[tree] deprecate implementation detail header TreeUtils.h

[ferdymercury]

it's only used by .cxx files and there is already public interface for it

[pcanal]

Thanks.

[github-actions]

Test Results

    23 files      23 suites   3d 19h 52m 5s ⏱️
 3 879 tests  3 879 ✅ 0 💤 0 ❌
80 055 runs  80 055 ✅ 0 💤 0 ❌

Results for commit 1f42923.

[hageboeck]

There is a new warning in ROOT builds now:

[3232/6650] Generating G__Tree.cxx, ../../lib/Tree.pcm
In file included from input_line_10:46:
/root/build/include/TreeUtils.h:26:2: warning: "This header is deprecated and will be removed in ROOT 6.44, use instead TNtuple::ReadStream or TNtupleD::ReadStream" [-W#warnings]
#warning "This header is deprecated and will be removed in ROOT 6.44, use instead TNtuple::ReadStream or TNtupleD::ReadStream"
 ^
In file included from <<< cling interactive line includer >>>:38:
/root/build/include/TreeUtils.h:26:2: warning: "This header is deprecated and will be removed in ROOT 6.44, use instead TNtuple::ReadStream or TNtupleD::ReadStream" [-W#warnings]
#warning "This header is deprecated and will be removed in ROOT 6.44, use instead TNtuple::ReadStream or TNtupleD::ReadStream"
 ^

Could you have a look?

[guitargeek]

Here is how I typically avoid deprecation warnings when building ROOT itself:

• d9f48b0

The idea is to define some ROOFIT_BUILDS_ITSELF or similar macro that is only active when ROOT builds itself, and the deprecation warning is conditional on the macro being not defined.

[ferdymercury]

Could you have a look?

Maybe with #23413 ?