This generator expression is the inverse of `LINK_ONLY` and only coveys
usage requirements for the purposes of compilation. Its intended use is
to avoid needing to export targets that do not have link usage
requirements (e.g., header-only libraries) when used by another target.

See: #15415

This generator expression is the inverse of `LINK_ONLY` and only coveys
usage requirements for the purposes of compilation. Its intended use is
to avoid needing to export targets that do not have link usage
requirements (e.g., header-only libraries) when used by another target.

It will also be used to represent private usage requirements on exported
C++ module-containing targets in the future.

Eventually there should be logic to collapse nesting of
`$<COMPILE_ONLY>` and `$<LINK_ONLY>` when generating instances of
either. A TODO is left in the code for this case.

See: #15415

Issue a deprecation warning on calls to `cmake_minimum_required` or
`cmake_policy` that set policies based on versions older than 3.5.
Note that the effective policy version includes `...<max>` treatment.
Update the check from commit 5845c218d7 (Deprecate compatibility with
CMake versions older than 2.8.12, 2020-06-12, v3.19.0-rc1~629^2).

Fixes #24327

Move some `TARGET_PROPERTY` cases from `RunCMake.GeneratorExpression`.

Logically revert commit 390a7d8647 (cmTargetPropertyComputer: Implement
GetProperty without cmMakefile, 2016-10-13, v3.8.0-rc1~445^2~9).
It relied on using `cmListFileBacktrace` to get a scope in which to
look up policies.

This does remove a backtrace from `LOCATION` property errors at generate
time, but the backtrace we reported before was incorrect.  It pointed at
the addition of a target, not to the reference to the property.

The OLD behaviors of all policies are deprecated, but only by
documentation.  Add an explicit deprecation diagnostic for policies
introduced in CMake 3.14 and below to encourage projects to port
away from setting policies to OLD.

Fixes: #19696

Fixes: #20951