Use new str_is_set() instead of ad-hoc checks

lib/dpkg/parsehelp.c

@@ -166,7 +166,7 @@ void varbufversion
   }
   if (version->version)
     varbuf_add_str(vb, version->version);
-  if (version->revision && *version->revision) {
+  if (str_is_set(version->revision)) {
     varbuf_add_char(vb, '-');
     varbuf_add_str(vb, version->revision);
   }

lib/dpkg/version.c

@@ -23,6 +23,7 @@
 
 #include <dpkg/dpkg.h> /* cis* */
 #include <dpkg/ehandle.h>
+#include <dpkg/string.h>
 #include <dpkg/version.h>
 
 void
@@ -37,8 +38,8 @@ bool
 dpkg_version_is_informative(const struct dpkg_version *version)
 {
 	return (version->epoch ||
-	        (version->version && *version->version) ||
-	        (version->revision && *version->revision));
+	        str_is_set(version->version) ||
+	        str_is_set(version->revision));
 }
 
 /**

src/enquiry.c

@@ -44,6 +44,7 @@
 #include <dpkg/dpkg-db.h>
 #include <dpkg/arch.h>
 #include <dpkg/pkg-show.h>
+#include <dpkg/string.h>
 #include <dpkg/options.h>
 
 #include "filesdb.h"
@@ -238,8 +239,8 @@ yettobeunpacked(struct pkginfo *pkg, const char **thissect)
     return false;
   case stat_notinstalled: case stat_halfinstalled: case stat_configfiles:
     if (thissect)
-      *thissect = pkg->section && *pkg->section ? pkg->section :
-                                                  C_("section", "<unknown>");
+      *thissect = str_is_set(pkg->section) ? pkg->section :
+                                             C_("section", "<unknown>");
     return true;
   default:
     internerr("unknown package status '%d'", pkg->status);