strtold() conflicting with MSVCRT

[kinke]

Microsoft's C runtime includes a strtold() implementation (returning a 64-bit double) since VS 2013. druntime defines its own strtold() (returning a real) in core.stdc.stdlib, leading obviously to linking conflicts.

In the long run, we should define real as 64-bit double on Windows x64 due to the lack of x87 support in MSVCRT.

Until then, the following patch redirects strtold to the renamed druntime wrapper with the correct signature:

diff --git a/src/core/stdc/stdlib.d b/src/core/stdc/stdlib.d
index 3e73137..96ea21b 100644
--- a/src/core/stdc/stdlib.d
+++ b/src/core/stdc/stdlib.d
@@ -72,10 +72,20 @@ ulong   strtoull(in char* nptr, char** endptr, int base);

 version (Win64)
 {
-    real strtold(in char* nptr, char** endptr)
-    {   // Fake it 'till we make it
-        return strtod(nptr, endptr);
-    }
+  version (none)
+  {
+    // requires MSVCRT >= 12 (VS 2013) and real to be defined as 64-bit double
+    static assert(real.sizeof == double.sizeof);
+    real strtold(in char* nptr, char** endptr);
+  }
+  else
+  {
+     real strtold_druntime(in char* nptr, char** endptr)
+     {   // Fake it 'till we make it
+         return strtod(nptr, endptr);
+     }
+     alias strtold_druntime strtold;
+  }
 }
 else version (MinGW)
 {

[kinke]

This is fixed in upstream: dlang/druntime@98215d6

Relevant piece:

-    real strtold(in char* nptr, char** endptr)
+    // strtold exists starting from VS2013, so we make this a template to avoid link errors
+    real strtold()(in char* nptr, char** endptr)

[redstar]

Fixed in master. I only included the relevant code from the mentioned commit.