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cmake: check for Cap'n Proto / Clang / C++20 incompatibility #205

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Merged
merged 2 commits into from
Sep 5, 2025
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cmake: check for Cap'n Proto / Clang / C++20 incompatibility #205

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d314057
cmake: check for Cap'n Proto / Clang / C++20 incompatibility
willcl-ark Sep 2, 2025
657d806
cmake: capnproto pkg missing helpful error
willcl-ark Sep 4, 2025
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55 changes: 50 additions & 5 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,20 @@ endif()
include("cmake/compat_find.cmake")

find_package(Threads REQUIRED)
find_package(CapnProto 0.7 REQUIRED NO_MODULE)
find_package(CapnProto 0.7 QUIET NO_MODULE)
if(NOT CapnProto_FOUND)
message(FATAL_ERROR
"Cap'n Proto is required but was not found.\n"
"To resolve, choose one of the following:\n"
" - Install Cap'n Proto (version 1.0+ recommended)\n"
" - For Bitcoin Core compilation build with -DENABLE_IPC=OFF to disable multiprocess support\n"
)
endif()
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mis-indentation?


# Cap'n Proto compatibility checks
set(CAPNPROTO_ISSUES "")
set(CAPNPROTO_CVE_AFFECTED FALSE)
set(CAPNPROTO_CLANG_INCOMPATIBLE FALSE)

# Check for list-of-pointers memory access bug from Nov 2022
# https://nvd.nist.gov/vuln/detail/CVE-2022-46149
Expand All @@ -29,11 +42,43 @@ if(CapnProto_VERSION STREQUAL "0.7.0"
OR CapnProto_VERSION STREQUAL "0.10.0"
OR CapnProto_VERSION STREQUAL "0.10.1"
OR CapnProto_VERSION STREQUAL "0.10.2")
set(CAPNPROTO_CVE_AFFECTED TRUE)
string(APPEND CAPNPROTO_ISSUES "- CVE-2022-46149 security vulnerability (details: https://github.com/advisories/GHSA-qqff-4vw4-f6hx)\n")
endif()

# Check for Cap'n Proto / Clang / C++20 incompatibility
# Cap'n Proto 0.9.x and 0.10.x are incompatible with Clang 16+ when using C++20
# due to P2468R2 implementation. This was fixed in Cap'n Proto 1.0+.
# See: https://github.com/bitcoin-core/libmultiprocess/issues/199
if((CapnProto_VERSION VERSION_GREATER_EQUAL "0.9.0") AND
(CapnProto_VERSION VERSION_LESS "1.0.0") AND
(CMAKE_CXX_COMPILER_ID STREQUAL "Clang") AND
(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "16") AND
(CMAKE_CXX_STANDARD EQUAL 20))
set(CAPNPROTO_CLANG_INCOMPATIBLE TRUE)
string(APPEND CAPNPROTO_ISSUES "- Incompatible with Clang ${CMAKE_CXX_COMPILER_VERSION} when using C++20\n")
endif()

if(CAPNPROTO_CVE_AFFECTED OR CAPNPROTO_CLANG_INCOMPATIBLE)
set(RESOLUTION_OPTIONS "")

# Fixes both issues
string(APPEND RESOLUTION_OPTIONS " - Upgrade to Cap'n Proto version 1.0 or newer (recommended)\n")

if(CAPNPROTO_CVE_AFFECTED AND NOT CAPNPROTO_CLANG_INCOMPATIBLE)
string(APPEND RESOLUTION_OPTIONS " - Upgrade to a patched minor version (0.7.1, 0.8.1, 0.9.2, 0.10.3, or later)\n")
elseif(CAPNPROTO_CLANG_INCOMPATIBLE AND NOT CAPNPROTO_CVE_AFFECTED)
string(APPEND RESOLUTION_OPTIONS " - Use GCC instead of Clang\n")
endif()

string(APPEND RESOLUTION_OPTIONS " - For Bitcoin Core compilation build with -DENABLE_IPC=OFF to disable multiprocess support\n")
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In commit "cmake: check for Cap'n Proto / Clang / C++20 incompatibility" (d314057)

This might be more readable with a comma after "compilation". Also I think the "if you do not need IPC functionality" phrasing from bitcoin/bitcoin#33290 might make the effects of this easier to understand than "to disable multiprocess support". Maybe my suggestion would be to change this to something like "If building Bitcoin Core and you do not need IPC functionality, configure cmake with -DENABLE_IPC=OFF" here in and in the next commit.

This also seems fine for now though, and later we can drop if "If building Bitcoin Core" part by supporting a MP_SUBPROJECT_ERROR variable as suggested in the other issue.


message(FATAL_ERROR
"Cap'n Proto ${CapnProto_VERSION} is affected by CVE-2022-46149.\n"
"Please install an updated package.\n"
"Details: https://github.com/advisories/GHSA-qqff-4vw4-f6hx
")
"The version of Cap'n Proto detected: ${CapnProto_VERSION} has known compatibility issues:\n"
"${CAPNPROTO_ISSUES}"
"To resolve, choose one of the following:\n"
"${RESOLUTION_OPTIONS}"
)
endif()

set(MPGEN_EXECUTABLE "" CACHE FILEPATH "If specified, should be full path to an external mpgen binary to use rather than the one built internally.")
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