From 814de4c2ce8a4a9198672c68d64a2eb9c8e30e8b Mon Sep 17 00:00:00 2001
From: Joerg Bornemann <joerg.bornemann@qt.io>
Date: Thu, 21 Sep 2023 08:48:53 +0200
Subject: [PATCH] CMake: Fix config condition evaluator

Use recursive descent to handle parentheses in config condition
expressions. This fixes cases like 'NOT (A AND B)'.

Fixes: QTBUG-117053
Change-Id: Iab1b6173abe00d763808bb972a9a5443ffa0938d
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Amir Masoud Abdol <amir.abdol@qt.io>
---
 cmake/QtFeature.cmake                         | 49 ++++++++++++-------
 .../test_config_expressions/CMakeLists.txt    |  6 +--
 2 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/cmake/QtFeature.cmake b/cmake/QtFeature.cmake
index 2c6fa94c255..ee7e0ab824f 100644
--- a/cmake/QtFeature.cmake
+++ b/cmake/QtFeature.cmake
@@ -81,35 +81,23 @@ function(qt_evaluate_to_boolean expressionVar)
     endif()
 endfunction()
 
-function(qt_evaluate_config_expression resultVar)
+function(qt_internal_evaluate_config_expression resultVar outIdx startIdx)
     set(result "")
-    set(nestingLevel 0)
     set(expression "${ARGN}")
     list(LENGTH expression length)
 
-    set(memberIdx -1)
+    math(EXPR memberIdx "${startIdx} - 1")
     math(EXPR length "${length}-1")
     while(memberIdx LESS ${length})
         math(EXPR memberIdx "${memberIdx} + 1")
         list(GET expression ${memberIdx} member)
 
         if("${member}" STREQUAL "(")
-            if(${nestingLevel} GREATER 0)
-                list(APPEND result ${member})
-            endif()
-            math(EXPR nestingLevel "${nestingLevel} + 1")
+            math(EXPR memberIdx "${memberIdx} + 1")
+            qt_internal_evaluate_config_expression(sub_result memberIdx ${memberIdx} ${expression})
+            list(APPEND result ${sub_result})
         elseif("${member}" STREQUAL ")")
-            math(EXPR nestingLevel "${nestingLevel} - 1")
-            if(nestingLevel LESS 0)
-                break()
-            endif()
-            if(${nestingLevel} EQUAL 0)
-                qt_evaluate_config_expression(result ${result})
-            else()
-                list(APPEND result ${member})
-            endif()
-        elseif(${nestingLevel} GREATER 0)
-            list(APPEND result ${member})
+            break()
         elseif("${member}" STREQUAL "NOT")
             list(APPEND result ${member})
         elseif("${member}" STREQUAL "AND")
@@ -166,9 +154,34 @@ function(qt_evaluate_config_expression resultVar)
         qt_evaluate_to_boolean(result)
     endif()
 
+    # When in recursion, we must skip to the next closing parenthesis on nesting level 0. The outIdx
+    # must point to the matching closing parenthesis, and that's not the case if we're early exiting
+    # in AND/OR.
+    if(startIdx GREATER 0)
+        set(nestingLevel 1)
+        while(TRUE)
+            list(GET expression ${memberIdx} member)
+            if("${member}" STREQUAL ")")
+                math(EXPR nestingLevel "${nestingLevel} - 1")
+                if(nestingLevel EQUAL 0)
+                    break()
+                endif()
+            elseif("${member}" STREQUAL "(")
+                math(EXPR nestingLevel "${nestingLevel} + 1")
+            endif()
+            math(EXPR memberIdx "${memberIdx} + 1")
+        endwhile()
+    endif()
+
+    set(${outIdx} ${memberIdx} PARENT_SCOPE)
     set(${resultVar} ${result} PARENT_SCOPE)
 endfunction()
 
+function(qt_evaluate_config_expression resultVar)
+    qt_internal_evaluate_config_expression(result unused 0 ${ARGN})
+    set("${resultVar}" "${result}" PARENT_SCOPE)
+endfunction()
+
 function(_qt_internal_get_feature_condition_keywords out_var)
     set(keywords "EQUAL" "LESS" "LESS_EQUAL" "GREATER" "GREATER_EQUAL" "STREQUAL" "STRLESS"
         "STRLESS_EQUAL" "STRGREATER" "STRGREATER_EQUAL" "VERSION_EQUAL" "VERSION_LESS"
diff --git a/tests/auto/cmake/test_config_expressions/CMakeLists.txt b/tests/auto/cmake/test_config_expressions/CMakeLists.txt
index 4061728113e..e3863b738ad 100644
--- a/tests/auto/cmake/test_config_expressions/CMakeLists.txt
+++ b/tests/auto/cmake/test_config_expressions/CMakeLists.txt
@@ -88,9 +88,9 @@ assert_F(A AND B)
 assert_T(A AND (B OR C))
 assert_T((A AND B) OR C)
 assert_T((A AND B) OR (NOT B AND C))
-expect_failure_F(NOT (B OR C))          # QTBUG-117053
-expect_failure_T(NOT (A AND B))         # QTBUG-117053
-expect_failure_F(NOT (B OR C))          # QTBUG-117053
+assert_F(NOT (B OR C))
+assert_T(NOT (A AND B))
+assert_F(NOT (B OR C))
 
 # target check
 set(lib1_cpp "${CMAKE_CURRENT_BINARY_DIR}/lib1.cpp")