Use C locale in lexer (pytorch#12739)

Summary:
Possible fix for pytorch#11326. Testing in CI for windows code.
Pull Request resolved: pytorch#12739

Differential Revision: D10417038

Pulled By: zdevito

fbshipit-source-id: 1d5f2f9a24eceef7047dc218669faca8a187c65c

Author: zdevito

torch/csrc/jit/script/lexer.h

@@ -5,6 +5,12 @@
 #include <sstream>
 #include <string>
 #include <unordered_map>
+#ifdef _WIN32
+#include <locale.h>
+#else
+#include <xlocale.h>
+#endif
+
 #include <vector>
 #include "torch/csrc/jit/assertions.h"
 #include "torch/csrc/jit/source_range.h"
@@ -146,6 +152,17 @@ struct SharedParserData {
     TC_FORALL_TOKEN_KINDS(ADD_CASE)
 #undef ADD_CASE
   }
+#ifdef _WIN32
+  double strtod_c(const char * str, char** end) {
+    static _locale_t loc = _create_locale(LC_ALL, "C");
+    return _strtod_l(str, end, loc);
+  }
+#else
+  double strtod_c(const char * str, char** end) {
+    static locale_t loc = newlocale(LC_ALL_MASK, "C", nullptr);
+    return strtod_l(str, end, loc);
+  }
+#endif
   // 1. skip whitespace
   // 2. handle comment or newline
   //
@@ -159,7 +176,7 @@ struct SharedParserData {
       return false;
     const char* startptr = str.c_str() + start;
     char* endptr;
-    std::strtod(startptr, &endptr);
+    strtod_c(startptr, &endptr);
     *len = endptr - startptr;
     return *len > 0;
   }