pathspec doc: parse_pathspec does not maintain references to args

The command line arguments passed to main() are valid for the life of
a program, but the same is not true for all other argv-style arrays
(e.g.  when a caller creates an argv_array).  Clarify that
parse_pathspec does not rely on the argv passed to it to remain valid.

This makes it easier to tell that callers like "git rev-list --stdin"
are safe and ensures that that is more likely to remain true as the
implementation of parse_pathspec evolves.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.c

@@ -526,10 +526,6 @@ static void NORETURN unsupported_magic(const char *pattern,
 	    pattern, sb.buf);
 }
 
-/*
- * Given command line arguments and a prefix, convert the input to
- * pathspec. die() if any magic in magic_mask is used.
- */
 void parse_pathspec(struct pathspec *pathspec,
 		    unsigned magic_mask, unsigned flags,
 		    const char *prefix, const char **argv)

pathspec.h

@@ -70,6 +70,13 @@ struct pathspec {
  */
 #define PATHSPEC_LITERAL_PATH (1<<6)
 
+/*
+ * Given command line arguments and a prefix, convert the input to
+ * pathspec. die() if any magic in magic_mask is used.
+ *
+ * Any arguments used are copied. It is safe for the caller to modify
+ * or free 'prefix' and 'args' after calling this function.
+ */
 extern void parse_pathspec(struct pathspec *pathspec,
 			   unsigned magic_mask,
 			   unsigned flags,