per-config build output using VPATH

based on https://make.mad-scientist.net/papers/multi-architecture-builds/

.gitignore

@@ -4,4 +4,5 @@ out
 .direnv
 .envrc
 result
-mutants.*
+mutants.*
+_out_*

build.rs

@@ -4,32 +4,55 @@
 //! the out directory. This can be used to use the build script as a command line tool from other
 //! build tools.
 
-use std::{env, fs::copy};
+use std::{env, fs};
 
 fn main() {
     let crate_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
-    println!("cargo::rerun-if-changed={crate_dir}");
+    println!("cargo::rerun-if-changed={crate_dir}/src");
+    println!("cargo::rerun-if-changed={crate_dir}/build.rs");
+    println!("cargo::rerun-if-changed={crate_dir}/Cargo.toml");
+    println!("cargo::rerun-if-changed={crate_dir}/Cargo.lock");
+    println!("cargo::rerun-if-changed={crate_dir}/cbindgen.toml");
+    println!("cargo::rerun-if-env-changed=SERVICEPOINT_HEADER_OUT");
 
     let config =
         cbindgen::Config::from_file(crate_dir.clone() + "/cbindgen.toml")
             .unwrap();
-
     let output_dir = env::var("OUT_DIR").unwrap();
     let header_file = output_dir.clone() + "/servicepoint.h";
 
-    if let Ok(bindings) = cbindgen::generate_with_config(crate_dir, config) {
-        bindings.write_to_file(&header_file);
-
-        println!("cargo:include={output_dir}");
-
-        println!("cargo::rerun-if-env-changed=SERVICEPOINT_HEADER_OUT");
-        if let Ok(header_out) = env::var("SERVICEPOINT_HEADER_OUT") {
-            let header_copy = header_out + "/servicepoint.h";
-            println!("cargo:warning=Copying header to {header_copy}");
-            copy(header_file, &header_copy).unwrap();
-            println!("cargo::rerun-if-changed={header_copy}");
+    let bindings = match cbindgen::generate_with_config(crate_dir, config) {
+        Ok(bindings) => bindings,
+        Err(e) => {
+            eprintln!("cargo:warning=Servicepoint header could not be generated: {e:?}");
+            return;
         }
-    } else {
-        eprintln!("cargo:warning=Servicepoint header could not be generated");
+    };
+
+    bindings.write_to_file(&header_file);
+    println!("cargo:include={output_dir}");
+
+    if let Ok(header_out) = env::var("SERVICEPOINT_HEADER_OUT") {
+        let header_copy = header_out + "/servicepoint.h";
+        
+        if fs::exists(&header_copy).ok().unwrap_or(false) {
+            // check if content changed to prevent rebuild of dependents if not
+
+            let mut bindings_text = Vec::new();
+            bindings.write(&mut bindings_text);
+            
+            match fs::read(&header_copy) {
+                Ok(old_content) if old_content == bindings_text => {
+                    println!("cargo:warning=Header did not change, not updating timestamp");
+                    return;
+                }
+                _  => {}
+            };
+        }
+        
+        // file does not exist or is different
+        println!("cargo:warning=Copying header to {header_copy}");
+        fs::copy(header_file, &header_copy).unwrap();
+        println!("cargo::rerun-if-changed={header_copy}");
     }
 }

example/Makefile

@@ -1,137 +1,136 @@
+# based on https://make.mad-scientist.net/papers/multi-architecture-builds/
+
+_libc := $(if $(LIBC),$(LIBC),gnu)
+ifeq (,$(filter gnu musl,$(_libc)))
+  _link_type := $(error "LIBC has to be set to one of: gnu, musl")
+endif
+
+_link_type := $(if $(LINK),$(LINK),dynamic)
+ifeq (,$(filter dynamic static,$(_link_type)))
+  _link_type := $(error "LINK has to be set to one of: dynamic, static")
+endif
+
+_profile := $(if $(PROFILE),$(PROFILE),release)
+ifeq (,$(filter release debug size-optimized,$(_profile)))
+  _profile := $(error "PROFILE has to be set to one of: debug, release, size-optimized")
+endif
+
+ARCH ?= $(shell uname -m)
+RUST_TARGET := $(ARCH)-unknown-linux-$(_libc)
+
+#----- Begin Boilerplate
+ifeq (,$(filter _out_%,$(notdir $(CURDIR))))
+  include target.mk
+else
+#----- End Boilerplate
+
+VPATH	  = $(SRCDIR)
+
 CARGO ?= cargo
 STRIP ?= strip
+CC ?= gcc
 
