Vendor argh sources

Further customization will come in future commits

native/src/Cargo.lock

@@ -14,35 +14,6 @@ version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "862ed96ca487e809f1c8e5a8447f6ee2cf102f846893800b20cebdf541fc6bbd"
 
-[[package]]
-name = "argh"
-version = "0.1.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34ff18325c8a36b82f992e533ece1ec9f9a9db446bd1c14d4f936bac88fcd240"
-dependencies = [
- "argh_derive",
- "argh_shared",
- "rust-fuzzy-search",
-]
-
-[[package]]
-name = "argh_derive"
-version = "0.1.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "adb7b2b83a50d329d5d8ccc620f5c7064028828538bdf5646acd60dc1f767803"
-dependencies = [
- "argh_shared",
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "argh_shared"
-version = "0.1.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a464143cc82dedcdc3928737445362466b7674b5db4e2eb8e869846d6d84f4f6"
-
 [[package]]
 name = "autocfg"
 version = "1.5.0"
@@ -53,13 +24,13 @@ checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
 name = "base"
 version = "0.0.0"
 dependencies = [
- "argh",
  "bitflags",
  "bytemuck",
  "cfg-if",
  "const_format",
  "cxx",
  "cxx-gen",
+ "derive",
  "libc",
  "nix",
  "num-derive",
@@ -648,14 +619,12 @@ dependencies = [
 name = "magisk"
 version = "0.0.0"
 dependencies = [
- "argh",
  "base",
  "bit-set",
  "bitflags",
  "bytemuck",
  "cxx",
  "cxx-gen",
- "derive",
  "nix",
  "num-derive",
  "num-traits",
@@ -668,7 +637,6 @@ dependencies = [
 name = "magiskboot"
 version = "0.0.0"
 dependencies = [
- "argh",
  "base",
  "bytemuck",
  "byteorder",
@@ -710,7 +678,6 @@ dependencies = [
 name = "magiskpolicy"
 version = "0.0.0"
 dependencies = [
- "argh",
  "base",
  "cxx",
  "cxx-gen",
@@ -952,12 +919,6 @@ dependencies = [
  "zeroize",
 ]
 
-[[package]]
-name = "rust-fuzzy-search"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a157657054ffe556d8858504af8a672a054a6e0bd9e8ee531059100c0fa11bb2"
-
 [[package]]
 name = "rustversion"
 version = "1.0.22"

native/src/Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 exclude = ["external"]
-members = ["base", "boot", "core", "core/derive", "init", "sepolicy"]
+members = ["base", "base/derive", "boot", "core", "init", "sepolicy"]
 resolver = "2"
 
 [workspace.package]
@@ -9,7 +9,7 @@ edition = "2024"
 
 [workspace.dependencies]
 base = { path = "base" }
-derive = { path = "core/derive" }
+derive = { path = "base/derive" }
 magiskpolicy = { path = "sepolicy" }
 cxx = { path = "external/cxx-rs" }
 cxx-gen = { path = "external/cxx-rs/gen/lib" }
@@ -27,7 +27,6 @@ bit-set = "0.8.0"
 syn = "2.0.106"
 quote = "1.0.40"
 proc-macro2 = "1.0.101"
-argh = { version = "0.1.13", default-features = false }
 pb-rs = { version = "0.10.0", default-features = false }
 quick-protobuf = "0.8.1"
 flate2 = { version = "1.1.2", default-features = false }

native/src/base/Cargo.toml

@@ -13,11 +13,11 @@ selinux = []
 cxx-gen = { workspace = true }
 
 [dependencies]
+derive = { workspace = true }
 cxx = { workspace = true }
 libc = { workspace = true }
 cfg-if = { workspace = true }
 thiserror = { workspace = true }
-argh = { workspace = true }
 bytemuck = { workspace = true }
 num-traits = { workspace = true }
 num-derive = { workspace = true }

native/src/base/derive/argh/errors.rs

@@ -0,0 +1,185 @@
+// Copyright (c) 2020 Google LLC All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+use proc_macro2::{Span, TokenStream};
+use quote::ToTokens;
+use std::cell::RefCell;
+
+/// A type for collecting procedural macro errors.
+#[derive(Default)]
+pub struct Errors {
+    errors: RefCell<Vec<syn::Error>>,
+}
+
+/// Produce functions to expect particular literals in `syn::Expr`
+macro_rules! expect_lit_fn {
+    ($(($fn_name:ident, $syn_type:ident, $variant:ident, $lit_name:literal),)*) => {
+        $(
+            pub fn $fn_name<'a>(&self, e: &'a syn::Expr) -> Option<&'a syn::$syn_type> {
+                if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::$variant(inner), .. }) = e {
+                    Some(inner)
+                } else {
+                    self.unexpected_lit($lit_name, e);
+                    None
+                }
+            }
+        )*
+    }
+}
+
+/// Produce functions to expect particular variants of `syn::Meta`
+macro_rules! expect_meta_fn {
+    ($(($fn_name:ident, $syn_type:ident, $variant:ident, $meta_name:literal),)*) => {
+        $(
+            pub fn $fn_name<'a>(&self, meta: &'a syn::Meta) -> Option<&'a syn::$syn_type> {
+                if let syn::Meta::$variant(inner) = meta {
+                    Some(inner)
+                } else {
+                    self.unexpected_meta($meta_name, meta);
+                    None
+                }
+            }
+        )*
+    }
+}
+
+impl Errors {
+    /// Issue an error like:
+    ///
+    /// Duplicate foo attribute
+    /// First foo attribute here
+    pub fn duplicate_attrs(
+        &self,
+        attr_kind: &str,
+        first: &impl syn::spanned::Spanned,
+        second: &impl syn::spanned::Spanned,
+    ) {
+        self.duplicate_attrs_inner(attr_kind, first.span(), second.span())
+    }
+
+    fn duplicate_attrs_inner(&self, attr_kind: &str, first: Span, second: Span) {
+        self.err_span(second, &["Duplicate ", attr_kind, " attribute"].concat());
+        self.err_span(first, &["First ", attr_kind, " attribute here"].concat());
+    }
+
+    expect_lit_fn![
+        (expect_lit_str, LitStr, Str, "string"),
+        (expect_lit_char, LitChar, Char, "character"),
+        (expect_lit_int, LitInt, Int, "integer"),
+    ];
+
+    expect_meta_fn![
+        (expect_meta_word, Path, Path, "path"),
+        (expect_meta_list, MetaList, List, "list"),
+        (
+            expect_meta_name_value,
+            MetaNameValue,
+            NameValue,
+            "name-value pair"
+        ),
+    ];
+
+    fn unexpected_lit(&self, expected: &str, found: &syn::Expr) {
+        fn lit_kind(lit: &syn::Lit) -> &'static str {
+            use syn::Lit::{Bool, Byte, ByteStr, Char, Float, Int, Str, Verbatim};
+            match lit {
+                Str(_) => "string",
+                ByteStr(_) => "bytestring",
+                Byte(_) => "byte",
+                Char(_) => "character",
+                Int(_) => "integer",
+                Float(_) => "float",
+                Bool(_) => "boolean",
+                Verbatim(_) => "unknown (possibly extra-large integer)",
+                _ => "unknown literal kind",
+            }
+        }
+
+        if let syn::Expr::Lit(syn::ExprLit { lit, .. }) = found {
+            self.err(
+                found,
+                &[
+                    "Expected ",
+                    expected,
+                    " literal, found ",
+                    lit_kind(lit),
+                    " literal",
+                ]
+                .concat(),
+            )
+        } else {
+            self.err(
+                found,
+                &[
+                    "Expected ",
+                    expected,
+                    " literal, found non-literal expression.",
+                ]
+                .concat(),
+            )
+        }
+    }
+
+    fn unexpected_meta(&self, expected: &str, found: &syn::Meta) {
+        fn meta_kind(meta: &syn::Meta) -> &'static str {
+            use syn::Meta::{List, NameValue, Path};
+            match meta {
+                Path(_) => "path",
+                List(_) => "list",
+                NameValue(_) => "name-value pair",
+            }
+        }
+
+        self.err(
+            found,
+            &[
+                "Expected ",
+                expected,
+                " attribute, found ",
+                meta_kind(found),
+                " attribute",
+            ]
+            .concat(),
+        )
+    }
+
+    /// Issue an error relating to a particular `Spanned` structure.
+    pub fn err(&self, spanned: &impl syn::spanned::Spanned, msg: &str) {
+        self.err_span(spanned.span(), msg);
+    }
+
+    /// Issue an error relating to a particular `Span`.
+    pub fn err_span(&self, span: Span, msg: &str) {
+        self.push(syn::Error::new(span, msg));
+    }
+
+    /// Issue an error spanning over the given syntax tree node.
+    pub fn err_span_tokens<T: ToTokens>(&self, tokens: T, msg: &str) {
+        self.push(syn::Error::new_spanned(tokens, msg));
+    }
+
+    /// Push a `syn::Error` onto the list of errors to issue.
+    pub fn push(&self, err: syn::Error) {
+        self.errors.borrow_mut().push(err);
+    }
+
+    /// Convert a `syn::Result` to an `Option`, logging the error if present.
+    pub fn ok<T>(&self, r: syn::Result<T>) -> Option<T> {
+        match r {
+            Ok(v) => Some(v),
+            Err(e) => {
+                self.push(e);
+                None
+            }
+        }
+    }
+}
+
+impl ToTokens for Errors {
+    /// Convert the errors into tokens that, when emit, will cause
+    /// the user of the macro to receive compiler errors.
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.extend(self.errors.borrow().iter().map(|e| e.to_compile_error()));
+    }
+}

