Clean up cross bootstrapping

For a long time, we've had `crossLibcStdenv`, `*Cross` libc attributes,
and `*bsdCross` pre-libc package sets. This was always bad because
having "cross" things is "not declarative": the naming doesn't reflect
what packages *need* but rather how we *provide* something. This is
ugly, and creates needless friction between cross and native building.

Now, almost all of these `*Cross` attributes are gone: just these are
kept:

- Glibc's and Musl's are kept, because those packages are widely used
  and I didn't want to risk changing the native builds of those at this
  time.

- generic `libcCross`, `theadsCross`, and friends, because these relate
  to the convolulted GCC bootstrap which still needs to be redone.

The BSD and obscure Linux or freestnanding libcs have conversely all
been made to use a new `stdenvNoLibc`, which is like the old
`crossLibcStdenv` except:

1. It usable for native and cross alike

2. It named according to what it *is* ("a standard environment without
   libc but with a C compiler"), rather than some non-compositional
   jargon ("the stdenv used for building libc when cross compiling",
   yuck).

I should have done this change long ago, but I was stymied because of
"infinite recursions". The problem was that in too many cases we are
overriding `stdenv` to *remove* things we don't need, and this risks
cyles since those more minimal stdenvs are used to build things in the
more maximal stdenvs.

The solution is to pass `stage.nix` `stdenvNoCC`, so we can override to
*build up* rather than *tear down*. For now, the full `stdenv` is also
passed, so I don't need to change the native bootstraps, but I can see
this changing as we make things more uniform and clean those up.

Finally, the BSDs also had to be cleaned up, since they have a few
pre-libc dependencies, demanding a systematic approach. I realized what
rhelmot did in 61202561d92cf1cd74532fcbd8b9d6662c5bc57b (specify what
packages just need `stdenvNoLibc`) is definitely the right approach for
this, and adjusted NetBSD and OpenBSD to likewise use it.

3 files changed, 46 insertions, 62 deletions

diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 9a3eefd2d184d..e576abd64125f 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -97,6 +97,7 @@ mapAliases ({
   auditBlasHook = throw "'auditBlasHook' has been removed since it never worked"; # Added 2024-04-02
   authy = throw "'authy' has been removed since it reached end of life"; # Added 2024-04-19
   avldrums-lv2 = x42-avldrums; # Added 2020-03-29
+  avrlibcCross = avrlibc; # Added 2024-06-18
   awesome-4-0 = awesome; # Added 2022-05-05
   aws-env = throw "aws-env has been removed as the upstream project was unmaintained"; # Added 2024-06-11
 
@@ -197,6 +198,7 @@ mapAliases ({
   cope = throw "'cope' has been removed, as it is broken in nixpkgs since it was added, and fixing it is not trivial"; # Added 2024-04-12
   cpp-ipfs-api = cpp-ipfs-http-client; # Project has been renamed. Added 2022-05-15
   crispyDoom = crispy-doom; # Added 2023-05-01
+  crossLibcStdenv = stdenvNoLibc; # Added 2024-06-18
   cryptowatch-desktop = throw "Cryptowatch Desktop was sunset on September 30th 2023 and has been removed from nixpkgs"; # Added 2023-12-22
   clash = throw "'clash' has been removed, upstream gone. Consider using 'mihomo' instead."; # added 2023-11-10
   clasp = clingo; # added 2022-12-22
@@ -874,6 +876,7 @@ mapAliases ({
   mpd_clientlib = libmpdclient; # Added 2021-02-11
   mpdevil = plattenalbum; # Added 2024-05-22
   mpg321 = throw "'mpg321' has been removed due to it being unmaintained by upstream. Consider using mpg123 instead."; # Added 2024-05-10
+  msp430NewlibCross = msp430Newlib; # Added 2024-06-18
   mumble_git = throw "'mumble_git' has been renamed to/replaced by 'pkgs.mumble'"; # Converted to throw 2023-09-10
   murmur_git = throw "'murmur_git' has been renamed to/replaced by 'pkgs.murmur'"; # Converted to throw 2023-09-10
   mutt-with-sidebar = mutt; # Added 2022-09-17
@@ -907,6 +910,8 @@ mapAliases ({
   nagiosPluginsOfficial = monitoring-plugins;
   neochat = libsForQt5.kdeGear.neochat; # added 2022-05-10
   neoload = throw "'neoload' has been removed as it is broken and unmaintained"; # Added 2024-03-02
+  newlibCross = newlib; # Added 2024-06-18
+  newlib-nanoCross = newlib-nano; # Added 2024-06-18
   nitrokey-udev-rules = libnitrokey; # Added 2023-03-25
   nix-direnv-flakes = nix-direnv;
   nix-repl = throw (
@@ -1333,6 +1338,8 @@ mapAliases ({
   uade123 = uade; # Added 2022-07-30
   uberwriter = apostrophe; # Added 2020-04-23
   ubootBeagleboneBlack = ubootAmx335xEVM; # Added 2020-01-21
+  uclibc = uclibc-ng; # Added 2022-06-16
+  uclibcCross = uclibc-ng; # Added 2022-06-16
   ue4 = throw "ue4 has been removed, because the package was broken for years"; # Added 2023-11-22
   uhd3_5 = throw "uhd3_5 has been removed, because it was no longer needed"; # Added 2023-10-07
   uhhyou.lv2 = throw "'uhhyou.lv2' has been removed, upstream gone"; # Added 2023-06-21
@@ -1470,6 +1477,10 @@ mapAliases ({
   inherit (stdenv.hostPlatform) system; # Added 2021-10-22
   inherit (stdenv) buildPlatform hostPlatform targetPlatform; # Added 2023-01-09
 
