lib.systems: elaborate Rust metadata

We need this stuff to be available in lib so make-derivation.nix can
access it to construct the Meson cross file.

This has a couple of other advantages:

 - It makes Rust less special.  Now figuring out what Rust calls a
   platform is the same as figuring out what Linux or QEMU call it.

 - We can unify the schema used to define Rust targets, and the schema
   used to access those values later.  Just like you can set "config"
   or "system" in a platform definition, and then access those same
   keys on the elaborated platform, you can now set "rustcTarget" in
   your crossSystem, and then access "stdenv.hostPlatform.rustcTarget"
   in your code.

"rustcTarget", "rustcTargetSpec", "cargoShortTarget", and
"cargoEnvVarTarget" have the "rustc" and "cargo" prefixes because
these are not exposed to code by the compiler, and are not
standardized.  The arch/os/etc. variables are all named to match the
forms in the Rust target spec JSON.

The new rust.target-family only takes a list, since we don't need to
worry about backwards compatibility when that name is used.

The old APIs are all still functional with no warning for now, so that
it's possible for external code to use a single API on both 23.05 and
23.11.  We can introduce the warnings once 23.05 is EOL, and make them
hard errors when 23.11 is EOL.

37 files changed, 211 insertions, 219 deletions

diff --git a/lib/systems/default.nix b/lib/systems/default.nix
index 2790ea08d97..ada8c66e361 100644
--- a/lib/systems/default.nix
+++ b/lib/systems/default.nix
@@ -43,6 +43,10 @@ rec {
   elaborate = args': let
     args = if lib.isString args' then { system = args'; }
            else args';
+
+    # TODO: deprecate args.rustc in favour of args.rust after 23.05 is EOL.
+    rust = assert !(args ? rust && args ? rustc); args.rust or args.rustc or {};
+
     final = {
       # Prefer to parse `config` as it is strictly more informative.
       parsed = parse.mkSystemFromString (if args ? config then args.config else args.system);
@@ -159,9 +163,101 @@ rec {
         ({
           linux-kernel = args.linux-kernel or {};
           gcc = args.gcc or {};
-          rustc = args.rustc or {};
         } // platforms.select final)
-        linux-kernel gcc rustc;
+        linux-kernel gcc;
+
+      # TODO: remove after 23.05 is EOL, with an error pointing to the rust.* attrs.
+      rustc = args.rustc or {};
+
+      rust = rust // {
+        # Once args.rustc.platform.target-family is deprecated and
+        # removed, there will no longer be any need to modify any
+        # values from args.rust.platform, so we can drop all the
+        # "args ? rust" etc. checks, and merge args.rust.platform in
+        # /after/.
+        platform = rust.platform or {} // {
+          # https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch
+          arch =
+            /**/ if rust ? platform then rust.platform.arch
+            else if final.isAarch32 then "arm"
+            else if final.isMips64  then "mips64"     # never add "el" suffix
+            else if final.isPower64 then "powerpc64"  # never add "le" suffix
+            else final.parsed.cpu.name;
+
+          # https://doc.rust-lang.org/reference/conditional-compilation.html#target_os
+          os =
+            /**/ if rust ? platform then rust.platform.os or "none"
+            else if final.isDarwin then "macos"
+            else final.parsed.kernel.name;
+
+          # https://doc.rust-lang.org/reference/conditional-compilation.html#target_family
+          target-family =
+            /**/ if args ? rust.platform.target-family then args.rust.platform.target-family
+            else if args ? rustc.platform.target-family
+            then
+              (
+                # Since https://github.com/rust-lang/rust/pull/84072
+                # `target-family` is a list instead of single value.
+                let
+                  f = args.rustc.platform.target-family;
+                in
+                  if builtins.isList f then f else [ f ]
+              )
+            else lib.optional final.isUnix "unix"
+                 ++ lib.optional final.isWindows "windows";
+
+          # https://doc.rust-lang.org/reference/conditional-compilation.html#target_vendor
+          vendor = let
+            inherit (final.parsed) vendor;
+          in rust.platform.vendor or {
+            "w64" = "pc";
+          }.${vendor.name} or vendor.name;
+        };
+
+        # The name of the rust target, even if it is custom. Adjustments are
+        # because rust has slightly different naming conventions than we do.
+        rustcTarget = let
+          inherit (final.parsed) cpu kernel abi;
+          cpu_ = rust.platform.arch or {
+            "armv7a" = "armv7";
+            "armv7l" = "armv7";
+            "armv6l" = "arm";
+            "armv5tel" = "armv5te";
+            "riscv64" = "riscv64gc";
+          }.${cpu.name} or cpu.name;
+          vendor_ = final.rust.platform.vendor;
+        in rust.config
+          or "${cpu_}-${vendor_}-${kernel.name}${lib.optionalString (abi.name != "unknown") "-${abi.name}"}";
+
+        # The name of the rust target if it is standard, or the json file
+        # containing the custom target spec.
+        rustcTargetSpec =
+          /**/ if rust ? platform
+          then builtins.toFile (final.rust.rustcTarget + ".json") (builtins.toJSON rust.platform)
+          else final.rust.rustcTarget;
+
+        # The name of the rust target if it is standard, or the
+        # basename of the file containing the custom target spec,
+        # without the .json extension.
+        #
+        # This is the name used by Cargo for target subdirectories.
+        cargoShortTarget =
+          lib.removeSuffix ".json" (baseNameOf "${final.rust.rustcTargetSpec}");
+
+        # When used as part of an environment variable name, triples are
+        # uppercased and have all hyphens replaced by underscores:
+        #
+        # https://github.com/rust-lang/cargo/pull/9169
+        # https://github.com/rust-lang/cargo/issues/8285#issuecomment-634202431
+        cargoEnvVarTarget =
+          lib.strings.replaceStrings ["-"] ["_"]
+            (lib.strings.toUpper final.rust.cargoShortTarget);
+
+        # True if the target is no_std
+        # https://github.com/rust-lang/rust/blob/2e44c17c12cec45b6a682b1e53a04ac5b5fcc9d2/src/bootstrap/config.rs#L415-L421
+        isNoStdTarget =
+          builtins.any (t: lib.hasInfix t final.rust.rustcTarget) ["-none" "nvptx" "switch" "-uefi"];
+      };
 
       linuxArch =
         if final.isAarch32 then "arm"
diff --git a/pkgs/applications/blockchains/zcash/default.nix b/pkgs/applications/blockchains/zcash/default.nix
index c07f94e5bae..dbada09c1b6 100644
--- a/pkgs/applications/blockchains/zcash/default.nix
+++ b/pkgs/applications/blockchains/zcash/default.nix
@@ -1,5 +1,5 @@
 { autoreconfHook, boost180, cargo, coreutils, curl, cxx-rs, db62, fetchFromGitHub
-, git, hexdump, lib, libevent, libsodium, makeWrapper, rust, rustPlatform
+, git, hexdump, lib, libevent, libsodium, makeWrapper, rustPlatform
 , pkg-config, Security, stdenv, testers, tl-expected, utf8cpp, util-linux, zcash, zeromq
 }:
 
