From 07c091119fc56bc455133060bfbceda36debfb95 Mon Sep 17 00:00:00 2001
From: Joseph Brill <48932340+jcbrill@users.noreply.github.com>
Date: Fri, 7 Aug 2020 06:09:09 -0400
Subject: Rework vc.py caching of installed vcs and remove
 cached_get_installed_vcs function. Replace external references to
 cached_get_installed_vcs with get_installed_vcs. Update CHANGES.txt.

---
 CHANGES.txt               |  4 ++++
 SCons/Tool/MSCommon/vc.py | 20 +++++++++-----------
 test/MSVC/MSVC_UWP_APP.py |  2 +-
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 7250a9b..cfc3a02 100755
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -8,6 +8,10 @@ NOTE: The 4.0.0 Release of SCons dropped Python 2.7 Support
 
 RELEASE  VERSION/DATE TO BE FILLED IN LATER
 
+  From Joseph Brill:
+    - MSVC and test updates: Rework the msvc installed versions cache so that it is not
+      exposed externally and update external references accordingly.
+
   From William Deegan:
     - Fix yacc tool, not respecting YACC set at time of tool initialization.
 
diff --git a/SCons/Tool/MSCommon/vc.py b/SCons/Tool/MSCommon/vc.py
index c6417e9..886288a 100644
--- a/SCons/Tool/MSCommon/vc.py
+++ b/SCons/Tool/MSCommon/vc.py
@@ -657,16 +657,12 @@ def _check_cl_exists_in_vc_dir(env, vc_dir, msvc_version):
 
     return False
 
-def cached_get_installed_vcs(env=None):
+def get_installed_vcs(env=None):
     global __INSTALLED_VCS_RUN
 
-    if __INSTALLED_VCS_RUN is None:
-        ret = get_installed_vcs(env)
-        __INSTALLED_VCS_RUN = ret
-
-    return __INSTALLED_VCS_RUN
+    if __INSTALLED_VCS_RUN is not None:
+        return __INSTALLED_VCS_RUN
 
-def get_installed_vcs(env=None):
     installed_versions = []
 
     for ver in _VCVER:
@@ -687,7 +683,9 @@ def get_installed_vcs(env=None):
             raise
         except VisualCException as e:
             debug('did not find VC %s: caught exception %s' % (ver, str(e)))
-    return installed_versions
+
+    __INSTALLED_VCS_RUN = installed_versions
+    return __INSTALLED_VCS_RUN
 
 def reset_installed_vcs():
     """Make it try again to find VC.  This is just for the tests."""
@@ -758,7 +756,7 @@ def get_default_version(env):
         return msvs_version
 
     if not msvc_version:
-        installed_vcs = cached_get_installed_vcs(env)
+        installed_vcs = get_installed_vcs(env)
         debug('installed_vcs:%s' % installed_vcs)
         if not installed_vcs:
             #msg = 'No installed VCs'
@@ -853,7 +851,7 @@ def msvc_find_valid_batch_script(env, version):
             warn_msg = "VC version %s not installed.  " + \
                        "C/C++ compilers are most likely not set correctly.\n" + \
                        " Installed versions are: %s"
-            warn_msg = warn_msg % (version, cached_get_installed_vcs(env))
+            warn_msg = warn_msg % (version, get_installed_vcs(env))
             SCons.Warnings.warn(SCons.Warnings.VisualCMissingWarning, warn_msg)
             continue
 
@@ -948,7 +946,7 @@ def msvc_setup_env(env):
         SCons.Warnings.warn(SCons.Warnings.VisualCMissingWarning, warn_msg)
 
 def msvc_exists(env=None, version=None):
-    vcs = cached_get_installed_vcs(env)
+    vcs = get_installed_vcs(env)
     if version is None:
         return len(vcs) > 0
     return version in vcs
diff --git a/test/MSVC/MSVC_UWP_APP.py b/test/MSVC/MSVC_UWP_APP.py
index 0f33dda..4bb2f5c 100644
--- a/test/MSVC/MSVC_UWP_APP.py
+++ b/test/MSVC/MSVC_UWP_APP.py
@@ -82,7 +82,7 @@ test = TestSCons.TestSCons()
 
 test.skip_if_not_msvc()
 
-installed_msvc_versions = msvc.cached_get_installed_vcs()
+installed_msvc_versions = msvc.get_installed_vcs()
 # MSVC guaranteed to be at least one version on the system or else
 # skip_if_not_msvc() function would have skipped the test
 
-- 
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