+  freebsdCross = freebsd; # Added 2024-06-18
+  netbsdCross = netbsd; # Added 2024-06-18
+  openbsdCross = openbsd; # Added 2024-06-18
+
   # LLVM packages for (integration) testing that should not be used inside Nixpkgs:
   llvmPackages_latest = llvmPackages_18;
   llvmPackages_git = recurseIntoAttrs (callPackage ../development/compilers/llvm/git {
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 24e580134d775..b395d60353dfa 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -31,19 +31,6 @@ with pkgs;
   # it's just the plain stdenv.
   stdenv_32bit = lowPrio (if stdenv.hostPlatform.is32bit then stdenv else multiStdenv);
 
-  stdenvNoCC = stdenv.override (
-    { cc = null; hasCC = false; }
-
-    // lib.optionalAttrs (stdenv.hostPlatform.isDarwin && (stdenv.hostPlatform != stdenv.buildPlatform)) {
-      # TODO: This is a hack to use stdenvNoCC to produce a CF when cross
-      # compiling. It's not very sound. The cross stdenv has:
-      #   extraBuildInputs = [ targetPackages.darwin.apple_sdks.frameworks.CoreFoundation ]
-      # and uses stdenvNoCC. In order to make this not infinitely recursive, we
-      # need to exclude this extraBuildInput.
-      extraBuildInputs = [];
-    }
-  );
-
   mkStdenvNoLibs = stdenv: let
     bintools = stdenv.cc.bintools.override {
       libc = null;
@@ -61,7 +48,7 @@ with pkgs;
   };
 
   stdenvNoLibs =
-    if stdenv.hostPlatform != stdenv.buildPlatform && (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.useLLVM or false)
+    if stdenvNoCC.hostPlatform != stdenvNoCC.buildPlatform
     then
       # We cannot touch binutils or cc themselves, because that will cause
       # infinite recursion. So instead, we just choose a libc based on the
@@ -74,7 +61,17 @@ with pkgs;
       # thing to to create an earlier thing (leading to infinite recursion) and
       # we also would still respect the stage arguments choices for these
       # things.
-      overrideCC stdenv buildPackages.llvmPackages.clangNoCompilerRt
+      (if stdenvNoCC.hostPlatform.isDarwin || stdenvNoCC.hostPlatform.useLLVM or false
+       then overrideCC stdenvNoCC buildPackages.llvmPackages.clangNoCompilerRt
+       else gccCrossLibcStdenv)
+    else mkStdenvNoLibs stdenv;
+
+  stdenvNoLibc =
+    if stdenvNoCC.hostPlatform != stdenvNoCC.buildPlatform
+    then
+      (if stdenvNoCC.hostPlatform.isDarwin || stdenvNoCC.hostPlatform.useLLVM or false
+       then overrideCC stdenvNoCC buildPackages.llvmPackages.clangNoLibc
+       else gccCrossLibcStdenv)
     else mkStdenvNoLibs stdenv;
 
   gccStdenvNoLibs = mkStdenvNoLibs gccStdenv;
@@ -15466,11 +15463,6 @@ with pkgs;
 
   gccCrossLibcStdenv = overrideCC stdenvNoCC buildPackages.gccWithoutTargetLibc;
 