@@ -57,7 +57,7 @@ rustPlatform.buildRustPackage.override { inherit stdenv; } rec {
   configureFlags = [
     "--disable-tests"
     "--with-boost-libdir=${lib.getLib boost180}/lib"
-    "RUST_TARGET=${rust.toRustTargetSpec stdenv.hostPlatform}"
+    "RUST_TARGET=${stdenv.hostPlatform.rust.rustcTargetSpec}"
   ];
 
   enableParallelBuilding = true;
diff --git a/pkgs/applications/misc/effitask/default.nix b/pkgs/applications/misc/effitask/default.nix
index a380a06741e..50172b9d1cb 100644
--- a/pkgs/applications/misc/effitask/default.nix
+++ b/pkgs/applications/misc/effitask/default.nix
@@ -5,7 +5,6 @@
 , openssl
 , gtk3
 , stdenv
-, rust
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -28,7 +27,7 @@ rustPlatform.buildRustPackage rec {
   # default installPhase don't install assets
   installPhase = ''
     runHook preInstall
-    make install PREFIX="$out" TARGET="target/${rust.toRustTarget stdenv.hostPlatform}/release/effitask"
+    make install PREFIX="$out" TARGET="target/${stdenv.hostPlatform.rust.rustcTarget}/release/effitask"
     runHook postInstall
   '';
 
diff --git a/pkgs/applications/window-managers/cosmic/applets/default.nix b/pkgs/applications/window-managers/cosmic/applets/default.nix
index f64f6b31247..87da5b580e2 100644
--- a/pkgs/applications/window-managers/cosmic/applets/default.nix
+++ b/pkgs/applications/window-managers/cosmic/applets/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, rust, rustPlatform
+{ lib, stdenv, fetchFromGitHub, rustPlatform
 , cargo, just, pkg-config, util-linuxMinimal
 , dbus, glib, libxkbcommon, pulseaudio, wayland
 }:
@@ -41,11 +41,11 @@ rustPlatform.buildRustPackage {
 
   justFlags = [
     "--set" "prefix" (placeholder "out")
-    "--set" "target" "${rust.lib.toRustTargetSpecShort stdenv.hostPlatform}/release"
+    "--set" "target" "${stdenv.hostPlatform.rust.cargoShortTarget}/release"
   ];
 
   # Force linking to libwayland-client, which is always dlopen()ed.
-  "CARGO_TARGET_${rust.toRustTargetForUseInEnvVars stdenv.hostPlatform}_RUSTFLAGS" =
+  "CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_RUSTFLAGS" =
     map (a: "-C link-arg=${a}") [
       "-Wl,--push-state,--no-as-needed"
       "-lwayland-client"
diff --git a/pkgs/applications/window-managers/cosmic/panel/default.nix b/pkgs/applications/window-managers/cosmic/panel/default.nix
index 7908eeb3057..e5000fe184e 100644
--- a/pkgs/applications/window-managers/cosmic/panel/default.nix
+++ b/pkgs/applications/window-managers/cosmic/panel/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, cargo, just, pkg-config, rust, rustPlatform
+{ lib, stdenv, fetchFromGitHub, cargo, just, pkg-config, rustPlatform
 , libglvnd, libxkbcommon, wayland
 }:
 
@@ -33,11 +33,11 @@ rustPlatform.buildRustPackage {
 
   justFlags = [
     "--set" "prefix" (placeholder "out")
-    "--set" "bin-src" "target/${rust.lib.toRustTargetSpecShort stdenv.hostPlatform}/release/cosmic-panel"
+    "--set" "bin-src" "target/${stdenv.hostPlatform.rust.cargoShortTarget}/release/cosmic-panel"
   ];
 
   # Force linking to libEGL, which is always dlopen()ed.
-  "CARGO_TARGET_${rust.toRustTargetForUseInEnvVars stdenv.hostPlatform}_RUSTFLAGS" =
+  "CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_RUSTFLAGS" =
     map (a: "-C link-arg=${a}") [
       "-Wl,--push-state,--no-as-needed"
       "-lEGL"
diff --git a/pkgs/applications/window-managers/cosmic/settings/default.nix b/pkgs/applications/window-managers/cosmic/settings/default.nix
index 6767f963846..100d1ec316f 100644
--- a/pkgs/applications/window-managers/cosmic/settings/default.nix
+++ b/pkgs/applications/window-managers/cosmic/settings/default.nix
@@ -61,7 +61,7 @@ rustPlatform.buildRustPackage {
     (placeholder "out")
     "--set"
     "bin-src"
-    "target/${rust.lib.toRustTargetSpecShort stdenv.hostPlatform}/release/cosmic-settings"
+    "target/${stdenv.hostPlatform.rust.cargoShortTarget}/release/cosmic-settings"
   ];
 
   meta = with lib; {
diff --git a/pkgs/build-support/rust/build-rust-crate/build-crate.nix b/pkgs/build-support/rust/build-rust-crate/build-crate.nix
index 944434472b0..e842b6a3f50 100644
--- a/pkgs/build-support/rust/build-rust-crate/build-crate.nix
+++ b/pkgs/build-support/rust/build-rust-crate/build-crate.nix
@@ -1,6 +1,5 @@
 { lib, stdenv
 , mkRustcDepArgs, mkRustcFeatureArgs, needUnstableCLI
-, rust
 }:
 
 { crateName,
@@ -21,7 +20,7 @@
         (mkRustcDepArgs dependencies crateRenames)
         (mkRustcFeatureArgs crateFeatures)
       ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
-        "--target" (rust.toRustTargetSpec stdenv.hostPlatform)
+        "--target" stdenv.hostPlatform.rust.rustcTargetSpec
       ] ++ lib.optionals (needUnstableCLI dependencies) [
         "-Z" "unstable-options"
       ] ++ extraRustcOpts
diff --git a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
index 60310f17874..a6f2528a82b 100644
--- a/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
+++ b/pkgs/build-support/rust/build-rust-crate/configure-crate.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, rust, echo_colored, noisily, mkRustcDepArgs, mkRustcFeatureArgs }:
+{ lib, stdenv, echo_colored, noisily, mkRustcDepArgs, mkRustcFeatureArgs }:
 {
   build
 , buildDependencies
@@ -124,8 +124,8 @@ in ''
   export CARGO_PKG_AUTHORS="${authors}"
   export CARGO_PKG_DESCRIPTION="${crateDescription}"
 
-  export CARGO_CFG_TARGET_ARCH=${rust.toTargetArch stdenv.hostPlatform}
-  export CARGO_CFG_TARGET_OS=${rust.toTargetOs stdenv.hostPlatform}
+  export CARGO_CFG_TARGET_ARCH=${stdenv.hostPlatform.rust.platform.arch}
+  export CARGO_CFG_TARGET_OS=${stdenv.hostPlatform.rust.platform.os}
   export CARGO_CFG_TARGET_FAMILY="unix"
   export CARGO_CFG_UNIX=1
   export CARGO_CFG_TARGET_ENV="gnu"
@@ -136,8 +136,8 @@ in ''
   export CARGO_MANIFEST_DIR=$(pwd)
   export DEBUG="${toString (!release)}"
   export OPT_LEVEL="${toString optLevel}"
-  export TARGET="${rust.toRustTargetSpec stdenv.hostPlatform}"
-  export HOST="${rust.toRustTargetSpec stdenv.buildPlatform}"
+  export TARGET="${stdenv.hostPlatform.rust.rustcTargetSpec}"
+  export HOST="${stdenv.buildPlatform.rust.rustcTargetSpec}"
   export PROFILE=${if release then "release" else "debug"}
   export OUT_DIR=$(pwd)/target/build/${crateName}.out
   export CARGO_PKG_VERSION_MAJOR=${lib.elemAt version 0}
diff --git a/pkgs/build-support/rust/build-rust-crate/default.nix b/pkgs/build-support/rust/build-rust-crate/default.nix
index d977fb9f7c2..d569142af66 100644
--- a/pkgs/build-support/rust/build-rust-crate/default.nix
+++ b/pkgs/build-support/rust/build-rust-crate/default.nix
@@ -10,7 +10,6 @@
 , fetchCrate
 , pkgsBuildBuild
 , rustc
-, rust
 , cargo
 , jq
 , libiconv
@@ -71,18 +70,14 @@ let
   inherit (import ./log.nix { inherit lib; }) noisily echo_colored;
 
   configureCrate = import ./configure-crate.nix {
-    inherit lib stdenv rust echo_colored noisily mkRustcDepArgs mkRustcFeatureArgs;
+    inherit lib stdenv echo_colored noisily mkRustcDepArgs mkRustcFeatureArgs;
   };
 
   buildCrate = import ./build-crate.nix {
-    inherit lib stdenv mkRustcDepArgs mkRustcFeatureArgs needUnstableCLI rust;
+    inherit lib stdenv mkRustcDepArgs mkRustcFeatureArgs needUnstableCLI;
   };
 
   installCrate = import ./install-crate.nix { inherit stdenv; };
-
-  # Allow access to the rust attribute set from inside buildRustCrate, which
-  # has a parameter that shadows the name.
-  rustAttrs = rust;
 in
 