native/src/base/derive/argh/mod.rs

@@ -0,0 +1,911 @@
+// Copyright (c) 2020 Google LLC All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+use syn::ext::IdentExt as _;
+
+/// Implementation of the `FromArgs` and `argh(...)` derive attributes.
+///
+/// For more thorough documentation, see the `argh` crate itself.
+extern crate proc_macro;
+
+use errors::Errors;
+use parse_attrs::{FieldAttrs, FieldKind, TypeAttrs, check_long_name};
+use proc_macro2::{Span, TokenStream};
+use quote::{ToTokens, quote, quote_spanned};
+use std::collections::HashMap;
+use std::str::FromStr;
+use syn::spanned::Spanned;
+use syn::{GenericArgument, LitStr, PathArguments, Type};
+
+mod errors;
+mod parse_attrs;
+
+/// Transform the input into a token stream containing any generated implementations,
+/// as well as all errors that occurred.
+pub(crate) fn impl_from_args(input: &syn::DeriveInput) -> TokenStream {
+    let errors = &Errors::default();
+    let type_attrs = &TypeAttrs::parse(errors, input);
+    let mut output_tokens = match &input.data {
+        syn::Data::Struct(ds) => {
+            impl_from_args_struct(errors, &input.ident, type_attrs, &input.generics, ds)
+        }
+        syn::Data::Enum(de) => {
+            impl_from_args_enum(errors, &input.ident, type_attrs, &input.generics, de)
+        }
+        syn::Data::Union(_) => {
+            errors.err(input, "`#[derive(FromArgs)]` cannot be applied to unions");
+            TokenStream::new()
+        }
+    };
+    errors.to_tokens(&mut output_tokens);
+    output_tokens
+}
+
+/// The kind of optionality a parameter has.
+enum Optionality {
+    None,
+    Defaulted(TokenStream),
+    Optional,
+    Repeating,
+    DefaultedRepeating(TokenStream),
+}
+
+impl PartialEq<Optionality> for Optionality {
+    fn eq(&self, other: &Optionality) -> bool {
+        use Optionality::*;
+        // NB: (Defaulted, Defaulted) can't contain the same token streams
+        matches!((self, other), (Optional, Optional) | (Repeating, Repeating))
+    }
+}
+
+impl Optionality {
+    /// Whether or not this is `Optionality::None`
+    fn is_required(&self) -> bool {
+        matches!(self, Optionality::None)
+    }
+}
+
+/// A field of a `#![derive(FromArgs)]` struct with attributes and some other
+/// notable metadata appended.
+struct StructField<'a> {
+    /// The original parsed field
+    field: &'a syn::Field,
+    /// The parsed attributes of the field
+    attrs: FieldAttrs,
+    /// The field name. This is contained optionally inside `field`,
+    /// but is duplicated non-optionally here to indicate that all field that
+    /// have reached this point must have a field name, and it no longer
+    /// needs to be unwrapped.
+    name: &'a syn::Ident,
+    /// Similar to `name` above, this is contained optionally inside `FieldAttrs`,
+    /// but here is fully present to indicate that we only have to consider fields
+    /// with a valid `kind` at this point.
+    kind: FieldKind,
+    // If `field.ty` is `Vec<T>` or `Option<T>`, this is `T`, otherwise it's `&field.ty`.
+    // This is used to enable consistent parsing code between optional and non-optional
+    // keyed and subcommand fields.
+    ty_without_wrapper: &'a syn::Type,
+    // Whether the field represents an optional value, such as an `Option` subcommand field
+    // or an `Option` or `Vec` keyed argument, or if it has a `default`.
+    optionality: Optionality,
+    // The `--`-prefixed name of the option, if one exists.
+    long_name: Option<String>,
+}
+
+impl<'a> StructField<'a> {
+    /// Attempts to parse a field of a `#[derive(FromArgs)]` struct, pulling out the
+    /// fields required for code generation.
+    fn new(errors: &Errors, field: &'a syn::Field, attrs: FieldAttrs) -> Option<Self> {
+        let name = field.ident.as_ref().expect("missing ident for named field");
+
+        // Ensure that one "kind" is present (switch, option, subcommand, positional)
+        let kind = if let Some(field_type) = &attrs.field_type {
+            field_type.kind
+        } else {
+            errors.err(
+                field,
+                concat!(
+                    "Missing `argh` field kind attribute.\n",
+                    "Expected one of: `switch`, `option`, `remaining`, `subcommand`, `positional`",
+                ),
+            );
+            return None;
+        };
+
+        // Parse out whether a field is optional (`Option` or `Vec`).
+        let optionality;
+        let ty_without_wrapper;
+        match kind {
+            FieldKind::Switch => {
+                if !ty_expect_switch(errors, &field.ty) {
+                    return None;
+                }
+                optionality = Optionality::Optional;
+                ty_without_wrapper = &field.ty;
+            }
+            FieldKind::Option | FieldKind::Positional => {
+                if let Some(default) = &attrs.default {
+                    let tokens = match TokenStream::from_str(&default.value()) {
+                        Ok(tokens) => tokens,
+                        Err(_) => {
+                            errors.err(&default, "Invalid tokens: unable to lex `default` value");
+                            return None;
+                        }
+                    };
+                    // Set the span of the generated tokens to the string literal
+                    let tokens: TokenStream = tokens
+                        .into_iter()
+                        .map(|mut tree| {
+                            tree.set_span(default.span());
+                            tree
+                        })
+                        .collect();
+                    let inner = if let Some(x) = ty_inner(&["Vec"], &field.ty) {
+                        optionality = Optionality::DefaultedRepeating(tokens);
+                        x
+                    } else {
+                        optionality = Optionality::Defaulted(tokens);
+                        &field.ty
+                    };
+                    ty_without_wrapper = inner;
+                } else {
+                    let mut inner = None;
+                    optionality = if let Some(x) = ty_inner(&["Option"], &field.ty) {
+                        inner = Some(x);
+                        Optionality::Optional
+                    } else if let Some(x) = ty_inner(&["Vec"], &field.ty) {
+                        inner = Some(x);
+                        Optionality::Repeating
+                    } else {
+                        Optionality::None
+                    };
+                    ty_without_wrapper = inner.unwrap_or(&field.ty);
+                }
+            }
+            FieldKind::SubCommand => {
+                let inner = ty_inner(&["Option"], &field.ty);
+                optionality = if inner.is_some() {
+                    Optionality::Optional
+                } else {
+                    Optionality::None
+                };
+                ty_without_wrapper = inner.unwrap_or(&field.ty);
+            }
+        }
+
+        // Determine the "long" name of options and switches.
+        // Defaults to the kebab-case'd field name if `#[argh(long = "...")]` is omitted.
+        let long_name = match kind {
+            FieldKind::Switch | FieldKind::Option => {
+                let long_name = attrs
+                    .long
+                    .as_ref()
+                    .map(syn::LitStr::value)
+                    .unwrap_or_else(|| {
+                        let kebab_name = to_kebab_case(&name.unraw().to_string());
+                        check_long_name(errors, name, &kebab_name);
+                        kebab_name
+                    });
+                if long_name == "help" {
+                    errors.err(field, "Custom `--help` flags are not supported.");
+                }
+                let long_name = format!("--{}", long_name);
+                Some(long_name)
+            }
+            FieldKind::SubCommand | FieldKind::Positional => None,
+        };
+
+        Some(StructField {
+            field,
+            attrs,
+            kind,
+            optionality,
+            ty_without_wrapper,
+            name,
+            long_name,
+        })
+    }
+
+    pub(crate) fn positional_arg_name(&self) -> String {
+        self.attrs
+            .arg_name
+            .as_ref()
+            .map(LitStr::value)
+            .unwrap_or_else(|| self.name.to_string().trim_matches('_').to_owned())
+    }
+}
+
+fn to_kebab_case(s: &str) -> String {
+    let words = s.split('_').filter(|word| !word.is_empty());
