build: Set AUTHOR_WARNING on warnings #33144

1. 
   maflcko commented at 2:27 pm on August 6, 2025: member

   Now that the cmake setting -Werror=dev is set since commit 6a13a6106e3c1ebe95ba6430184d6260a7b942bd for the CI, guix and the dev cmake preset, it could make sense to notify developers about any warnings.

   So do that with a single AUTHOR_WARNING.

   This can be tested by introducing a bug, like:

    0diff --git a/CMakeLists.txt b/CMakeLists.txt
    1index 6017775fa7..5610e03c66 100644
    2--- a/CMakeLists.txt
    3+++ b/CMakeLists.txt
    4@@ -589,7 +589,7 @@ set(Python3_FIND_FRAMEWORK LAST CACHE STRING "")
    5 # improves compatibility with Python version managers that use shims.
    6 set(Python3_FIND_UNVERSIONED_NAMES FIRST CACHE STRING "")
    7 mark_as_advanced(Python3_FIND_FRAMEWORK Python3_FIND_UNVERSIONED_NAMES)
    8-find_package(Python3 3.10 COMPONENTS Interpreter)
    9+find_package(Python3 3.210 COMPONENTS Interpreter)
   10 if(NOT TARGET Python3::Interpreter)
   11   list(APPEND configure_warnings
   12     "Minimum required Python not found."
   

   Fixes #31476.

2. build: Set AUTHOR_WARNING on warnings fa6497ba71
3. DrahtBot added the label Build system on Aug 6, 2025
4. 
   DrahtBot commented at 2:28 pm on August 6, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33144.

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   ACK	l0rinc

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   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #32865 (cmake: Use AUTHOR_WARNING for warnings by fanquake)

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

5. 
   l0rinc commented at 6:45 pm on August 6, 2025: contributor

   Rebased, tested it with:

    0diff --git a/CMakeLists.txt b/CMakeLists.txt
    1--- a/CMakeLists.txt	(revision 27e4b8c6856194fa8db028b6f7356f83ea3d7e3a)
    2+++ b/CMakeLists.txt	(date 1754504896922)
    3@@ -186,6 +186,7 @@
    4 string(APPEND CMAKE_CXX_LINK_EXECUTABLE " ${APPEND_LDFLAGS}")
    5
    6 set(configure_warnings)
    7+list(APPEND configure_warnings "Testing [#33144](/bitcoin-bitcoin/33144/)")
    8
    9 include(CheckLinkerSupportsPIE)
   10 check_linker_supports_pie(configure_warnings)
   

   running:

   0rm -rfd build && cmake -B build 2>&1 | grep -C1 Warning
   

   Prints before the change:

   0CMake Warning at CMakeLists.txt:709 (message):
   1  Testing [#33144](/bitcoin-bitcoin/33144/)
   

   After the change:

   0CMake Warning at CMakeLists.txt:709 (message):
   1  Testing [#33144](/bitcoin-bitcoin/33144/)
   2--
   3
   4CMake Warning (dev) at CMakeLists.txt:712 (message):
   5  Warnings have been encountered!
   6This warning is for project developers.  Use -Wno-dev to suppress it.
   

   ACK fa6497ba71e9573d341c1c051af09b3ec2fc8d74

Contributors
maflcko DrahtBot l0rinc

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