   /* The overridable pkgs.buildRustCrate function.
@@ -310,7 +305,7 @@ crate_: lib.makeOverridable
           depsMetadata = lib.foldl' (str: dep: str + dep.metadata) "" (dependencies ++ buildDependencies);
           hashedMetadata = builtins.hashString "sha256"
             (crateName + "-" + crateVersion + "___" + toString (mkRustcFeatureArgs crateFeatures) +
-              "___" + depsMetadata + "___" + rustAttrs.toRustTarget stdenv.hostPlatform);
+              "___" + depsMetadata + "___" + stdenv.hostPlatform.rust.rustcTarget);
         in
         lib.substring 0 10 hashedMetadata;
 
diff --git a/pkgs/build-support/rust/build-rust-package/default.nix b/pkgs/build-support/rust/build-rust-package/default.nix
index 0b28121a5b7..cf2ddbd084b 100644
--- a/pkgs/build-support/rust/build-rust-package/default.nix
+++ b/pkgs/build-support/rust/build-rust-package/default.nix
@@ -1,7 +1,6 @@
 { lib
 , importCargoLock
 , fetchCargoTarball
-, rust
 , stdenv
 , callPackage
 , cargoBuildHook
@@ -78,13 +77,13 @@ let
       sha256 = args.cargoSha256;
     } // depsExtraArgs);
 
-  target = rust.toRustTargetSpec stdenv.hostPlatform;
+  target = stdenv.hostPlatform.rust.rustcTargetSpec;
   targetIsJSON = lib.hasSuffix ".json" target;
   useSysroot = targetIsJSON && !__internal_dontAddSysroot;
 
   sysroot = callPackage ./sysroot { } {
     inherit target;
-    shortTarget = rust.lib.toRustTargetSpecShort stdenv.hostPlatform;
+    shortTarget = stdenv.hostPlatform.rust.cargoShortTarget;
     RUSTFLAGS = args.RUSTFLAGS or "";
     originalCargoToml = src + /Cargo.toml; # profile info is later extracted
   };
diff --git a/pkgs/build-support/rust/build-rust-package/sysroot/default.nix b/pkgs/build-support/rust/build-rust-package/sysroot/default.nix
index a6d53056d9c..bb95b7bdc35 100644
--- a/pkgs/build-support/rust/build-rust-package/sysroot/default.nix
+++ b/pkgs/build-support/rust/build-rust-package/sysroot/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, rust, rustPlatform, buildPackages }:
+{ lib, stdenv, rustPlatform, buildPackages }:
 
 { shortTarget, originalCargoToml, target, RUSTFLAGS }:
 
@@ -26,7 +26,7 @@ in rustPlatform.buildRustPackage {
     done
 
     export RUST_SYSROOT=$(rustc --print=sysroot)
-    host=${rust.toRustTarget stdenv.buildPlatform}
+    host=${stdenv.buildPlatform.rust.rustcTarget}
     cp -r $RUST_SYSROOT/lib/rustlib/$host $out
   '';
 
diff --git a/pkgs/build-support/rust/hooks/default.nix b/pkgs/build-support/rust/hooks/default.nix
index 205d085d350..7703ff4abad 100644
--- a/pkgs/build-support/rust/hooks/default.nix
+++ b/pkgs/build-support/rust/hooks/default.nix
@@ -13,7 +13,7 @@
 # This confusingly-named parameter indicates the *subdirectory of
 # `target/` from which to copy the build artifacts.  It is derived
 # from a stdenv platform (or a JSON file).
-, target ? rust.lib.toRustTargetSpecShort stdenv.hostPlatform
+, target ? stdenv.hostPlatform.rust.cargoShortTarget
 }:
 
 {
@@ -65,10 +65,10 @@
         diff = "${lib.getBin buildPackages.diffutils}/bin/diff";
 
         cargoConfig = ''
-          [target."${rust.toRustTarget stdenv.buildPlatform}"]
+          [target."${stdenv.buildPlatform.rust.rustcTarget}"]
           "linker" = "${rust.envVars.ccForBuild}"
           ${lib.optionalString (stdenv.buildPlatform.config != stdenv.hostPlatform.config) ''
-            [target."${rust.toRustTarget stdenv.hostPlatform}"]
+            [target."${stdenv.hostPlatform.rust.rustcTarget}"]
             "linker" = "${rust.envVars.ccForHost}"
           ''}
           "rustflags" = [ "-C", "target-feature=${if stdenv.hostPlatform.isStatic then "+" else "-"}crt-static" ]
diff --git a/pkgs/build-support/rust/lib/default.nix b/pkgs/build-support/rust/lib/default.nix
index ceca7323176..dad8ab52823 100644
--- a/pkgs/build-support/rust/lib/default.nix
+++ b/pkgs/build-support/rust/lib/default.nix
@@ -5,89 +5,6 @@
 }:
 
 rec {
-  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch
-  toTargetArch = platform:
-    /**/ if platform ? rustc.platform then platform.rustc.platform.arch
-    else if platform.isAarch32 then "arm"
-    else if platform.isMips64  then "mips64"     # never add "el" suffix
-    else if platform.isPower64 then "powerpc64"  # never add "le" suffix
-    else platform.parsed.cpu.name;
-
-  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_os
-  toTargetOs = platform:
-    /**/ if platform ? rustc.platform then platform.rustc.platform.os or "none"
-    else if platform.isDarwin then "macos"
-    else platform.parsed.kernel.name;
-
-  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_family
-  toTargetFamily = platform:
-    if platform ? rustc.platform.target-family
-    then
-      (
-        # Since https://github.com/rust-lang/rust/pull/84072
-        # `target-family` is a list instead of single value.
-        let
-          f = platform.rustc.platform.target-family;
-        in
-        if builtins.isList f then f else [ f ]
-      )
-    else lib.optional platform.isUnix "unix"
-      ++ lib.optional platform.isWindows "windows";
-
-  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_vendor
-  toTargetVendor = platform: let
-    inherit (platform.parsed) vendor;
-  in platform.rustc.platform.vendor or {
-    "w64" = "pc";
-  }.${vendor.name} or vendor.name;
-
-  # Returns the name of the rust target, even if it is custom. Adjustments are
-  # because rust has slightly different naming conventions than we do.
-  toRustTarget = platform: let
-    inherit (platform.parsed) cpu kernel abi;
-    cpu_ = platform.rustc.platform.arch or {
-      "armv7a" = "armv7";
-      "armv7l" = "armv7";
-      "armv6l" = "arm";
-      "armv5tel" = "armv5te";
-      "riscv64" = "riscv64gc";
-    }.${cpu.name} or cpu.name;
-    vendor_ = toTargetVendor platform;
-  in platform.rustc.config
-    or "${cpu_}-${vendor_}-${kernel.name}${lib.optionalString (abi.name != "unknown") "-${abi.name}"}";
-
-  # Returns the name of the rust target if it is standard, or the json file
-  # containing the custom target spec.
-  toRustTargetSpec = platform:
-    if platform ? rustc.platform
-    then builtins.toFile (toRustTarget platform + ".json") (builtins.toJSON platform.rustc.platform)
-    else toRustTarget platform;
-
-  # Returns the name of the rust target if it is standard, or the
-  # basename of the file containing the custom target spec, without
-  # the .json extension.
-  #
-  # This is the name used by Cargo for target subdirectories.
-  toRustTargetSpecShort = platform:
-    lib.removeSuffix ".json"
-      (baseNameOf "${toRustTargetSpec platform}");
-
-  # When used as part of an environment variable name, triples are
-  # uppercased and have all hyphens replaced by underscores:
-  #
-  # https://github.com/rust-lang/cargo/pull/9169
-  # https://github.com/rust-lang/cargo/issues/8285#issuecomment-634202431
-  #
-  toRustTargetForUseInEnvVars = platform:
-    lib.strings.replaceStrings ["-"] ["_"]
-      (lib.strings.toUpper
-        (toRustTargetSpecShort platform));
-
-  # Returns true if the target is no_std
-  # https://github.com/rust-lang/rust/blob/2e44c17c12cec45b6a682b1e53a04ac5b5fcc9d2/src/bootstrap/config.rs#L415-L421
-  IsNoStdTarget = platform: let rustTarget = toRustTarget platform; in
-    builtins.any (t: lib.hasInfix t rustTarget) ["-none" "nvptx" "switch" "-uefi"];
-
   # These environment variables must be set when using `cargo-c` and
   # several other tools which do not deal well with cross
   # compilation.  The symptom of the problem they fix is errors due
@@ -107,12 +24,12 @@ rec {
     ccForTarget = "${targetPackages.stdenv.cc}/bin/${targetPackages.stdenv.cc.targetPrefix}cc";
     cxxForTarget = "${targetPackages.stdenv.cc}/bin/${targetPackages.stdenv.cc.targetPrefix}c++";
 
