Recover the complicated situation after my bad merge

I made a mistake merge.  Reverting it in c778945806 undid the state
on master, but now I realize it crippled the git merge mechanism.
As the merge contained a mix of commits from `master..staging-next`
and other commits from `staging-next..staging`, it got the
`staging-next` branch into a state that was difficult to recover.

I reconstructed the "desired" state of staging-next tree by:
 - checking out the last commit of the problematic range: 4effe769e2
 - `git rebase -i --preserve-merges a8a018ddc0` - dropping the mistaken
   merge commit and its revert from that range (while keeping
   reapplication from 4effe769e2)
 - merging the last unaffected staging-next commit (803ca85c20)
 - fortunately no other commits have been pushed to staging-next yet
 - applying a diff on staging-next to get it into that state

pkgs/development/tools/build-managers/cmake/default.nix

@@ -5,6 +5,7 @@
 , ps
 , isBootstrap ? false
 , useSharedLibraries ? (!isBootstrap && !stdenv.isCygwin)
+, useOpenSSL ? !isBootstrap, openssl
 , useNcurses ? false, ncurses
 , useQt4 ? false, qt4
 , withQt5 ? false, qtbase
@@ -44,15 +45,17 @@ stdenv.mkDerivation rec {
 
   setupHook = ./setup-hook.sh;
 
-  buildInputs =
-    [ setupHook pkgconfig ]
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+
+  nativeBuildInputs = [ setupHook pkgconfig ];
+
+  buildInputs = []
     ++ lib.optionals useSharedLibraries [ bzip2 curl expat libarchive xz zlib libuv rhash ]
+    ++ lib.optional useOpenSSL openssl
     ++ lib.optional useNcurses ncurses
     ++ lib.optional useQt4 qt4
     ++ lib.optional withQt5 qtbase;
 
-  depsBuildBuild = [ buildPackages.stdenv.cc ];
-
   propagatedBuildInputs = lib.optional stdenv.isDarwin ps;
 
   preConfigure = ''
@@ -91,13 +94,15 @@ stdenv.mkDerivation rec {
     "-DCMAKE_AR=${lib.getBin stdenv.cc.bintools.bintools}/bin/${stdenv.cc.targetPrefix}ar"
     "-DCMAKE_RANLIB=${lib.getBin stdenv.cc.bintools.bintools}/bin/${stdenv.cc.targetPrefix}ranlib"
     "-DCMAKE_STRIP=${lib.getBin stdenv.cc.bintools.bintools}/bin/${stdenv.cc.targetPrefix}strip"
-  ]
+
+    "-DCMAKE_USE_OPENSSL=${if useOpenSSL then "ON" else "OFF"}"
     # Avoid depending on frameworks.
-    ++ lib.optional (!useNcurses) "-DBUILD_CursesDialog=OFF";
+    "-DBUILD_CursesDialog=${if useNcurses then "ON" else "OFF"}"
+  ];
 
   # make install attempts to use the just-built cmake
   preInstall = lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) ''
-    sed -i 's|bin/cmake|${buildPackages.cmake}/bin/cmake|g' Makefile
+    sed -i 's|bin/cmake|${buildPackages.cmakeMinimal}/bin/cmake|g' Makefile
   '';
 
   dontUseCmakeConfigure = true;

pkgs/development/tools/build-managers/meson/boost-Do-not-add-system-paths-on-nix.patch

@@ -0,0 +1,40 @@
+From 536108b10271f2f42d41c7d9ddb4ce2ea1851f4f Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Niklas=20Hamb=C3=BCchen?= <mail@nh2.me>
+Date: Sat, 17 Oct 2020 19:27:08 +0200
+Subject: [PATCH] boost: Do not add system paths on nix
+
+---
+ mesonbuild/dependencies/boost.py | 17 +----------------
+ 1 file changed, 1 insertion(+), 16 deletions(-)
+
+diff --git a/mesonbuild/dependencies/boost.py b/mesonbuild/dependencies/boost.py
+index 907c0c275..ecaf11b18 100644
+--- a/mesonbuild/dependencies/boost.py
++++ b/mesonbuild/dependencies/boost.py
+@@ -643,22 +643,7 @@ class BoostDependency(ExternalDependency):
+             roots += [x for x in candidates if x.name.lower().startswith('boost') and x.is_dir()]
+         else:
+             tmp = []  # type: T.List[Path]
+-
+-            # Homebrew
+-            brew_boost = Path('/usr/local/Cellar/boost')
+-            if brew_boost.is_dir():
+-                tmp += [x for x in brew_boost.iterdir()]
+-
+-            # Add some default system paths
+-            tmp += [Path('/opt/local')]
+-            tmp += [Path('/usr/local/opt/boost')]
+-            tmp += [Path('/usr/local')]
+-            tmp += [Path('/usr')]
+-
+-            # Cleanup paths
+-            tmp = [x for x in tmp if x.is_dir()]
+-            tmp = [x.resolve() for x in tmp]
+-            roots += tmp
++            # Do not add any non-explicit paths on nix
+ 
+         return roots
+ 
+-- 
+2.25.4
+

pkgs/development/tools/build-managers/meson/default.nix

@@ -52,6 +52,11 @@ python3.pkgs.buildPythonApplication rec {
     # cut-in-half-by-\0 store path references.
     # Let’s just clear the whole rpath and hope for the best.
     ./clear-old-rpath.patch
+
+    # Patch out default boost search paths to avoid impure builds on
+    # unsandboxed non-NixOS builds, see:
+    # https://github.com/NixOS/nixpkgs/issues/86131#issuecomment-711051774
+    ./boost-Do-not-add-system-paths-on-nix.patch
   ];
 
   setupHook = ./setup-hook.sh;