CMake: detect_MADNESS_configuration() fails against MADNESS >= 48dc6494b (MADmisc genex leaks into try_compile)

[evaleev]

Summary

detect_MADNESS_configuration() fails to configure against any MADNESS newer than
48dc6494b
(Aug 21 2026). It copies MADworld's INTERFACE_INCLUDE_DIRECTORIES verbatim into
CMAKE_REQUIRED_INCLUDES and then runs CHECK_CXX_SOURCE_COMPILES, but that property now
contains an unevaluated generator expression naming a MADNESS target. try_compile()
generates a standalone project in which no MADNESS target exists, so the expression is a
hard error there rather than an include path.

This does not affect the currently pinned TA_TRACKED_MADNESS_TAG (666765ca6, May 21
2026), which predates the MADNESS change — it bites anyone pointing
FETCHCONTENT_SOURCE_DIR_MADNESS at a current MADNESS checkout, and it will block the next
pin bump.

Reproducer

cmake -S . -B build \
  -DFETCHCONTENT_SOURCE_DIR_MADNESS=<a MADNESS checkout at or after 48dc6494b> \
  ...

-- Performing Test MADNESS_HAS_TBB
CMake Error at build/CMakeFiles/CMakeScratch/TryCompile-SE5mo9/CMakeLists.txt:11 (include_directories):
  Error evaluating generator expression:

    $<TARGET_PROPERTY:MADmisc,INTERFACE_INCLUDE_DIRECTORIES>

  Target "MADmisc" not found.

CMake Error at .../Internal/CheckSourceCompiles.cmake:104 (try_compile):
  Failed to generate test project build system.
Call Stack (most recent call first):
  .../CheckCXXSourceCompiles.cmake:58 (cmake_check_source_compiles)
  cmake/modules/DetectMADNESSConfig.cmake:27 (CHECK_CXX_SOURCE_COMPILES)
  CMakeLists.txt:347 (detect_MADNESS_configuration)

-- Configuring incomplete, errors occurred!

Reproduces on both MADNESS_TASK_BACKEND=Pthreads and PaRSEC.

Cause

MADNESS 48dc6494b ("misc: make it a leaf component so world can depend on it") inverted
the previously cyclic misc/world edge:

-add_mad_library(world MADWORLD_SOURCES MADWORLD_HEADERS "common;${ELEMENTAL_PACKAGE_NAME}" "madness/world")
+add_mad_library(world MADWORLD_SOURCES MADWORLD_HEADERS "misc;common;${ELEMENTAL_PACKAGE_NAME}" "madness/world")

add_mad_library propagates a dependency's include dirs as an unevaluated generator
expression (MADNESS cmake/modules/AddMADLibrary.cmake):

if(TARGET ${deptargetname})
    target_include_directories(${targetname} PUBLIC
        $<TARGET_PROPERTY:${deptargetname},INTERFACE_INCLUDE_DIRECTORIES>)

so MADworld's INTERFACE_INCLUDE_DIRECTORIES now literally contains the string
$<TARGET_PROPERTY:MADmisc,INTERFACE_INCLUDE_DIRECTORIES>.

That injection is guarded by if(TARGET MAD${_dep}), and misc is the first MAD*
library target world has ever depended on — common has no MADcommon target
anywhere, so it was silently skipped. That is why this only surfaces now.

Note the MADNESS change is not itself at fault: it explicitly handles
MADNESS_BUILD_MADWORLD_ONLY=ON ("because MADworld links it,
MADNESS_BUILD_MADWORLD_ONLY=ON now configures, builds and installs MADmisc"), and
MADmisc is defined in TA's configuration. The failure is purely that a generator
expression cannot survive into a try_compile sub-project.

Suggested fix

TA already carries an ad-hoc version of this workaround in the same macro — an
if (TARGET El) branch that strips El-matching entries, i.e. a one-off patch for exactly
this hazard. Generalize it: drop every entry containing $< before it reaches
CMAKE_REQUIRED_INCLUDES. A generator expression is never a usable include path in a
try_compile, and the plain directories that remain are what the madness/config.h probe
actually needs.

This also subsumes the El special case (those entries are genexes too) and is more
precise than a substring match on El, which would drop a legitimate path containing
those letters.