-    rustBuildPlatform = toRustTarget stdenv.buildPlatform;
-    rustBuildPlatformSpec = toRustTargetSpec stdenv.buildPlatform;
-    rustHostPlatform = toRustTarget stdenv.hostPlatform;
-    rustHostPlatformSpec = toRustTargetSpec stdenv.hostPlatform;
-    rustTargetPlatform = toRustTarget stdenv.targetPlatform;
-    rustTargetPlatformSpec = toRustTargetSpec stdenv.targetPlatform;
+    rustBuildPlatform = stdenv.buildPlatform.rust.rustcTarget;
+    rustBuildPlatformSpec = stdenv.buildPlatform.rust.rustcTargetSpec;
+    rustHostPlatform = stdenv.hostPlatform.rust.rustcTarget;
+    rustHostPlatformSpec = stdenv.hostPlatform.rust.rustcTargetSpec;
+    rustTargetPlatform = stdenv.targetPlatform.rust.rustcTarget;
+    rustTargetPlatformSpec = stdenv.targetPlatform.rust.rustcTargetSpec;
   in {
     inherit
       ccForBuild  cxxForBuild  rustBuildPlatform   rustBuildPlatformSpec
@@ -131,20 +48,34 @@ rec {
     # the following lines when rustTargetPlatform collides with
     # rustHostPlatform.
     + lib.optionalString (rustTargetPlatform != rustHostPlatform) ''
-      "CC_${toRustTargetForUseInEnvVars stdenv.targetPlatform}=${ccForTarget}" \
-      "CXX_${toRustTargetForUseInEnvVars stdenv.targetPlatform}=${cxxForTarget}" \
-      "CARGO_TARGET_${toRustTargetForUseInEnvVars stdenv.targetPlatform}_LINKER=${ccForTarget}" \
+      "CC_${stdenv.targetPlatform.rust.cargoEnvVarTarget}=${ccForTarget}" \
+      "CXX_${stdenv.targetPlatform.rust.cargoEnvVarTarget}=${cxxForTarget}" \
+      "CARGO_TARGET_${stdenv.targetPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForTarget}" \
     '' + ''
-      "CC_${toRustTargetForUseInEnvVars stdenv.hostPlatform}=${ccForHost}" \
-      "CXX_${toRustTargetForUseInEnvVars stdenv.hostPlatform}=${cxxForHost}" \
-      "CARGO_TARGET_${toRustTargetForUseInEnvVars stdenv.hostPlatform}_LINKER=${ccForHost}" \
+      "CC_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${ccForHost}" \
+      "CXX_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${cxxForHost}" \
+      "CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForHost}" \
     '' + ''
-      "CC_${toRustTargetForUseInEnvVars stdenv.buildPlatform}=${ccForBuild}" \
-      "CXX_${toRustTargetForUseInEnvVars stdenv.buildPlatform}=${cxxForBuild}" \
-      "CARGO_TARGET_${toRustTargetForUseInEnvVars stdenv.buildPlatform}_LINKER=${ccForBuild}" \
+      "CC_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${ccForBuild}" \
+      "CXX_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${cxxForBuild}" \
+      "CARGO_TARGET_${stdenv.buildPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForBuild}" \
       "CARGO_BUILD_TARGET=${rustBuildPlatform}" \
       "HOST_CC=${buildPackages.stdenv.cc}/bin/cc" \
       "HOST_CXX=${buildPackages.stdenv.cc}/bin/c++" \
     '';
   };
+} // lib.mapAttrs (old: new: platform:
+  # TODO: enable warning after 23.05 is EOL.
+  # lib.warn "`rust.${old} platform` is deprecated. Use `platform.rust.${new}` instead."
+    lib.getAttrFromPath new platform.rust)
+{
+  toTargetArch = [ "platform" "arch" ];
+  toTargetOs = [ "platform" "os" ];
+  toTargetFamily = [ "platform" "target-family" ];
+  toTargetVendor = [ "platform" "vendor" ];
+  toRustTarget = [ "rustcTarget" ];
+  toRustTargetSpec = [ "rustcTargetSpec" ];
+  toRustTargetSpecShort = [ "cargoShortTarget" ];
+  toRustTargetForUseInEnvVars = [ "cargoEnvVarTarget" ];
+  IsNoStdTarget = [ "isNoStdTarget" ];
 }
diff --git a/pkgs/desktops/gnome/core/gnome-tour/default.nix b/pkgs/desktops/gnome/core/gnome-tour/default.nix
index c471417d616..26ac73f546d 100644
--- a/pkgs/desktops/gnome/core/gnome-tour/default.nix
+++ b/pkgs/desktops/gnome/core/gnome-tour/default.nix
@@ -17,7 +17,6 @@
 , libadwaita
 , librsvg
 , rustc
-, rust
 , writeText
 , cargo
 }:
@@ -65,7 +64,7 @@ stdenv.mkDerivation rec {
       # ERROR: 'rust' compiler binary not defined in cross or native file
       crossFile = writeText "cross-file.conf" ''
         [binaries]
-        rust = [ 'rustc', '--target', '${rust.toRustTargetSpec stdenv.hostPlatform}' ]
+        rust = [ 'rustc', '--target', '${stdenv.hostPlatform.rust.rustcTargetSpec}' ]
       '';
     in
     lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [ "--cross-file=${crossFile}" ];
diff --git a/pkgs/development/compilers/mrustc/bootstrap.nix b/pkgs/development/compilers/mrustc/bootstrap.nix
index a8bf26bacdf..0996702ec62 100644
--- a/pkgs/development/compilers/mrustc/bootstrap.nix
+++ b/pkgs/development/compilers/mrustc/bootstrap.nix
@@ -2,7 +2,6 @@
 , fetchurl
 , mrustc
 , mrustc-minicargo
-, rust
 , llvm_12
 , llvmPackages_12
 , libffi
@@ -74,7 +73,7 @@ stdenv.mkDerivation rec {
     "MRUSTC=${mrustc}/bin/mrustc"
     #"MINICARGO=${mrustc-minicargo}/bin/minicargo"  # FIXME: we need to rebuild minicargo locally so --manifest-overrides is applied
     "LLVM_CONFIG=${llvm_12.dev}/bin/llvm-config"
-    "RUSTC_TARGET=${rust.toRustTarget stdenv.targetPlatform}"
+    "RUSTC_TARGET=${stdenv.targetPlatform.rust.rustcTarget}"
   ];
 
   buildPhase = ''
@@ -129,7 +128,7 @@ stdenv.mkDerivation rec {
     cp run_rustc/${outputDir}/prefix/bin/rustc_binary $out/bin/rustc
 
     cp -r run_rustc/${outputDir}/prefix/lib/* $out/lib/
-    cp $out/lib/rustlib/${rust.toRustTarget stdenv.targetPlatform}/lib/*.so $out/lib/
+    cp $out/lib/rustlib/${stdenv.targetPlatform.rust.rustcTarget}/lib/*.so $out/lib/
     runHook postInstall
   '';
 
