Hi,

During testing and using a locally modified version of ccache to
support "-gsplit-dwarf" (see bug 10005 )
I noticed that the popular compiler flag to pass parameters to linker
-Wl,... (... is a string that denotes the parameters to the linker)
is not ignored for computing hash and thus
the sequence of commands,

ccache gcc -c /tmp/t.c
ccache gcc -c /tmp/t.c -Wl,...

does not cause a cache hit when the second command is issued.
It should.

A simple change like the following would suffice:
(Sorry this is not in a diff form.)
Simply process "-Wl,..." like -Lpath.

static struct file_hash *
calculate_object_hash(struct args *args, struct mdfour *hash, int direct_mode)
{
	int i;
	char *manifest_name;
	struct stat st;
	int result;
	struct file_hash *object_hash = NULL;
	char *p;

	if (direct_mode) {
		hash_delimiter(hash, "manifest version");
		hash_int(hash, MANIFEST_VERSION);
	}

	/* first the arguments */
	for (i = 1; i < args->argc; i++) {
		/* -L doesn't affect compilation. */
		if (i < args->argc-1 && str_eq(args->argv[i], "-L")) {
			i++;
			continue;
		}
		if (str_startswith(args->argv[i], "-L")) {
			continue;
		}

		/* for gcc, -Wl,... is for linker options and so does not affect
		   compilation */
		if (str_startswith(args->argv[i], "-Wl,")) {
			cc_log("(debug) -Wl,... is ignored from hashing.");
			continue;
		}



I have tested this and it works. make test pass, so I have not incorporated a new bug (maybe I need more test cases, etc.)

Thank you in advance for your attention.