From b6d794fb8df09b9b5d86f3fe2a2789631215f8b5 Mon Sep 17 00:00:00 2001
From: YI <uuuuuu@protonmail.com>
Date: Sun, 1 Mar 2020 16:11:22 +0800
Subject: [PATCH] display attr-path only when queried available

---
 doc/manual/command-ref/nix-env.xml | 3 ++-
 src/nix-env/nix-env.cc             | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/doc/manual/command-ref/nix-env.xml b/doc/manual/command-ref/nix-env.xml
index d257a5e49..9c03ccce1 100644
--- a/doc/manual/command-ref/nix-env.xml
+++ b/doc/manual/command-ref/nix-env.xml
@@ -1066,7 +1066,8 @@ user environment elements, etc. -->
     the derivation, which can be used to unambiguously select it using
     the <link linkend="opt-attr"><option>--attr</option> option</link>
     available in commands that install derivations like
-    <literal>nix-env --install</literal>.</para></listitem>
+    <literal>nix-env --install</literal>. This option only works
+    together with <option>--available</option></para></listitem>
 
   </varlistentry>
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index a40d0c7e6..106dfe0b6 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -914,6 +914,8 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
             throw UsageError(format("unknown flag '%1%'") % arg);
     }
 
+    if (printAttrPath && source != sAvailable)
+        throw UsageError("--attr-path(-P) only works with --available");
 
     /* Obtain derivation information from the specified source. */
     DrvInfos availElems, installedElems;