* stdenv.mkDerivation now takes an optional attribute "meta" that

contains arbitrary information about a package, like this:

  meta = {
    homepage = "http://gcc.gnu.org/";
    license = "GPL/LGPL";
    description = "GNU Compiler Collection, 4.0.x";
  };

  The "meta" attribute is not passed to the actual derivation
  operation, so it's not a dependency --- changes to "meta" attributes
  don't trigger a recompilation.

  Now we have to standardise some useful attributes ;-)

svn path=/nixpkgs/branches/usability/; revision=5024

pkgs/applications/networking/browsers/firefox-wrapper/default.nix

@@ -11,4 +11,8 @@ stdenv.mkDerivation {
   # Let each plugin tell us (through its `mozillaPlugin') attribute
   # where to find the plugin in its tree.
   plugins = map (x: x ~ x.mozillaPlugin) plugins;
+
+  meta = {
+    description = firefox.meta.description + " (with various plugins)";
+  };
 }

pkgs/applications/networking/browsers/firefox/default.nix

@@ -15,4 +15,8 @@ stdenv.mkDerivation {
   inherit gtk;
 
   patches = [./writable-copies.patch];
+
+  meta = {
+    description = "Mozilla Firefox - the browser, reloaded";
+  };
 }

pkgs/build-support/gcc-cross-wrapper/default.nix

@@ -27,4 +27,7 @@ stdenv.mkDerivation {
   langCC = if nativeTools then true else gcc.langCC;
   langF77 = if nativeTools then false else gcc.langF77;
   shell = if shell == "" then stdenv.shell else shell;
+  meta = if gcc != null then gcc.meta else
+    { description = "System C compiler wrapper";
+    };
 }

pkgs/build-support/gcc-wrapper/default.nix

@@ -27,4 +27,7 @@ stdenv.mkDerivation {
   langCC = if nativeTools then true else gcc.langCC;
   langF77 = if nativeTools then false else gcc.langF77;
   shell = if shell == "" then stdenv.shell else shell;
+  meta = if gcc != null then gcc.meta else
+    { description = "System C compiler wrapper";
+    };
 }

pkgs/development/compilers/gcc-4.0-cross/default.nix

@@ -26,4 +26,10 @@ stdenv.mkDerivation {
   buildInputs = [binutilsCross];
   inherit kernelHeadersCross binutilsCross;
   platform = cross;
+
+  meta = {
+    homepage = "http://gcc.gnu.org/";
+    license = "GPL/LGPL";
+    description = "GNU Compiler Collection, 4.0.x (cross-compiler for " + cross + ")";
+  };
 }

pkgs/development/compilers/gcc-4.0/default.nix

@@ -15,4 +15,10 @@ stdenv.mkDerivation {
   # !!! apply only if noSysDirs is set
   patches = [./no-sys-dirs.patch];
   inherit noSysDirs langC langCC langF77 profiledCompiler;
+
+  meta = {
+    homepage = "http://gcc.gnu.org/";
+    license = "GPL/LGPL";
+    description = "GNU Compiler Collection, 4.0.x";
+  };
 }

pkgs/development/libraries/aterm/aterm-2.4.nix

@@ -6,4 +6,9 @@ stdenv.mkDerivation {
     url = http://nix.cs.uu.nl/dist/tarballs/aterm-2.4.2.tar.gz;
     md5 = "18617081dd112d85e6c4b1b552628114";
   };
+  meta = {
+    homepage = http://www.cwi.nl/htbin/sen1/twiki/bin/view/SEN1/ATerm;
+    license = "LGPL";
+    description = "Library for manipulation of term data structures in C";
+  };
 }

pkgs/stdenv/generic/default.nix

@@ -26,13 +26,25 @@ let {
     # stdenv and its shell.
     // {
     
-      mkDerivation = attrs: derivation (attrs // {
-        builder = if attrs ? realBuilder then attrs.realBuilder else shell;
-        args = if attrs ? args then attrs.args else
-          ["-e" (if attrs ? builder then attrs.builder else ./default-builder.sh)];
-        stdenv = body;
-        system = body.system;
-      });
+      mkDerivation = attrs:
+        (derivation (
+          (removeAttrs attrs ["meta"])
+          //
+          {
+            builder = if attrs ? realBuilder then attrs.realBuilder else shell;
+            args = if attrs ? args then attrs.args else
+              ["-e" (if attrs ? builder then attrs.builder else ./default-builder.sh)];
+            stdenv = body;
+            system = body.system;
+          })
+        )
+        //
+        # The meta attribute is passed in the resulting attribute set,
+        # but it's not part of the actual derivation, i.e., it's not
+        # passed to the builder and is not a dependency.  But since we
+        # include it in the result, it *is* available to nix-env for
+        # queries.
+        { meta = if attrs ? meta then attrs.meta else {}; };
 
     }