+    let mut res = String::with_capacity(s.len());
+    for word in words {
+        if !res.is_empty() {
+            res.push('-')
+        }
+        res.push_str(word)
+    }
+    res
+}
+
+#[test]
+fn test_kebabs() {
+    #[track_caller]
+    fn check(s: &str, want: &str) {
+        let got = to_kebab_case(s);
+        assert_eq!(got.as_str(), want)
+    }
+    check("", "");
+    check("_", "");
+    check("foo", "foo");
+    check("__foo_", "foo");
+    check("foo_bar", "foo-bar");
+    check("foo__Bar", "foo-Bar");
+    check("foo_bar__baz_", "foo-bar-baz");
+}
+
+/// Implements `FromArgs` and `TopLevelCommand` or `SubCommand` for a `#[derive(FromArgs)]` struct.
+fn impl_from_args_struct(
+    errors: &Errors,
+    name: &syn::Ident,
+    type_attrs: &TypeAttrs,
+    generic_args: &syn::Generics,
+    ds: &syn::DataStruct,
+) -> TokenStream {
+    let fields = match &ds.fields {
+        syn::Fields::Named(fields) => fields,
+        syn::Fields::Unnamed(_) => {
+            errors.err(
+                &ds.struct_token,
+                "`#![derive(FromArgs)]` is not currently supported on tuple structs",
+            );
+            return TokenStream::new();
+        }
+        syn::Fields::Unit => {
+            errors.err(
+                &ds.struct_token,
+                "#![derive(FromArgs)]` cannot be applied to unit structs",
+            );
+            return TokenStream::new();
+        }
+    };
+
+    let fields: Vec<_> = fields
+        .named
+        .iter()
+        .filter_map(|field| {
+            let attrs = FieldAttrs::parse(errors, field);
+            StructField::new(errors, field, attrs)
+        })
+        .collect();
+
+    ensure_unique_names(errors, &fields);
+    ensure_only_last_positional_is_optional(errors, &fields);
+
+    let impl_span = Span::call_site();
+
+    let from_args_method = impl_from_args_struct_from_args(errors, type_attrs, &fields);
+
+    let top_or_sub_cmd_impl = top_or_sub_cmd_impl(errors, name, type_attrs, generic_args);
+
+    let (impl_generics, ty_generics, where_clause) = generic_args.split_for_impl();
+    let trait_impl = quote_spanned! { impl_span =>
+        #[automatically_derived]
+        impl #impl_generics argh::FromArgs for #name #ty_generics #where_clause {
+            #from_args_method
+        }
+
+        #top_or_sub_cmd_impl
+    };
+
+    trait_impl
+}
+
+fn impl_from_args_struct_from_args<'a>(
+    errors: &Errors,
+    type_attrs: &TypeAttrs,
+    fields: &'a [StructField<'a>],
+) -> TokenStream {
+    let init_fields = declare_local_storage_for_from_args_fields(fields);
+    let unwrap_fields = unwrap_from_args_fields(fields);
+    let positional_fields: Vec<&StructField<'_>> = fields
+        .iter()
+        .filter(|field| field.kind == FieldKind::Positional)
+        .collect();
+    let positional_field_idents = positional_fields.iter().map(|field| &field.field.ident);
+    let positional_field_names = positional_fields.iter().map(|field| field.name.to_string());
+    let last_positional_is_repeating = positional_fields
+        .last()
+        .map(|field| field.optionality == Optionality::Repeating)
+        .unwrap_or(false);
+    let last_positional_is_greedy = positional_fields
+        .last()
+        .map(|field| field.kind == FieldKind::Positional && field.attrs.greedy.is_some())
+        .unwrap_or(false);
+
+    let flag_output_table = fields.iter().filter_map(|field| {
+        let field_name = &field.field.ident;
+        match field.kind {
+            FieldKind::Option => Some(quote! { argh::ParseStructOption::Value(&mut #field_name) }),
+            FieldKind::Switch => Some(quote! { argh::ParseStructOption::Flag(&mut #field_name) }),
+            FieldKind::SubCommand | FieldKind::Positional => None,
+        }
+    });
+
+    let flag_str_to_output_table_map = flag_str_to_output_table_map_entries(fields);
+
+    let mut subcommands_iter = fields
+        .iter()
+        .filter(|field| field.kind == FieldKind::SubCommand)
+        .fuse();
+
+    let subcommand: Option<&StructField<'_>> = subcommands_iter.next();
+    for dup_subcommand in subcommands_iter {
+        errors.duplicate_attrs(
+            "subcommand",
+            subcommand.unwrap().field,
+            dup_subcommand.field,
+        );
+    }
+
+    let impl_span = Span::call_site();
+
+    let missing_requirements_ident = syn::Ident::new("__missing_requirements", impl_span);
+
+    let append_missing_requirements =
+        append_missing_requirements(&missing_requirements_ident, fields);
+
+    let parse_subcommands = if let Some(subcommand) = subcommand {
+        let name = subcommand.name;
+        let ty = subcommand.ty_without_wrapper;
+        quote_spanned! { impl_span =>
+            Some(argh::ParseStructSubCommand {
+                subcommands: <#ty as argh::SubCommands>::COMMANDS,
+                dynamic_subcommands: &<#ty as argh::SubCommands>::dynamic_commands(),
+                parse_func: &mut |__command, __remaining_args| {
+                    #name = Some(<#ty as argh::FromArgs>::from_args(__command, __remaining_args)?);
+                    Ok(())
+                },
+            })
+        }
+    } else {
+        quote_spanned! { impl_span => None }
+    };
+
+    let help_triggers = get_help_triggers(type_attrs);
+
+    let help = quote! { String::new() };
+
+    let method_impl = quote_spanned! { impl_span =>
+        fn from_args(__cmd_name: &[&str], __args: &[&str])
+            -> std::result::Result<Self, argh::EarlyExit>
+        {
+            #![allow(clippy::unwrap_in_result)]
+
+            #( #init_fields )*
+
+            argh::parse_struct_args(
+                __cmd_name,
+                __args,
+                argh::ParseStructOptions {
+                    arg_to_slot: &[ #( #flag_str_to_output_table_map ,)* ],
+                    slots: &mut [ #( #flag_output_table, )* ],
+                    help_triggers: &[ #( #help_triggers ),* ],
+                },
+                argh::ParseStructPositionals {
+                    positionals: &mut [
+                        #(
+                            argh::ParseStructPositional {
+                                name: #positional_field_names,
+                                slot: &mut #positional_field_idents as &mut dyn argh::ParseValueSlot,
+                            },
+                        )*
+                    ],
+                    last_is_repeating: #last_positional_is_repeating,
+                    last_is_greedy: #last_positional_is_greedy,
+                },
+                #parse_subcommands,
+                &|| #help,
+            )?;
+
+            let mut #missing_requirements_ident = argh::MissingRequirements::default();
+            #(
+                #append_missing_requirements
+            )*
+            #missing_requirements_ident.err_on_any()?;
+
+            Ok(Self {
+                #( #unwrap_fields, )*
+            })
+        }
+    };
+
+    method_impl
+}
+
+/// get help triggers vector from type_attrs.help_triggers as a [`Vec<String>`]
+///
+/// Defaults to vec!["--help", "help"] if type_attrs.help_triggers is None
+fn get_help_triggers(type_attrs: &TypeAttrs) -> Vec<String> {
+    type_attrs.help_triggers.as_ref().map_or_else(
+        || vec!["--help".to_owned(), "help".to_owned()],
+        |s| {
+            s.iter()
+                .filter_map(|s| {
+                    let trigger = s.value();
+                    let trigger_trimmed = trigger.trim().to_owned();
+                    if trigger_trimmed.is_empty() {
+                        None
+                    } else {
+                        Some(trigger_trimmed)
+                    }
+                })
+                .collect::<Vec<_>>()
+        },
+    )
+}
+
+/// Ensures that only the last positional arg is non-required.
+fn ensure_only_last_positional_is_optional(errors: &Errors, fields: &[StructField<'_>]) {
+    let mut first_non_required_span = None;
+    for field in fields {
+        if field.kind == FieldKind::Positional {
+            if let Some(first) = first_non_required_span {
+                errors.err_span(
+                    first,
+                    "Only the last positional argument may be `Option`, `Vec`, or defaulted.",
+                );
+                errors.err(&field.field, "Later positional argument declared here.");
+                return;
+            }
+            if !field.optionality.is_required() {
+                first_non_required_span = Some(field.field.span());
+            }
+        }
+    }
+}
+
+/// Ensures that only one short or long name is used.
