Add deprecation warnings for policies CMP0120 and below

The OLD behaviors of all policies are deprecated, but only by
documentation.  Add an explicit deprecation diagnostic for policies
introduced in CMake 3.20 and below to encourage projects to port
away from setting policies to OLD.

1 files changed, 12 insertions, 1 deletions

diff --git a/Tests/RunCMake/CMP0116/CMP0116-Mixed-stderr.txt b/Tests/RunCMake/CMP0116/CMP0116-Mixed-stderr.txt
index 10e83a9..930dd3c 100644
--- a/Tests/RunCMake/CMP0116/CMP0116-Mixed-stderr.txt
+++ b/Tests/RunCMake/CMP0116/CMP0116-Mixed-stderr.txt
@@ -1,4 +1,15 @@
-^CMake Warning \(dev\) at CMP0116-Mixed\.cmake:1 \(add_custom_command\):
+^CMake Deprecation Warning at CMP0116-Mixed\.cmake:[0-9]+ \(cmake_policy\):
+  The OLD behavior for policy CMP0116 will be removed from a future version
+  of CMake\.
+
+  The cmake-policies\(7\) manual explains that the OLD behaviors of all
+  policies are deprecated and that a policy should be set to OLD only under
+  specific short-term circumstances\.  Projects should be ported to the NEW
+  behavior and not rely on setting a policy to OLD\.
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:[0-9]+ \(include\)
++
+CMake Warning \(dev\) at CMP0116-Mixed\.cmake:1 \(add_custom_command\):
   Policy CMP0116 is not set: Ninja generators transform DEPFILEs from
   add_custom_command\(\)\.  Run "cmake --help-policy CMP0116" for policy
   details\.  Use the cmake_policy command to set the policy and suppress this