Add assert() for debug assertions

assert() is like BUG_ON() but compiles to nothing unless DEBUG is defined.
This is useful when a condition is an error but a board reset is unlikely
to fix it, so it is better to soldier on in hope. Assertion failures should
be caught during development/test.

It turns out that assert() is defined separately in a few places in U-Boot
with various meanings. This patch cleans up some of these.

Build errors exposed by this change (and defining DEBUG) are also fixed in
this patch.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/dlmalloc.c

@@ -286,13 +286,6 @@ extern "C" {
 
 */
 
-#ifdef DEBUG
-#include <assert.h>
-#else
-#define assert(x) ((void)0)
-#endif
-
-
 /*
   INTERNAL_SIZE_T is the word-size used for internal bookkeeping
   of chunk sizes. On a 64-bit machine, you can reduce malloc

include/common.h

@@ -124,6 +124,27 @@ typedef volatile unsigned char	vu_char;
 #define debugX(level,fmt,args...)
 #endif	/* DEBUG */
 
+#ifdef DEBUG
+# define _DEBUG 1
+#else
+# define _DEBUG 0
+#endif
+
+/*
+ * An assertion is run-time check done in debug mode only. If DEBUG is not
+ * defined then it is skipped. If DEBUG is defined and the assertion fails,
+ * then it calls panic*( which may or may not reset/halt U-Boot (see
+ * CONFIG_PANIC_HANG), It is hoped that all failing assertions are found
+ * before release, and after release it is hoped that they don't matter. But
+ * in any case these failing assertions cannot be fixed with a reset (which
+ * may just do the same assertion again).
+ */
+void __assert_fail(const char *assertion, const char *file, unsigned line,
+		   const char *function);
+#define assert(x) \
+	({ if (!(x) && _DEBUG) \
+		__assert_fail(#x, __FILE__, __LINE__, __func__); })
+
 #define error(fmt, args...) do {					\
 		printf("ERROR: " fmt "\nat %s:%d/%s()\n",		\
 			##args, __FILE__, __LINE__, __func__);		\

include/malloc.h

@@ -285,14 +285,6 @@ extern "C" {
 
 */
 
-#ifdef DEBUG
-/* #include <assert.h> */
-#define assert(x) ((void)0)
-#else
-#define assert(x) ((void)0)
-#endif
-
-
 /*
   INTERNAL_SIZE_T is the word-size used for internal bookkeeping
   of chunk sizes. On a 64-bit machine, you can reduce malloc

lib/qsort.c

@@ -17,11 +17,6 @@
 
 #include <linux/types.h>
 #include <exports.h>
-#if 0
-#include <assert.h>
-#else
-#define assert(arg)
-#endif
 
 void qsort(void  *base,
 	   size_t nel,

lib/vsprintf.c

@@ -730,3 +730,11 @@ void panic(const char *fmt, ...)
 	while (1)
 		;
 }
+
+void __assert_fail(const char *assertion, const char *file, unsigned line,
+		   const char *function)
+{
+	/* This will not return */
+	panic("%s:%u: %s: Assertion `%s' failed.", file, line, function,
+	      assertion);
+}