build: Refactor configuration

We now use a recursive make invocation to do the work of `make config`.
The new implementation is also compatible with GNU make 3.81 found on
macOS.

1 files changed, 119 insertions, 0 deletions

diff --git a/config/flags.mk b/config/flags.mk
new file mode 100644
index 0000000..e62e26e
--- /dev/null
+++ b/config/flags.mk
@@ -0,0 +1,119 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/flags.mk
+
+include config/prelude.mk
+include ${GEN}/vars.mk
+
+# Immutable flags
+export BFS_CPPFLAGS= \
+    -D__EXTENSIONS__ \
+    -D_ATFILE_SOURCE \
+    -D_BSD_SOURCE \
+    -D_DARWIN_C_SOURCE \
+    -D_DEFAULT_SOURCE \
+    -D_GNU_SOURCE \
+    -D_LARGEFILE64_SOURCE \
+    -D_POSIX_PTHREAD_SEMANTICS \
+    -D_FILE_OFFSET_BITS=64 \
+    -D_TIME_BITS=64
+export BFS_CFLAGS= -std=c17 -pthread
+
+# Platform-specific system libraries
+LDLIBS,DragonFly := -lposix1e
+LDLIBS,Linux := -lrt
+LDLIBS,NetBSD := -lutil
+LDLIBS,SunOS := -lsocket -lnsl
+export BFS_LDLIBS=${LDLIBS,${OS}}
+
+# Make sure we pick up any default flags from e.g. sys.mk
+export XCPPFLAGS=${CPPFLAGS}
+export XCFLAGS=${CFLAGS}
+export XLDFLAGS=${LDFLAGS}
+export XLDLIBS=${LDLIBS}
+
+# Build profiles
+_ASAN := ${TRUTHY,${ASAN}}
+_LSAN := ${TRUTHY,${LSAN}}
+_MSAN := ${TRUTHY,${MSAN}}
+_TSAN := ${TRUTHY,${TSAN}}
+_UBSAN := ${TRUTHY,${UBSAN}}
+_GCOV := ${TRUTHY,${GCOV}}
+_LINT := ${TRUTHY,${LINT}}
+_RELEASE := ${TRUTHY,${RELEASE}}
+
+# https://github.com/google/sanitizers/issues/342
+TSAN_CPPFLAGS,y := -DBFS_USE_TARGET_CLONES=0
+export TSAN_CPPFLAGS=${TSAN_CPPFLAGS,${_TSAN}}
+
+ASAN_CFLAGS,y := -fsanitize=address
+LSAN_CFLAGS,y := -fsanitize=leak
+MSAN_CFLAGS,y := -fsanitize=memory -fsanitize-memory-track-origins
+TSAN_CFLAGS,y := -fsanitize=thread
+UBSAN_CFLAGS.y := -fsanitize=undefined
+
+export ASAN_CFLAGS=${ASAN_CFLAGS,${_ASAN}}
+export LSAN_CFLAGS=${LSAN_CFLAGS,${_LSAN}}
+export MSAN_CFLAGS=${MSAN_CFLAGS,${_MSAN}}
+export TSAN_CFLAGS=${TSAN_CFLAGS,${_TSAN}}
+export UBSAN_CFLAGS=${UBSAN_CFLAGS,${_UBSAN}}
+
+SAN_CFLAGS,y := -fno-sanitize-recover=all
+SAN := ${NOT,${NOR,${_ASAN},${_LSAN},${_MSAN},${_TSAN},${_UBSAN}}}
+export SAN_CFLAGS=${SAN_CFLAGS,${SAN}}
+
+# MSAN and TSAN both need all code to be instrumented
+NOLIBS ?= ${NOT,${NOR,${_MSAN},${_TSAN}}}
+export XNOLIBS=${NOLIBS}
+
+# gcov only intercepts fork()/exec() with -std=gnu*
+GCOV_CFLAGS,y := -std=gnu17 --coverage
+export GCOV_CFLAGS=${GCOV_CFLAGS,${_GCOV}}
+
+LINT_CPPFLAGS,y := -D_FORTIFY_SOURCE=3 -DBFS_LINT
+LINT_CFLAGS,y := -Werror -O2
+
+export LINT_CPPFLAGS=${LINT_CPPFLAGS,${_LINT}}
+export LINT_CFLAGS=${LINT_CFLAGS,${_LINT}}
+
+RELEASE_CPPFLAGS,y := -DNDEBUG
+RELEASE_CFLAGS,y := -O3 -flto=auto
+
+export RELEASE_CPPFLAGS=${RELEASE_CPPFLAGS,${_RELEASE}}
+export RELEASE_CFLAGS=${RELEASE_CFLAGS,${_RELEASE}}
+
+# Set a variable
+SETVAR = printf '%s := %s\n' >>$@
+
+# Append to a variable, if non-empty
+APPEND = append() { test -z "$$2" || printf '%s += %s\n' "$$1" "$$2" >>$@; }; append
+
+${GEN}/flags.mk::
+	${MSG} "[ GEN] $@"
+	printf '# %s\n' "$@" >$@
+	${SETVAR} CPPFLAGS "$$BFS_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$TSAN_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$LINT_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$RELEASE_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$XCPPFLAGS"
+	${APPEND} CPPFLAGS "$$EXTRA_CPPFLAGS"
+	${SETVAR} CFLAGS "$$BFS_CFLAGS"
+	${APPEND} CFLAGS "$$ASAN_CFLAGS"
+	${APPEND} CFLAGS "$$LSAN_CFLAGS"
+	${APPEND} CFLAGS "$$MSAN_CFLAGS"
+	${APPEND} CFLAGS "$$TSAN_CFLAGS"
+	${APPEND} CFLAGS "$$UBSAN_CFLAGS"
+	${APPEND} CFLAGS "$$SAN_CFLAGS"
+	${APPEND} CFLAGS "$$GCOV_CFLAGS"
+	${APPEND} CFLAGS "$$LINT_CFLAGS"
+	${APPEND} CFLAGS "$$RELEASE_CFLAGS"
+	${APPEND} CFLAGS "$$XCFLAGS"
+	${APPEND} CFLAGS "$$EXTRA_CFLAGS"
+	${SETVAR} LDFLAGS "$$XLDFLAGS"
+	${SETVAR} LDLIBS "$$XLDLIBS"
+	${APPEND} LDLIBS "$$EXTRA_LDLIBS"
+	${APPEND} LDLIBS "$$BFS_LDLIBS"
+	${SETVAR} NOLIBS "$$XNOLIBS"
+	test "${OS}-${SAN}" != FreeBSD-y || printf 'POSTLINK = elfctl -e +noaslr $$@\n' >>$@
+	${VCAT} $@