gf: Temporarily suppress warning C4018 in GfIntegerCompareLess

This code reportedly began emitting this warning in OpenUSD 25.11.
For now, we simply silence this warning rather than make any
low-level changes this late in the release cycle. We expect to remove
this in the subsequent release.

This change also adds the unit test cases for bool conversions in
GfNumericCast from pull request #3855.

See #3855

(Internal change: 2382628)

Author: sunyab

pxr/base/gf/numericCast.h

@@ -10,6 +10,7 @@
 #include "pxr/pxr.h"
 
 #include "pxr/base/gf/traits.h"
+#include "pxr/base/arch/pragmas.h"
 
 #include <cmath>
 #include <limits>
@@ -29,6 +30,15 @@ template <class T, class U>
 constexpr bool
 GfIntegerCompareLess(T t, U u) noexcept
 {
+    // XXX: 
+    // On Visual Studio warning C4018 (signed/unsigned mismatch) is emitted
+    // when this function is used with boolean values. Just disable this
+    // for now.
+#if defined(ARCH_COMPILER_MSVC)
+    ARCH_PRAGMA_PUSH
+    ARCH_PRAGMA(warning(disable:4018))
+#endif    
+
     static_assert(std::is_integral_v<T> && std::is_integral_v<U>);
 
     if constexpr (std::is_signed_v<T> == std::is_signed_v<U>) {
@@ -40,6 +50,10 @@ GfIntegerCompareLess(T t, U u) noexcept
     else {
         return u >= 0 && t < std::make_unsigned_t<U>(u);
     }
+
+#if defined(ARCH_COMPILER_MSVC)
+    ARCH_PRAGMA_POP
+#endif
 }
 
 enum GfNumericCastFailureType {

pxr/base/gf/testenv/testGfHardToReach.cpp

@@ -252,6 +252,33 @@ main(int argc, char *argv[])
                      static_cast<float>(
                          std::numeric_limits<int16_t>::lowest()) - 1.0f,
                      &failType) && failType == GfNumericCastNegOverflow);
+
+        // bool -> int
+        TF_AXIOM(GfNumericCast<int>(true).value() == 1);
+        TF_AXIOM(GfNumericCast<int>(false).value() == 0);
+
+        // int -> bool
+        TF_AXIOM(GfNumericCast<bool>(0).value() == false);
+        TF_AXIOM(GfNumericCast<bool>(1).value() == true);
+
+        TF_AXIOM(!GfNumericCast<bool>(-1, &failType) &&
+                 failType == GfNumericCastNegOverflow);
+
+        TF_AXIOM(!GfNumericCast<bool>(2, &failType) &&
+                 failType == GfNumericCastPosOverflow);
+
+        TF_AXIOM(GfNumericCast<bool>(
+                    static_cast<unsigned>(0)).value() == false);
+        TF_AXIOM(GfNumericCast<bool>(
+                    static_cast<unsigned>(1)).value() == true);
+
+        TF_AXIOM(!GfNumericCast<bool>(
+                    static_cast<unsigned>(2), &failType) &&
+                 failType == GfNumericCastPosOverflow);
+
+        TF_AXIOM(!GfNumericCast<bool>(
+                     std::numeric_limits<unsigned>::max(), &failType) &&
+                 failType == GfNumericCastPosOverflow);
 
         // unsigned
         TF_AXIOM(GfNumericCast<uint16_t>(