@@ -146,4 +145,3 @@ stdenv.mkDerivation rec {
     platforms = [ "x86_64-linux" ];
   };
 }
-
diff --git a/pkgs/development/compilers/rust/bootstrap.nix b/pkgs/development/compilers/rust/bootstrap.nix
index 7c0b46d5593..97ac6927025 100644
--- a/pkgs/development/compilers/rust/bootstrap.nix
+++ b/pkgs/development/compilers/rust/bootstrap.nix
@@ -1,7 +1,7 @@
-{ stdenv, fetchurl, rust, callPackage, version, hashes }:
+{ stdenv, fetchurl, callPackage, version, hashes }:
 
 let
-  platform = rust.toRustTarget stdenv.hostPlatform;
+  platform = stdenv.hostPlatform.rust.rustcTarget;
 
   src = fetchurl {
      url = "https://static.rust-lang.org/dist/rust-${version}-${platform}.tar.gz";
diff --git a/pkgs/development/compilers/rust/cargo.nix b/pkgs/development/compilers/rust/cargo.nix
index 46e238ff479..8eb628aa536 100644
--- a/pkgs/development/compilers/rust/cargo.nix
+++ b/pkgs/development/compilers/rust/cargo.nix
@@ -1,6 +1,6 @@
 { lib, stdenv, pkgsBuildHost, pkgsHostHost
 , file, curl, pkg-config, python3, openssl, cmake, zlib
-, installShellFiles, makeWrapper, rustPlatform, rust, rustc
+, installShellFiles, makeWrapper, rustPlatform, rustc
 , CoreFoundation, Security
 , auditable ? !cargo-auditable.meta.broken
 , cargo-auditable
@@ -116,6 +116,6 @@ rustPlatform.buildRustPackage.override {
     broken = stdenv.hostPlatform.isx86 && stdenv.buildPlatform != stdenv.hostPlatform;
   };
 }
-// lib.optionalAttrs (rust.toRustTarget stdenv.buildPlatform != rust.toRustTarget stdenv.hostPlatform) {
+// lib.optionalAttrs (stdenv.buildPlatform.rust.rustcTarget != stdenv.hostPlatform.rust.rustcTarget) {
   HOST_PKG_CONFIG_PATH="${pkgsBuildBuild.pkg-config}/bin/pkg-config";
 })
diff --git a/pkgs/development/compilers/rust/rustc.nix b/pkgs/development/compilers/rust/rustc.nix
index 44c290acbd3..5f97b0f4019 100644
--- a/pkgs/development/compilers/rust/rustc.nix
+++ b/pkgs/development/compilers/rust/rustc.nix
@@ -1,7 +1,7 @@
 { lib, stdenv, removeReferencesTo, pkgsBuildBuild, pkgsBuildHost, pkgsBuildTarget, targetPackages
 , llvmShared, llvmSharedForBuild, llvmSharedForHost, llvmSharedForTarget, llvmPackages
 , fetchurl, file, python3
-, darwin, cargo, cmake, rust, rustc
+, darwin, cargo, cmake, rustc
 , pkg-config, openssl, xz
 , libiconv
 , which, libffi
@@ -51,7 +51,7 @@ in stdenv.mkDerivation rec {
   # but it does support checking these idiosyncratic PKG_CONFIG_${TRIPLE}
   # environment variables.
   # [1]: https://github.com/rust-lang/pkg-config-rs/issues/53
-  "PKG_CONFIG_${builtins.replaceStrings ["-"] ["_"] (rust.toRustTarget stdenv.buildPlatform)}" =
+  "PKG_CONFIG_${builtins.replaceStrings ["-"] ["_"] stdenv.buildPlatform.rust.rustcTarget}" =
     "${pkgsBuildHost.stdenv.cc.targetPrefix}pkg-config";
 
   NIX_LDFLAGS = toString (
@@ -69,9 +69,9 @@ in stdenv.mkDerivation rec {
     prefixForStdenv = stdenv: "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}";
     ccPrefixForStdenv = stdenv: "${prefixForStdenv stdenv}${if (stdenv.cc.isClang or false) then "clang" else "cc"}";
     cxxPrefixForStdenv = stdenv: "${prefixForStdenv stdenv}${if (stdenv.cc.isClang or false) then "clang++" else "c++"}";
-    setBuild  = "--set=target.${rust.toRustTarget stdenv.buildPlatform}";
-    setHost   = "--set=target.${rust.toRustTarget stdenv.hostPlatform}";
-    setTarget = "--set=target.${rust.toRustTarget stdenv.targetPlatform}";
+    setBuild  = "--set=target.${stdenv.buildPlatform.rust.rustcTarget}";
+    setHost   = "--set=target.${stdenv.hostPlatform.rust.rustcTarget}";
+    setTarget = "--set=target.${stdenv.targetPlatform.rust.rustcTarget}";
     ccForBuild  = ccPrefixForStdenv pkgsBuildBuild.targetPackages.stdenv;
     cxxForBuild  = cxxPrefixForStdenv pkgsBuildBuild.targetPackages.stdenv;
     ccForHost  = ccPrefixForStdenv pkgsBuildHost.targetPackages.stdenv;
@@ -85,23 +85,23 @@ in stdenv.mkDerivation rec {
     "--tools=rustc,rust-analyzer-proc-macro-srv"
     "--enable-rpath"
     "--enable-vendor"
-    "--build=${rust.toRustTargetSpec stdenv.buildPlatform}"
-    "--host=${rust.toRustTargetSpec stdenv.hostPlatform}"
+    "--build=${stdenv.buildPlatform.rust.rustcTargetSpec}"
+    "--host=${stdenv.hostPlatform.rust.rustcTargetSpec}"
     # std is built for all platforms in --target.
     "--target=${concatStringsSep "," ([
-      (rust.toRustTargetSpec stdenv.targetPlatform)
+      stdenv.targetPlatform.rust.rustcTargetSpec
 
     # (build!=target): When cross-building a compiler we need to add
     # the build platform as well so rustc can compile build.rs
     # scripts.
     ] ++ optionals (stdenv.buildPlatform != stdenv.targetPlatform && !fastCross) [
-      (rust.toRustTargetSpec stdenv.buildPlatform)
+      stdenv.buildPlatform.rust.rustcTargetSpec
 
     # (host!=target): When building a cross-targeting compiler we
     # need to add the host platform as well so rustc can compile
     # build.rs scripts.
     ] ++ optionals (stdenv.hostPlatform != stdenv.targetPlatform && !fastCross) [
-      (rust.toRustTargetSpec stdenv.hostPlatform)
+      stdenv.hostPlatform.rust.rustcTargetSpec
     ])}"
 
