Pass use_pep517 option to resolver

src/pip/_internal/commands/install.py

@@ -310,6 +310,7 @@ def run(self, options, args):
                         ignore_requires_python=options.ignore_requires_python,
                         ignore_installed=options.ignore_installed,
                         isolated=options.isolated_mode,
+                        use_pep517=options.use_pep517
                     )
                     resolver.resolve(requirement_set)
 

src/pip/_internal/req/constructors.py

@@ -274,7 +274,8 @@ def install_req_from_line(
 
 
 def install_req_from_req(
-    req, comes_from=None, isolated=False, wheel_cache=None
+    req, comes_from=None, isolated=False, wheel_cache=None,
+    use_pep517=None
 ):
     try:
         req = Requirement(req)
@@ -293,7 +294,7 @@ def install_req_from_req(
             "%s depends on %s " % (comes_from.name, req)
         )
 
-    # TODO: use_pep517?
     return InstallRequirement(
-        req, comes_from, isolated=isolated, wheel_cache=wheel_cache
+        req, comes_from, isolated=isolated, wheel_cache=wheel_cache,
+        use_pep517=use_pep517
     )

src/pip/_internal/resolve.py

@@ -35,7 +35,7 @@ class Resolver(object):
 
     def __init__(self, preparer, session, finder, wheel_cache, use_user_site,
                  ignore_dependencies, ignore_installed, ignore_requires_python,
-                 force_reinstall, isolated, upgrade_strategy):
+                 force_reinstall, isolated, upgrade_strategy, use_pep517=None):
         super(Resolver, self).__init__()
         assert upgrade_strategy in self._allowed_strategies
 
@@ -56,6 +56,7 @@ def __init__(self, preparer, session, finder, wheel_cache, use_user_site,
         self.ignore_installed = ignore_installed
         self.ignore_requires_python = ignore_requires_python
         self.use_user_site = use_user_site
+        self.use_pep517 = use_pep517
 
         self._discovered_dependencies = defaultdict(list)
 
@@ -273,6 +274,7 @@ def add_req(subreq, extras_requested):
                 req_to_install,
                 isolated=self.isolated,
                 wheel_cache=self.wheel_cache,
+                use_pep517=self.use_pep517
             )
             parent_req_name = req_to_install.name
             to_scan_again, add_to_parent = requirement_set.add_requirement(