macOS: Added new location for Homebrew.

The build script for macOS dependencies expects to find bison provided
by Homebrew under /usr/local. Since the default install location for
Homebrew changes on macOS/ARM, the script now looks at the host
architecture and switches to /opt/homebrew on Macs with Apple Silicon.

build_files/build_environment/cmake/check_software.cmake

@@ -42,7 +42,13 @@ if(UNIX)
   endforeach()
 
   if(APPLE)
-    if(NOT EXISTS "/usr/local/opt/bison/bin/bison")
+    # Homebrew has different default locations for ARM and Intel macOS.
+    if("${CMAKE_HOST_SYSTEM_PROCESSOR}" STREQUAL "arm64")
+      set(HOMEBREW_LOCATION "/opt/homebrew")
+    else()
+      set(HOMEBREW_LOCATION "/usr/local")
+    endif()
+    if(NOT EXISTS "${HOMEBREW_LOCATION}/opt/bison/bin/bison")
       string(APPEND _software_missing " bison")
     endif()
   endif()

build_files/build_environment/cmake/ispc.cmake

@@ -25,8 +25,13 @@ if(WIN32)
 elseif(APPLE)
   # Use bison installed via Homebrew.
   # The one which comes which Xcode toolset is too old.
+  if("${CMAKE_HOST_SYSTEM_PROCESSOR}" STREQUAL "arm64")
+    set(HOMEBREW_LOCATION "/opt/homebrew")
+  else()
+    set(HOMEBREW_LOCATION "/usr/local")
+  endif()
   set(ISPC_EXTRA_ARGS_APPLE
-    -DBISON_EXECUTABLE=/usr/local/opt/bison/bin/bison
+    -DBISON_EXECUTABLE=${HOMEBREW_LOCATION}/opt/bison/bin/bison
   )
 elseif(UNIX)
   set(ISPC_EXTRA_ARGS_UNIX