-FEATURES := "env_logger"
+FEATURES := ""#"env_logger"
 
 THIS_DIR := $(dir $(realpath $(lastword $(MAKEFILE_LIST))))
 REPO_ROOT := $(realpath $(THIS_DIR)/..)
-export SERVICEPOINT_HEADER_OUT := $(REPO_ROOT)/include
 
-override CFG_MUSL := $(if $(CFG_MUSL),$(CFG_MUSL),$(if $(MUSL),$(MUSL),0))
-override CFG_PROFILE := $(if $(CFG_PROFILE),$(CFG_PROFILE),$(if $(PROFILE),$(PROFILE),release))
+# TODO: check if override is needed
+_rust_cli_profile := $(if $(filter $(_profile),debug),dev,$(_profile))
 
-CCFLAGS += -Wall -Wextra -pedantic -fwhole-program -fPIE -pie
-
-STRIPFLAGS := -s --strip-unneeded -R .comment -R .gnu.version -R .note -R .note.gnu.build-id -R .note.ABI-tag
-
-#ifeq ($(CFG_PROFILE), size-optimized)
-#	CCFLAGS += -nodefaultlibs -lc
-#endif
-
-STATIC_LINK_LIBS := -lservicepoint_binding_c
-
-ifeq ($(CFG_PROFILE), size-optimized)
-	CARGO_PROFILE := size-optimized
-	CCFLAGS += -Oz \
-		-fwrapv -fomit-frame-pointer -fno-stack-protector\
-		-fno-unroll-loops \
-		-fno-unwind-tables -fno-asynchronous-unwind-tables \
-		-fmerge-all-constants \
-		-Wl,-z,norelro \
-		-Wl,--hash-style=gnu \
-		-fvisibility=hidden \
-		-Bsymbolic \
-		-Wl,--exclude-libs,ALL \
-		-fno-ident \
-		-fno-exceptions
-	CARGOFLAGS += -Zbuild-std="core,std,alloc,proc_macro,panic_abort" \
-		-Zbuild-std-features="panic_immediate_abort"
-	RUSTFLAGS += -Zlocation-detail=none \
-		-Zfmt-debug=none \
-		-C link-arg=-z,norelro \
-		-C panic=abort
-		#-C link-arg=--hash-style=gnu
-else
-	FEATURES := $(FEATURES),all_compressions
-	STATIC_LINK_LIBS += -llzma
-	ifeq ($(CFG_PROFILE), release)
-		CARGO_PROFILE := release
-		CCFLAGS += -O2
-	else ifeq ($(CFG_PROFILE), debug)
-		CCFLAGS += -Og
-		CARGO_PROFILE := dev
-	else
-		CFG_PROFILE := $(error "PROFILE has to be set to one of: debug, release, size-optimized")
-	endif
-endif
-
-
-ifeq ($(CFG_MUSL), 1)
-	TARGET ?= x86_64-unknown-linux-musl
-	CC ?= musl-gcc
-	CCFLAGS += -static $(STATIC_LINK_LIBS)
-	RUSTFLAGS += --crate-type=staticlib -Ctarget-feature=-crt-static
-else
-	TARGET ?= x86_64-unknown-linux-gnu
-	CC ?= gcc
-	#CCFLAGS += -shared
-	CCFLAGS += -Wl,-Bstatic $(STATIC_LINK_LIBS) -Wl,-Bdynamic
-endif
+# TODO: `make LINK=static` fails with linker error "undefined reference to `_dl_find_object'" in libgcc_eh.a
 
+STRIPFLAGS += -s --strip-unneeded -R .comment -R .gnu.version -R .note -R .note.gnu.build-id -R .note.ABI-tag
+STATIC_LINK_LIBS += -lservicepoint_binding_c
 
+size-optimized_CARGOFLAGS += -Zbuild-std="core,std,alloc,proc_macro,panic_abort" \
+	-Zbuild-std-features="panic_immediate_abort"
 CARGOFLAGS += --manifest-path=$(REPO_ROOT)/Cargo.toml \
-	--profile=$(CARGO_PROFILE) \
+	--profile=$(_rust_cli_profile) \
 	--no-default-features \
 	--features=$(FEATURES) \
-	--target=$(TARGET)
+	--target=$(RUST_TARGET) \
+	$($(_profile)_CARGOFLAGS) \
+	--target-dir=cargo
 
