2 files changed, 28 insertions, 21 deletions

diff --git a/src/lisp.h b/src/lisp.h
index ca833476c03..61cc20e9d42 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -144,11 +144,13 @@ typedef intmax_t printmax_t;
 typedef uintmax_t uprintmax_t;
 # define pMd PRIdMAX
 # define pMu PRIuMAX
+# define pMx PRIxMAX
 #else
 typedef EMACS_INT printmax_t;
 typedef EMACS_UINT uprintmax_t;
 # define pMd pI"d"
 # define pMu pI"u"
+# define pMx pI"x"
 #endif
 
 /* Use pD to format ptrdiff_t values, which suffice for indexes into
diff --git a/src/print.c b/src/print.c
index 08c39d34664..406abbf4a3f 100644
--- a/src/print.c
+++ b/src/print.c
@@ -1361,6 +1361,19 @@ print_prune_string_charset (Lisp_Object string)
   return string;
 }
 
+#ifdef HAVE_MODULES
+/* Return a data pointer equal to FUNCPTR.  */
+
+static void const *
+data_from_funcptr (void (*funcptr) (void))
+{
+  /* The module code, and the POSIX API for dynamic linking, already
+     assume that function and data pointers are represented
+     interchangeably, so it's OK to assume that here too.  */
+  return (void const *) funcptr;
+}
+#endif
+
 static bool
 print_vectorlike (Lisp_Object obj, Lisp_Object printcharfun, bool escapeflag,
                   char *buf)
@@ -1788,30 +1801,20 @@ print_vectorlike (Lisp_Object obj, Lisp_Object printcharfun, bool escapeflag,
       {
         print_c_string ("#<module function ", printcharfun);
         module_funcptr ptr = module_function_address (XMODULE_FUNCTION (obj));
-        const char *file = NULL;
-        const char *symbol = NULL;
+        char const *file;
+        char const *symbol;
         dynlib_addr (ptr, &file, &symbol);
 
         if (symbol == NULL)
           {
-            print_c_string ("at 0x", printcharfun);
-            /* See https://stackoverflow.com/a/2741896 for how to
-               portably print a function pointer.  */
-            const unsigned char *p = (const unsigned char *) &ptr;
-            for (size_t i = 0; i < sizeof ptr; ++i)
-              {
-#ifdef WORDS_BIGENDIAN
-                unsigned char b = p[i];
-#else
-                unsigned char b = p[sizeof ptr - i - 1];
-#endif
-                enum { digits = (CHAR_BIT + 4 - 1) / 4 };
-                char buffer[digits + 1];
-                int needed
-                  = snprintf (buffer, sizeof buffer, "%0*x", digits, b);
-                eassert (needed == digits);
-                print_c_string (buffer, printcharfun);
-              }
+            uintptr_t ui = (uintptr_t) data_from_funcptr (ptr);
+
+            /* In theory this assignment could lose info on pre-C99
+               hosts, but in practice it doesn't.  */
+            uprintmax_t up = ui;
+
+            int len = sprintf (buf, "at 0x%"pMx, up);
+            strout (buf, len, len, printcharfun);
           }
         else
           print_c_string (symbol, printcharfun);
@@ -1839,7 +1842,9 @@ print_object (Lisp_Object obj, Lisp_Object printcharfun, bool escapeflag)
 {
   char buf[max (sizeof "from..to..in " + 2 * INT_STRLEN_BOUND (EMACS_INT),
                 max (sizeof " . #" + INT_STRLEN_BOUND (printmax_t),
-                     40))];
+                     max ((sizeof "at 0x"
+                           + (sizeof (uprintmax_t) * CHAR_BIT + 4 - 1) / 4),
+                          40)))];
   current_thread->stack_top = buf;
   maybe_quit ();