Introduced debug parameter in floating point to string conversion

Author: wokalski

stdlib/public/core/Runtime.swift.gyb

@@ -355,19 +355,20 @@ struct _Buffer72 {
 @_silgen_name("swift_float${bits}ToString")
 func _float${bits}ToStringImpl(
   buffer: UnsafeMutablePointer<UTF8.CodeUnit>,
-  _ bufferLength: UInt, _ value: Float${bits}
+  _ bufferLength: UInt, _ value: Float${bits},
+  _ debug: Bool
 ) -> UInt
 
 @warn_unused_result
-func _float${bits}ToString(value: Float${bits}) -> String {
+func _float${bits}ToString(value: Float${bits}, debug: Bool) -> String {
   _sanityCheck(sizeof(_Buffer32.self) == 32)
   _sanityCheck(sizeof(_Buffer72.self) == 72)
 
   var buffer = _Buffer32()
   return withUnsafeMutablePointer(&buffer) {
     (bufferPtr) in
     let bufferUTF8Ptr = UnsafeMutablePointer<UTF8.CodeUnit>(bufferPtr)
-    let actualLength = _float${bits}ToStringImpl(bufferUTF8Ptr, 32, value)
+    let actualLength = _float${bits}ToStringImpl(bufferUTF8Ptr, 32, value, debug)
     return String._fromWellFormedCodeUnitSequence(
       UTF8.self,
       input: UnsafeBufferPointer(

stdlib/public/stubs/Stubs.cpp

@@ -141,12 +141,15 @@ static int swift_snprintf_l(char *Str, size_t StrSize, locale_t Locale,
 
 template <typename T>
 static uint64_t swift_floatingPointToString(char *Buffer, size_t BufferLength,
-                                            T Value, const char *Format) {
+                                            T Value, const char *Format, bool Debug) {
   if (BufferLength < 32)
     swift::crash("swift_floatingPointToString: insufficient buffer size");
 
-  const int Precision = std::numeric_limits<T>::max_digits10;
-
+  int Precision = std::numeric_limits<T>::digits10;
+  if (Debug) {
+    Precision = std::numeric_limits<T>::max_digits10;
+  }
+  
   // Pass a null locale to use the C locale.
   int i = swift_snprintf_l(Buffer, BufferLength, /*locale=*/nullptr, Format,
                            Precision, Value);
@@ -170,21 +173,21 @@ static uint64_t swift_floatingPointToString(char *Buffer, size_t BufferLength,
 }
 
 extern "C" uint64_t swift_float32ToString(char *Buffer, size_t BufferLength,
-                                          float Value) {
+                                          float Value, bool Debug) {
   return swift_floatingPointToString<float>(Buffer, BufferLength, Value,
-                                            "%0.*g");
+                                            "%0.*g", Debug);
 }
 
 extern "C" uint64_t swift_float64ToString(char *Buffer, size_t BufferLength,
-                                          double Value) {
+                                          double Value, bool Debug) {
   return swift_floatingPointToString<double>(Buffer, BufferLength, Value,
-                                             "%0.*g");
+                                             "%0.*g", Debug);
 }
 
 extern "C" uint64_t swift_float80ToString(char *Buffer, size_t BufferLength,
-                                          long double Value) {
+                                          long double Value, bool Debug) {
   return swift_floatingPointToString<long double>(Buffer, BufferLength, Value,
-                                                  "%0.*Lg");
+                                                  "%0.*Lg", Debug);
 }
 
 /// \param[out] LinePtr Replaced with the pointer to the malloc()-allocated