Latest `main` fails when built with `clang` 17

[virtualritz]

Very weird as I'm using clang 17 and I would expect this change to not affect older clang versions?

I think this is because of the same issue as this.

The build succeeds if I rename cmd->isPure() to cmd->isPureVirtual() in cpp_context.cpp:711, as suggested by the Chromium issue linked above.

Prep step:

❯ cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release            

-- The C compiler identification is Clang 17.0.6
-- The CXX compiler identification is Clang 17.0.6
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test HAVE_FFI_CALL
-- Performing Test HAVE_FFI_CALL - Success
-- Found FFI: /usr/lib/x86_64-linux-gnu/libffi.so
-- Looking for histedit.h
-- Looking for histedit.h - found
-- Found LibEdit: /usr/include (found version "2.11")
-- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.3.1")
-- Found zstd: /usr/lib/x86_64-linux-gnu/libzstd.so
-- Found LibXml2: /usr/lib/x86_64-linux-gnu/libxml2.so (found version "2.9.14")
-- Found CURL: /usr/lib/x86_64-linux-gnu/libcurl.so (found version "8.12.1")
-- Found LLVM 20.1.2: /usr/lib/llvm-20
-- Build spdlog: 1.12.0
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE
-- Build type: Release
-- Configuring done (2.1s)
-- Generating done (0.0s)
-- Build files have been written to: /home/ritz/code/babble/build

Build step:

❯ cmake --build build -j12 --config Release                     
[18/48] Building CXX object bbl/CMakeFiles/bbl.dir/src/cpp_context.cpp.o
FAILED: bbl/CMakeFiles/bbl.dir/src/cpp_context.cpp.o 
/usr/bin/c++ -DSPDLOG_COMPILED_LIB -I/home/ritz/code/babble/bbl/include -I/usr/lib/llvm-20/include -I/home/ritz/code/babble/ext/spdlog/include -O3 -DNDEBUG -fPIC -std=c++17 -Wno-deprecated-declarations -MD -MT bbl/CMakeFiles/bbl.dir/src/cpp_context.cpp.o -MF bbl/CMakeFiles/bbl.dir/src/cpp_context.cpp.o.d -o bbl/CMakeFiles/bbl.dir/src/cpp_context.cpp.o -c /home/ritz/code/babble/bbl/src/cpp_context.cpp
/home/ritz/code/babble/bbl/src/cpp_context.cpp:711:14: error: no member named 'isPure' in 'clang::CXXMethodDecl'
  711 |         cmd->isPure(),
      |         ~~~  ^
1 error generated.
[20/48] Building CXX object bbl/CMakeFiles/bbl-genbind.dir/src/bbl-genbind.cpp.o
ninja: build stopped: subcommand failed.

This is on Ubuntu 25.04.