From 4a3ee6a74a1416451cfc94be9be788b39e2f97ec Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Thu, 5 Jan 2017 10:57:00 +0000
Subject: [PATCH] Relax base-package and SimGear version checks.
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As discussed on the devel list, only require the major+minor versions
of FG+SG+data to match by default. If we encounter a situation on
a release branch where stronger checks are needed, it’s easy to
restore.
---
 CMakeLists.txt       | 13 +++++++++++--
 src/Main/options.cxx | 13 +++++++++----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index be2584b4e..ae717fabd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -314,8 +314,17 @@ endif (ENABLE_QT)
 
 find_package(PLIB REQUIRED puaux pu js fnt)
 
-# FlightGear and SimGear versions need to match
-find_package(SimGear ${FLIGHTGEAR_VERSION} CONFIG REQUIRED)
+# FlightGear and SimGear versions need to match major + minor
+# split version string into components, note CMAKE_MATCH_0 is the entire regexp match
+string(REGEX MATCH "([0-9]+)\\.([0-9]+)\\.([0-9]+)" VERSION_REGEX ${FLIGHTGEAR_VERSION} )
+set(FG_VERSION_MAJOR ${CMAKE_MATCH_1})
+set(FG_VERSION_MINOR ${CMAKE_MATCH_2})
+set(FG_VERSION_PATCH ${CMAKE_MATCH_3})
+
+set(MIN_SIMGEAR_VERSION "${FG_VERSION_MAJOR}.${FG_VERSION_MINOR}.0")
+message(STATUS "Min Simgear version is ${MIN_SIMGEAR_VERSION}")
+
+find_package(SimGear ${MIN_SIMGEAR_VERSION} CONFIG REQUIRED)
 
 ##############################################################################
 
diff --git a/src/Main/options.cxx b/src/Main/options.cxx
index ad12ba0ec..96a6fb538 100644
--- a/src/Main/options.cxx
+++ b/src/Main/options.cxx
@@ -2711,15 +2711,18 @@ void Options::setupRoot(int argc, char **argv)
   }
 
   globals->set_fg_root(root);
-    static char required_version[] = FLIGHTGEAR_VERSION;
     string base_version = fgBasePackageVersion(root);
 
+
 #if defined(HAVE_QT)
+    // only compare major and minor version, not the patch level.
+    const int versionComp = simgear::strutils::compare_versions(FLIGHTGEAR_VERSION, base_version, 2);
+
     // note we never end up here if restoring a user selected root via
     // the Qt GUI, since that code pre-validates the path. But if we're using
     // a command-line, env-var or default root this check can fail and
     // we still want to use the GUI in that case
-    if (base_version != required_version) {
+    if (versionComp != 0) {
         flightgear::initApp(argc, argv);
         SetupRootDialog::runDialog(usingDefaultRoot);
     }
@@ -2733,12 +2736,14 @@ void Options::setupRoot(int argc, char **argv)
         exit(-1);
     }
 
-    if (base_version != required_version) {
+    // only compare major and minor version, not the patch level.
+    const int versionComp = simgear::strutils::compare_versions(FLIGHTGEAR_VERSION, base_version, 2);
+    if (versionComp != 0) {
       flightgear::fatalMessageBox("Base package version mismatch",
                                   "Version check failed: please check your installation.",
                                   "Found data files for version '" + base_version +
                                   "' at '" + globals->get_fg_root().str() + "', version '"
-                                  + required_version + "' is required.");
+                                  + std::string(FLIGHTGEAR_VERSION) + "' is required.");
 
     exit(-1);
   }