+fn ensure_unique_names(errors: &Errors, fields: &[StructField<'_>]) {
+    let mut seen_short_names = HashMap::new();
+    let mut seen_long_names = HashMap::new();
+
+    for field in fields {
+        if let Some(short_name) = &field.attrs.short {
+            let short_name = short_name.value();
+            if let Some(first_use_field) = seen_short_names.get(&short_name) {
+                errors.err_span_tokens(
+                    first_use_field,
+                    &format!(
+                        "The short name of \"-{}\" was already used here.",
+                        short_name
+                    ),
+                );
+                errors.err_span_tokens(field.field, "Later usage here.");
+            }
+
+            seen_short_names.insert(short_name, &field.field);
+        }
+
+        if let Some(long_name) = &field.long_name {
+            if let Some(first_use_field) = seen_long_names.get(&long_name) {
+                errors.err_span_tokens(
+                    *first_use_field,
+                    &format!("The long name of \"{}\" was already used here.", long_name),
+                );
+                errors.err_span_tokens(field.field, "Later usage here.");
+            }
+
+            seen_long_names.insert(long_name, field.field);
+        }
+    }
+}
+
+/// Implement `argh::TopLevelCommand` or `argh::SubCommand` as appropriate.
+fn top_or_sub_cmd_impl(
+    errors: &Errors,
+    name: &syn::Ident,
+    type_attrs: &TypeAttrs,
+    generic_args: &syn::Generics,
+) -> TokenStream {
+    let description = String::new();
+    let (impl_generics, ty_generics, where_clause) = generic_args.split_for_impl();
+    if type_attrs.is_subcommand.is_none() {
+        // Not a subcommand
+        quote! {
+            #[automatically_derived]
+            impl #impl_generics argh::TopLevelCommand for #name #ty_generics #where_clause {}
+        }
+    } else {
+        let empty_str = syn::LitStr::new("", Span::call_site());
+        let subcommand_name = type_attrs.name.as_ref().unwrap_or_else(|| {
+            errors.err(
+                name,
+                "`#[argh(name = \"...\")]` attribute is required for subcommands",
+            );
+            &empty_str
+        });
+        quote! {
+            #[automatically_derived]
+            impl #impl_generics argh::SubCommand for #name #ty_generics #where_clause {
+                const COMMAND: &'static argh::CommandInfo = &argh::CommandInfo {
+                    name: #subcommand_name,
+                    description: #description,
+                };
+            }
+        }
+    }
+}
+
+/// Declare a local slots to store each field in during parsing.
+///
+/// Most fields are stored in `Option<FieldType>` locals.
+/// `argh(option)` fields are stored in a `ParseValueSlotTy` along with a
+/// function that knows how to decode the appropriate value.
+fn declare_local_storage_for_from_args_fields<'a>(
+    fields: &'a [StructField<'a>],
+) -> impl Iterator<Item = TokenStream> + 'a {
+    fields.iter().map(|field| {
+        let field_name = &field.field.ident;
+        let field_type = &field.ty_without_wrapper;
+
+        // Wrap field types in `Option` if they aren't already `Option` or `Vec`-wrapped.
+        let field_slot_type = match field.optionality {
+            Optionality::Optional | Optionality::Repeating => (&field.field.ty).into_token_stream(),
+            Optionality::None | Optionality::Defaulted(_) => {
+                quote! { std::option::Option<#field_type> }
+            }
+            Optionality::DefaultedRepeating(_) => {
+                quote! { std::option::Option<std::vec::Vec<#field_type>> }
+            }
+        };
+
+        match field.kind {
+            FieldKind::Option | FieldKind::Positional => {
+                let from_str_fn = match &field.attrs.from_str_fn {
+                    Some(from_str_fn) => from_str_fn.into_token_stream(),
+                    None => {
+                        quote! {
+                            <#field_type as argh::FromArgValue>::from_arg_value
+                        }
+                    }
+                };
+
+                quote! {
+                    let mut #field_name: argh::ParseValueSlotTy<#field_slot_type, #field_type>
+                        = argh::ParseValueSlotTy {
+                            slot: std::default::Default::default(),
+                            parse_func: |_, value| { #from_str_fn(value) },
+                        };
+                }
+            }
+            FieldKind::SubCommand => {
+                quote! { let mut #field_name: #field_slot_type = None; }
+            }
+            FieldKind::Switch => {
+                quote! { let mut #field_name: #field_slot_type = argh::Flag::default(); }
+            }
+        }
+    })
+}
+
+/// Unwrap non-optional fields and take options out of their tuple slots.
+fn unwrap_from_args_fields<'a>(
+    fields: &'a [StructField<'a>],
+) -> impl Iterator<Item = TokenStream> + 'a {
+    fields.iter().map(|field| {
+        let field_name = field.name;
+        match field.kind {
+            FieldKind::Option | FieldKind::Positional => match &field.optionality {
+                Optionality::None => quote! {
+                    #field_name: #field_name.slot.unwrap()
+                },
+                Optionality::Optional | Optionality::Repeating => {
+                    quote! { #field_name: #field_name.slot }
+                }
+                Optionality::Defaulted(tokens) | Optionality::DefaultedRepeating(tokens) => {
+                    quote! {
+                        #field_name: #field_name.slot.unwrap_or_else(|| #tokens)
+                    }
+                }
+            },
+            FieldKind::Switch => field_name.into_token_stream(),
+            FieldKind::SubCommand => match field.optionality {
+                Optionality::None => quote! { #field_name: #field_name.unwrap() },
+                Optionality::Optional | Optionality::Repeating => field_name.into_token_stream(),
+                Optionality::Defaulted(_) | Optionality::DefaultedRepeating(_) => unreachable!(),
+            },
+        }
+    })
+}
+
+/// Entries of tokens like `("--some-flag-key", 5)` that map from a flag key string
+/// to an index in the output table.
+fn flag_str_to_output_table_map_entries<'a>(fields: &'a [StructField<'a>]) -> Vec<TokenStream> {
+    let mut flag_str_to_output_table_map = vec![];
+    for (i, (field, long_name)) in fields
+        .iter()
+        .filter_map(|field| field.long_name.as_ref().map(|long_name| (field, long_name)))
+        .enumerate()
+    {
+        if let Some(short) = &field.attrs.short {
+            let short = format!("-{}", short.value());
+            flag_str_to_output_table_map.push(quote! { (#short, #i) });
+        }
+
+        flag_str_to_output_table_map.push(quote! { (#long_name, #i) });
+    }
+    flag_str_to_output_table_map
+}
+
+/// For each non-optional field, add an entry to the `argh::MissingRequirements`.
+fn append_missing_requirements<'a>(
+    // missing_requirements_ident
+    mri: &syn::Ident,
+    fields: &'a [StructField<'a>],
+) -> impl Iterator<Item = TokenStream> + 'a {
+    let mri = mri.clone();
+    fields
+        .iter()
+        .filter(|f| f.optionality.is_required())
+        .map(move |field| {
+            let field_name = field.name;
+            match field.kind {
+                FieldKind::Switch => unreachable!("switches are always optional"),
+                FieldKind::Positional => {
+                    let name = field.positional_arg_name();
+                    quote! {
+                        if #field_name.slot.is_none() {
+                            #mri.missing_positional_arg(#name)
+                        }
+                    }
+                }
+                FieldKind::Option => {
+                    let name = field
+                        .long_name
+                        .as_ref()
+                        .expect("options always have a long name");
+                    quote! {
+                        if #field_name.slot.is_none() {
+                            #mri.missing_option(#name)
+                        }
+                    }
+                }
+                FieldKind::SubCommand => {
+                    let ty = field.ty_without_wrapper;
+                    quote! {
+                        if #field_name.is_none() {
+                            #mri.missing_subcommands(
+                                <#ty as argh::SubCommands>::COMMANDS
