profile: make --all exclusive

src/nix/profile.cc

@@ -541,6 +541,15 @@ class MixProfileElementMatchers : virtual Args, virtual StoreCommand
             throw UsageError("No packages specified.");
         }
 
+        if (std::find_if(_matchers.begin(), _matchers.end(), [](const Matcher & m) { return m.name == "All"; }) != _matchers.end() && _matchers.size() > 1) {
+            throw UsageError("--all cannot be used with package names or regular expressions.");
+        }
+
+        if (manifest.elements.empty()) {
+            warn("There are no packages in the profile.");
+            return {};
+        }
+
         std::set<std::string> result;
         for (auto & matcher : _matchers) {
             bool foundMatch = false;

tests/functional/nix-profile.sh

@@ -84,6 +84,12 @@ nix profile upgrade --all
 nix profile rollback
 printf 1.0 > $flake1Dir/version
 
+# Test --all exclusivity.
+assertStderr nix --offline profile upgrade --all foo << EOF
+error: --all cannot be used with package names or regular expressions.
+Try 'nix --help' for more information.
+EOF
+
 # Test matching no packages using literal package name.
 assertStderr nix --offline profile upgrade this_package_is_not_installed << EOF
 warning: Package name 'this_package_is_not_installed' does not match any packages from profile.