1 files changed, 12 insertions, 10 deletions
diff --git a/zen/legacy_compiler.cpp b/zen/legacy_compiler.cpp
index 81efb4dd..6c5489d5 100644
--- a/zen/legacy_compiler.cpp
+++ b/zen/legacy_compiler.cpp
@@ -5,22 +5,24 @@
 // *****************************************************************************
 
 #include "legacy_compiler.h"
-#ifdef __cpp_lib_to_chars
-    #error get rid of workarounds
-#endif
+#include <charconv>
+/*  1. including <charconv> in header file blows up VC++:
+       - string_tools.h: "An internal error has occurred in the compiler. (compiler file 'd:\agent\_work\1\s\src\vctools\Compiler\Utc\src\p2\p2symtab.c', line 2618)"
+       - PCH: "fatal error C1076: compiler limit: internal heap limit reached"
+        => include in separate compilation unit
+    2. Disable "C/C++ -> Code Generation -> Smaller Type Check" (and PCH usage!), at least for this compilation unit: https://github.com/microsoft/STL/pull/171   */
 
 double zen::fromChars(const char* first, const char* last)
 {
-    return std::strtod(std::string(first, last).c_str(), nullptr);
+    double num = 0;
+    [[maybe_unused]] const std::from_chars_result rv = std::from_chars(first, last, num);
+    return num;
 }
 
 
 const char* zen::toChars(char* first, char* last, double num)
 {
-    const size_t bufSize = last - first;
-    const int charsWritten = std::snprintf(first, bufSize, "%g", num);
-    //C99: returns number of chars written if successful, < 0 or >= bufferSize on failure
-
-    return 0 <= charsWritten && charsWritten < static_cast<int>(bufSize) ?
-           first + charsWritten : first;
+    const std::to_chars_result rv = std::to_chars(first, last, num);
+    return rv.ec == std::errc{} ? rv.ptr : first;
 }
+