     "${setBuild}.cc=${ccForBuild}"
@@ -132,7 +132,7 @@ in stdenv.mkDerivation rec {
     "${setHost}.musl-root=${pkgsBuildHost.targetPackages.stdenv.cc.libc}"
   ] ++ optionals stdenv.targetPlatform.isMusl [
     "${setTarget}.musl-root=${pkgsBuildTarget.targetPackages.stdenv.cc.libc}"
-  ] ++ optionals (rust.IsNoStdTarget stdenv.targetPlatform) [
+  ] ++ optionals stdenv.targetPlatform.rust.isNoStdTarget [
     "--disable-docs"
   ] ++ optionals (stdenv.isDarwin && stdenv.isx86_64) [
     # https://github.com/rust-lang/rust/issues/92173
@@ -144,12 +144,12 @@ in stdenv.mkDerivation rec {
   buildPhase = if fastCross then "
     runHook preBuild
 
-    mkdir -p build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-{std,rustc}/${rust.toRustTargetSpec stdenv.hostPlatform}/release/
-    ln -s ${rustc}/lib/rustlib/${rust.toRustTargetSpec stdenv.hostPlatform}/libstd-*.so build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-std/${rust.toRustTargetSpec stdenv.hostPlatform}/release/libstd.so
-    ln -s ${rustc}/lib/rustlib/${rust.toRustTargetSpec stdenv.hostPlatform}/librustc_driver-*.so build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-rustc/${rust.toRustTargetSpec stdenv.hostPlatform}/release/librustc.so
-    ln -s ${rustc}/bin/rustc build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-rustc/${rust.toRustTargetSpec stdenv.hostPlatform}/release/rustc-main
-    touch build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-std/${rust.toRustTargetSpec stdenv.hostPlatform}/release/.libstd.stamp
-    touch build/${rust.toRustTargetSpec stdenv.hostPlatform}/stage0-rustc/${rust.toRustTargetSpec stdenv.hostPlatform}/release/.librustc.stamp
+    mkdir -p build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-{std,rustc}/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/
+    ln -s ${rustc}/lib/rustlib/${stdenv.hostPlatform.rust.rustcTargetSpec}/libstd-*.so build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-std/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/libstd.so
+    ln -s ${rustc}/lib/rustlib/${stdenv.hostPlatform.rust.rustcTargetSpec}/librustc_driver-*.so build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-rustc/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/librustc.so
+    ln -s ${rustc}/bin/rustc build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-rustc/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/rustc-main
+    touch build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-std/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/.libstd.stamp
+    touch build/${stdenv.hostPlatform.rust.rustcTargetSpec}/stage0-rustc/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/.librustc.stamp
     python ./x.py --keep-stage=0 --stage=1 build library/std
 
     runHook postBuild
@@ -162,8 +162,8 @@ in stdenv.mkDerivation rec {
     mkdir -v $out/bin $doc $man
     makeWrapper ${rustc}/bin/rustc $out/bin/rustc --add-flags "--sysroot $out"
     makeWrapper ${rustc}/bin/rustdoc $out/bin/rustdoc --add-flags "--sysroot $out"
-    ln -s ${rustc}/lib/rustlib/{manifest-rust-std-,}${rust.toRustTargetSpec stdenv.hostPlatform} $out/lib/rustlib/
-    echo rust-std-${rust.toRustTargetSpec stdenv.hostPlatform} >> $out/lib/rustlib/components
+    ln -s ${rustc}/lib/rustlib/{manifest-rust-std-,}${stdenv.hostPlatform.rust.rustcTargetSpec} $out/lib/rustlib/
+    echo rust-std-${stdenv.hostPlatform.rust.rustcTargetSpec} >> $out/lib/rustlib/components
     lndir ${rustc.doc} $doc
     lndir ${rustc.man} $man
 
diff --git a/pkgs/development/interpreters/python/hooks/default.nix b/pkgs/development/interpreters/python/hooks/default.nix
index a907cda5f11..f7cc10274ae 100644
--- a/pkgs/development/interpreters/python/hooks/default.nix
+++ b/pkgs/development/interpreters/python/hooks/default.nix
@@ -183,16 +183,14 @@ in {
       };
     } ./setuptools-check-hook.sh) {};
 
-    setuptoolsRustBuildHook = callPackage ({ makePythonHook, setuptools-rust, rust }:
+    setuptoolsRustBuildHook = callPackage ({ makePythonHook, setuptools-rust }:
       makePythonHook {
         name = "setuptools-rust-setup-hook";
         propagatedBuildInputs = [ setuptools-rust ];
         substitutions = {
           pyLibDir = "${python}/lib/${python.libPrefix}";
-          cargoBuildTarget = rust.toRustTargetSpec stdenv.hostPlatform;
-          cargoLinkerVar = lib.toUpper (
-              builtins.replaceStrings ["-"] ["_"] (
-                rust.toRustTarget stdenv.hostPlatform));
+          cargoBuildTarget = stdenv.hostPlatform.rust.rustcTargetSpec;
+          cargoLinkerVar = stdenv.hostPlatform.rust.cargoEnvVarTarget;
           targetLinker = "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc";
         };
       } ./setuptools-rust-hook.sh) {};
diff --git a/pkgs/development/libraries/gstreamer/rs/default.nix b/pkgs/development/libraries/gstreamer/rs/default.nix
index e0d324936dd..1d06f880959 100644
--- a/pkgs/development/libraries/gstreamer/rs/default.nix
+++ b/pkgs/development/libraries/gstreamer/rs/default.nix
@@ -8,7 +8,6 @@
 , ninja
 , python3
 , pkg-config
-, rust
 , rustc
 , cargo
 , cargo-c
@@ -208,7 +207,7 @@ stdenv.mkDerivation rec {
   ] ++ (let
     crossFile = writeText "cross-file.conf" ''
       [binaries]
-      rust = [ 'rustc', '--target', '${rust.toRustTargetSpec stdenv.hostPlatform}' ]
+      rust = [ 'rustc', '--target', '${stdenv.hostPlatform.rust.rustcTargetSpec}' ]
     '';
   in lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
     "--cross-file=${crossFile}"
diff --git a/pkgs/development/libraries/libdovi/default.nix b/pkgs/development/libraries/libdovi/default.nix
index cf1a9a561f3..c70a217f6fc 100644
--- a/pkgs/development/libraries/libdovi/default.nix
+++ b/pkgs/development/libraries/libdovi/default.nix
@@ -5,9 +5,7 @@
 , rust
 , stdenv
 }:
-let
-  rustTargetPlatformSpec = rust.toRustTargetSpec stdenv.hostPlatform;
-in
+
 rustPlatform.buildRustPackage rec {
   pname = "libdovi";
   version = "3.1.2";
@@ -28,19 +26,19 @@ rustPlatform.buildRustPackage rec {
 
   buildPhase = ''
     runHook preBuild
-    ${rust.envVars.setEnv} cargo cbuild -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cbuild -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
     runHook postBuild
   '';
 
   installPhase = ''
     runHook preInstall
-    ${rust.envVars.setEnv} cargo cinstall -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cinstall -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
     runHook postInstall
   '';
 
   checkPhase = ''
     runHook preCheck
-    ${rust.envVars.setEnv} cargo ctest -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo ctest -j $NIX_BUILD_CORES --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
     runHook postCheck
   '';
 
diff --git a/pkgs/development/libraries/libimagequant/default.nix b/pkgs/development/libraries/libimagequant/default.nix
index 0ac6e89e23e..f60a1c7cab7 100644
--- a/pkgs/development/libraries/libimagequant/default.nix
+++ b/pkgs/development/libraries/libimagequant/default.nix
@@ -1,8 +1,5 @@
 { lib, stdenv, fetchFromGitHub, fetchurl, rust, rustPlatform, cargo-c, python3 }:
 