-  crossLibcStdenv =
-    if stdenv.hostPlatform.useLLVM or false || stdenv.hostPlatform.isDarwin
-    then overrideCC stdenv buildPackages.llvmPackages.clangNoLibc
-    else gccCrossLibcStdenv;
-
   # The GCC used to build libc for the target platform. Normal gccs will be
   # built with, and use, that cross-compiled libc.
   gccWithoutTargetLibc = assert stdenv.targetPlatform != stdenv.hostPlatform; let
@@ -17639,9 +17631,8 @@ with pkgs;
 
   h3 = h3_3;
 
-  avrlibc      = callPackage ../development/misc/avr/libc { };
-  avrlibcCross = callPackage ../development/misc/avr/libc {
-    stdenv = crossLibcStdenv;
+  avrlibc = callPackage ../development/misc/avr/libc {
+    stdenv = stdenvNoLibc;
   };
 
   avr8burnomat = callPackage ../development/misc/avr8-burn-omat { };
@@ -17715,10 +17706,7 @@ with pkgs;
 
   msp430GccSupport = callPackage ../development/misc/msp430/gcc-support.nix { };
 
-  msp430Newlib      = callPackage ../development/misc/msp430/newlib.nix { };
-  msp430NewlibCross = callPackage ../development/misc/msp430/newlib.nix {
-    newlib = newlibCross;
-  };
+  msp430Newlib = callPackage ../development/misc/msp430/newlib.nix { };
 
   mspds = callPackage ../development/misc/msp430/mspds { };
   mspds-bin = callPackage ../development/misc/msp430/mspds/binary.nix { };
@@ -20933,14 +20921,14 @@ with pkgs;
   };
 
   muslCross = musl.override {
-    stdenv = crossLibcStdenv;
+    stdenv = stdenvNoLibc;
   };
 
   # These are used when buiding compiler-rt / libgcc, prior to building libc.
   preLibcCrossHeaders = let
     inherit (stdenv.targetPlatform) libc;
   in     if stdenv.targetPlatform.isMinGW then targetPackages.windows.mingw_w64_headers or windows.mingw_w64_headers
-    else if libc == "nblibc" then targetPackages.netbsdCross.headers or netbsdCross.headers
+    else if libc == "nblibc" then targetPackages.netbsd.headers or netbsd.headers
     else if libc == "libSystem" && stdenv.targetPlatform.isAarch64 then targetPackages.darwin.LibsystemCross or darwin.LibsystemCross
     else null;
 
@@ -20951,13 +20939,13 @@ with pkgs;
     /**/ if name == null then null
     else if name == "glibc" then targetPackages.glibcCross or glibcCross
     else if name == "bionic" then targetPackages.bionic or bionic
-    else if name == "uclibc" then targetPackages.uclibcCross or uclibcCross
-    else if name == "avrlibc" then targetPackages.avrlibcCross or avrlibcCross
-    else if name == "newlib" && stdenv.targetPlatform.isMsp430 then targetPackages.msp430NewlibCross or msp430NewlibCross
+    else if name == "uclibc" then targetPackages.uclibc or uclibc
+    else if name == "avrlibc" then targetPackages.avrlibc or avrlibc
+    else if name == "newlib" && stdenv.targetPlatform.isMsp430 then targetPackages.msp430Newlib or msp430Newlib
     else if name == "newlib" && stdenv.targetPlatform.isVc4 then targetPackages.vc4-newlib or vc4-newlib
     else if name == "newlib" && stdenv.targetPlatform.isOr1k then targetPackages.or1k-newlib or or1k-newlib
-    else if name == "newlib" then targetPackages.newlibCross or newlibCross
-    else if name == "newlib-nano" then targetPackages.newlib-nanoCross or newlib-nanoCross
+    else if name == "newlib" then targetPackages.newlib or newlib
+    else if name == "newlib-nano" then targetPackages.newlib-nano or newlib-nano
     else if name == "musl" then targetPackages.muslCross or muslCross
     else if name == "msvcrt" then targetPackages.windows.mingw_w64 or windows.mingw_w64
     else if name == "ucrt" then targetPackages.windows.mingw_w64 or windows.mingw_w64
@@ -20965,9 +20953,9 @@ with pkgs;
       if stdenv.targetPlatform.useiOSPrebuilt
       then targetPackages.darwin.iosSdkPkgs.libraries or darwin.iosSdkPkgs.libraries
       else targetPackages.darwin.LibsystemCross or (throw "don't yet have a `targetPackages.darwin.LibsystemCross for ${stdenv.targetPlatform.config}`")
-    else if name == "fblibc" then targetPackages.freebsdCross.libc or freebsdCross.libc
-    else if name == "oblibc" then targetPackages.openbsdCross.libc or openbsdCross.libc
-    else if name == "nblibc" then targetPackages.netbsdCross.libc or netbsdCross.libc
+    else if name == "fblibc" then targetPackages.freebsd.libc or freebsd.libc
+    else if name == "oblibc" then targetPackages.openbsd.libc or openbsd.libc
+    else if name == "nblibc" then targetPackages.netbsd.libc or netbsd.libc
     else if name == "wasilibc" then targetPackages.wasilibc or wasilibc
     else if name == "relibc" then targetPackages.relibc or relibc
     else throw "Unknown libc ${name}";
@@ -20983,7 +20971,7 @@ with pkgs;
     };
 
