CMake: Drop 'git' in VERSION argument for dev builds

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.

QDoc carries a fork of `clang/AST/QualTypeNames` due to upstream changes
between LLVM 15 and LLVM 16 that were deemed incompatible with QDoc's
needs. As this class sees upstream modifications that break compilation,
there's a need to bisect LLVM to track down the offending upstream
change, so that QDoc's implementation can be modified to work correctly
alongside newer versions of LLVM. These builds contain version strings
that contain 'git' as a suffix, and thus break the developer experience
in qttools.git.

To mitigate this problem, this change strips the suffix by a simple
regular expression based string replacement. The new behavior is gated
with `QT_FEATURE_developer_build` (the feature flag defined by a
`-developer-build` configuration of qtbase.git). The rationale is that,
as this is strictly speaking a convenience for me, myself, and I, it
should not be the default behavior of the CMake script, and if run in
an environment that's a developer build, it's reasonable to expect that
the developer responsible for configuring qttools.git is able to find
and understand why this happens.

This change extends the logic implemented in
914e00b and is, as such, cherry-picked
as far back as to the branches that change targeted.

Task-number: QTBUG-139407
Pick-to: 6.8
Change-Id: Id5dea0678037cc5f86343b7aa0421b27c6ad13c0
Reviewed-by: Topi Reiniö <[email protected]>
Reviewed-by: David Boddie <[email protected]>
(cherry picked from commit 39f0f48)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>
(cherry picked from commit f61c47e)
Reviewed-by: Paul Wicking <[email protected]>

Author: paulwicking

cmake/FindWrapLibClang.cmake

@@ -17,11 +17,25 @@ 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)
+    if(QT_FEATURE_developer_build)
+        string(REGEX REPLACE "git$" "" _clean "${${IN}}")
+        if(_clean STREQUAL "")
+            set(_clean "${${IN}}")
+        endif()
+        set(${OUT} "${_clean}" PARENT_SCOPE)
+    else()
+        set(${OUT} "${${IN}}" PARENT_SCOPE)
+    endif()
+endfunction()
+
 if(QT_NO_FIND_PACKAGE_CLANG_WORKAROUND)
     set(Clang_FOUND FALSE)
     foreach(VERSION ${QDOC_SUPPORTED_CLANG_VERSIONS})
         if(NOT Clang_FOUND)
-            find_package(Clang ${VERSION} CONFIG QUIET)
+            strip_git_from_version(VERSION VERSION_CLEAN)
+            find_package(Clang ${VERSION_CLEAN} CONFIG QUIET)
         endif()
     endforeach()
 else()
@@ -36,7 +50,8 @@ else()
     set(LLVM_FOUND FALSE)
     foreach(VERSION ${QDOC_SUPPORTED_CLANG_VERSIONS})
         if(NOT LLVM_FOUND)
-            find_package(LLVM ${VERSION} CONFIG QUIET)
+            strip_git_from_version(VERSION VERSION_CLEAN)
+            find_package(LLVM ${VERSION_CLEAN} CONFIG QUIET)
         endif()
     endforeach()
     if(NOT LLVM_FOUND)
@@ -69,7 +84,8 @@ else()
     unset(__qt_wraplibclang CACHE)
 
     # Now, we're pretty certain that we can find the 'Clang' package without running into errors.
-    find_package(Clang ${LLVM_VERSION} EXACT CONFIG)
+    strip_git_from_version(LLVM_VERSION LLVM_VERSION_CLEAN)
+    find_package(Clang ${LLVM_VERSION_CLEAN} EXACT CONFIG)
 endif()
 
 # LLVM versions >= 16 come with Findzstd.cmake that creates a target for libzstd.