feat(c): add hello source

c/Makefile

@@ -0,0 +1,35 @@
+.POSIX:
+.SUFFIXES: .o
+
+CC ?= gcc
+OUT := hello
+
+SRC += main.c
+OBJ := $(SRC:.c=.o)
+
+CFLAGS += @compile_flags.txt
+CFLAGS += -ffunction-sections -fdata-sections
+
+LDFLAGS := -fwhole-program -flto
+LDFLAGS += -Wl,--gc-sections -s
+
+RM ?= rm -f
+
+.DEFAULT_GOAL: all
+.PHONY: all
+all: $(OUT)
+
+$(OUT): $(OBJ)
+	$(CC) -o $@ $<
+
+.PHONY: clean
+clean:
+	$(RM) $(OBJ)
+
+.PHONY: fclean
+fclean: clean
+	$(RM) -r $(OUT)
+
+.PHONY: re
+.NOTPARALLEL: re
+re: fclean all

c/compile_flags.txt

@@ -0,0 +1,18 @@
+-std=c99
+-pedantic
+-pipe
+
+-Wall
+-Wcast-qual
+-Wconversion
+-Werror=return-type
+-Werror=vla-larger-than=0
+-Wextra
+-Wmissing-prototypes
+-Wshadow
+-Wstrict-prototypes
+-Wwrite-strings
+
+-O2
+-march=native
+-mtune=native

c/main.c

@@ -0,0 +1,16 @@
+#include <stdlib.h>
+#include <unistd.h>
+
+#define lengthof(sstr) (sizeof (sstr) / sizeof *(sstr))
+#define sstr_len(sstr) (lengthof(sstr) - 1)
+#define sstr_unpack(sstr) (sstr), (sstr_len(sstr))
+
+static const char GREETING[] = "hello, world!\n";
+
+int main(void)
+{
+    return (
+        write(STDOUT_FILENO, sstr_unpack(GREETING))
+        == sstr_len(GREETING)
+    ) ? EXIT_SUCCESS : EXIT_FAILURE;
+}