allow install of build-deps from cache via --include-build-deps switch (#19955)

* allow install of build-deps from cache via --include-build-deps switch

* make clear that --include-build-deps is useful for CI pipeline troubleshooting

lib/spack/spack/cmd/install.py

@@ -43,6 +43,7 @@ def update_kwargs_from_args(args, kwargs):
         'dirty': args.dirty,
         'use_cache': args.use_cache,
         'cache_only': args.cache_only,
+        'include_build_deps': args.include_build_deps,
         'explicit': True,  # Always true for install command
         'stop_at': args.until,
         'unsigned': args.unsigned,
@@ -105,6 +106,11 @@ def setup_parser(subparser):
         '--cache-only', action='store_true', dest='cache_only', default=False,
         help="only install package from binary mirrors")
 
+    subparser.add_argument(
+        '--include-build-deps', action='store_true', dest='include_build_deps',
+        default=False, help="""include build deps when installing from cache,
+which is useful for CI pipeline troubleshooting""")
+
     subparser.add_argument(
         '--no-check-signature', action='store_true',
         dest='unsigned', default=False,

lib/spack/spack/installer.py

@@ -1367,7 +1367,6 @@ def install(self):
 
             pkg, pkg_id, spec = task.pkg, task.pkg_id, task.pkg.spec
             tty.verbose('Processing {0}: task={1}'.format(pkg_id, task))
-
             # Ensure that the current spec has NO uninstalled dependencies,
             # which is assumed to be reflected directly in its priority.
             #
@@ -1967,7 +1966,8 @@ def get_deptypes(self, pkg):
             (tuple) required dependency type(s) for the package
         """
         deptypes = ['link', 'run']
-        if not self.install_args.get('cache_only'):
+        include_build_deps = self.install_args.get('include_build_deps')
+        if not self.install_args.get('cache_only') or include_build_deps:
             deptypes.append('build')
         if self.run_tests(pkg):
             deptypes.append('test')