Ask candidates for dependencies even on --no-deps

ExtrasCandidate need to provide one dependency on the non-extra-ed self.

src/pip/_internal/resolution/resolvelib/base.py

@@ -69,8 +69,8 @@ class Candidate(object):
         # type: () -> Optional[Link]
         raise NotImplementedError("Override in subclass")
 
-    def iter_dependencies(self):
-        # type: () -> Iterable[Optional[Requirement]]
+    def iter_dependencies(self, ignore_dependencies):
+        # type: (bool) -> Iterable[Optional[Requirement]]
         raise NotImplementedError("Override in subclass")
 
     def get_install_requirement(self):

src/pip/_internal/resolution/resolvelib/candidates.py

@@ -275,8 +275,10 @@ class _InstallRequirementBackedCandidate(Candidate):
             return None
         return spec
 
-    def iter_dependencies(self):
-        # type: () -> Iterable[Optional[Requirement]]
+    def iter_dependencies(self, ignore_dependencies):
+        # type: (bool) -> Iterable[Optional[Requirement]]
+        if ignore_dependencies:
+            return
         for r in self.dist.requires():
             yield self._factory.make_requirement_from_spec(str(r), self._ireq)
         python_dep = self._factory.make_requires_python_requirement(
@@ -420,8 +422,10 @@ class AlreadyInstalledCandidate(Candidate):
         # type: () -> str
         return "{} {} (Installed)".format(self.name, self.version)
 
-    def iter_dependencies(self):
-        # type: () -> Iterable[Optional[Requirement]]
+    def iter_dependencies(self, ignore_dependencies):
+        # type: (bool) -> Iterable[Optional[Requirement]]
+        if ignore_dependencies:
+            return
         for r in self.dist.requires():
             yield self._factory.make_requirement_from_spec(str(r), self._ireq)
 
@@ -519,10 +523,16 @@ class ExtrasCandidate(Candidate):
         # type: () -> Optional[Link]
         return self.base.source_link
 
-    def iter_dependencies(self):
-        # type: () -> Iterable[Optional[Requirement]]
+    def iter_dependencies(self, ignore_dependencies):
+        # type: (bool) -> Iterable[Optional[Requirement]]
         factory = self.base._factory
 
+        # Add a dependency on the exact base
+        # (See note 2b in the class docstring)
+        yield factory.make_requirement_from_candidate(self.base)
+        if ignore_dependencies:
+            return
+
         # The user may have specified extras that the candidate doesn't
         # support. We ignore any unsupported extras here.
         valid_extras = self.extras.intersection(self.base.dist.extras)
@@ -535,10 +545,6 @@ class ExtrasCandidate(Candidate):
                 extra
             )
 
-        # Add a dependency on the exact base
-        # (See note 2b in the class docstring)
-        yield factory.make_requirement_from_candidate(self.base)
-
         for r in self.base.dist.requires(valid_extras):
             requirement = factory.make_requirement_from_spec(
                 str(r), self.base._ireq, valid_extras,
@@ -585,8 +591,8 @@ class RequiresPythonCandidate(Candidate):
         # type: () -> str
         return "Python {}".format(self.version)
 
-    def iter_dependencies(self):
-        # type: () -> Iterable[Optional[Requirement]]
+    def iter_dependencies(self, ignore_dependencies):
+        # type: (bool) -> Iterable[Optional[Requirement]]
         return ()
 
     def get_install_requirement(self):

src/pip/_internal/resolution/resolvelib/provider.py

@@ -145,6 +145,8 @@ class PipProvider(AbstractProvider):
 
     def get_dependencies(self, candidate):
         # type: (Candidate) -> Sequence[Requirement]
-        if self._ignore_dependencies:
-            return []
-        return [r for r in candidate.iter_dependencies() if r is not None]
+        return [
+            r
+            for r in candidate.iter_dependencies(self._ignore_dependencies)
+            if r is not None
+        ]