build(core/rust): enable panic_immediate_abort for firmware

ci/shell.nix

@@ -37,7 +37,7 @@ let
     ];
     # we use rustfmt from nixpkgs because it's built with the nighly flag needed for wrap_comments
     # to use official binary, remove rustfmt from buildInputs and add it to extensions:
-    extensions = [ "clippy" "rustfmt" ];
+    extensions = [ "rust-src" "clippy" "rustfmt" ];
   };
   llvmPackages = nixpkgs.llvmPackages_13;
   # see pyright/README.md for update procedure

core/SConscript.firmware

@@ -719,7 +719,16 @@ def cargo_build():
         if PYOPT == '0':
             features.append('ui_debug')
 
-    return f'cd embed/rust; cargo build {profile} --target={RUST_TARGET} --target-dir=../../build/firmware/rust --no-default-features --features "{" ".join(features)}"'
+    cargo_opts = [
+        f'--target={RUST_TARGET}',
+        f'--target-dir=../../build/firmware/rust',
+        '--no-default-features',
+        '--features ' + ','.join(features),
+        '-Z build-std=core',
+        '-Z build-std-features=panic_immediate_abort',
+    ]
+
+    return f'cd embed/rust; cargo build {profile} ' + ' '.join(cargo_opts)
 
 rust = env.Command(
     target=RUST_LIBPATH,