lib: make extendDerivation lighter on eval

the fix to extendDerivation in #140051 unwittingly worsened eval performance by
quite a bit. set elements alone needed over 1GB extra after the change, which
seems disproportionate to how small it was. if we flip the logic used to
determine which outputs to install around and keep a "this one exactly" flag in
the specific outputs instead of a "all of them" in the root we can avoid most
of that cost.

lib/attrsets.nix

@@ -487,7 +487,7 @@ rec {
        => "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev"
   */
   getOutput = output: pkg:
-    if pkg.outputUnspecified or false
+    if ! pkg ? outputSpecified || ! pkg.outputSpecified
       then pkg.${output} or pkg.out or pkg
       else pkg;
 

lib/customisation.nix

@@ -145,14 +145,14 @@ rec {
     let
       outputs = drv.outputs or [ "out" ];
 
-      commonAttrs = (removeAttrs drv [ "outputUnspecified" ]) //
-        (builtins.listToAttrs outputsList) //
+      commonAttrs = drv // (builtins.listToAttrs outputsList) //
         ({ all = map (x: x.value) outputsList; }) // passthru;
 
       outputToAttrListElement = outputName:
         { name = outputName;
           value = commonAttrs // {
             inherit (drv.${outputName}) type outputName;
+            outputSpecified = true;
             drvPath = assert condition; drv.${outputName}.drvPath;
             outPath = assert condition; drv.${outputName}.outPath;
           };
@@ -160,7 +160,6 @@ rec {
 
       outputsList = map outputToAttrListElement outputs;
     in commonAttrs // {
-      outputUnspecified = true;
       drvPath = assert condition; drv.drvPath;
       outPath = assert condition; drv.outPath;
     };

pkgs/build-support/buildenv/default.nix

@@ -62,7 +62,7 @@ runCommand name
         # and otherwise use `meta.outputsToInstall`. The attribute is guaranteed
         # to exist in mkDerivation-created cases. The other cases (e.g. runCommand)
         # aren't expected to have multiple outputs.
-        (if drv.outputUnspecified or false
+        (if (! drv ? outputSpecified || ! drv.outputSpecified)
             && drv.meta.outputsToInstall or null != null
           then map (outName: drv.${outName}) drv.meta.outputsToInstall
           else [ drv ])

pkgs/development/compilers/llvm/10/default.nix

@@ -63,14 +63,14 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     # disabled until recommonmark supports sphinx 3
     #Llvm-manpages = lowPrio (tools.libllvm.override {

pkgs/development/compilers/llvm/11/default.nix

@@ -65,21 +65,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     clang-polly-unwrapped = callPackage ./clang {
       inherit llvm_meta;

pkgs/development/compilers/llvm/12/default.nix

@@ -66,14 +66,14 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     # disabled until recommonmark supports sphinx 3
     #Llvm-manpages = lowPrio (tools.libllvm.override {

pkgs/development/compilers/llvm/13/default.nix

@@ -68,14 +68,14 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     llvm-manpages = lowPrio (tools.libllvm.override {
       enableManpages = true;

pkgs/development/compilers/llvm/5/default.nix

@@ -39,21 +39,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     llvm-manpages = lowPrio (tools.libllvm.override {
       enableManpages = true;

pkgs/development/compilers/llvm/6/default.nix

@@ -39,21 +39,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     llvm-manpages = lowPrio (tools.libllvm.override {
       enableManpages = true;

pkgs/development/compilers/llvm/7/default.nix

@@ -63,21 +63,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     clang-polly-unwrapped = callPackage ./clang {
       inherit llvm_meta;

pkgs/development/compilers/llvm/8/default.nix

@@ -63,21 +63,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     clang-polly-unwrapped = callPackage ./clang {
       inherit llvm_meta;

pkgs/development/compilers/llvm/9/default.nix

@@ -63,21 +63,21 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libllvm-polly = callPackage ./llvm {
       inherit llvm_meta;
       enablePolly = true;
     };
 
-    llvm-polly = tools.libllvm-polly.lib // { outputUnspecified = true; };
+    llvm-polly = tools.libllvm-polly.lib // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit clang-tools-extra_src llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     clang-polly-unwrapped = callPackage ./clang {
       inherit llvm_meta;

pkgs/development/compilers/llvm/git/default.nix

@@ -68,14 +68,14 @@ let
     };
 
     # `llvm` historically had the binaries.  When choosing an output explicitly,
-    # we need to reintroduce `outputUnspecified` to get the expected behavior e.g. of lib.get*
-    llvm = tools.libllvm.out // { outputUnspecified = true; };
+    # we need to reintroduce `outputSpecified` to get the expected behavior e.g. of lib.get*
+    llvm = tools.libllvm.out // { outputSpecified = false; };
 
     libclang = callPackage ./clang {
       inherit llvm_meta;
     };
 
-    clang-unwrapped = tools.libclang.out // { outputUnspecified = true; };
+    clang-unwrapped = tools.libclang.out // { outputSpecified = false; };
 
     llvm-manpages = lowPrio (tools.libllvm.override {
       enableManpages = true;