-let
-  rustTargetPlatformSpec = rust.toRustTargetSpec stdenv.hostPlatform;
-in
 rustPlatform.buildRustPackage rec {
   pname = "libimagequant";
   version = "4.2.2";
@@ -26,13 +23,13 @@ rustPlatform.buildRustPackage rec {
 
   postBuild = ''
     pushd imagequant-sys
-    ${rust.envVars.setEnv} cargo cbuild --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cbuild --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
     popd
   '';
 
   postInstall = ''
     pushd imagequant-sys
-    ${rust.envVars.setEnv} cargo cinstall --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cinstall --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
     popd
   '';
 
diff --git a/pkgs/development/libraries/librsvg/default.nix b/pkgs/development/libraries/librsvg/default.nix
index a0843d4b2ef..7ba6f1963e7 100644
--- a/pkgs/development/libraries/librsvg/default.nix
+++ b/pkgs/development/libraries/librsvg/default.nix
@@ -15,7 +15,6 @@
 , libobjc
 , rustPlatform
 , rustc
-, rust
 , cargo-auditable-cargo-wrapper
 , gi-docgen
 , python3Packages
@@ -106,7 +105,7 @@ stdenv.mkDerivation (finalAttrs: {
 
     "--enable-always-build-tests"
   ] ++ lib.optional stdenv.isDarwin "--disable-Bsymbolic"
-    ++ lib.optional (stdenv.buildPlatform != stdenv.hostPlatform) "RUST_TARGET=${rust.toRustTarget stdenv.hostPlatform}";
+    ++ lib.optional (stdenv.buildPlatform != stdenv.hostPlatform) "RUST_TARGET=${stdenv.hostPlatform.rust.rustcTarget}";
 
   doCheck = false; # all tests fail on libtool-generated rsvg-convert not being able to find coreutils
 
diff --git a/pkgs/development/libraries/relibc/default.nix b/pkgs/development/libraries/relibc/default.nix
index 28ed971a25e..3bc476ccc0f 100644
--- a/pkgs/development/libraries/relibc/default.nix
+++ b/pkgs/development/libraries/relibc/default.nix
@@ -64,7 +64,7 @@ redoxRustPlatform.buildRustPackage rec {
   '';
 
   # TODO: should be hostPlatform
-  TARGET = buildPackages.rust.toRustTargetSpec stdenvNoCC.targetPlatform;
+  TARGET = stdenvNoCC.targetPlatform.rust.rustcTargetSpec;
 
   cargoLock = {
     lockFile = ./Cargo.lock;
diff --git a/pkgs/development/libraries/rustc-demangle/default.nix b/pkgs/development/libraries/rustc-demangle/default.nix
index 6dd6d46e30b..4e142c58452 100644
--- a/pkgs/development/libraries/rustc-demangle/default.nix
+++ b/pkgs/development/libraries/rustc-demangle/default.nix
@@ -1,4 +1,4 @@
-{ rustPlatform, fetchFromGitHub, rust, lib, stdenv }:
+{ rustPlatform, fetchFromGitHub, lib, stdenv }:
 
 rustPlatform.buildRustPackage rec {
   pname = "rustc-demangle";
@@ -24,7 +24,7 @@ rustPlatform.buildRustPackage rec {
 
   postInstall = ''
     mkdir -p $out/lib
-    cp target/${rust.toRustTargetSpec stdenv.hostPlatform}/release/librustc_demangle.so $out/lib
+    cp target/${stdenv.hostPlatform.rust.rustcTargetSpec}/release/librustc_demangle.so $out/lib
     cp -R crates/capi/include $out
   '';
 
diff --git a/pkgs/development/tools/lalrpop/default.nix b/pkgs/development/tools/lalrpop/default.nix
index 0bc8bddefbd..32e6ec7a35b 100644
--- a/pkgs/development/tools/lalrpop/default.nix
+++ b/pkgs/development/tools/lalrpop/default.nix
@@ -1,6 +1,5 @@
 { lib
 , rustPlatform
-, rust
 , fetchFromGitHub
 , substituteAll
 , stdenv
@@ -24,7 +23,7 @@ rustPlatform.buildRustPackage rec {
   patches = [
     (substituteAll {
       src = ./use-correct-binary-path-in-tests.patch;
-      target_triple = rust.toRustTarget stdenv.hostPlatform;
+      target_triple = stdenv.hostPlatform.rust.rustcTarget;
     })
   ];
 
diff --git a/pkgs/development/tools/rust/cargo-benchcmp/default.nix b/pkgs/development/tools/rust/cargo-benchcmp/default.nix
index 4aa3c411f12..d46a57355d7 100644
--- a/pkgs/development/tools/rust/cargo-benchcmp/default.nix
+++ b/pkgs/development/tools/rust/cargo-benchcmp/default.nix
@@ -2,7 +2,6 @@
 , rustPlatform
 , fetchFromGitHub
 , substituteAll
-, rust
 , stdenv
 }:
 
@@ -23,7 +22,7 @@ rustPlatform.buildRustPackage rec {
     # patch the binary path so tests can find the binary when `--target` is present
     (substituteAll {
       src = ./fix-test-binary-path.patch;
-      shortTarget = rust.toRustTarget stdenv.hostPlatform;
+      shortTarget = stdenv.hostPlatform.rust.rustcTarget;
     })
   ];
 
diff --git a/pkgs/development/tools/rust/cargo-watch/default.nix b/pkgs/development/tools/rust/cargo-watch/default.nix
index fda47b5070a..63217b655ac 100644
--- a/pkgs/development/tools/rust/cargo-watch/default.nix
+++ b/pkgs/development/tools/rust/cargo-watch/default.nix
@@ -5,7 +5,6 @@
 , Cocoa
 , CoreServices
 , Foundation
-, rust
 , libiconv
 }:
 
@@ -27,7 +26,7 @@ rustPlatform.buildRustPackage rec {
   # `test with_cargo` tries to call cargo-watch as a cargo subcommand
   # (calling cargo-watch with command `cargo watch`)
   preCheck = ''
-    export PATH="$(pwd)/target/${rust.toRustTarget stdenv.hostPlatform}/release:$PATH"
+    export PATH="$(pwd)/target/${stdenv.hostPlatform.rust.rustcTarget}/release:$PATH"
   '';
 
   meta = with lib; {
diff --git a/pkgs/development/web/deno/librusty_v8.nix b/pkgs/development/web/deno/librusty_v8.nix
index 20fd20a5b98..e4d2a2fec70 100644
--- a/pkgs/development/web/deno/librusty_v8.nix
+++ b/pkgs/development/web/deno/librusty_v8.nix
@@ -1,11 +1,10 @@
 # auto-generated file -- DO NOT EDIT!
-{ rust, stdenv, fetchurl }:
+{ stdenv, fetchurl }:
 
 let
-  arch = rust.toRustTarget stdenv.hostPlatform;
   fetch_librusty_v8 = args: fetchurl {
     name = "librusty_v8-${args.version}";
-    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${arch}.a";
+    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${stdenv.hostPlatform.rust.rustcTarget}.a";
     sha256 = args.shas.${stdenv.hostPlatform.system};
     meta = { inherit (args) version; };
   };
diff --git a/pkgs/development/web/deno/update/librusty_v8.ts b/pkgs/development/web/deno/update/librusty_v8.ts
index b38e0a28f1a..39831f6ea27 100644
--- a/pkgs/development/web/deno/update/librusty_v8.ts
+++ b/pkgs/development/web/deno/update/librusty_v8.ts
@@ -40,13 +40,12 @@ fetchurl {
 
 const templateDeps = (version: string, deps: PrefetchResult[]) =>
   `# auto-generated file -- DO NOT EDIT!
-{ rust, stdenv, fetchurl }:
+{ stdenv, fetchurl }:
 