-ifneq ($(CFG_PROFILE), debug)
-	CCFLAGS += -ffunction-sections -fdata-sections -Wl,--gc-sections
+CFLAGS += -Wall -Wextra -pedantic -fwhole-program -fPIE -pie
+_no_debug_cflags := -ffunction-sections -fdata-sections -Wl,--gc-sections
+size-optimized_CFLAGS += -Oz \
+	-fwrapv -fomit-frame-pointer -fno-stack-protector\
+	-fno-unroll-loops \
+	-fno-unwind-tables -fno-asynchronous-unwind-tables \
+	-fmerge-all-constants \
+	-Wl,-z,norelro \
+	-Wl,--hash-style=gnu \
+	-fvisibility=hidden \
+	-Bsymbolic \
+	-Wl,--exclude-libs,ALL \
+	-fno-ident \
+	-fno-exceptions \
+	$(_no_debug_cflags)
+release_CFLAGS += -O2 \
+	$(_no_debug_cflags)
+debug_CFLAGS += -Og
+static_CFLAGS += -static $(STATIC_LINK_LIBS)
+dynamic_CFLAGS += -Wl,-Bstatic $(STATIC_LINK_LIBS) -Wl,-Bdynamic
+
+size-optimized_RUSTFLAGS += -Zlocation-detail=none \
+	-Zfmt-debug=none \
+	-C link-arg=-z,norelro \
+	-C panic=abort
+	#-C link-arg=--hash-style=gnu
+musl_RUSTFLAGS += --crate-type=staticlib -Ctarget-feature=-crt-static
+
+RUSTFLAGS += $($(_libc)_RUSTFLAGS) $($(_profile)_RUSTFLAGS) $($(_link_type)_RUSTFLAGS)
+ifneq ($(_profile), debug)
 	RUSTFLAGS += -C link-arg=-s -C link-arg=-Wl,--gc-sections
 endif
 
+CARGO_OBJDIR := cargo/$(RUST_TARGET)/$(_profile)
+_servicepoint_cflags := -I $(REPO_ROOT)/include -L $(CARGO_OBJDIR)
+
+CFLAGS += $($(_libc)_CFLAGS) $($(_profile)_CFLAGS) $($(_link_type)_CFLAGS) $(_servicepoint_cflags)
 ifeq ($(LTO), 1)
-	CCFLAGS += -flto
+	CFLAGS += -flto
 endif
 
-RUST_TARGET_DIR := $(REPO_ROOT)/target/$(TARGET)/$(CFG_PROFILE)
 
-_c_src := $(wildcard ./src/*.c)
+# TODO: wildcard does not work with VPATH
+_c_src := src/announce.c src/brightness_tester.c src/header_logger.c \
+	src/moving_line.c src/random_stuff.c src/wiping_clear.c
 _programs := $(basename $(notdir $(_c_src)))
-_bins := $(addprefix out/, $(_programs))
+_bins := $(_programs)
 _unstripped_bins := $(addsuffix _unstripped, $(_bins))
 _run_programs := $(addprefix run_, $(_programs))
-_rs_src := $(wildcard ../src/**.rs) ../Cargo.lock ../Cargo.toml ../cbindgen.toml
-_sp_artifacts := $(SERVICEPOINT_HEADER_OUT)/servicepoint.h $(RUST_TARGET_DIR)/libservicepoint_binding_c.a $(RUST_TARGET_DIR)/libservicepoint_binding_c.so
+
+# TODO: use cargo --target-dir to put rust binaries into same dir
 
 all: $(_bins)
 
-clean: clean-c clean-rust
+.PHONY: all clean sizes $(_run_programs) clean-c clean-rust build-rust help FORCE
 
-clean-c:
-	rm -r out || true
+$(_unstripped_bins): %_unstripped: src/%.c src/helpers.h build-rust
+	$(CC) $< $(CFLAGS) -o $@
 
