From 0fb06f0524c8b5747e7acc15b73cf31abb434398 Mon Sep 17 00:00:00 2001
From: David Wang <david.wang@elemindtech.com>
Date: Wed, 16 Jul 2025 20:48:41 -0400
Subject: [PATCH] Improve Mac/Windows consistency in parsing very small and
 large floats represented in scientific-notation.

---
 lib/lexer.lxx | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/lib/lexer.lxx b/lib/lexer.lxx
index cdaeb7551..86b2b8fb1 100644
--- a/lib/lexer.lxx
+++ b/lib/lexer.lxx
@@ -16,6 +16,8 @@
 
 %top{
 #include <cstdint>
+#include <cerrno>
+#include <cstdlib>
 }
 
 %{
@@ -101,9 +103,28 @@ namespace MiniZinc {
   }
 
   bool strtofloatval(const char* s, double& v) {
-    std::istringstream iss(s);
-    iss >> v;
-    return !iss.fail();
+    char* endptr;
+    errno = 0;
+    v = std::strtod(s, &endptr);
+    
+    // Check if the entire string was consumed
+    if (*endptr != '\0') {
+      return false;
+    }
+    
+    // Check for overflow or underflow
+    if (errno == ERANGE) {
+      // ERANGE can indicate overflow to infinity or underflow to zero
+      // Both are valid floating point representations, so we accept them
+      return true;
+    }
+    
+    // Any other errno value indicates an error
+    if (errno != 0) {
+      return false;
+    }
+    
+    return true;
   }
 
   void clearBuffer(void* parm) {