build_usd.py: Ensure use of TBB libraries from build script

This fixes an issue where the OpenUSD build could incorrectly pick up a
oneTBB library from somewhere else on the system instead of the library
built by the build script.

This change adds a new PXR_FIND_TBB_IN_CONFIG option to explicitly control
whether to find TBB in config mode or via the FindTBB.cmake module. build_usd.py
enables this option if using oneTBB and disables it when using legacy TBB.
This ensures the build only uses the appropriate mechanism for whichever
library is built by the script.

By default this option is unset, so clients building OpenUSD via cmake directly
will see no changes in behavior.

Fixes #3610

(Internal change: 2380256)

Author: tallytalwar

build_scripts/build_usd.py

@@ -1672,6 +1672,11 @@ def InstallUSD(context, force, buildArgs):
         extraArgs.append('-DPXR_PREFER_SAFETY_OVER_SPEED={}'
                          .format('ON' if context.safetyFirst else 'OFF'))
 
+        if context.buildOneTBB:
+            extraArgs.append('-DPXR_FIND_TBB_IN_CONFIG=ON')
+        else:
+            extraArgs.append('-DPXR_FIND_TBB_IN_CONFIG=OFF')
+
         if context.buildPython:
             extraArgs.append('-DPXR_ENABLE_PYTHON_SUPPORT=ON')
 

cmake/defaults/Packages.cmake

@@ -106,12 +106,23 @@ if(WIN32)
 endif()
 
 # --TBB
-find_package(TBB CONFIG COMPONENTS tbb)
-if(TBB_FOUND) 
-    set(PXR_FIND_TBB_IN_CONFIG ON)
+if (DEFINED PXR_FIND_TBB_IN_CONFIG)
+    if (PXR_FIND_TBB_IN_CONFIG)
+        find_package(TBB CONFIG REQUIRED COMPONENTS tbb)
+    else()
+        find_package(TBB REQUIRED COMPONENTS tbb)
+    endif()
 else()
-    find_package(TBB REQUIRED COMPONENTS tbb)
-    set(PXR_FIND_TBB_IN_CONFIG OFF)
+    # Set PXR_FIND_TBB_IN_CONFIG appropriately so that downstream
+    # pxrConfig knows how TBB was found and appropriately encodes the 
+    # dependency.
+    find_package(TBB CONFIG COMPONENTS tbb)
+    if (TBB_FOUND)
+        set(PXR_FIND_TBB_IN_CONFIG ON)
+    else()
+        find_package(TBB REQUIRED COMPONENTS tbb)
+        set(PXR_FIND_TBB_IN_CONFIG OFF)
+    endif()
 endif()
 
 # --math