Pacify gcc 11.1.1 -Wanalyzer-null-argument

* lib-src/etags.c (regexp): Omit member force_explicit_name,
since it’s always true.  All uses removed.  This lets us
remove calls to strlen (name) where GCC isn’t smart enough
to deduce that name must be nonnull.
* lib-src/movemail.c (main): Fix bug that could cause
link (tempname, NULL) to be called.
* src/emacs.c (argmatch): Break check into two ‘if’s,
since GCC doesn’t seem to be smart enough to check the single ‘if’.
* src/gtkutil.c (xg_update_menu_item): Fix bug where strcmp
could be given a NULL arg.
* src/xfont.c (xfont_list_family): Use nonnull value for dummy
initial value.

3 files changed, 8 insertions, 3 deletions

diff --git a/src/emacs.c b/src/emacs.c
index b7982ece646..866e43fda94 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -670,7 +670,9 @@ argmatch (char **argv, int argc, const char *sstr, const char *lstr,
     }
   arglen = (valptr != NULL && (p = strchr (arg, '=')) != NULL
             ? p - arg : strlen (arg));
-  if (lstr == 0 || arglen < minlen || strncmp (arg, lstr, arglen) != 0)
+  if (!lstr)
+    return 0;
+  if (arglen < minlen || strncmp (arg, lstr, arglen) != 0)
     return 0;
   else if (valptr == NULL)
     {
diff --git a/src/gtkutil.c b/src/gtkutil.c
index dee2a930891..313cfc82c26 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -3221,7 +3221,7 @@ xg_update_menu_item (widget_value *val,
       gtk_label_set_text (wkey, utf8_key);
     }
 
-  if (! old_label || strcmp (utf8_label, old_label) != 0)
+  if (utf8_label && (! old_label || strcmp (utf8_label, old_label) != 0))
     {
       label_changed = true;
       gtk_label_set_text (wlbl, utf8_label);
diff --git a/src/xfont.c b/src/xfont.c
index 0570ee96a90..81d356175a4 100644
--- a/src/xfont.c
+++ b/src/xfont.c
@@ -596,7 +596,10 @@ xfont_list_family (struct frame *f)
   char **names;
   int num_fonts, i;
   Lisp_Object list;
-  char *last_family UNINIT;
+  char const *last_family;
+#if defined GCC_LINT || defined lint
+  last_family = "";
+#endif
   int last_len;
 
   block_input ();