rustc: don't try to use non-existent rust-lld

This removes the need to manually override Rust's default linker for
every package that builds for wasm32-unknown-unknown.

pkgs/applications/blockchains/polkadot/default.nix

@@ -82,8 +82,6 @@ rustPlatform.buildRustPackage rec {
   # available for `rustc-wasm32`
   WASM_BUILD_STD = 0;
 
-  # NOTE: we need to force lld otherwise rust-lld is not found for wasm32 target
-  CARGO_TARGET_WASM32_UNKNOWN_UNKNOWN_LINKER = "lld";
   OPENSSL_NO_VENDOR = 1;
   PROTOC = "${protobuf}/bin/protoc";
   ROCKSDB_LIB_DIR = "${rocksdb}/lib";

pkgs/applications/misc/pagefind/default.nix

@@ -96,7 +96,6 @@ rustPlatform.buildRustPackage rec {
     echo entering pagefind_web...
     (
       cd pagefind_web
-      export RUSTFLAGS="-C linker=lld"
       bash ./local_build.sh
     )
 

pkgs/by-name/re/rerun/package.nix

@@ -78,8 +78,6 @@ rustPlatform.buildRustPackage rec {
     ]
     ++ lib.optionals stdenv.isLinux [ (lib.getLib wayland) ];
 
-  env.CARGO_TARGET_WASM32_UNKNOWN_UNKNOWN_LINKER = "lld";
-
   addDlopenRunpaths = map (p: "${lib.getLib p}/lib") (
     lib.optionals stdenv.hostPlatform.isLinux [
       libxkbcommon

pkgs/by-name/su/surrealist/package.nix

@@ -83,7 +83,7 @@ in stdenv.mkDerivation (finalAttrs: {
     ];
 
     postBuild = ''
-      CC=clang CARGO_TARGET_WASM32_UNKNOWN_UNKNOWN_LINKER=lld cargo build \
+      CC=clang cargo build \
         --target wasm32-unknown-unknown \
         --release
 

pkgs/by-name/te/tetrio-desktop/tetrio-plus.nix

@@ -63,7 +63,7 @@ let
     ];
 
     buildPhase = ''
-      HOME=$(mktemp -d) RUSTFLAGS="-C linker=lld" wasm-pack build --target web --release
+      HOME=$(mktemp -d) wasm-pack build --target web --release
     '';
 
     installPhase = ''

pkgs/development/compilers/rust/rustc.nix

@@ -192,6 +192,12 @@ in stdenv.mkDerivation (finalAttrs: {
   postPatch = ''
     patchShebangs src/etc
 
+    # rust-lld is the name rustup uses for its bundled lld, so that it
+    # doesn't conflict with any system lld.  This is not an
+    # appropriate default for Nixpkgs, where there is no rust-lld.
+    substituteInPlace compiler/rustc_target/src/spec/*/*.rs \
+      --replace-quiet '"rust-lld"' '"lld"'
+
     ${optionalString (!withBundledLLVM) "rm -rf src/llvm"}
 
     # Useful debugging parameter

pkgs/servers/ldap/lldap/default.nix

@@ -51,7 +51,7 @@ let
     ];
 
     buildPhase = ''
-      HOME=`pwd` RUSTFLAGS="-C linker=lld" ./app/build.sh
+      HOME=`pwd` ./app/build.sh
     '';
 
     installPhase = ''

pkgs/servers/teleport/generic.nix

@@ -76,10 +76,6 @@ let
 
     cargoDeps = rustPlatform.importCargoLock cargoLock;
 
-    RUSTFLAGS = builtins.concatStringsSep " " [
-      "-C linker=lld"
-    ];
-
     nativeBuildInputs = [ nodejs yarn fixup-yarn-lock ] ++
       lib.optional (lib.versionAtLeast version "15") [
         binaryen