+                                    .iter()
+                                    .cloned()
+                                    .chain(
+                                        <#ty as argh::SubCommands>::dynamic_commands()
+                                            .iter()
+                                            .copied()
+                                    ),
+                            )
+                        }
+                    }
+                }
+            }
+        })
+}
+
+/// Require that a type can be a `switch`.
+/// Throws an error for all types except booleans and integers
+fn ty_expect_switch(errors: &Errors, ty: &syn::Type) -> bool {
+    fn ty_can_be_switch(ty: &syn::Type) -> bool {
+        if let syn::Type::Path(path) = ty {
+            if path.qself.is_some() {
+                return false;
+            }
+            if path.path.segments.len() != 1 {
+                return false;
+            }
+            let ident = &path.path.segments[0].ident;
+            // `Option<bool>` can be used as a `switch`.
+            if ident == "Option"
+                && let PathArguments::AngleBracketed(args) = &path.path.segments[0].arguments
+                && let GenericArgument::Type(Type::Path(p)) = &args.args[0]
+                && p.path.segments[0].ident == "bool"
+            {
+                return true;
+            }
+            [
+                "bool", "u8", "u16", "u32", "u64", "u128", "i8", "i16", "i32", "i64", "i128",
+            ]
+            .iter()
+            .any(|path| ident == path)
+        } else {
+            false
+        }
+    }
+
+    let res = ty_can_be_switch(ty);
+    if !res {
+        errors.err(
+            ty,
+            "switches must be of type `bool`, `Option<bool>`, or integer type",
+        );
+    }
+    res
+}
+
+/// Returns `Some(T)` if a type is `wrapper_name<T>` for any `wrapper_name` in `wrapper_names`.
+fn ty_inner<'a>(wrapper_names: &[&str], ty: &'a syn::Type) -> Option<&'a syn::Type> {
+    if let syn::Type::Path(path) = ty {
+        if path.qself.is_some() {
+            return None;
+        }
+        // Since we only check the last path segment, it isn't necessarily the case that
+        // we're referring to `std::vec::Vec` or `std::option::Option`, but there isn't
+        // a fool proof way to check these since name resolution happens after macro expansion,
+        // so this is likely "good enough" (so long as people don't have their own types called
+        // `Option` or `Vec` that take one generic parameter they're looking to parse).
+        let last_segment = path.path.segments.last()?;
+        if !wrapper_names.iter().any(|name| last_segment.ident == *name) {
+            return None;
+        }
+        if let syn::PathArguments::AngleBracketed(gen_args) = &last_segment.arguments {
+            let generic_arg = gen_args.args.first()?;
+            if let syn::GenericArgument::Type(ty) = &generic_arg {
+                return Some(ty);
+            }
+        }
+    }
+    None
+}
+
+/// Implements `FromArgs` and `SubCommands` for a `#![derive(FromArgs)]` enum.
+fn impl_from_args_enum(
+    errors: &Errors,
+    name: &syn::Ident,
+    type_attrs: &TypeAttrs,
+    generic_args: &syn::Generics,
+    de: &syn::DataEnum,
+) -> TokenStream {
+    parse_attrs::check_enum_type_attrs(errors, type_attrs, &de.enum_token.span);
+
+    // An enum variant like `<name>(<ty>)`
+    struct SubCommandVariant<'a> {
+        name: &'a syn::Ident,
+        ty: &'a syn::Type,
+    }
+
+    let mut dynamic_type_and_variant = None;
+
+    let variants: Vec<SubCommandVariant<'_>> = de
+        .variants
+        .iter()
+        .filter_map(|variant| {
+            let name = &variant.ident;
+            let ty = enum_only_single_field_unnamed_variants(errors, &variant.fields)?;
+            if parse_attrs::VariantAttrs::parse(errors, variant)
+                .is_dynamic
+                .is_some()
+            {
+                if dynamic_type_and_variant.is_some() {
+                    errors.err(variant, "Only one variant can have the `dynamic` attribute");
+                }
+                dynamic_type_and_variant = Some((ty, name));
+                None
+            } else {
+                Some(SubCommandVariant { name, ty })
+            }
+        })
+        .collect();
+
+    let name_repeating = std::iter::repeat(name.clone());
+    let variant_ty = variants.iter().map(|x| x.ty).collect::<Vec<_>>();
+    let variant_names = variants.iter().map(|x| x.name).collect::<Vec<_>>();
+    let dynamic_from_args =
+        dynamic_type_and_variant
+            .as_ref()
+            .map(|(dynamic_type, dynamic_variant)| {
+                quote! {
+                    if let Some(result) = <#dynamic_type as argh::DynamicSubCommand>::try_from_args(
+                        command_name, args) {
+                        return result.map(#name::#dynamic_variant);
+                    }
+                }
+            });
+    let dynamic_commands = dynamic_type_and_variant.as_ref().map(|(dynamic_type, _)| {
+        quote! {
+            fn dynamic_commands() -> &'static [&'static argh::CommandInfo] {
+                <#dynamic_type as argh::DynamicSubCommand>::commands()
+            }
+        }
+    });
+
+    let (impl_generics, ty_generics, where_clause) = generic_args.split_for_impl();
+    quote! {
+        impl #impl_generics argh::FromArgs for #name #ty_generics #where_clause {
+            fn from_args(command_name: &[&str], args: &[&str])
+                -> std::result::Result<Self, argh::EarlyExit>
+            {
+                let subcommand_name = if let Some(subcommand_name) = command_name.last() {
+                    *subcommand_name
+                } else {
+                    return Err(argh::EarlyExit::from("no subcommand name".to_owned()));
+                };
+
+                #(
+                    if subcommand_name == <#variant_ty as argh::SubCommand>::COMMAND.name {
+                        return Ok(#name_repeating::#variant_names(
+                            <#variant_ty as argh::FromArgs>::from_args(command_name, args)?
+                        ));
+                    }
+                )*
+
+                #dynamic_from_args
+
+                Err(argh::EarlyExit::from("no subcommand matched".to_owned()))
+            }
+        }
+
+        impl #impl_generics argh::SubCommands for #name #ty_generics #where_clause {
+            const COMMANDS: &'static [&'static argh::CommandInfo] = &[#(
+                <#variant_ty as argh::SubCommand>::COMMAND,
+            )*];
+
+            #dynamic_commands
+        }
+    }
+}
+
+/// Returns `Some(Bar)` if the field is a single-field unnamed variant like `Foo(Bar)`.
+/// Otherwise, generates an error.
+fn enum_only_single_field_unnamed_variants<'a>(
+    errors: &Errors,
+    variant_fields: &'a syn::Fields,
+) -> Option<&'a syn::Type> {
+    macro_rules! with_enum_suggestion {
+        ($help_text:literal) => {
+            concat!(
+                $help_text,
+                "\nInstead, use a variant with a single unnamed field for each subcommand:\n",
+                "    enum MyCommandEnum {\n",
+                "        SubCommandOne(SubCommandOne),\n",
+                "        SubCommandTwo(SubCommandTwo),\n",
+                "    }",
+            )
+        };
+    }
+
+    match variant_fields {
+        syn::Fields::Named(fields) => {
+            errors.err(
+                fields,
+                with_enum_suggestion!(
+                    "`#![derive(FromArgs)]` `enum`s do not support variants with named fields."
+                ),
+            );
+            None
+        }
+        syn::Fields::Unit => {
+            errors.err(
+                variant_fields,
+                with_enum_suggestion!(
+                    "`#![derive(FromArgs)]` does not support `enum`s with no variants."
+                ),
+            );
+            None
+        }
+        syn::Fields::Unnamed(fields) => {
+            if fields.unnamed.len() != 1 {
+                errors.err(
+                    fields,
+                    with_enum_suggestion!(
+                        "`#![derive(FromArgs)]` `enum` variants must only contain one field."
+                    ),
+                );
+                None
+            } else {
+                // `unwrap` is okay because of the length check above.
+                let first_field = fields.unnamed.first().unwrap();
+                Some(&first_field.ty)
+            }
+        }
+    }
+}

