Fix clang-13 unused-private-field

This change guards unused private members that exist purely for ABI compatibility between USD builds with and without Python support enabled (see #1716) with a new pragma to disable warnings on clang. Part of PR #1684 from @charlesfleche (Internal change: 2265598)
PixarAnimationStudios · Mar 14, 2023 · 73622a0 · 73622a0
1 parent f08f530
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diff --git a/pxr/base/arch/pragmas.h b/pxr/base/arch/pragmas.h
@@ -93,6 +93,9 @@
     #define ARCH_PRAGMA_UNUSED_FUNCTION \
         _Pragma("clang diagnostic ignored \"-Wunused-function\"")
 
+    #define ARCH_PRAGMA_UNUSED_PRIVATE_FIELD \
+        _Pragma("clang diagnostic ignored \"-Wunused-private-field\"")
+
     #define ARCH_PRAGMA_INSTANTIATION_AFTER_SPECIALIZATION \
         _Pragma("clang diagnostic ignored \"-Winstantiation-after-specialization\"")
 
@@ -195,6 +198,10 @@
     #define ARCH_PRAGMA_UNUSED_FUNCTION
 #endif
 
+#if !defined ARCH_PRAGMA_UNUSED_PRIVATE_FIELD
+    #define ARCH_PRAGMA_UNUSED_PRIVATE_FIELD
+#endif
+
 #if !defined ARCH_PRAGMA_MACRO_TOO_FEW_ARGUMENTS
     #define ARCH_PRAGMA_MACRO_TOO_FEW_ARGUMENTS
 #endif

diff --git a/pxr/base/tf/pyObjWrapper.h b/pxr/base/tf/pyObjWrapper.h
@@ -27,6 +27,7 @@
 #include "pxr/pxr.h"
 
 #include "pxr/base/tf/api.h"
+#include "pxr/base/arch/pragmas.h"
 
 #ifdef PXR_PYTHON_SUPPORT_ENABLED
 // Include this header first to pick up additional mitigations
@@ -57,7 +58,10 @@ class TfPyObjWrapperStub
     static constexpr std::size_t Align = 8;
 
 private:
+    ARCH_PRAGMA_PUSH
+    ARCH_PRAGMA_UNUSED_PRIVATE_FIELD
     std::aligned_storage<Size, Align>::type _stub;
+    ARCH_PRAGMA_POP
 };
 
 

diff --git a/pxr/base/trace/collector.h b/pxr/base/trace/collector.h
@@ -45,6 +45,8 @@
 #include "pxr/base/tf/weakBase.h"
 #include "pxr/base/tf/weakPtr.h"
 
+#include "pxr/base/arch/pragmas.h"
+
 #include <atomic>
 #include <string>
 #include <vector>
@@ -619,8 +621,18 @@ class TraceCollector : public TfWeakBase {
 
     TimeStamp _measuredScopeOverhead;
 
+    // These members are unused if Python support is disabled. However, we
+    // leave them in place and just mark them unused to provide ABI
+    // compatibility between USD builds with and without Python enabled.
+#ifndef PXR_PYTHON_SUPPORT_ENABLED    
+    ARCH_PRAGMA_PUSH
+    ARCH_PRAGMA_UNUSED_PRIVATE_FIELD
+#endif
     std::atomic<int> _isPythonTracingEnabled;
     TfPyTraceFnId _pyTraceFnId;
+#ifndef PXR_PYTHON_SUPPORT_ENABLED
+    ARCH_PRAGMA_POP
+#endif
 };
 
 TRACE_API_TEMPLATE_CLASS(TfSingleton<TraceCollector>);