CMake: Extract major.minor.patch in VERSION argument

LLVM has a strict compatibility check in the CMake packages they
provide. Therefore, we cannot pass a non-conformant version string,
such as `21.0.0git`, to the `find_package()` call for Clang or LLVM.

A recent change modified the FindWrapLibclang.cmake script such that
developer builds would strip out the `git` suffix. Of course, release
candidates have other suffixes, so dropping `git` is too narrow. A
more robust solution is to extract the major.minor.patch version,
i.e. turning both of `21.1.0-rc3` and `21.1.0git` into `21.1.0`.

The function that does the work is renamed to better reflect its
purpose, and all three call-sites are updated. The change is
cherry-picked to the branches that were targeted by the parent change.

This change amends 39f0f48.

Task-number: QTBUG-139407
Pick-to: 6.10 6.9 6.8
Change-Id: I06409a394c5f994f88d516efd5d9e03de06cb468
Reviewed-by: Topi Reiniö <[email protected]>

Author: paulwicking

cmake/FindWrapLibClang.cmake

@@ -17,10 +17,10 @@ endif()
 include(FindPackageHandleStandardArgs)
 set(WrapLibClang_FOUND FALSE)
 
-# Strip a possible trailing `git` from the version string for developer builds.
-function(strip_git_from_version IN OUT)
+# Extract major.minor.patch version from version string for developer builds.
+function(normalize_version_for_dev_build IN OUT)
     if(QT_FEATURE_developer_build)
-        string(REGEX REPLACE "git$" "" _clean "${${IN}}")
+        string(REGEX MATCH "^([0-9]+\\.[0-9]+\\.[0-9]+)" _clean "${${IN}}")
         if(_clean STREQUAL "")
             set(_clean "${${IN}}")
         endif()
@@ -46,7 +46,7 @@ if(QT_NO_FIND_PACKAGE_CLANG_WORKAROUND)
     set(Clang_FOUND FALSE)
     foreach(VERSION ${QDOC_SUPPORTED_CLANG_VERSIONS})
         if(NOT Clang_FOUND)
-            strip_git_from_version(VERSION VERSION_CLEAN)
+            normalize_version_for_dev_build(VERSION VERSION_CLEAN)
             find_package(Clang ${VERSION_CLEAN} CONFIG QUIET)
         endif()
     endforeach()
@@ -62,7 +62,7 @@ else()
     set(LLVM_FOUND FALSE)
     foreach(VERSION ${QDOC_SUPPORTED_CLANG_VERSIONS})
         if(NOT LLVM_FOUND)
-            strip_git_from_version(VERSION VERSION_CLEAN)
+            normalize_version_for_dev_build(VERSION VERSION_CLEAN)
             find_package(LLVM ${VERSION_CLEAN} CONFIG QUIET)
         endif()
     endforeach()
@@ -96,7 +96,7 @@ else()
     unset(__qt_wraplibclang CACHE)
 
     # Now, we're pretty certain that we can find the 'Clang' package without running into errors.
-    strip_git_from_version(LLVM_VERSION LLVM_VERSION_CLEAN)
+    normalize_version_for_dev_build(LLVM_VERSION LLVM_VERSION_CLEAN)
     find_package(Clang ${LLVM_VERSION_CLEAN} EXACT CONFIG)
 endif()