setup_platform_environment before package env mods (#41205)

This roughly restores the order of operation from Spack 0.20,
where where `AutotoolsPackage.setup_build_environment` would
override the env variable set in `setup_platform_environment` on
macOS.

1 files changed, 6 insertions, 5 deletions

diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index 4c4eca6567..36574259d0 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -743,15 +743,16 @@ def setup_package(pkg, dirty, context: Context = Context.BUILD):
         set_compiler_environment_variables(pkg, env_mods)
         set_wrapper_variables(pkg, env_mods)
 
-    tty.debug("setup_package: grabbing modifications from dependencies")
-    env_mods.extend(setup_context.get_env_modifications())
-    tty.debug("setup_package: collected all modifications from dependencies")
-
-    # architecture specific setup
+    # Platform specific setup goes before package specific setup. This is for setting
+    # defaults like MACOSX_DEPLOYMENT_TARGET on macOS.
     platform = spack.platforms.by_name(pkg.spec.architecture.platform)
     target = platform.target(pkg.spec.architecture.target)
     platform.setup_platform_environment(pkg, env_mods)
 
+    tty.debug("setup_package: grabbing modifications from dependencies")
+    env_mods.extend(setup_context.get_env_modifications())
+    tty.debug("setup_package: collected all modifications from dependencies")
+
     if context == Context.TEST:
         env_mods.prepend_path("PATH", ".")
     elif context == Context.BUILD and not dirty and not env_mods.is_unset("CPATH"):