boost: support for cross-compiling boost to a mips64 target

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

pkgs/development/libraries/boost/generic.nix

@@ -84,7 +84,7 @@ let
     # TODO: make this unconditional
   ] ++ optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
     "address-model=${toString stdenv.hostPlatform.parsed.cpu.bits}"
-    "architecture=${toString stdenv.hostPlatform.parsed.cpu.family}"
+    "architecture=${if stdenv.hostPlatform.isMips64 then "mips64" else toString stdenv.hostPlatform.parsed.cpu.family}"
     "binary-format=${toString stdenv.hostPlatform.parsed.kernel.execFormat.name}"
     "target-os=${toString stdenv.hostPlatform.parsed.kernel.name}"
 
@@ -92,7 +92,8 @@ let
     # https://www.boost.org/doc/libs/1_66_0/libs/context/doc/html/context/architectures.html
     "abi=${if stdenv.hostPlatform.parsed.cpu.family == "arm" then "aapcs"
            else if stdenv.hostPlatform.isWindows then "ms"
-           else if stdenv.hostPlatform.isMips then "o32"
+           else if stdenv.hostPlatform.isMips32 then "o32"
+           else if stdenv.hostPlatform.isMips64n64 then "n64"
            else "sysv"}"
   ] ++ optional (link != "static") "runtime-link=${runtime-link}"
     ++ optional (variant == "release") "debug-symbols=off"
@@ -133,6 +134,13 @@ stdenv.mkDerivation {
       sha256 = "15d2a636hhsb1xdyp44x25dyqfcaws997vnp9kl1mhzvxjzz7hb0";
       stripLen = 1;
     })
+  ++ optional (versionAtLeast version "1.65" && versionOlder version "1.70") (fetchpatch {
+    # support for Mips64n64 appeared in boost-context 1.70; this patch won't apply to pre-1.65 cleanly
+    url = "https://github.com/boostorg/context/commit/e3f744a1862164062d579d1972272d67bdaa9c39.patch";
+    sha256 = "sha256-qjQy1b4jDsIRrI+UYtcguhvChrMbGWO0UlEzEJHYzRI=";
+    stripLen = 1;
+    extraPrefix = "libs/context/";
+  })
   ++ optional (and (versionAtLeast version "1.70") (!versionAtLeast version "1.73")) ./cmake-paths.patch
   ++ optional (versionAtLeast version "1.73") ./cmake-paths-173.patch
   ++ optional (version == "1.77.0") (fetchpatch {
@@ -150,6 +158,14 @@ stdenv.mkDerivation {
                  ++ optional ((versionOlder version "1.57") || version == "1.58") "x86_64-darwin"
                  ++ optionals (versionOlder version "1.73") lib.platforms.riscv;
     maintainers = with maintainers; [ hjones2199 ];
+
+    broken =
+      # boost-context lacks support for the N32 ABI on mips64.  The build
+      # will succeed, but packages depending on boost-context will fail with
+      # a very cryptic error message.
+      stdenv.hostPlatform.isMips64n32 ||
+      # the patch above does not apply cleanly to pre-1.65 boost
+      (stdenv.hostPlatform.isMips64n64 && (versionOlder version "1.65"));
   };
 
   preConfigure = optionalString useMpi ''