cmTarget: Raise error if imported target location is not set

Previously we would synthesize <TARGET_NAME>-NOTFOUND as the location. This
would then end up on the link line and cause build failures.
Policy CMP0110 is added to control this behaviour.

Fixes #19080, #19943.

1 files changed, 20 insertions, 0 deletions

diff --git a/Help/policy/CMP0111.rst b/Help/policy/CMP0111.rst
new file mode 100644
index 0000000..37e5ad5
--- /dev/null
+++ b/Help/policy/CMP0111.rst
@@ -0,0 +1,20 @@
+CMP0111
+-------
+
+.. versionadded:: 3.19
+
+An imported target with a missing location fails during generation.
+
+Prior to this the location would be generated as ``<TARGET_NAME>-NOTFOUND``,
+which would result in build failures.
+
+The ``OLD`` behavior of this policy is to generate the location of an imported
+unknown, static or shared library target as ``<TARGET_NAME>-NOTFOUND`` if not
+set.
+The ``NEW`` behavior is to raise an error.
+
+This policy was introduced in CMake version 3.19.  CMake version |release|
+warns when the policy is not set and uses ``OLD`` behavior. Use the
+:command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
+
+.. include:: DEPRECATED.txt