Fix warnings

This change fixes Cosmopolitan so it has fewer opinions about compiler
warnings. The whole repository had to be cleaned up to be buildable in
-Werror -Wall mode. This lets us benefit from things like strict const
checking. Some actual bugs might have been caught too.

libc/x/utf16to32.c

@@ -31,9 +31,7 @@
 wchar_t *utf16to32(const char16_t *p, size_t n, size_t *z) {
   wint_t x, y;
   wchar_t *r, *q;
-  unsigned m, j, w;
   const char16_t *e;
-  int16_t v1[8], v2[8], v3[8], vz[8];
   if (z) *z = 0;
   if (n == -1) n = p ? strlen16(p) : 0;
   if ((q = r = malloc(n * 4 + 8 + 1))) {

libc/x/utf16to8.c

@@ -41,9 +41,9 @@ static const int16_t kDel16[8] = {127, 127, 127, 127, 127, 127, 127, 127};
  * @param z if non-NULL receives output length
  */
 char *utf16to8(const char16_t *p, size_t n, size_t *z) {
+  unsigned w;
   char *r, *q;
   wint_t x, y;
-  unsigned m, j, w;
   const char16_t *e;
   int16_t v1[8], v2[8], v3[8], vz[8];
   if (z) *z = 0;

libc/x/utf8to32.c

@@ -37,7 +37,6 @@
  * @param z if non-NULL receives output length
  */
 wchar_t *utf8to32(const char *p, size_t n, size_t *z) {
-  int e;
   size_t i;
   unsigned m, j;
   wint_t x, a, b;

libc/x/xasprintf.h

@@ -3,7 +3,7 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-char *xasprintf(const char *, ...) printfesque(1) paramsnonnull((1))
+char *xasprintf(const char *, ...) paramsnonnull((1))
     returnspointerwithnoaliases dontthrow nocallback dontdiscard returnsnonnull;
 char *xvasprintf(const char *, va_list) paramsnonnull()
     returnspointerwithnoaliases dontthrow nocallback dontdiscard returnsnonnull;

libc/x/xbarf.c

@@ -31,9 +31,9 @@
  * @note this is uninterruptible
  */
 int xbarf(const char *path, const void *data, size_t size) {
-  char *p;
   ssize_t rc;
   int fd, res;
+  const char *p;
   size_t i, wrote;
   res = 0;
   p = data;

libc/x/xbasename.c

@@ -26,8 +26,9 @@
  */
 char *xbasename(const char *path) {
   char *base;
-  path = xstrdup(path);
-  base = xstrdup(basename(path));
-  free(path);
+  char *path2;
+  path2 = xstrdup(path);
+  base = xstrdup(basename(path2));
+  free(path2);
   return base;
 }

libc/x/xdirname.c

@@ -25,8 +25,9 @@
  */
 char *xdirname(const char *path) {
   char *dirp;
-  path = xstrdup(path);
-  dirp = xstrdup(dirname(path));
-  free(path);
+  char *path2;
+  path2 = xstrdup(path);
+  dirp = xstrdup(dirname(path2));
+  free(path2);
   return dirp;
 }

libc/x/xhomedir.c

@@ -25,7 +25,6 @@
  * Returns home directory.
  */
 char *xhomedir(void) {
-  int fd;
   const char *a, *b;
   if ((a = getenv("HOME"))) {
     b = "";

libc/x/xslurp.c

@@ -33,8 +33,8 @@
  */
 void *xslurp(const char *path, size_t *opt_out_size) {
   int fd;
+  char *res;
   size_t i, got;
-  char *res, *p;
   ssize_t rc, size;
   res = NULL;
   if ((fd = open(path, O_RDONLY)) != -1) {

libc/x/xstrmul.c

@@ -25,7 +25,7 @@
  */
 char *xstrmul(const char *s, size_t n) {
   char *p;
-  size_t i, m, size;
+  size_t i, m;
   m = strlen(s);
   p = xcalloc(n + 1, m);
   for (i = 0; i < n; ++i) memcpy(p + i * m, s, m);