[ci]: slience some clang-tidy warnings

the warnings on r_readdir(), img_load_gif() and strcpy seems to be false
positives. the warning about fmt being unused is valid, but not worth
fixing with additional #ifdef guards.

use `assert` to silence the false positive cases when possible,
otherwise use a NOLINT comment with an explanation.

autoreload.c

@@ -79,7 +79,7 @@ void arl_setup(arl_t *arl, const char *filepath)
 	if (base != NULL) {
 		arl->filename[++base - filepath] = '\0';
 		add_watch(arl->fd, &arl->wd_dir, arl->filename, IN_CREATE | IN_MOVED_TO);
-		strcpy(arl->filename, base);
+		strcpy(arl->filename, base); /* NOLINT: basename will always be shorter than fullpath */
 	}
 }
 

image.c

@@ -21,6 +21,7 @@
 #define INCLUDE_IMAGE_CONFIG
 #include "config.h"
 
+#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
@@ -262,6 +263,7 @@ static bool img_load_gif(img_t *img, const fileinfo_t *file)
 							*ptr = bgpixel;
 						}
 					} else {
+						assert(cmap != NULL);
 						r = cmap->Colors[rows[i-y][j-x]].Red;
 						g = cmap->Colors[rows[i-y][j-x]].Green;
 						b = cmap->Colors[rows[i-y][j-x]].Blue;
@@ -447,7 +449,7 @@ bool img_load(img_t *img, const fileinfo_t *file)
 	exif_auto_orientate(file);
 #endif
 
-	if ((fmt = imlib_image_format()) != NULL) {
+	if ((fmt = imlib_image_format()) != NULL) { /* NOLINT: fmt might be unused, not worth fixing */
 #if HAVE_LIBGIF
 		if (STREQ(fmt, "gif"))
 			img_load_gif(img, file);

util.c

@@ -19,6 +19,7 @@
 
 #include "nsxiv.h"
 
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
@@ -178,6 +179,7 @@ char* r_readdir(r_dir_t *rdir, bool skip_dotfiles)
 
 		if (rdir->recursive && rdir->stlen > 0) {
 			/* open next subdirectory */
+			assert(rdir->dir != NULL);
 			closedir(rdir->dir);
 			if (rdir->d != 0)
 				free(rdir->name);