+    int m_i = 0;
 };
 
 void from_json(const json&, Evil&) {}
@@ -816,6 +820,10 @@ TEST_CASE("Issue #924")
 
     CHECK_NOTHROW(j.get<Evil>());
     CHECK_NOTHROW(j.get<std::vector<Evil>>());
+
+    // silence Wunused-template warnings
+    Evil e(1);
+    CHECK(e.m_i >= 0);
 }
 
 TEST_CASE("Issue #1237")

test/thirdparty/doctest/doctest.h

@@ -2913,7 +2913,7 @@ typedef timer_large_integer::type ticks_t;
         //unsigned int getElapsedMilliseconds() const {
         //    return static_cast<unsigned int>(getElapsedMicroseconds() / 1000);
         //}
-        double getElapsedSeconds() const { return (getCurrentTicks() - m_ticks) / 1000000.0; }
+        double getElapsedSeconds() const { return static_cast<double>((getCurrentTicks() - m_ticks)) / 1000000.0; }
 
     private:
         ticks_t m_ticks = 0;