-clean-rust:
-	rm $(SERVICEPOINT_HEADER_OUT)/servicepoint.h || true
-	cargo clean
-
-.PHONY: all clean sizes $(_run_programs) clean-c clean-rust
-
-$(_unstripped_bins): out/%_unstripped: src/%.c $(SERVICEPOINT_HEADER_OUT)/servicepoint.h src/helpers.h $(_sp_artifacts)
-	mkdir -p out || true
-	$(CC) $< \
-		-I $(SERVICEPOINT_HEADER_OUT) \
-		-L $(RUST_TARGET_DIR) \
-		$(CCFLAGS) \
-		-o $@
-
-$(_bins): out/%: out/%_unstripped
+$(_bins): %: %_unstripped
 	$(STRIP) $(STRIPFLAGS) $^ -o $@
 
-$(_sp_artifacts): $(_rs_src)
-	mkdir -p $(SERVICEPOINT_HEADER_OUT) || true
+build-rust: FORCE
 	# generate servicepoint header and library to link against
 	$(CARGO) rustc $(CARGOFLAGS) -- $(RUSTFLAGS)
 
-$(_run_programs): run_%: out/% FORCE
-	./$<
-
-sizes: $(_bins)
-	ls -lB out
-
-analyze-size: out/$(BIN)_unstripped
-	nm --print-size --size-sort --reverse-sort --radix=d --demangle out/$(BIN)_unstripped \
-		| awk '{size=$$2+0; print size "\t" $$4}' \
-		| less
-
 FORCE: ;
+
+help:
+	@echo "You have the choice of the following parameters:"
+	@echo ""
+	@echo "Variable | Description                       | Default   | Values"
+	@echo "---------+-----------------------------------+-----------+---------------------------"
+	@echo "CARGO    | which cargo binary to use         | 'cargo'   | 'rustup run nightly cargo'"
+	@echo "CC       | which C compiler to use           | 'gcc'     | 'musl-gcc'"
+	@echo "STRIP    | which strip command to use        | 'strip'   | -"
+	@echo "MUSL     | if set, use musl instead of glibc | unset     | '1'"
+	@echo "PROFILE  | Compilation profile               | 'release' | 'debug' or 'size-optimized'"
+
+#----- Begin Boilerplate
+endif

example/src/header_logger.c

@@ -16,7 +16,7 @@ void handle_error(const char *msg) {
 }
 
 int main(int argc, char **argv) {
-    init_env_logger();
+    //init_env_logger();
 
     int udp_socket = socket(AF_INET, SOCK_DGRAM, 0);
     if (udp_socket == -1)

example/target.mk

@@ -0,0 +1,38 @@
+# Based on https://make.mad-scientist.net/papers/multi-architecture-builds/
+
+.SUFFIXES:
+
+OBJDIR := _out_$(RUST_TARGET)-$(_link_type)-$(_profile)
+
+# Define the rules to build in the target subdirectories.
+#
+MAKETARGET = $(MAKE) --no-print-directory -C $@ -f $(CURDIR)/Makefile \
+		SRCDIR=$(CURDIR) $(MAKECMDGOALS)
+
+.PHONY: $(OBJDIR)
+$(OBJDIR):
+	+@[ -d "$@" ] || mkdir -p "$@"
+	+@$(MAKETARGET)
+
+# These rules keep make from trying to use the match-anything rule below to
+# rebuild the makefiles--ouch!  Obviously, if you don't follow my convention
+# of using a `.mk' suffix on all non-standard makefiles you'll need to change
+# the pattern rule.
+#
+Makefile : ;
+%.mk :: ;
+
+# Anything we don't know how to build will use this rule.  The command is a
+# do-nothing command, but the prerequisites ensure that the appropriate
+# recursive invocations of make will occur.
+#
+% :: $(OBJDIR) ;
+
+# The clean rule is best handled from the source directory: since we're
+# rigorous about keeping the target directories containing only target files
+# and the source directory containing only source files, `clean' is as trivial
+# as removing the target directories!
+#
+.PHONY: clean
+clean:
+	rm -rf $(OBJDIR)

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1747862697,
-        "narHash": "sha256-U4HaNZ1W26cbOVm0Eb5OdGSnfQVWQKbLSPrSSa78KC0=",
+        "lastModified": 1748037224,
+        "narHash": "sha256-92vihpZr6dwEMV6g98M5kHZIttrWahb9iRPBm1atcPk=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "2baa12ff69913392faf0ace833bc54bba297ea95",
+        "rev": "f09dede81861f3a83f7f06641ead34f02f37597f",
         "type": "github"
       },
       "original": {