Merge topic 'deprecate-policy-old'

9710790a39 Help/dev: Add maintainer guide step for initial post-release development
6f6651f728 Add deprecation warnings for policies CMP0072 and below

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !4884

4 files changed, 44 insertions, 1 deletions

diff --git a/Help/dev/maint.rst b/Help/dev/maint.rst
index a1c1a6f..9b6774b 100644
--- a/Help/dev/maint.rst
+++ b/Help/dev/maint.rst
@@ -299,3 +299,28 @@ announcing that post-release development is open::
   before staging or merging.
 
 .. _`CMake Discourse Forum Development Category`: https://discourse.cmake.org/c/development
+
+Initial Post-Release Development
+--------------------------------
+
+Deprecate policies more than 8 release series old by updating the
+policy range check in ``cmMakefile::SetPolicy``.
+Commit with a message such as::
+
+  Add deprecation warnings for policies CMP#### and below
+
+  The OLD behaviors of all policies are deprecated, but only by
+  documentation.  Add an explicit deprecation diagnostic for policies
+  introduced in CMake $OLDVER and below to encourage projects to port
+  away from setting policies to OLD.
+
+Update the ``cmake_policy`` version range generated by ``install(EXPORT)``
+in ``cmExportFileGenerator::GeneratePolicyHeaderCode`` to end at the
+previous release.  We use one release back since we now know all the
+policies added for that version.  Commit with a message such as::
+
+  export: Increase maximum policy version in exported files to $prev
+
+  The files generatd by `install(EXPORT)` and `export()` commands
+  are known to work with policies as of CMake $prev, so enable them
+  in sufficiently new CMake versions.
diff --git a/Help/release/dev/deprecate-policy-old.rst b/Help/release/dev/deprecate-policy-old.rst
new file mode 100644
index 0000000..f92aea7
--- /dev/null
+++ b/Help/release/dev/deprecate-policy-old.rst
@@ -0,0 +1,8 @@
+deprecate-policy-old
+--------------------
+
+* An explicit deprecation diagnostic was added for policy ``CMP0071``
+  (``CMP0071`` and below were already deprecated).
+  The :manual:`cmake-policies(7)` manual explains that the OLD behaviors
+  of all policies are deprecated and that projects should port to the
+  NEW behaviors.
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index c78b751..5c3063b 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -4554,7 +4554,7 @@ bool cmMakefile::SetPolicy(cmPolicies::PolicyID id,
 
   // Deprecate old policies, especially those that require a lot
   // of code to maintain the old behavior.
-  if (status == cmPolicies::OLD && id <= cmPolicies::CMP0071 &&
+  if (status == cmPolicies::OLD && id <= cmPolicies::CMP0072 &&
       !(this->GetCMakeInstance()->GetIsInTryCompile() &&
         (
           // Policies set by cmCoreTryCompile::TryCompileCode.
diff --git a/Tests/RunCMake/FindOpenGL/CMP0072-OLD-stderr.txt b/Tests/RunCMake/FindOpenGL/CMP0072-OLD-stderr.txt
new file mode 100644
index 0000000..68d23d4
--- /dev/null
+++ b/Tests/RunCMake/FindOpenGL/CMP0072-OLD-stderr.txt
@@ -0,0 +1,10 @@
+^CMake Deprecation Warning at CMP0072-OLD.cmake:1 \(cmake_policy\):
+  The OLD behavior for policy CMP0072 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:3 \(include\)$