Use std::source_location to construct source_loc if available

Signed-off-by: Stephan Lachnit <stephanlachnit@debian.org>

include/spdlog/common.h

@@ -107,7 +107,13 @@
 #endif
 
 #ifndef SPDLOG_FUNCTION
-    #define SPDLOG_FUNCTION static_cast<const char *>(__FUNCTION__)
+    // use std::source_location instead of macros if available
+    #ifdef __cpp_lib_source_location
+        #define SPDLOG_STD_SOURCE_LOCATION
+        #include <source_location>
+    #else
+        #define SPDLOG_FUNCTION static_cast<const char *>(__FUNCTION__)
+    #endif
 #endif
 
 #ifdef SPDLOG_NO_EXCEPTIONS
@@ -325,6 +331,13 @@ struct source_loc {
           line{line_in},
           funcname{funcname_in} {}
 
+    #ifdef SPDLOG_STD_SOURCE_LOCATION
+    SPDLOG_CONSTEXPR source_loc(const std::source_location& loc)
+        : filename{loc.file_name()},
+          line{loc.line()},
+          funcname{loc.function_name()} {}
+    #endif
+
     SPDLOG_CONSTEXPR bool empty() const SPDLOG_NOEXCEPT { return line == 0; }
     const char *filename{nullptr};
     std::uint_least32_t line{0};

include/spdlog/spdlog.h

@@ -284,8 +284,13 @@ inline void critical(const T &msg) {
 //
 
 #ifndef SPDLOG_NO_SOURCE_LOC
-    #define SPDLOG_LOGGER_CALL(logger, level, ...) \
-        (logger)->log(spdlog::source_loc{__FILE__, __LINE__, SPDLOG_FUNCTION}, level, __VA_ARGS__)
+    #ifdef SPDLOG_STD_SOURCE_LOCATION
+        #define SPDLOG_LOGGER_CALL(logger, level, ...) \
+            (logger)->log(spdlog::source_loc{std::source_location::current()}, level, __VA_ARGS__)
+    #else
+        #define SPDLOG_LOGGER_CALL(logger, level, ...) \
+            (logger)->log(spdlog::source_loc{__FILE__, __LINE__, SPDLOG_FUNCTION}, level, __VA_ARGS__)
+    #endif
 #else
     #define SPDLOG_LOGGER_CALL(logger, level, ...) \
         (logger)->log(spdlog::source_loc{}, level, __VA_ARGS__)

include/spdlog/tweakme.h

@@ -131,7 +131,8 @@
 // Uncomment (and change if desired) macro to use for function names.
 // This is compiler dependent.
 // __PRETTY_FUNCTION__ might be nicer in clang/gcc, and __FUNCTION__ in msvc.
-// Defaults to __FUNCTION__ (should work on all compilers) if not defined.
+// Defaults to __FUNCTION__ (should work on all compilers) if not defined and
+// std::source_location (introduced in C++20) is not available..
 //
 // #ifdef __PRETTY_FUNCTION__
 // # define SPDLOG_FUNCTION __PRETTY_FUNCTION__