fix: try fix clang libcxx charconv issue.

- add compile checker in cmake to detect charconv support status.
- and expose macro for yycc to enable different part of charconv repectively to prevent duplicated defines.

cmake/check_charconv/chars_format.cpp

@@ -0,0 +1,8 @@
+#include <charconv>
+
+int main(int argc, char **argv) {
+    auto scientific = std::chars_format::scientific;
+    auto fixed = std::chars_format::fixed;
+    auto general = std::chars_format::general;
+    auto hex = std::chars_format::hex;
+}

cmake/check_charconv/from_chars_float.cpp

@@ -0,0 +1,16 @@
+#include <charconv>
+
+int main(int argc, char **argv) {
+    const char probe[] = "0.0";
+    const char* first = probe;
+    const char* last = first + sizeof(probe);
+
+    {
+        float value;
+        auto rv = std::from_chars(first, last, value, std::chars_format::general);
+    }
+    {
+        double value;
+        auto rv = std::from_chars(first, last, value, std::chars_format::general);
+    }
+}

cmake/check_charconv/from_chars_int.cpp

@@ -0,0 +1,41 @@
+#include <charconv>
+#include <cstdint>
+
+int main(int argc, char **argv) {
+    const char probe[] = "0";
+    const char* first = probe;
+    const char* last = first + sizeof(probe);
+
+    {
+        std::int8_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::int16_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::int32_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::int64_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::uint8_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::uint16_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::uint32_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+    {
+        std::uint64_t value;
+        auto rv = std::from_chars(first, last, value, 10);
+    }
+}

cmake/check_charconv/from_chars_result.cpp

@@ -0,0 +1,9 @@
+#include <charconv>
+#include <system_error>
+
+int main(int argc, char **argv) {
+    std::from_chars_result result {
+        .ptr = nullptr,
+        .ec = std::errc{},
+    };
+}

cmake/check_charconv/to_chars_float.cpp

@@ -0,0 +1,16 @@
+#include <charconv>
+
+int main(int argc, char **argv) {
+    char buffer[1024];
+    char* first = buffer;
+    char* last = first + sizeof(buffer);
+
+    {
+        float value = 0;
+        auto rv = std::to_chars(first, last, value, std::chars_format::general, 6);
+    }
+    {
+        double value = 0;
+        auto rv = std::to_chars(first, last, value, std::chars_format::general, 6);
+    }
+}

cmake/check_charconv/to_chars_int.cpp

@@ -0,0 +1,41 @@
+#include <charconv>
+#include <cstdint>
+
+int main(int argc, char **argv) {
+    char buffer[1024];
+    char* first = buffer;
+    char* last = first + sizeof(buffer);
+
+    {
+        std::int8_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::int16_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::int32_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::int64_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::uint8_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::uint16_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::uint32_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+    {
+        std::uint64_t value = 0;
+        auto rv = std::to_chars(first, last, value, 10);
+    }
+}

cmake/check_charconv/to_chars_result.cpp

@@ -0,0 +1,9 @@
+#include <charconv>
+#include <system_error>
+
+int main(int argc, char **argv) {
+    std::to_chars_result result {
+        .ptr = nullptr,
+        .ec = std::errc{},
+    };
+}