   wasilibc = callPackage ../development/libraries/wasilibc {
-    stdenv = crossLibcStdenv;
+    stdenv = stdenvNoLibc;
   };
 
   relibc = callPackage ../development/libraries/relibc { };
@@ -27974,14 +27962,6 @@ with pkgs;
     buildBarebox
     bareboxTools;
 
-  uclibc-ng-cross = uclibc-ng.override {
-    stdenv = crossLibcStdenv;
-  };
-
-  # Aliases
-  uclibc = uclibc-ng;
-  uclibcCross = uclibc-ng-cross;
-
   eudev = callPackage ../by-name/eu/eudev/package.nix {
     util-linux = util-linuxMinimal;
   };
@@ -40611,18 +40591,11 @@ with pkgs;
     name = "bsd-setup-hook";
   } ../os-specific/bsd/setup-hook.sh;
 
-  inherit (callPackage ../os-specific/bsd/freebsd { })
-    freebsd freebsdCross;
+  freebsd = callPackage ../os-specific/bsd/freebsd { };
 
   netbsd = callPackage ../os-specific/bsd/netbsd { };
-  netbsdCross = callPackage ../os-specific/bsd/netbsd {
-    stdenv = crossLibcStdenv;
-  };
 
   openbsd = callPackage ../os-specific/bsd/openbsd { };
-  openbsdCross = callPackage ../os-specific/bsd/openbsd {
-    stdenv = crossLibcStdenv;
-  };
 
   powershell = callPackage ../shells/powershell { };
 
@@ -40646,18 +40619,14 @@ with pkgs;
 
   new-session-manager = callPackage ../applications/audio/new-session-manager { };
 
-  newlib = callPackage ../development/misc/newlib { };
-  newlibCross = callPackage ../development/misc/newlib {
-    stdenv = crossLibcStdenv;
+  newlib = callPackage ../development/misc/newlib {
+    stdenv = stdenvNoLibc;
   };
 
   newlib-nano = callPackage ../development/misc/newlib {
+    stdenv = stdenvNoLibc;
     nanoizeNewlib = true;
   };
-  newlib-nanoCross = callPackage ../development/misc/newlib {
-    nanoizeNewlib = true;
-    stdenv = crossLibcStdenv;
-  };
 
   omnisharp-roslyn = callPackage ../development/tools/omnisharp-roslyn { };
 
diff --git a/pkgs/top-level/stage.nix b/pkgs/top-level/stage.nix
index 087b43c3cb145..025b6089f471b 100644
--- a/pkgs/top-level/stage.nix
+++ b/pkgs/top-level/stage.nix
@@ -49,6 +49,10 @@ in
 , # The standard environment to use for building packages.
   stdenv
 
+, # `stdenv` without a C compiler. Passing in this helps avoid infinite
+  # recursions, and may eventually replace passing in the full stdenv.
+  stdenvNoCC ? stdenv.override { cc = null; hasCC = false; }
+
 , # This is used because stdenv replacement and the stdenvCross do benefit from
   # the overridden configuration provided by the user, as opposed to the normal
   # bootstrapping stdenvs.
@@ -141,7 +145,7 @@ let
     pkgs = self.pkgsHostTarget;
     targetPackages = self.pkgsTargetTarget;
 
-    inherit stdenv;
+    inherit stdenv stdenvNoCC;
   };
 
   splice = self: super: import ./splice.nix lib self (adjacentPackages != null);