miscellaneous changes

Makefile

@@ -1,22 +1,39 @@
 #
+# Use 'make help' to list available targets.
+#
 # Define V=1 to enable "verbose" mode, showing all executed commands.
 #
-# Define DECOMPRESSION_ONLY=yes to omit all compression code, building a
+# Define DECOMPRESSION_ONLY to omit all compression code, building a
 # decompression-only library.  If doing this, you must also build a specific
 # library target such as 'libxpack.a', as the programs will no longer compile.
 #
 # TODO: ENABLE_PREPROCESSING option
 #
+##############################################################################
+
+#### Common compiler flags.
+#### Flags given here are not intended to be overridden, but you can add more
+#### by defining CFLAGS in the environment or on the 'make' command line.
+
+cc-option = $(shell if $(CC) $(1) -c -x c /dev/null -o /dev/null \
+	      1>&2 2>/dev/null; then echo $(1); fi)
+
+override CFLAGS :=							\
+	$(CFLAGS) -O2 -fomit-frame-pointer -std=gnu89 -I. -Icommon	\
+	-Wall -Wundef							\
+	$(call cc-option,-Wdeclaration-after-statement)			\
+	$(call cc-option,-Wmissing-prototypes)				\
+	$(call cc-option,-Wstrict-prototypes)				\
+	$(call cc-option,-Wvla)
 
-CC ?= gcc
-AR ?= ar
+##############################################################################
 
 STATIC_LIB_SUFFIX := .a
 SHARED_LIB_SUFFIX := .so
 PROG_SUFFIX       :=
 PROG_CFLAGS       :=
-PIC_REQUIRED      := yes
-HARD_LINKS        := yes
+PIC_REQUIRED      := 1
+HARD_LINKS        := 1
 
 # Compiling for Windows with MinGW?
 ifneq ($(findstring -mingw,$(CC)),)
@@ -27,20 +44,12 @@ ifneq ($(findstring -mingw,$(CC)),)
     SHARED_LIB_SUFFIX := .dll
     PROG_SUFFIX       := .exe
     PROG_CFLAGS       := -static -municode
-    PIC_REQUIRED      := no
-    HARD_LINKS        := no
+    PIC_REQUIRED      :=
+    HARD_LINKS        :=
 endif
 
 ##############################################################################
 
-#### Common compiler flags; not intended to be overridden
-
-override CFLAGS += -O2 -fomit-frame-pointer -std=gnu89 -I. -Icommon	\
-		-Wall -Wundef -Wdeclaration-after-statement		\
-		-Wmissing-prototypes -Wstrict-prototypes
-
-##############################################################################
-
 #### Quiet make is enabled by default.  Define V=1 to disable.
 
 ifneq ($(findstring s,$(MAKEFLAGS)),s)
@@ -66,13 +75,13 @@ SHARED_LIB := libxpack$(SHARED_LIB_SUFFIX)
 
 LIB_CFLAGS += $(CFLAGS) -fvisibility=hidden -D_ANSI_SOURCE
 
-DECOMPRESSION_ONLY := no
-ifeq ($(DECOMPRESSION_ONLY),yes)
+DECOMPRESSION_ONLY :=
+ifdef DECOMPRESSION_ONLY
     LIB_CFLAGS += -DDECOMPRESSION_ONLY=1
 endif
 
-ENABLE_PREPROCESSING := no
-ifeq ($(ENABLE_PREPROCESSING),yes)
+ENABLE_PREPROCESSING :=
+ifdef ENABLE_PREPROCESSING
     LIB_CFLAGS += -DENABLE_PREPROCESSING=1
 endif
 
@@ -85,7 +94,7 @@ LIB_SRC := lib/x86_cpu_features.c	\
 
 LIB_OBJ := $(LIB_SRC:.c=.o)
 LIB_PIC_OBJ := $(LIB_SRC:.c=.pic.o)
-ifeq ($(PIC_REQUIRED),yes)
+ifdef PIC_REQUIRED
     SHLIB_OBJ := $(LIB_PIC_OBJ)
 else
     SHLIB_OBJ := $(LIB_OBJ)
@@ -156,7 +165,7 @@ xpack$(PROG_SUFFIX):programs/xpack.o $(PROG_COMMON_OBJ) $(STATIC_LIB)
 
 ALL_TARGETS += xpack$(PROG_SUFFIX)
 
-ifeq ($(HARD_LINKS),yes)
+ifdef HARD_LINKS
 # Hard link xunpack to xpack
 xunpack$(PROG_SUFFIX):xpack$(PROG_SUFFIX)
 	$(QUIET_LN) ln -f $< $@

README.md

@@ -61,8 +61,9 @@ file for details.
 
 ## For UNIX
 
-Just run `make`.  You need GNU Make and either GCC or Clang.  There is no `make
-install` yet; just copy the file(s) to where you want.
+Just run `make`.  You need GNU Make and either GCC or Clang.  GCC is recommended
+because it builds slightly faster binaries.  There is no `make install` yet;
+just copy the file(s) to where you want.
 
 By default, all targets are built, including the library and programs.  `make
 help` shows the available targets.  There are also several options which can be

common/common_defs.h

@@ -130,15 +130,11 @@ typedef size_t machine_word_t;
 /*                          Miscellaneous macros                              */
 /* ========================================================================== */
 
-#define ARRAY_LEN(A)	(sizeof(A) / sizeof((A)[0]))
-#define MIN(a, b)	((a) <= (b) ? (a) : (b))
-#define MAX(a, b)	((a) >= (b) ? (a) : (b))
-
-#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
-#  define STATIC_ASSERT(expr)	_Static_assert((expr), "")
-#else
-#  define STATIC_ASSERT(expr)	((void)sizeof(char[1 - 2 * !(expr)]))
-#endif
+#define ARRAY_LEN(A)		(sizeof(A) / sizeof((A)[0]))
+#define MIN(a, b)		((a) <= (b) ? (a) : (b))
+#define MAX(a, b)		((a) >= (b) ? (a) : (b))
+#define DIV_ROUND_UP(n, d)	(((n) + (d) - 1) / (d))
+#define STATIC_ASSERT(expr)	((void)sizeof(char[1 - 2 * !(expr)]))
 
 /* ========================================================================== */
 /*                           Endianness handling                              */

tools/make-windows-releases

@@ -3,7 +3,7 @@
 set -eu
 
 for arch in 'i686' 'x86_64'; do
-	make -j CC=${arch}-w64-mingw32-gcc
+	make -j CC=${arch}-w64-mingw32-gcc CFLAGS="-Werror"
 	dir=xpack-$(git describe --tags | tr -d v)-windows-${arch}-bin
 	rm -rf $dir ${dir}.zip
 	mkdir $dir