set(CACHE): do not remove normal variable

Fixes: #22038

7 files changed, 81 insertions, 0 deletions

diff --git a/Tests/RunCMake/CMP0126/CMP0126-NEW.cmake b/Tests/RunCMake/CMP0126/CMP0126-NEW.cmake
new file mode 100644
index 0000000..2f8562b
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/CMP0126-NEW.cmake
@@ -0,0 +1,28 @@
+
+# enforce policy CMP0125 to ensure predictable result of find_* commands
+cmake_policy(SET CMP0125 NEW)
+
+cmake_policy(SET CMP0126 NEW)
+
+set(VAR 1)
+set(VAR 2 CACHE STRING "")
+
+if (NOT VAR EQUAL 1)
+  message(FATAL_ERROR "normal variable does not exist anymore.")
+endif()
+
+
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/file.txt" "")
+set(VAR file.txt)
+set(VAR "" CACHE STRING "" FORCE)
+set_property(CACHE VAR PROPERTY TYPE UNINITIALIZED)
+
+find_file(VAR NAMES file.txt PATHS "${CMAKE_CURRENT_BINARY_DIR}")
+
+unset(VAR CACHE)
+if (NOT DEFINED VAR)
+  message(FATAL_ERROR "find_file: normal variable does not exist anymore.")
+endif()
+if (NOT VAR STREQUAL "${CMAKE_CURRENT_BINARY_DIR}/file.txt")
+  message(FATAL_ERROR "find_file: failed to set normal variable.")
+endif()
diff --git a/Tests/RunCMake/CMP0126/CMP0126-NEW_CL.cmake b/Tests/RunCMake/CMP0126/CMP0126-NEW_CL.cmake
new file mode 100644
index 0000000..cfaa1e3
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/CMP0126-NEW_CL.cmake
@@ -0,0 +1,9 @@
+
+cmake_policy(SET CMP0126 NEW)
+
+set(VAR 1)
+set(VAR 2 CACHE STRING "")
+
+if (NOT VAR EQUAL 1)
+  message(FATAL_ERROR "normal variable does not exist anymore.")
+endif()
diff --git a/Tests/RunCMake/CMP0126/CMP0126-OLD.cmake b/Tests/RunCMake/CMP0126/CMP0126-OLD.cmake
new file mode 100644
index 0000000..22a5037
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/CMP0126-OLD.cmake
@@ -0,0 +1,25 @@
+
+# enforce policy CMP0125 to ensure predictable result of find_* commands
+cmake_policy(SET CMP0125 NEW)
+
+cmake_policy(SET CMP0126 OLD)
+
+set(VAR 1)
+set(VAR 2 CACHE STRING "")
+
+if (VAR EQUAL 1)
+  message(FATAL_ERROR "normal variable still exist.")
+endif()
+
+
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/file.txt" "")
+set(VAR file.txt)
+set(VAR "" CACHE STRING "" FORCE)
+set_property(CACHE VAR PROPERTY TYPE UNINITIALIZED)
+
+find_file(VAR NAMES file.txt PATHS "${CMAKE_CURRENT_BINARY_DIR}")
+
+unset(VAR CACHE)
+if (DEFINED VAR)
+    message(FATAL_ERROR "find_file: normal variable still exist.")
+endif()
diff --git a/Tests/RunCMake/CMP0126/CMP0126-OLD_CL.cmake b/Tests/RunCMake/CMP0126/CMP0126-OLD_CL.cmake
new file mode 100644
index 0000000..5d72a87
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/CMP0126-OLD_CL.cmake
@@ -0,0 +1,9 @@
+
+cmake_policy(SET CMP0126 OLD)
+
+set(VAR 1)
+set(VAR 2 CACHE STRING "")
+
+if (NOT VAR EQUAL 3)
+  message(FATAL_ERROR "normal variable still exist.")
+endif()
diff --git a/Tests/RunCMake/CMP0126/CMakeLists.txt b/Tests/RunCMake/CMP0126/CMakeLists.txt
new file mode 100644
index 0000000..7cabeb6
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.20)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/CMP0126/RunCMakeTest.cmake b/Tests/RunCMake/CMP0126/RunCMakeTest.cmake
new file mode 100644
index 0000000..ae988f4
--- /dev/null
+++ b/Tests/RunCMake/CMP0126/RunCMakeTest.cmake
@@ -0,0 +1,6 @@
+include(RunCMake)
+
+run_cmake(CMP0126-OLD)
+run_cmake_with_options(CMP0126-OLD_CL -DVAR=3)
+run_cmake(CMP0126-NEW)
+run_cmake_with_options(CMP0126-NEW_CL -DVAR=3)
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index afaeaef..14a7fa3 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -140,6 +140,7 @@ if (CMAKE_SYSTEM_NAME MATCHES "(Linux|Darwin)")
   add_RunCMake_test(CMP0125 -DCMAKE_SHARED_LIBRARY_PREFIX=${CMAKE_SHARED_LIBRARY_PREFIX}
                             -DCMAKE_SHARED_LIBRARY_SUFFIX=${CMAKE_SHARED_LIBRARY_SUFFIX})
 endif()
+add_RunCMake_test(CMP0126)
 
 # The test for Policy 65 requires the use of the
 # CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS variable, which both the VS and Xcode