native/src/base/derive/argh/parse_attrs.rs

@@ -0,0 +1,671 @@
+// Copyright (c) 2020 Google LLC All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+use syn::parse::Parser;
+use syn::punctuated::Punctuated;
+
+use super::errors::Errors;
+use proc_macro2::Span;
+use std::collections::hash_map::{Entry, HashMap};
+
+/// Attributes applied to a field of a `#![derive(FromArgs)]` struct.
+#[derive(Default)]
+pub struct FieldAttrs {
+    pub default: Option<syn::LitStr>,
+    pub description: Option<Description>,
+    pub from_str_fn: Option<syn::ExprPath>,
+    pub field_type: Option<FieldType>,
+    pub long: Option<syn::LitStr>,
+    pub short: Option<syn::LitChar>,
+    pub arg_name: Option<syn::LitStr>,
+    pub greedy: Option<syn::Path>,
+    pub hidden_help: bool,
+}
+
+/// The purpose of a particular field on a `#![derive(FromArgs)]` struct.
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum FieldKind {
+    /// Switches are booleans that are set to "true" by passing the flag.
+    Switch,
+    /// Options are `--key value`. They may be optional (using `Option`),
+    /// or repeating (using `Vec`), or required (neither `Option` nor `Vec`)
+    Option,
+    /// Subcommand fields (of which there can be at most one) refer to enums
+    /// containing one of several potential subcommands. They may be optional
+    /// (using `Option`) or required (no `Option`).
+    SubCommand,
+    /// Positional arguments are parsed literally if the input
+    /// does not begin with `-` or `--` and is not a subcommand.
+    /// They are parsed in declaration order, and only the last positional
+    /// argument in a type may be an `Option`, `Vec`, or have a default value.
+    Positional,
+}
+
+/// The type of a field on a `#![derive(FromArgs)]` struct.
+///
+/// This is a simple wrapper around `FieldKind` which includes the `syn::Ident`
+/// of the attribute containing the field kind.
+pub struct FieldType {
+    pub kind: FieldKind,
+    pub ident: syn::Ident,
+}
+
+/// A description of a `#![derive(FromArgs)]` struct.
+///
+/// Defaults to the docstring if one is present, or `#[argh(description = "...")]`
+/// if one is provided.
+pub struct Description {
+    /// Whether the description was an explicit annotation or whether it was a doc string.
+    pub explicit: bool,
+    pub content: syn::LitStr,
+}
+
+impl FieldAttrs {
+    pub fn parse(errors: &Errors, field: &syn::Field) -> Self {
+        let mut this = Self::default();
+
+        for attr in &field.attrs {
+            if is_doc_attr(attr) {
+                parse_attr_doc(errors, attr, &mut this.description);
+                continue;
+            }
+
+            let ml = if let Some(ml) = argh_attr_to_meta_list(errors, attr) {
+                ml
+            } else {
+                continue;
+            };
+
+            for meta in ml {
+                let name = meta.path();
+                if name.is_ident("arg_name") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_arg_name(errors, m);
+                    }
+                } else if name.is_ident("default") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_default(errors, m);
+                    }
+                } else if name.is_ident("description") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        parse_attr_description(errors, m, &mut this.description);
+                    }
+                } else if name.is_ident("from_str_fn") {
+                    if let Some(m) = errors.expect_meta_list(&meta) {
+                        this.parse_attr_from_str_fn(errors, m);
+                    }
+                } else if name.is_ident("long") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_long(errors, m);
+                    }
+                } else if name.is_ident("option") {
+                    parse_attr_field_type(errors, &meta, FieldKind::Option, &mut this.field_type);
+                } else if name.is_ident("short") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_short(errors, m);
+                    }
+                } else if name.is_ident("subcommand") {
+                    parse_attr_field_type(
+                        errors,
+                        &meta,
+                        FieldKind::SubCommand,
+                        &mut this.field_type,
+                    );
+                } else if name.is_ident("switch") {
+                    parse_attr_field_type(errors, &meta, FieldKind::Switch, &mut this.field_type);
+                } else if name.is_ident("positional") {
+                    parse_attr_field_type(
+                        errors,
+                        &meta,
+                        FieldKind::Positional,
+                        &mut this.field_type,
+                    );
+                } else if name.is_ident("greedy") {
+                    this.greedy = Some(name.clone());
+                } else if name.is_ident("hidden_help") {
+                    this.hidden_help = true;
+                } else {
+                    errors.err(
+                        &meta,
+                        concat!(
+                            "Invalid field-level `argh` attribute\n",
+                            "Expected one of: `arg_name`, `default`, `description`, `from_str_fn`, `greedy`, ",
+                            "`long`, `option`, `short`, `subcommand`, `switch`, `hidden_help`",
+                        ),
+                    );
+                }
+            }
+        }
+
+        if let (Some(default), Some(field_type)) = (&this.default, &this.field_type) {
+            match field_type.kind {
+                FieldKind::Option | FieldKind::Positional => {}
+                FieldKind::SubCommand | FieldKind::Switch => errors.err(
+                    default,
+                    "`default` may only be specified on `#[argh(option)]` \
+                     or `#[argh(positional)]` fields",
+                ),
+            }
+        }
+
+        match (&this.greedy, this.field_type.as_ref().map(|f| f.kind)) {
+            (Some(_), Some(FieldKind::Positional)) => {}
+            (Some(greedy), Some(_)) => errors.err(
+                &greedy,
+                "`greedy` may only be specified on `#[argh(positional)]` \
+                    fields",
+            ),
+            _ => {}
+        }
+
+        if let Some(d) = &this.description {
+            check_option_description(errors, d.content.value().trim(), d.content.span());
+        }
+
+        this
+    }
+
+    fn parse_attr_from_str_fn(&mut self, errors: &Errors, m: &syn::MetaList) {
+        parse_attr_fn_name(errors, m, "from_str_fn", &mut self.from_str_fn)
+    }
+
+    fn parse_attr_default(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_single_string(errors, m, "default", &mut self.default);
+    }
+
+    fn parse_attr_arg_name(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_single_string(errors, m, "arg_name", &mut self.arg_name);
+    }
+
+    fn parse_attr_long(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_single_string(errors, m, "long", &mut self.long);
+        let long = self.long.as_ref().unwrap();
+        let value = long.value();
+        check_long_name(errors, long, &value);
+    }
+
+    fn parse_attr_short(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        if let Some(first) = &self.short {
+            errors.duplicate_attrs("short", first, m);
+        } else if let Some(lit_char) = errors.expect_lit_char(&m.value) {
+            self.short = Some(lit_char.clone());
+            if !lit_char.value().is_ascii() {
+                errors.err(lit_char, "Short names must be ASCII");
+            }
+        }
+    }
+}
+
+pub(crate) fn check_long_name(errors: &Errors, spanned: &impl syn::spanned::Spanned, value: &str) {
+    if !value.is_ascii() {
+        errors.err(spanned, "Long names must be ASCII");
+    }
+    if !value
+        .chars()
+        .all(|c| c.is_lowercase() || c == '-' || c.is_ascii_digit())
+    {
+        errors.err(
+            spanned,
+            "Long names may only contain lowercase letters, digits, and dashes",
+        );
+    }
+}
+
+fn parse_attr_fn_name(
+    errors: &Errors,
+    m: &syn::MetaList,
+    attr_name: &str,
+    slot: &mut Option<syn::ExprPath>,
+) {
+    if let Some(first) = slot {
+        errors.duplicate_attrs(attr_name, first, m);
+    }
+
+    *slot = errors.ok(m.parse_args());
+}
+
+fn parse_attr_field_type(
+    errors: &Errors,
+    meta: &syn::Meta,
+    kind: FieldKind,
+    slot: &mut Option<FieldType>,
+) {
+    if let Some(path) = errors.expect_meta_word(meta) {
+        if let Some(first) = slot {
+            errors.duplicate_attrs("field kind", &first.ident, path);
+        } else if let Some(word) = path.get_ident() {
+            *slot = Some(FieldType {
+                kind,
+                ident: word.clone(),
+            });
+        }
+    }
+}
+
+// Whether the attribute is one like `#[<name> ...]`
+fn is_matching_attr(name: &str, attr: &syn::Attribute) -> bool {
+    attr.path().segments.len() == 1 && attr.path().segments[0].ident == name
+}
+
+/// Checks for `#[doc ...]`, which is generated by doc comments.
+fn is_doc_attr(attr: &syn::Attribute) -> bool {
+    is_matching_attr("doc", attr)
+}
+
+/// Checks for `#[argh ...]`
+fn is_argh_attr(attr: &syn::Attribute) -> bool {
+    is_matching_attr("argh", attr)
+}
+
+/// Filters out non-`#[argh(...)]` attributes and converts to a sequence of `syn::Meta`.
+fn argh_attr_to_meta_list(
+    errors: &Errors,
+    attr: &syn::Attribute,
+) -> Option<impl IntoIterator<Item = syn::Meta>> {
+    if !is_argh_attr(attr) {
+        return None;
+    }
+    let ml = errors.expect_meta_list(&attr.meta)?;
+    errors.ok(ml.parse_args_with(
+        syn::punctuated::Punctuated::<syn::Meta, syn::Token![,]>::parse_terminated,
+    ))
+}
+
+/// Represents a `#[derive(FromArgs)]` type's top-level attributes.
+#[derive(Default)]
+pub struct TypeAttrs {
+    pub is_subcommand: Option<syn::Ident>,
+    pub name: Option<syn::LitStr>,
+    pub description: Option<Description>,
+    pub examples: Vec<syn::LitStr>,
+    pub notes: Vec<syn::LitStr>,
+    pub error_codes: Vec<(syn::LitInt, syn::LitStr)>,
+    /// Arguments that trigger printing of the help message
+    pub help_triggers: Option<Vec<syn::LitStr>>,
+}
+
+impl TypeAttrs {
+    /// Parse top-level `#[argh(...)]` attributes
+    pub fn parse(errors: &Errors, derive_input: &syn::DeriveInput) -> Self {
+        let mut this = TypeAttrs::default();
+
+        for attr in &derive_input.attrs {
+            if is_doc_attr(attr) {
+                parse_attr_doc(errors, attr, &mut this.description);
+                continue;
+            }
+
+            let ml = if let Some(ml) = argh_attr_to_meta_list(errors, attr) {
+                ml
+            } else {
+                continue;
+            };
+
+            for meta in ml {
+                let name = meta.path();
+                if name.is_ident("description") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        parse_attr_description(errors, m, &mut this.description);
+                    }
+                } else if name.is_ident("error_code") {
+                    if let Some(m) = errors.expect_meta_list(&meta) {
+                        this.parse_attr_error_code(errors, m);
+                    }
+                } else if name.is_ident("example") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_example(errors, m);
+                    }
+                } else if name.is_ident("name") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_name(errors, m);
+                    }
+                } else if name.is_ident("note") {
+                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                        this.parse_attr_note(errors, m);
+                    }
+                } else if name.is_ident("subcommand") {
+                    if let Some(ident) = errors.expect_meta_word(&meta).and_then(|p| p.get_ident())
