This is confusing / undermines the output printed, so it’d be good if it could be improved, or fixed entirely.
Seeing:
0Linker flags .......................... <a bunch of compiler flags> i.e `-ftrivial-auto-var-init=pattern`
just doesn’t make sense.
The CMAKE_<LANG>_FLAGS are applied language-wide, which means:
These flags will be passed to all invocations of the compiler. This includes invocations that drive compiling and those that drive linking.
Passing {C,CXX}FLAGS variables when using Autotools exhibits the same behaviour.
Passing {C,CXX}FLAGS variables when using Autotools exhibits the same behaviour.
No it doesn’t:
0./autogen.sh && ./configure CXXFLAGS="-ftrivial-auto-var-init=pattern"
1 CXXFLAGS = -g -O2 -fdebug-prefix-map=$(abs_top_srcdir)=. -Wstack-protector -fstack-protector-all -mbranch-protection=bti -Wall -Wextra -Wgnu -Wformat -Wformat-security -Wvla -Wshadow-field -Wthread-safety -Wloop-analysis -Wredundant-decls -Wunused-member-function -Wdate-time -Wconditional-uninitialized -Woverloaded-virtual -Wsuggest-override -Wimplicit-fallthrough -Wunreachable-code -Wdocumentation -Wself-assign -Wundef -Wno-unused-parameter -ftrivial-auto-var-init=pattern
2 LDFLAGS = -lpthread -Wl,-fixup_chains -Wl,-headerpad_max_install_names -Wl,-dead_strip -Wl,-dead_strip_dylibs
My point is not what may or may not be happening behinds the scenes, my point is we are presenting output doesn’t make sense.
Passing {C,CXX}FLAGS variables when using Autotools exhibits the same behaviour.
No it doesn’t:
0./autogen.sh && ./configure CXXFLAGS="-ftrivial-auto-var-init=pattern" 1 CXXFLAGS = -g -O2 -fdebug-prefix-map=$(abs_top_srcdir)=. -Wstack-protector -fstack-protector-all -mbranch-protection=bti -Wall -Wextra -Wgnu -Wformat -Wformat-security -Wvla -Wshadow-field -Wthread-safety -Wloop-analysis -Wredundant-decls -Wunused-member-function -Wdate-time -Wconditional-uninitialized -Woverloaded-virtual -Wsuggest-override -Wimplicit-fallthrough -Wunreachable-code -Wdocumentation -Wself-assign -Wundef -Wno-unused-parameter -ftrivial-auto-var-init=pattern 2 LDFLAGS = -lpthread -Wl,-fixup_chains -Wl,-headerpad_max_install_names -Wl,-dead_strip -Wl,-dead_strip_dylibs
It does:
0$ ./autogen.sh && ./configure CXXFLAGS="-ftrivial-auto-var-init=pattern"
1$ make src/bitcoind V=1 | grep -e "-ftrivial-auto-var-init=pattern"
2...
3/bin/bash ../libtool --tag=CXX --preserve-dup-deps --mode=link /usr/bin/ccache g++ -std=c++20 -g -O2 -fno-extended-identifiers -fstack-reuse=none -fdebug-prefix-map=/home/hebasto/git/bitcoin=. -Wstack-protector -fstack-protector-all -fcf-protection=full -fstack-clash-protection -Wall -Wextra -Wformat -Wformat-security -Wvla -Wredundant-decls -Wdate-time -Wduplicated-branches -Wduplicated-cond -Wlogical-op -Woverloaded-virtual -Wsuggest-override -Wimplicit-fallthrough -Wunreachable-code -Wundef -Wno-unused-parameter -fPIE -ftrivial-auto-var-init=pattern -Wl,-z,relro -Wl,-z,now -Wl,-z,separate-code -pie -pthread -lpthread -o bitcoind bitcoind-bitcoind.o init/bitcoind-bitcoind.o libbitcoin_node.a libbitcoin_wallet.a libbitcoin_common.a libbitcoin_util.a libunivalue.la libbitcoin_zmq.a libbitcoin_consensus.a crypto/libbitcoin_crypto_base.la crypto/libbitcoin_crypto_sse41.la crypto/libbitcoin_crypto_x86_shani.la crypto/libbitcoin_crypto_avx2.la leveldb/libleveldb.la crc32c/libcrc32c.la crc32c/libcrc32c_sse42.la leveldb/libmemenv.la secp256k1/libsecp256k1.la -lminiupnpc -lnatpmp -levent_pthreads -levent -levent -lzmq -lsqlite3
4libtool: link: /usr/bin/ccache g++ -std=c++20 -g -O2 -fno-extended-identifiers -fstack-reuse=none -fdebug-prefix-map=/home/hebasto/git/bitcoin=. -Wstack-protector -fstack-protector-all -fcf-protection=full -fstack-clash-protection -Wall -Wextra -Wformat -Wformat-security -Wvla -Wredundant-decls -Wdate-time -Wduplicated-branches -Wduplicated-cond -Wlogical-op -Woverloaded-virtual -Wsuggest-override -Wimplicit-fallthrough -Wunreachable-code -Wundef -Wno-unused-parameter -fPIE -ftrivial-auto-var-init=pattern -Wl,-z -Wl,relro -Wl,-z -Wl,now -Wl,-z -Wl,separate-code -pie -o bitcoind bitcoind-bitcoind.o init/bitcoind-bitcoind.o -lpthread libbitcoin_node.a libbitcoin_wallet.a libbitcoin_common.a libbitcoin_util.a ./.libs/libunivalue.a libbitcoin_zmq.a libbitcoin_consensus.a crypto/.libs/libbitcoin_crypto_base.a crypto/.libs/libbitcoin_crypto_sse41.a crypto/.libs/libbitcoin_crypto_x86_shani.a crypto/.libs/libbitcoin_crypto_avx2.a leveldb/.libs/libleveldb.a crc32c/.libs/libcrc32c.a crc32c/.libs/libcrc32c_sse42.a leveldb/.libs/libmemenv.a secp256k1/.libs/libsecp256k1.a -lminiupnpc -lnatpmp -levent_pthreads -levent -levent -lzmq -lsqlite3 -pthread
The point is that CMake correctly reports the flags passed during the linkage step, whereas Autotools fails to do so.
My point is not what may or may not be happening behinds the scenes
Nothing is “happening behinds the scenes”. Rather, everything is well documented in the CMake docs.
my point is we are presenting output doesn’t make sense.
The following diff might help:
0--- a/cmake/module/FlagsSummary.cmake
1+++ b/cmake/module/FlagsSummary.cmake
2@@ -34,10 +34,8 @@ function(print_flags_per_config config indent_num)
3 string(STRIP "${combined_cxx_flags} ${APPEND_CXXFLAGS}" combined_cxx_flags)
4 indent_message("C++ compiler flags ...................." "${combined_cxx_flags}" ${indent_num})
5
6- string(STRIP "${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${config_uppercase}}" combined_linker_flags)
7- string(STRIP "${combined_linker_flags} ${CMAKE_EXE_LINKER_FLAGS}" combined_linker_flags)
8 get_target_interface(common_link_options "${config}" core_interface LINK_OPTIONS)
9- string(STRIP "${combined_linker_flags} ${common_link_options}" combined_linker_flags)
10+ string(STRIP "${CMAKE_EXE_LINKER_FLAGS} ${common_link_options}" combined_linker_flags)
11 if(CMAKE_CXX_LINK_PIE_SUPPORTED)
12 string(JOIN " " combined_linker_flags ${combined_linker_flags} ${CMAKE_CXX_LINK_OPTIONS_PIE})
13 endif()