Fix six Linux/gcc portability gaps surfaced building flare - #64
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Verified by building the whole flare RPC framework end to end on aarch64
Linux/gcc (Ubuntu container): every target compiles + links, the tests
run, and cc-check-undefined reports zero findings -- matching the macOS
baseline. clang had masked all six; they only bit on Linux/gcc.
Build/link (internal/cc, internal/build):
* precreate build-dir include directories. A globally-configured
-Ibuild_dir/<pkg> (flare's cc_config.extra_incs lists
build_dir/thirdparty) is a fatal -Wmissing-include-dirs under -Werror
when the dir doesn't exist yet; ninja's lazy per-edge mkdir races the
first compile. Blade sidesteps this by makedirs'ing build_dir/<pkg>
per target -- we now do the same (+ any build-dir-rooted global -I).
clang silently ignores a missing -I dir, so this only failed on gcc.
* put vcpkg archives inside the target's --start-group on ELF. GNU ld
re-scans only within a group, so curl -> ssl -> crypto forward refs
across the group boundary went unresolved; ld64 re-scans regardless.
* apply per-target extra_cppflags/extra_cxxflags/extra_cflags/
extra_asflags (#492) -- flare's crypto md5/sha pass
-Wno-deprecated-declarations for OpenSSL 3.x's HMAC deprecation.
* normalize incs/export_incs like Blade's _incs_to_fullpath: a leading
// is root-relative (strip it), else package-relative. flare's
foreign_cc_library sets export_incs='//'+build_dir/.../include, which
reached gcc as the nonexistent -I//build_dir/... .
* select a foreign_cc_library's archive by lib<name>.a, not an
arbitrary .a. One autotools gen_rule (gperftools_build) emits many
archives shared by sibling targets (tcmalloc, profiler, ...); the old
"any .a" left consumers of :profiler without libprofiler.a
(ProfilerStart/Stop/Flush undefined across 45 targets).
cc-check-undefined system baseline on Linux (internal/ccundef):
* strip ELF symbol-version suffixes (sym@@GLIBCXX_3.4 -> sym) so the
versioned libstdc++/libc/libgcc exports match a consumer's bare
undefined ref -- otherwise every C++ target flagged std symbols.
* treat nm IFUNC types i/I as defined (glibc memcpy/memmove/... are
indirect functions).
* follow the glibc `libc.so` linker script to its members (libc.so.6 +
libc_nonshared.a + AS_NEEDED loader) and scan every resolvable lib
spelling, so the real versioned ELF (libgcc_s.so.1 -> _Unwind_Resume)
and the static helpers are both covered; also scan libgcc.a (aarch64
outline atomics __aarch64_ldadd*/cas*/swp*).
* baseline __stack_chk_* (loader-provided; U in every scannable lib).
Unit tests cover ELF link grouping, // include normalization, foreign
archive selection, and the stack-protector baseline.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Building the whole flare RPC framework end to end on aarch64 Linux/gcc (in an Ubuntu container) surfaced six portability gaps that clang had masked. After these fixes every
//flare/...target compiles + links, the tests run, andcc-check-undefinedreports zero findings — matching the macOS/Python baseline.Build / link (
internal/cc,internal/build)-I-dir race — a globally-configured-Ibuild_dir/<pkg>(flare listsbuild_dir/thirdpartyincc_config.extra_incs) is fatal under-Wmissing-include-dirs -Werrorwhen the dir doesn't exist yet; ninja's lazy per-edgemkdirraces the first compile. Now precreatebuild_dir/<pkg>per target (as Blade'smakedirsdoes) + any build-dir-rooted global-I. clang silently ignores a missing-Idir, so this only broke on gcc.--start-groupsocurl → ssl → crypto/protobuf → abslforward refs resolve (GNU ld re-scans only within a group; ld64 re-scans regardless).extra_cppflags/extra_cxxflags/extra_cflags/extra_asflags(#492) — flare's cryptomd5/shapass-Wno-deprecated-declarationsfor OpenSSL 3.x's HMAC deprecation.//-rooted include normalization — mirror Blade's_incs_to_fullpath(leading//= root-relative; else package-relative). flare'sforeign_cc_librarysetsexport_incs='//'+build_dir/.../include, which reached gcc as a nonexistent-I//build_dir/....foreign_cc_libraryselection — picklib<name>.a, not an arbitrary.a. One gen_rule (gperftools_build) emits many archives shared by sibling targets; the old code left consumers of:profilerwithoutlibprofiler.a(ProfilerStart/Stop/Flushundefined across 45 targets).cc-check-undefinedLinux baseline (internal/ccundef)sym@@GLIBCXX_3.4 → sym); treat nm IFUNCi/Ias defined (glibcmemcpy/memmove); follow the glibclibc.solinker script + scan every resolvable spelling (reallibgcc_s.so.1→_Unwind_Resume,libc_nonshared.a) and scanlibgcc.a(aarch64 outline atomics); baseline__stack_chk_*(loader-provided,Ueverywhere). Without these, every C++ target on Linux flagged std-library symbols.Tests
Unit tests cover ELF link grouping,
//include normalization, foreign archive selection, and the stack-protector baseline; the flare whole-repo build/link/test + clean undefined-check is the integration proof.