+                    {
+                        this.parse_attr_subcommand(errors, ident);
+                    }
+                } else if name.is_ident("help_triggers") {
+                    if let Some(m) = errors.expect_meta_list(&meta) {
+                        Self::parse_help_triggers(m, errors, &mut this);
+                    }
+                } else {
+                    errors.err(
+                        &meta,
+                        concat!(
+                            "Invalid type-level `argh` attribute\n",
+                            "Expected one of: `description`, `error_code`, `example`, `name`, ",
+                            "`note`, `subcommand`",
+                        ),
+                    );
+                }
+            }
+        }
+
+        this.check_error_codes(errors);
+        this
+    }
+
+    /// Checks that error codes are within range for `i32` and that they are
+    /// never duplicated.
+    fn check_error_codes(&self, errors: &Errors) {
+        // map from error code to index
+        let mut map: HashMap<u64, usize> = HashMap::new();
+        for (index, (lit_int, _lit_str)) in self.error_codes.iter().enumerate() {
+            let value = match lit_int.base10_parse::<u64>() {
+                Ok(v) => v,
+                Err(e) => {
+                    errors.push(e);
+                    continue;
+                }
+            };
+            if value > (i32::MAX as u64) {
+                errors.err(lit_int, "Error code out of range for `i32`");
+            }
+            match map.entry(value) {
+                Entry::Occupied(previous) => {
+                    let previous_index = *previous.get();
+                    let (previous_lit_int, _previous_lit_str) = &self.error_codes[previous_index];
+                    errors.err(lit_int, &format!("Duplicate error code {}", value));
+                    errors.err(
+                        previous_lit_int,
+                        &format!("Error code {} previously defined here", value),
+                    );
+                }
+                Entry::Vacant(slot) => {
+                    slot.insert(index);
+                }
+            }
+        }
+    }
+
+    fn parse_attr_error_code(&mut self, errors: &Errors, ml: &syn::MetaList) {
+        errors.ok(ml.parse_args_with(|input: syn::parse::ParseStream| {
+            let err_code = input.parse()?;
+            input.parse::<syn::Token![,]>()?;
+            let err_msg = input.parse()?;
+            if let (Some(err_code), Some(err_msg)) = (
+                errors.expect_lit_int(&err_code),
+                errors.expect_lit_str(&err_msg),
+            ) {
+                self.error_codes.push((err_code.clone(), err_msg.clone()));
+            }
+            Ok(())
+        }));
+    }
+
+    fn parse_attr_example(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_multi_string(errors, m, &mut self.examples)
+    }
+
+    fn parse_attr_name(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_single_string(errors, m, "name", &mut self.name);
+        if let Some(name) = &self.name
+            && name.value() == "help"
+        {
+            errors.err(name, "Custom `help` commands are not supported.");
+        }
+    }
+
+    fn parse_attr_note(&mut self, errors: &Errors, m: &syn::MetaNameValue) {
+        parse_attr_multi_string(errors, m, &mut self.notes)
+    }
+
+    fn parse_attr_subcommand(&mut self, errors: &Errors, ident: &syn::Ident) {
+        if let Some(first) = &self.is_subcommand {
+            errors.duplicate_attrs("subcommand", first, ident);
+        } else {
+            self.is_subcommand = Some(ident.clone());
+        }
+    }
+
+    // get the list of arguments that trigger printing of the help message as a vector of strings (help_arguments("-h", "--help", "help"))
+    fn parse_help_triggers(m: &syn::MetaList, errors: &Errors, this: &mut TypeAttrs) {
+        let parser = Punctuated::<syn::Expr, syn::Token![,]>::parse_terminated;
+        match parser.parse(m.tokens.clone().into()) {
+            Ok(args) => {
+                let mut triggers = Vec::new();
+                for arg in args {
+                    if let syn::Expr::Lit(syn::ExprLit {
+                        lit: syn::Lit::Str(lit_str),
+                        ..
+                    }) = arg
+                    {
+                        triggers.push(lit_str);
+                    }
+                }
+
+                this.help_triggers = Some(triggers);
+            }
+            Err(err) => errors.push(err),
+        }
+    }
+}
+
+/// Represents an enum variant's attributes.
+#[derive(Default)]
+pub struct VariantAttrs {
+    pub is_dynamic: Option<syn::Path>,
+}
+
+impl VariantAttrs {
+    /// Parse enum variant `#[argh(...)]` attributes
+    pub fn parse(errors: &Errors, variant: &syn::Variant) -> Self {
+        let mut this = VariantAttrs::default();
+
+        let fields = match &variant.fields {
+            syn::Fields::Named(fields) => Some(&fields.named),
+            syn::Fields::Unnamed(fields) => Some(&fields.unnamed),
+            syn::Fields::Unit => None,
+        };
+
+        for field in fields.into_iter().flatten() {
+            for attr in &field.attrs {
+                if is_argh_attr(attr) {
+                    err_unused_enum_attr(errors, attr);
+                }
+            }
+        }
+
+        for attr in &variant.attrs {
+            let ml = if let Some(ml) = argh_attr_to_meta_list(errors, attr) {
+                ml
+            } else {
+                continue;
+            };
+
+            for meta in ml {
+                let name = meta.path();
+                if name.is_ident("dynamic") {
+                    if let Some(prev) = this.is_dynamic.as_ref() {
+                        errors.duplicate_attrs("dynamic", prev, &meta);
+                    } else {
+                        this.is_dynamic = errors.expect_meta_word(&meta).cloned();
+                    }
+                } else {
+                    errors.err(
+                        &meta,
+                        "Invalid variant-level `argh` attribute\n\
+                         Variants can only have the #[argh(dynamic)] attribute.",
+                    );
+                }
+            }
+        }
+
+        this
+    }
+}
+
+fn check_option_description(errors: &Errors, desc: &str, span: Span) {
+    let chars = &mut desc.trim().chars();
+    match (chars.next(), chars.next()) {
+        (Some(x), _) if x.is_lowercase() => {}
+        // If both the first and second letter are not lowercase,
+        // this is likely an initialism which should be allowed.
+        (Some(x), Some(y)) if !x.is_lowercase() && (y.is_alphanumeric() && !y.is_lowercase()) => {}
+        _ => {
+            errors.err_span(span, "Descriptions must begin with a lowercase letter");
+        }
+    }
+}
+
+fn parse_attr_single_string(
+    errors: &Errors,
+    m: &syn::MetaNameValue,
+    name: &str,
+    slot: &mut Option<syn::LitStr>,
+) {
+    if let Some(first) = slot {
+        errors.duplicate_attrs(name, first, m);
+    } else if let Some(lit_str) = errors.expect_lit_str(&m.value) {
+        *slot = Some(lit_str.clone());
+    }
+}
+
+fn parse_attr_multi_string(errors: &Errors, m: &syn::MetaNameValue, list: &mut Vec<syn::LitStr>) {
+    if let Some(lit_str) = errors.expect_lit_str(&m.value) {
+        list.push(lit_str.clone());
+    }
+}
+
+fn parse_attr_doc(errors: &Errors, attr: &syn::Attribute, slot: &mut Option<Description>) {
+    let nv = if let Some(nv) = errors.expect_meta_name_value(&attr.meta) {
+        nv
+    } else {
+        return;
+    };
+
+    // Don't replace an existing explicit description.
+    if slot.as_ref().map(|d| d.explicit).unwrap_or(false) {
+        return;
+    }
+
+    if let Some(lit_str) = errors.expect_lit_str(&nv.value) {
+        let lit_str = if let Some(previous) = slot {
+            let previous = &previous.content;
+            let previous_span = previous.span();
+            syn::LitStr::new(
+                &(previous.value() + &unescape_doc(lit_str.value())),
+                previous_span,
+            )
+        } else {
+            syn::LitStr::new(&unescape_doc(lit_str.value()), lit_str.span())
+        };
+        *slot = Some(Description {
+            explicit: false,
+            content: lit_str,
+        });
+    }
+}
+
+/// Replaces escape sequences in doc-comments with the characters they represent.
+///
+/// Rustdoc understands CommonMark escape sequences consisting of a backslash followed by an ASCII
+/// punctuation character. Any other backslash is treated as a literal backslash.
+fn unescape_doc(s: String) -> String {
+    let mut result = String::with_capacity(s.len());
+
+    let mut characters = s.chars().peekable();
+    while let Some(mut character) = characters.next() {
+        if character == '\\'
+            && let Some(next_character) = characters.peek()
+            && next_character.is_ascii_punctuation()
+        {
+            character = *next_character;
+            characters.next();
+        }
+
+        // Braces must be escaped as this string will be used as a format string
+        if character == '{' || character == '}' {
+            result.push(character);
+        }
+
+        result.push(character);
+    }
+
+    result
+}
+
+fn parse_attr_description(errors: &Errors, m: &syn::MetaNameValue, slot: &mut Option<Description>) {
+    let lit_str = if let Some(lit_str) = errors.expect_lit_str(&m.value) {
+        lit_str
+    } else {
+        return;
+    };
+
+    // Don't allow multiple explicit (non doc-comment) descriptions
+    if let Some(description) = slot
+        && description.explicit
+    {
+        errors.duplicate_attrs("description", &description.content, lit_str);
+    }
+
+    *slot = Some(Description {
+        explicit: true,
+        content: lit_str.clone(),
+    });
+}
+
+/// Checks that a `#![derive(FromArgs)]` enum has an `#[argh(subcommand)]`
+/// attribute and that it does not have any other type-level `#[argh(...)]` attributes.
+pub fn check_enum_type_attrs(errors: &Errors, type_attrs: &TypeAttrs, type_span: &Span) {
+    let TypeAttrs {
+        is_subcommand,
+        name,
+        description,
+        examples,
+        notes,
+        error_codes,
+        help_triggers,
+    } = type_attrs;
+
+    // Ensure that `#[argh(subcommand)]` is present.
+    if is_subcommand.is_none() {
+        errors.err_span(
+            *type_span,
+            concat!(
+                "`#![derive(FromArgs)]` on `enum`s can only be used to enumerate subcommands.\n",
+                "Consider adding `#[argh(subcommand)]` to the `enum` declaration.",
+            ),
+        );
+    }
+
+    // Error on all other type-level attributes.
+    if let Some(name) = name {
+        err_unused_enum_attr(errors, name);
+    }
+    if let Some(description) = description
+        && description.explicit
+    {
+        err_unused_enum_attr(errors, &description.content);
+    }
+    if let Some(example) = examples.first() {
+        err_unused_enum_attr(errors, example);
+    }
+    if let Some(note) = notes.first() {
+        err_unused_enum_attr(errors, note);
+    }
+    if let Some(err_code) = error_codes.first() {
+        err_unused_enum_attr(errors, &err_code.0);
+    }
+    if let Some(triggers) = help_triggers
+        && let Some(trigger) = triggers.first()
+    {
+        err_unused_enum_attr(errors, trigger);
+    }
+}
+
+fn err_unused_enum_attr(errors: &Errors, location: &impl syn::spanned::Spanned) {
+    errors.err(
+        location,
+        concat!(
+            "Unused `argh` attribute on `#![derive(FromArgs)]` enum. ",
+            "Such `enum`s can only be used to dispatch to subcommands, ",
+            "and should only contain the #[argh(subcommand)] attribute.",
+        ),
+    );
+}

