cpp23: fix source so it compiles with c++23

CMakeLists.txt

@@ -174,6 +174,13 @@ if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANGCC OR CMAKE_COMPILER_IS_IC
         list(APPEND OSD_COMPILER_FLAGS -DNOMINMAX)
     endif()
 
+    if(CMAKE_COMPILER_IS_CLANGCC)
+        # Since C++23 libc++ is in the process of splitting larger headers into smaller modular headers.
+        # Force this behavior for the older dialects to keep the C++23 build green.
+        # See https://libcxx.llvm.org/DesignDocs/HeaderRemovalPolicy.html
+        list(APPEND OSD_COMPILER_FLAGS -D_LIBCPP_REMOVE_TRANSITIVE_INCLUDES)
+    endif()
+
     # HBR uses the offsetof macro on a templated struct, which appears
     # to spuriously set off this warning in both gcc and Clang
     list(APPEND OSD_COMPILER_FLAGS -Wno-invalid-offsetof)

opensubdiv/bfr/tessellation.cpp

@@ -10,6 +10,7 @@
 #include <cstring>
 #include <cstdio>
 #include <cassert>
+#include <cmath>
 #include <limits>
 #include <algorithm>
 

tutorials/bfr/tutorial_1_1/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_1_2/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_1_3/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_1_4/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_1_5/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_2_1/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_2_2/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_3_1/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }

tutorials/bfr/tutorial_3_2/objWriter.h

@@ -20,7 +20,7 @@ namespace tutorial {
 //
 class ObjWriter {
 public:
-    ObjWriter(std::string const &filename = 0);
+    ObjWriter(std::string const &filename = std::string());
     ~ObjWriter();
 
     int GetNumVertices() const { return _numVertices; }