lib: Clean up how linux and gcc config is specified

The `platform` field is pointless nesting: it's just stuff that happens
to be defined together, and that should be an implementation detail.

This instead makes `linux-kernel` and `gcc` top level fields in platform
configs. They join `rustc` there [all are optional], which was put there
and not in `platform` in anticipation of a change like this.

`linux-kernel.arch` in particular also becomes `linuxArch`, to match the
other `*Arch`es.

The next step after is this to combine the *specific* machines from
`lib.systems.platforms` with `lib.systems.examples`, keeping just the
"multiplatform" ones for defaulting.

lib/systems/default.nix

@@ -24,8 +24,6 @@ rec {
       # Either of these can be losslessly-extracted from `parsed` iff parsing succeeds.
       system = parse.doubleFromSystem final.parsed;
       config = parse.tripleFromSystem final.parsed;
-      # Just a guess, based on `system`
-      platform = platforms.select final;
       # Determine whether we are compatible with the provided CPU
       isCompatible = platform: parse.isCompatible final.parsed.cpu platform.parsed.cpu;
       # Derived meta-data
@@ -79,7 +77,16 @@ rec {
       };
       isStatic = final.isWasm || final.isRedox;
 
-      kernelArch =
+      # Just a guess, based on `system`
+      inherit
+        ({
+          linux-kernel = args.linux-kernel or {};
+          gcc = args.gcc or {};
+          rustc = args.rust or {};
+        } // platforms.select final)
+        linux-kernel gcc rustc;
+
+      linuxArch =
         if final.isAarch32 then "arm"
         else if final.isAarch64 then "arm64"
         else if final.isx86_32 then "x86"

lib/systems/examples.nix

@@ -7,7 +7,6 @@ let
 
   riscv = bits: {
     config = "riscv${bits}-unknown-linux-gnu";
-    platform = platforms.riscv-multiplatform;
   };
 in
 
@@ -17,84 +16,68 @@ rec {
   #
   powernv = {
     config = "powerpc64le-unknown-linux-gnu";
-    platform = platforms.powernv;
   };
   musl-power = {
     config = "powerpc64le-unknown-linux-musl";
-    platform = platforms.powernv;
   };
 
   sheevaplug = {
     config = "armv5tel-unknown-linux-gnueabi";
-    platform = platforms.sheevaplug;
-  };
+  } // platforms.sheevaplug;
 
   raspberryPi = {
     config = "armv6l-unknown-linux-gnueabihf";
-    platform = platforms.raspberrypi;
-  };
+  } // platforms.raspberrypi;
 
   remarkable1 = {
     config = "armv7l-unknown-linux-gnueabihf";
-    platform = platforms.zero-gravitas;
-  };
+  } // platforms.zero-gravitas;
 
   remarkable2 = {
     config = "armv7l-unknown-linux-gnueabihf";
-    platform = platforms.zero-sugar;
-  };
+  } // platforms.zero-sugar;
 
   armv7l-hf-multiplatform = {
     config = "armv7l-unknown-linux-gnueabihf";
-    platform = platforms.armv7l-hf-multiplatform;
   };
 
   aarch64-multiplatform = {
     config = "aarch64-unknown-linux-gnu";
-    platform = platforms.aarch64-multiplatform;
   };
 
   armv7a-android-prebuilt = {
     config = "armv7a-unknown-linux-androideabi";
     sdkVer = "29";
     ndkVer = "21";
-    platform = platforms.armv7a-android;
     useAndroidPrebuilt = true;
-  };
+  } // platforms.armv7a-android;
 
   aarch64-android-prebuilt = {
     config = "aarch64-unknown-linux-android";
     sdkVer = "29";
     ndkVer = "21";
-    platform = platforms.aarch64-multiplatform;
     useAndroidPrebuilt = true;
   };
 
-  scaleway-c1 = armv7l-hf-multiplatform // rec {
-    platform = platforms.scaleway-c1;
-    inherit (platform.gcc) fpu;
-  };
+  scaleway-c1 = armv7l-hf-multiplatform // platforms.scaleway-c1;
 
   pogoplug4 = {
     config = "armv5tel-unknown-linux-gnueabi";
-    platform = platforms.pogoplug4;
-  };
+  } // platforms.pogoplug4;
 
   ben-nanonote = {
     config = "mipsel-unknown-linux-uclibc";
-    platform = platforms.ben_nanonote;
-  };
+  } // platforms.ben_nanonote;
 
   fuloongminipc = {
     config = "mipsel-unknown-linux-gnu";
-    platform = platforms.fuloong2f_n32;
-  };
+  } // platforms.fuloong2f_n32;
 
   muslpi = raspberryPi // {
     config = "armv6l-unknown-linux-musleabihf";
   };
 
-  aarch64-multiplatform-musl = aarch64-multiplatform // {
+  aarch64-multiplatform-musl = {
     config = "aarch64-unknown-linux-musl";
   };
 
@@ -110,13 +93,11 @@ rec {
   riscv64-embedded = {
     config = "riscv64-none-elf";
     libc = "newlib";
-    platform = platforms.riscv-multiplatform;
   };
 
   riscv32-embedded = {
     config = "riscv32-none-elf";
     libc = "newlib";
-    platform = platforms.riscv-multiplatform;
   };
 
   mmix = {
@@ -136,13 +117,11 @@ rec {
   vc4 = {
     config = "vc4-elf";
     libc = "newlib";
-    platform = {};
   };
 
   or1k = {
     config = "or1k-elf";
     libc = "newlib";
-    platform = {};
   };
 
   arm-embedded = {
@@ -204,7 +183,6 @@ rec {
     xcodeVer = "11.3.1";
     xcodePlatform = "iPhoneOS";
     useiOSPrebuilt = true;
-    platform = {};
   };
 
   iphone32 = {
@@ -214,7 +192,6 @@ rec {
     xcodeVer = "11.3.1";
     xcodePlatform = "iPhoneOS";
     useiOSPrebuilt = true;
-    platform = {};
   };
 
   iphone64-simulator = {
@@ -224,7 +201,6 @@ rec {
     xcodeVer = "11.3.1";
     xcodePlatform = "iPhoneSimulator";
     useiOSPrebuilt = true;
-    platform = {};
   };
 
   iphone32-simulator = {
@@ -234,7 +210,6 @@ rec {
     xcodeVer = "11.3.1";
     xcodePlatform = "iPhoneSimulator";
     useiOSPrebuilt = true;
-    platform = {};
   };
 
   #
@@ -245,15 +220,13 @@ rec {
   mingw32 = {
     config = "i686-w64-mingw32";
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
-    platform = {};
   };
 
   # 64 bit mingw-w64
   mingwW64 = {
     # That's the triplet they use in the mingw-w64 docs.
     config = "x86_64-w64-mingw32";
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
-    platform = {};
   };
 
   # BSDs
@@ -275,6 +248,5 @@ rec {
   # Ghcjs
   ghcjs = {
     config = "js-unknown-ghcjs";
-    platform = {};
   };
 }