[cmake] Fix version derivation on win/mac (#4215)

On Windows and macOS, our version includes a "win" or "mac" suffix in
the `<build>` component. In actual releases, that is all that the
`<build>` component consists of. This updates that part of the version
derivation logic such that the semantic version grammar is respected and
WiX accepts our version. We no longer have "+full" in our release tags
and we need our suffixes to be properly separated from the rest of the
version. In particular, they need to come after a single plus ('+') and
must be separated from other parts of the `<build>` component with dots
('.').

See
https://semver.org/#backusnaur-form-grammar-for-valid-semver-versions.

Author: sharder996

CMakeLists.txt

@@ -220,15 +220,23 @@ function(determine_version OUTPUT_VARIABLE)
     message(FATAL_ERROR "Failed to parse version number: ${GIT_VERSION}")
   endif()
 
-  if(APPLE OR MSVC)
-    string(REGEX MATCH "\\+full$" FULL_SUFFIX_MATCH ${NEW_VERSION})
-    if(NOT FULL_SUFFIX_MATCH)
-      set(NEW_VERSION ${NEW_VERSION}.full)
+  # assert that the output of `git describe` does not include "full" any longer (after merger)
+  string(FIND "${NEW_VERSION}" "full" FULL_POSITION)
+  if(FULL_POSITION GREATER_EQUAL 0)
+      message(FATAL_ERROR "Version string should not contain 'full': ${NEW_VERSION}")
+  endif()
+
+  if(APPLE OR WIN32)
+    set(VERSION_SEPARATOR "+")
+    string(FIND "${NEW_VERSION}" "+" PLUS_POSITION)
+    if(PLUS_POSITION GREATER_EQUAL 0)
+      set(VERSION_SEPARATOR ".")
     endif()
+
     if(APPLE)
-      string(REPLACE "full" "mac" NEW_VERSION ${NEW_VERSION})
+      string(APPEND NEW_VERSION "${VERSION_SEPARATOR}mac")
     else()
-      string(REPLACE "full" "win" NEW_VERSION ${NEW_VERSION})
+      string(APPEND NEW_VERSION "${VERSION_SEPARATOR}win")
     endif()
   endif()