Synchronize upgrade-options.rst
+=============================================
Options that control the installation process
----------------------------------------------
+=============================================
When installing packages, pip chooses a distribution file, and installs it in
the user's environment. There are many choices involved in deciding which file
to install, and these are controlled by a variety of options.
+
Controlling what gets installed
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+===============================
These options directly affect how the resolver uses the list of available
distribution files to decide which one to install. So these modify the
@@ -51,8 +53,9 @@ current version in place. This occurs even if ``--upgrade`` is not set.
Act as if the currently installed version isn't there - so don't care about
``--upgrade``, and don't uninstall before (re-)installing.
+
Controlling what gets considered
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+================================
These options affect the list of distribution files that the resolver will
consider as candidates for installation. As such, they affect the data that
@@ -89,8 +92,9 @@ Index options
``--find-links``
+
Controlling dependency data
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
+===========================
These options control what dependency data the resolver sees for any given
package (or, in the case of ``--python-version``, the environment information
@@ -102,8 +106,9 @@ the resolver uses to *check* the dependency).
``--ignore-requires-python``
+
Special cases
-~~~~~~~~~~~~~
+=============
These need further investigation. They affect the install process, but not
necessarily resolution or what gets installed.
