Refuse regex for anything but searchby name and name-desc

It's perfectly valid for a package to provide something like libfoo.so,
but the AUR doesn't allow substring matching outside of name and
name-desc, so our fragment-finding logic would happily chop libfoo.so
into libfoo, and never return anything.

src/auracle/auracle.cc

@@ -321,12 +321,20 @@ int Auracle::Search(const std::vector<std::string>& args,
     });
   };
 
+  // 'name' and 'name-desc' are the only dimensions where the AUR allows
+  // substring matching, so that's the only case where we're able to provide
+  // something resembling regex support.
+  const bool allow_regex =
+      options.allow_regex &&
+      (options.search_by == aur::SearchRequest::SearchBy::NAME ||
+       options.search_by == aur::SearchRequest::SearchBy::NAME_DESC);
+
   std::vector<aur::Package> packages;
   for (const auto& arg : args) {
     std::string_view frag = arg;
-    if (options.allow_regex) {
+    if (allow_regex) {
       frag = GetSearchFragment(arg);
-      if (frag.empty() && options.allow_regex) {
+      if (frag.empty()) {
         std::cerr << "error: search string '" << arg
                   << "' insufficient for searching by regular expression.\n";
         return -EINVAL;

tests/test_search.py

@@ -21,10 +21,14 @@ def testSearchByDimensions(self):
             'name',
             'name-desc',
             'maintainer',
+            'comaintainers',
             'depends',
             'makedepends',
             'optdepends',
             'checkdepends',
+            'provides',
+            'replaces',
+            'conflicts',
         ]
 
         for dim in dimensions:
@@ -34,6 +38,14 @@ def testSearchByDimensions(self):
             self.assertEqual(1, len(r.requests_sent))
             self.assertIn(f'by={dim}', r.requests_sent[0].path)
 
+        for dim in dimensions[2:]:
+            r = self.Auracle(['search', '--searchby', dim, 'libfoo.so'])
+            self.assertEqual(0, r.process.returncode)
+
+            self.assertEqual(1, len(r.requests_sent))
+            self.assertIn('/libfoo.so', r.requests_sent[0].path)
+            self.assertIn(f'by={dim}', r.requests_sent[0].path)
+
     def testSearchByInvalidDimension(self):
         r = self.Auracle(['search', '--searchby=notvalid', 'somesearchterm'])
         self.assertNotEqual(0, r.process.returncode)