From 14adff17113dd2d4c0eb6c540a74308019829866 Mon Sep 17 00:00:00 2001
From: Bob van der Linden <bobvanderlinden@gmail.com>
Date: Mon, 26 Feb 2024 21:09:17 +0100
Subject: [PATCH] profile install: skip and warn on installing package twice

---
 src/nix/profile.cc              | 21 ++++++++++++++++++++-
 tests/functional/nix-profile.sh |  3 +++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index e04ae008d..d39a24d36 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -395,7 +395,26 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
 
             element.updateStorePaths(getEvalStore(), store, res);
 
-            manifest.addElement(std::move(element));
+            auto elementName = getNameFromElement(element);
+
+            // Check if the element already exists.
+            auto existingPair = manifest.elements.find(elementName);
+            if (existingPair != manifest.elements.end()) {
+                auto existingElement = existingPair->second;
+                auto existingSource = existingElement.source;
+                auto elementSource = element.source;
+                if (existingSource
+                    && elementSource
+                    && existingElement.priority == element.priority
+                    && existingSource->originalRef == elementSource->originalRef
+                    && existingSource->attrPath == elementSource->attrPath
+                    ) {
+                    warn("'%s' is already installed", elementName);
+                    continue;
+                }
+            }
+
+            manifest.addElement(elementName, std::move(element));
         }
 
         try {
diff --git a/tests/functional/nix-profile.sh b/tests/functional/nix-profile.sh
index 88b713d53..ee93251e9 100644
--- a/tests/functional/nix-profile.sh
+++ b/tests/functional/nix-profile.sh
@@ -64,6 +64,9 @@ nix profile install $flake1Dir
 [[ $($TEST_HOME/.local/state/nix/profile/bin/hello) = "Hello World" ]]
 unset NIX_CONFIG
 
+# Test conflicting package install.
+nix profile install $flake1Dir 2>&1 | grep "warning: 'flake1' is already installed"
+
 # Test upgrading a package.
 printf NixOS > $flake1Dir/who
 printf 2.0 > $flake1Dir/version