Silence all compiler warnings in source builds (clang/libc++, Python 3.14)

[Ooolab]

Building ALPS from source per the install instructions on macOS (AppleClang 17, libc++, macOS SDK 26.2, Homebrew Python 3.14) produced a stream of recurring warnings. This PR removes all of them — a full build including examples and tests now finishes with zero warnings. The bundled/downloaded Boost sources are untouched; everything is done in ALPS's own CMake files and two ALPS headers.

Preprocessor defines (top-level CMakeLists.txt)

• -DBOOST_NO_AUTO_PTR= (empty value instead of implicit 1): on libc++ in C++17 mode Boost's own boost/config/stdlib/libcpp.hpp also defines BOOST_NO_AUTO_PTR (empty), and the differing bodies triggered -Wmacro-redefined in every translation unit that includes Boost. Identical redefinitions are legal and silent. Side note: since the build adds this flag itself, the install page telling users to pass -DBOOST_NO_AUTO_PTR -DBOOST_FILESYSTEM_NO_CXX20_ATOMIC_REF in CMAKE_CXX_FLAGS is redundant (and reintroduces this warning) — the docs could drop it.
• -DBOOST_ALLOW_DEPRECATED_HEADERS: Boost's official opt-out for the <boost/timer.hpp> "header is deprecated" pragma message — we already opt into the old timer API via BOOST_TIMER_ENABLE_DEPRECATED.
• -DBOOST_BIND_GLOBAL_PLACEHOLDERS: Boost's official opt-in for the global _1, _2, ... bind placeholders that legacy ALPS code uses throughout, silencing the boost/bind.hpp pragma message.

Scoped warning suppressions for bundled Boost (src/boost/CMakeLists.txt)

• boost_python target: -Wno-deprecated-declarations — Boost.Python ≤ 1.87 calls _PyUnicode_AsString, deprecated since Python 3.14. It is a literal alias of PyUnicode_AsUTF8 in CPython's headers, so behavior is unaffected.
• boost target (clang only): -Wno-invalid-noreturn — Boost.MPI's environment::abort() is declared noreturn but relies on MPI_Abort not returning, which the compiler cannot verify.

Both are PRIVATE to the bundled Boost targets, so ALPS code keeps these warnings enabled.

Scoped suppression for legacy RNG (src/alps/CMakeLists.txt)

• random/rngfactory.C (clang only): -Wno-constant-conversion — the registered legacy lagged_fibonacci607 generator is lagged_fibonacci<uint32_t, 48, 607, 273>, a 48-bit word with a 32-bit result type, so max() truncates 2^48−1 to 2^32−1 by construction. Changing the types would change the random stream and break reproducibility of old simulations, so the parameterization is kept and the warning suppressed for this one file.

Real fixes: missing virtual destructors

• alps::mcbase (src/alps/mcbase.hpp): abstract class destroyed through base references by Boost.Python's rvalue converters (-Wdelete-abstract-non-virtual-dtor). Deleting a derived simulation through mcbase* was undefined behavior.
• alps::EigenvectorMeasurements (src/alps/scheduler/measurement_operators.h): has virtual save/load but had no virtual destructor (-Wdelete-non-abstract-non-virtual-dtor).

Both classes already had vtables, so adding the destructor changes no object layout and no ABI-visible behavior; derived classes' destructors become virtual overrides automatically.

Testing

Full from-source build (cmake --build, including examples and tests) on AppleClang 17 / macOS SDK 26.2 / Homebrew Python 3.14 with the bundled Boost 1.87: previously dozens of warning sites, now zero warnings. The clang-only -Wno-* flags are guarded by CMAKE_CXX_COMPILER_ID MATCHES "Clang" so GCC builds are unaffected.

🤖 Generated with Claude Code

https://claude.ai/code/session_01DaRLRTayS75a9Yk1iLvNu9

[egull]

Thank you! We had previous passes to make this compile without warnings on C++-14; it's quite amazing how much more C++-17 finds.

[marcusr2ML]

Not a big deal: with the bundled Boost, one file (libs/filesystem/src/directory.cpp) calls readdir_r, which recent macOS SDKs mark deprecated, so you get a single -Wdeprecated-declarations warning building libboost, it's on master too and harmless. To clear it, add -Wno-deprecated-declarations to the main boost target in src/boost/CMakeLists.txt, right where the PR already adds -Wno-invalid-noreturn to it.

[Ooolab]

Done in d7b6f07 — added -Wno-deprecated-declarations on the main boost target next to -Wno-invalid-noreturn. Left it outside the clang-only guard since GCC accepts the flag and glibc deprecates readdir_r as well.