native/src/base/derive/lib.rs

@@ -0,0 +1,19 @@
+#![recursion_limit = "256"]
+
+use proc_macro::TokenStream;
+
+mod argh;
+mod decodable;
+
+#[proc_macro_derive(Decodable)]
+pub fn derive_decodable(input: TokenStream) -> TokenStream {
+    decodable::derive_decodable(input)
+}
+
+/// Entrypoint for `#[derive(FromArgs)]`.
+#[proc_macro_derive(FromArgs, attributes(argh))]
+pub fn argh_derive(input: TokenStream) -> TokenStream {
+    let ast = syn::parse_macro_input!(input as syn::DeriveInput);
+    let token = argh::impl_from_args(&ast);
+    token.into()
+}

native/src/base/lib.rs

@@ -7,6 +7,7 @@ pub use cstr::{
     FsPathFollow, StrErr, Utf8CStr, Utf8CStrBuf, Utf8CStrBufArr, Utf8CStrBufRef, Utf8CString,
 };
 use cxx_extern::*;
+pub use derive;
 pub use dir::*;
 pub use ffi::{Utf8CStrRef, fork_dont_care, set_nice_name};
 pub use files::*;
@@ -14,6 +15,7 @@ pub use logging::*;
 pub use misc::*;
 pub use result::*;
 
+pub mod argh;
 pub mod cstr;
 mod cxx_extern;
 mod dir;

native/src/base/misc.rs

@@ -1,5 +1,5 @@
+use super::argh::{EarlyExit, MissingRequirements};
 use crate::{Utf8CStr, Utf8CString, cstr, ffi};
-use argh::{EarlyExit, MissingRequirements};
 use libc::c_char;
 use std::fmt::Arguments;
 use std::io::Write;

native/src/boot/Cargo.toml

@@ -17,7 +17,6 @@ cxx = { workspace = true }
 byteorder = { workspace = true }
 size = { workspace = true }
 quick-protobuf = { workspace = true }
-argh = { workspace = true }
 sha1 = { workspace = true }
 sha2 = { workspace = true }
 digest = { workspace = true }

native/src/boot/cli.rs

@@ -10,7 +10,7 @@ use base::libc::umask;
 use base::nix::fcntl::OFlag;
 use base::{
     CmdArgs, EarlyExitExt, LoggedResult, MappedFile, PositionalArgParser, ResultExt, Utf8CStr,
-    Utf8CString, WriteExt, cmdline_logging, cstr, log_err,
+    Utf8CString, WriteExt, argh, cmdline_logging, cstr, log_err,
 };
 use std::ffi::c_char;
 use std::io::{Seek, SeekFrom, Write};

native/src/boot/cpio.rs

@@ -1,5 +1,10 @@
 #![allow(clippy::useless_conversion)]
 
+use argh::FromArgs;
+use base::argh;
+use bytemuck::{Pod, Zeroable, from_bytes};
+use num_traits::cast::AsPrimitive;
+use size::{Base, Size, Style};
 use std::cmp::Ordering;
 use std::collections::{BTreeMap, HashMap};
 use std::fmt::{Display, Formatter};
@@ -9,11 +14,6 @@ use std::mem::size_of;
 use std::process::exit;
 use std::str;
 
-use argh::FromArgs;
-use bytemuck::{Pod, Zeroable, from_bytes};
-use num_traits::cast::AsPrimitive;
-use size::{Base, Size, Style};
-
 use crate::check_env;
 use crate::compress::{get_decoder, get_encoder};
 use crate::ffi::FileFormat;

native/src/boot/dtb.rs

@@ -1,10 +1,8 @@
-use std::cell::UnsafeCell;
-
 use argh::FromArgs;
+use base::{LoggedResult, MappedFile, Utf8CStr, argh};
 use fdt::node::{FdtNode, NodeProperty};
 use fdt::{Fdt, FdtError};
-
-use base::{LoggedResult, MappedFile, Utf8CStr};
+use std::cell::UnsafeCell;
 
 use crate::check_env;
 use crate::patch::patch_verity;

native/src/core/Cargo.toml

@@ -21,7 +21,6 @@ pb-rs = { workspace = true }
 
 [dependencies]
 base = { workspace = true, features = ["selinux"] }
-derive = { workspace = true }
 cxx = { workspace = true }
 num-traits = { workspace = true }
 num-derive = { workspace = true }
@@ -29,6 +28,5 @@ quick-protobuf = { workspace = true }
 bytemuck = { workspace = true, features = ["derive"] }
 thiserror = { workspace = true }
 bit-set = { workspace = true }
-argh = { workspace = true }
 nix = { workspace = true, features = ["fs", "mount", "poll", "signal", "term", "user", "zerocopy"] }
 bitflags = { workspace = true }

native/src/core/derive/lib.rs

@@ -1,8 +0,0 @@
-use proc_macro::TokenStream;
-
-mod decodable;
-
-#[proc_macro_derive(Decodable)]
-pub fn derive_decodable(input: TokenStream) -> TokenStream {
-    decodable::derive_decodable(input)
-}

native/src/core/lib.rs

@@ -9,8 +9,8 @@
 
 use crate::ffi::SuRequest;
 use crate::socket::Encodable;
+use base::derive::Decodable;
 use daemon::{MagiskD, connect_daemon_for_cxx};
-use derive::Decodable;
 use logging::{android_logging, zygisk_close_logd, zygisk_get_logd, zygisk_logging};
 use magisk::magisk_main;
 use mount::revert_unmount;

native/src/core/magisk.rs

@@ -5,7 +5,7 @@ use crate::mount::find_preinit_device;
 use crate::selinux::restorecon;
 use crate::socket::{Decodable, Encodable};
 use argh::FromArgs;
-use base::{CmdArgs, EarlyExitExt, LoggedResult, Utf8CString, clone_attr};
+use base::{CmdArgs, EarlyExitExt, LoggedResult, Utf8CString, argh, clone_attr};
 use nix::poll::{PollFd, PollFlags, PollTimeout};
 use std::ffi::c_char;
 use std::os::fd::AsFd;

native/src/core/resetprop/cli.rs

@@ -6,7 +6,7 @@ use argh::{EarlyExit, FromArgs, MissingRequirements};
 use base::libc::PROP_VALUE_MAX;
 use base::{
     BufReadExt, CmdArgs, EarlyExitExt, LogLevel, LoggedResult, ResultExt, Utf8CStr, Utf8CStrBuf,
-    Utf8CString, cstr, debug, log_err, set_log_level_state,
+    Utf8CString, argh, cstr, debug, log_err, set_log_level_state,
 };
 use nix::fcntl::OFlag;
 use std::collections::BTreeMap;

native/src/sepolicy/Cargo.toml

@@ -16,4 +16,3 @@ no-main = []
 [dependencies]
 base = { workspace = true }
 cxx = { workspace = true }
-argh = { workspace = true }

native/src/sepolicy/cli.rs

@@ -3,7 +3,8 @@ use crate::statement::format_statement_help;
 use argh::FromArgs;
 use base::libc::umask;
 use base::{
-    CmdArgs, EarlyExitExt, FmtAdaptor, LoggedResult, Utf8CString, cmdline_logging, cstr, log_err,
+    CmdArgs, EarlyExitExt, FmtAdaptor, LoggedResult, Utf8CString, argh, cmdline_logging, cstr,
+    log_err,
 };
 use std::ffi::c_char;
 use std::io::stderr;