Restore default RPATH settings but allow packages to limit to immediate deps. (#1954)

- Some packages (netcdf) NEED RPATHs for transitive deps.
- Others (dealii) will exceed OS limits when the DAG is too large.

lib/spack/spack/build_environment.py

@@ -383,8 +383,11 @@ def set_module_variables_for_package(pkg, module):
 
 
 def get_rpath_deps(pkg):
-    """We only need to RPATH immediate dependencies."""
-    return pkg.spec.dependencies(deptype='link')
+    """Return immediate or transitive RPATHs depending on the package."""
+    if pkg.transitive_rpaths:
+        return [d for d in pkg.spec.traverse(root=False, deptype=('link'))]
+    else:
+        return pkg.spec.dependencies(deptype='link')
 
 
 def get_rpaths(pkg):

lib/spack/spack/package.py

@@ -310,17 +310,26 @@ class SomePackage(Package):
     #
     """By default we build in parallel.  Subclasses can override this."""
     parallel = True
+
     """# jobs to use for parallel make. If set, overrides default of ncpus."""
     make_jobs = None
+
     """By default do not run tests within package's install()"""
     run_tests = False
+
     """Most packages are NOT extendable. Set to True if you want extensions."""
     extendable = False
+
+    """When True, add RPATHs for the entire DAG. When False, add RPATHs only
+       for immediate dependencies."""
+    transitive_rpaths = True
+
     """List of prefix-relative file paths (or a single path). If these do
        not exist after install, or if they exist but are not files,
        sanity checks fail.
     """
     sanity_check_is_file = []
+
     """List of prefix-relative directory paths (or a single path). If
        these do not exist after install, or if they exist but are not
        directories, sanity checks will fail.