build: require KJ exception support for IPC #36060

pull 151henry151 wants to merge 3 commits into bitcoin:master from 151henry151:36058-kj-exceptions changing 12 files +179 −0

151henry151 commented at 3:25 AM on August 24, 2026: contributor

IPC needs libkj built with exception support; runCatchingExceptions depends on getCaughtExceptionAsKj, which is omitted when KJ_NO_EXCEPTIONS is set.

Build depends capnproto with -DKJ_NO_EXCEPTIONS=0. Fail configure if the compiler or the installed libkj lacks exception support. Define the same macro privately on in-tree IPC targets so our headers match the library.

Addresses #36058

Tested with: make -C depends NO_QT=1 NO_QR=1 -j$(nproc) — passed cmake -B /tmp/btc-36058-deptc --toolchain depends/x86_64-pc-linux-gnu/toolchain.cmake -DBUILD_GUI=OFF -DBUILD_BENCH=OFF -DBUILD_TESTS=ON -DBUILD_FUZZ_BINARY=ON — passed cmake --build /tmp/btc-36058-deptc --target bitcoin_ipc multiprocess mputil mpgen bitcoin_ipc_test bitcoin_ipc_fuzz mptest bitcoind bitcoin-node bitcoin-cli bitcoin test_bitcoin fuzz — passed mptest — 16 passed test_bitcoin --run_test=ipc_tests — passed interface_ipc.py — passed interface_ipc_cli.py — passed interface_ipc_mining.py — passed cmake -DENABLE_IPC=OFF — passed cmake -DENABLE_IPC=ON -DCMAKE_CXX_FLAGS=-fno-exceptions — configure fails (compiler probe) cmake -DENABLE_IPC=ON -DWITH_EXTERNAL_LIBMULTIPROCESS=ON -DCMAKE_PREFIX_PATH=/tmp/mp-ext-prefix — passed test/lint/git-subtree-check.sh src/ipc/libmultiprocess — GOOD
depends: pin KJ_NO_EXCEPTIONS=0 when building capnproto
Also pin native_capnp, which host mpgen links.
4f71358ccb

cmake: check KJ exception support when ENABLE_IPC is on

The check is in Core cmake because src/ipc/libmultiprocess is a
subtree. Fail if the compiler cannot throw or libkj lacks
getCaughtExceptionAsKj. Header autodetection is not a configure
failure. Look up libkj next to the scraped headers so depends
and system copies cannot be mixed. The compiler probe uses
CMAKE_CXX_FLAGS; target-level -fno-exceptions would not trip it.

34201d5fb0

cmake: define KJ_NO_EXCEPTIONS=0 on in-tree IPC targets

PRIVATE so the define is not exported. Skip
WITH_EXTERNAL_LIBMULTIPROCESS; those TUs are already compiled.
Apply to bitcoin_ipc, bitcoin_ipc_test, bitcoin_ipc_fuzz, the
in-tree mp targets, and fuzz (which compiles ipc.cpp with kj
headers).

68bee5832c

DrahtBot added the label Build system on Aug 24, 2026
DrahtBot commented at 3:25 AM on August 24, 2026: contributor



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#36058 [RFC] ipc: Check / enforce exception support

build: require KJ exception support for IPC #36060

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