 let
-  arch = rust.toRustTarget stdenv.hostPlatform;
   fetch_librusty_v8 = args: fetchurl {
     name = "librusty_v8-\${args.version}";
-    url = "https://github.com/denoland/rusty_v8/releases/download/v\${args.version}/librusty_v8_release_\${arch}.a";
+    url = "https://github.com/denoland/rusty_v8/releases/download/v\${args.version}/librusty_v8_release_\${stdenv.hostPlatform.rust.rustcTarget}.a";
     sha256 = args.shas.\${stdenv.hostPlatform.system};
     meta = { inherit (args) version; };
   };
diff --git a/pkgs/development/web/edge-runtime/librusty_v8.nix b/pkgs/development/web/edge-runtime/librusty_v8.nix
index 6e9fc0a669f..1e0a306c13b 100644
--- a/pkgs/development/web/edge-runtime/librusty_v8.nix
+++ b/pkgs/development/web/edge-runtime/librusty_v8.nix
@@ -1,11 +1,10 @@
 # auto-generated file -- DO NOT EDIT!
-{ rust, stdenv, fetchurl }:
+{ stdenv, fetchurl }:
 
 let
-  arch = rust.toRustTarget stdenv.hostPlatform;
   fetch_librusty_v8 = args: fetchurl {
     name = "librusty_v8-${args.version}";
-    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${arch}.a";
+    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${stdenv.hostPlatform.rust.rustcTarget}.a";
     sha256 = args.shas.${stdenv.hostPlatform.system};
     meta = { inherit (args) version; };
   };
diff --git a/pkgs/servers/http/router/librusty_v8.nix b/pkgs/servers/http/router/librusty_v8.nix
index 60c6b4caef8..3e3bf55c757 100644
--- a/pkgs/servers/http/router/librusty_v8.nix
+++ b/pkgs/servers/http/router/librusty_v8.nix
@@ -1,10 +1,9 @@
-{ rust, stdenv, fetchurl }:
+{ stdenv, fetchurl }:
 
 let
-  arch = rust.toRustTarget stdenv.hostPlatform;
   fetch_librusty_v8 = args: fetchurl {
     name = "librusty_v8-${args.version}";
-    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${arch}.a";
+    url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${stdenv.hostPlatform.rust.rustcTarget}.a";
     sha256 = args.shas.${stdenv.hostPlatform.system};
     meta = { inherit (args) version; };
   };
diff --git a/pkgs/servers/matrix-synapse/matrix-hookshot/default.nix b/pkgs/servers/matrix-synapse/matrix-hookshot/default.nix
index 99b28a4defa..6113bd6ff41 100644
--- a/pkgs/servers/matrix-synapse/matrix-hookshot/default.nix
+++ b/pkgs/servers/matrix-synapse/matrix-hookshot/default.nix
@@ -5,7 +5,6 @@
 , makeWrapper
 , matrix-sdk-crypto-nodejs
 , mkYarnPackage
-, rust
 , cargo
 , rustPlatform
 , rustc
@@ -60,7 +59,7 @@ mkYarnPackage rec {
   buildPhase = ''
     runHook preBuild
     cd deps/${pname}
-    napi build --target ${rust.toRustTargetSpec stdenv.targetPlatform} --dts ../src/libRs.d.ts --release ./lib
+    napi build --target ${stdenv.targetPlatform.rust.rustcTargetSpec} --dts ../src/libRs.d.ts --release ./lib
     yarn run build:app:fix-defs
     yarn run build:app
     yarn run build:web
diff --git a/pkgs/servers/windmill/default.nix b/pkgs/servers/windmill/default.nix
index 6b822ade08b..a10610ea195 100644
--- a/pkgs/servers/windmill/default.nix
+++ b/pkgs/servers/windmill/default.nix
@@ -16,7 +16,6 @@
 , pixman
 , pkg-config
 , python3
-, rust
 , rustfmt
 , stdenv
 , swagger-cli
@@ -70,11 +69,10 @@ rustPlatform.buildRustPackage {
     SQLX_OFFLINE = "true";
     RUSTY_V8_ARCHIVE =
       let
-        arch = rust.toRustTarget stdenv.hostPlatform;
         fetch_librusty_v8 = args:
           fetchurl {
             name = "librusty_v8-${args.version}";
-            url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${arch}.a";
+            url = "https://github.com/denoland/rusty_v8/releases/download/v${args.version}/librusty_v8_release_${stdenv.hostPlatform.rust.rustcTarget}.a";
             sha256 = args.shas.${stdenv.hostPlatform.system} or (throw "Unsupported platform ${stdenv.hostPlatform.system}");
             meta = { inherit (args) version; };
           };
diff --git a/pkgs/tools/misc/halp/default.nix b/pkgs/tools/misc/halp/default.nix
index d9028a8392a..89867fe7a94 100644
--- a/pkgs/tools/misc/halp/default.nix
+++ b/pkgs/tools/misc/halp/default.nix
@@ -5,7 +5,6 @@
 , stdenv
 , darwin
 , unixtools
-, rust
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -48,7 +47,7 @@ rustPlatform.buildRustPackage rec {
 
   postPatch = ''
     substituteInPlace src/helper/args/mod.rs \
-      --subst-var-by releaseDir target/${rust.toRustTargetSpec stdenv.hostPlatform}/$cargoCheckType
+      --subst-var-by releaseDir target/${stdenv.hostPlatform.rust.rustcTargetSpec}/$cargoCheckType
   '';
 
   preCheck = ''
diff --git a/pkgs/tools/system/zram-generator/default.nix b/pkgs/tools/system/zram-generator/default.nix
index 81bf4082d5c..3d55d7c1961 100644
--- a/pkgs/tools/system/zram-generator/default.nix
+++ b/pkgs/tools/system/zram-generator/default.nix
@@ -1,7 +1,6 @@
 { lib
 , stdenv
 , fetchFromGitHub
-, rust
 , rustPlatform
 , pkg-config
 , ronn
@@ -28,7 +27,7 @@ rustPlatform.buildRustPackage rec {
   postPatch = ''
     cp ${./Cargo.lock} Cargo.lock
     substituteInPlace Makefile \
-      --replace 'target/$(BUILDTYPE)' 'target/${rust.toRustTargetSpec stdenv.hostPlatform}/$(BUILDTYPE)'
+      --replace 'target/$(BUILDTYPE)' 'target/${stdenv.hostPlatform.rust.rustcTargetSpec}/$(BUILDTYPE)'
     substituteInPlace src/generator.rs \
       --replace 'Command::new("systemd-detect-virt")' 'Command::new("${systemd}/bin/systemd-detect-virt")' \
       --replace 'Command::new("modprobe")' 'Command::new("${kmod}/bin/modprobe")'
diff --git a/pkgs/tools/video/rav1e/default.nix b/pkgs/tools/video/rav1e/default.nix
index 70e95cb4f01..146ff607254 100644
--- a/pkgs/tools/video/rav1e/default.nix
+++ b/pkgs/tools/video/rav1e/default.nix
@@ -13,10 +13,7 @@
 , buildPackages
 }:
 
-let
-  rustTargetPlatformSpec = rust.toRustTargetSpec stdenv.hostPlatform;
-
-in rustPlatform.buildRustPackage rec {
+rustPlatform.buildRustPackage rec {
   pname = "rav1e";
   version = "0.6.6";
 
@@ -47,11 +44,11 @@ in rustPlatform.buildRustPackage rec {
   checkType = "debug";
 
   postBuild =  ''
-    ${rust.envVars.setEnv} cargo cbuild --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cbuild --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
   '';
 
   postInstall = ''
-    ${rust.envVars.setEnv} cargo cinstall --release --frozen --prefix=${placeholder "out"} --target ${rustTargetPlatformSpec}
+    ${rust.envVars.setEnv} cargo cinstall --release --frozen --prefix=${placeholder "out"} --target ${stdenv.hostPlatform.rust.rustcTarget}
   '';
 
   meta = with lib; {