linux-bin.txt

# Linux — *final-link-only* flags shared by every Linux/$arch-bin profile.
# Appended after base.txt + linux.txt + linux-$arch.txt at the consuming
# project's executable / shared-library link step. Anything ELF-wide that
# would break a dependency build's intermediate conftest or test-binary
# link goes here. Per-arch final-link flags (currently none) live in the
# linux-$arch-bin.txt sibling.

# Drop unreferenced sections produced by -ffunction-sections /
# -fdata-sections (emitted in base.txt). The intermediate per-symbol
# section granularity is wasted code-size unless somebody runs DCE; this
# flag is the consumer of those flags. Safe at the final link only —
# applying it at intermediate dependency-build links strips symbols that
# a later stage still references.
-Wl,--gc-sections

# Reject any undefined symbol at link time. For shared libraries this
# means every external dep must be in DT_NEEDED; for executables, every
# external symbol must be resolvable. Catches missing libraries early
# instead of failing at dlopen / runtime. Pairs naturally with `-z now`
# (already enforced in linux.txt): if we're going to bind eagerly at
# load anyway, we may as well prove it links cleanly.
-Wl,-z,defs

# Compress DWARF debug sections with zstd. lld ≥ 18 writes the modern
# SHF_COMPRESSED form; binutils 2.42+, gdb 14+, and llvm-objdump 18+
# read it. Substantial size reduction with -g (~40-60% smaller .debug_*),
# zero runtime cost — debug sections aren't loaded into memory.
-Wl,--compress-debug-sections=zstd

# Make linker warnings fatal at the final link only. At intermediate
# dependency-build stages a benign warning (e.g. about a missing
# __start_/__stop_ alias that gets defined later, or a
# DT_TEXTREL produced by an incidental .S input) would otherwise abort
# the build before we got to do anything about it.
-Wl,--fatal-warnings