Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 985 insertions, 0 deletions

diff --git a/third_party/rust/clap_derive/src/attrs.rs b/third_party/rust/clap_derive/src/attrs.rs
new file mode 100644
index 0000000000..aaee167e31
--- /dev/null
+++ b/third_party/rust/clap_derive/src/attrs.rs
@@ -0,0 +1,985 @@
+// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>,
+// Kevin Knapp (@kbknapp) <kbknapp@gmail.com>, and
+// Ana Hobden (@hoverbear) <operator@hoverbear.org>
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// This work was derived from Structopt (https://github.com/TeXitoi/structopt)
+// commit#ea76fa1b1b273e65e3b0b1046643715b49bec51f which is licensed under the
+// MIT/Apache 2.0 license.
+
+use crate::{
+    parse::*,
+    utils::{process_doc_comment, Sp, Ty},
+};
+
+use std::env;
+
+use heck::{ToKebabCase, ToLowerCamelCase, ToShoutySnakeCase, ToSnakeCase, ToUpperCamelCase};
+use proc_macro2::{self, Span, TokenStream};
+use proc_macro_error::abort;
+use quote::{quote, quote_spanned, ToTokens};
+use syn::{
+    self, ext::IdentExt, spanned::Spanned, Attribute, Expr, Field, Ident, LitStr, MetaNameValue,
+    Type, Variant,
+};
+
+/// Default casing style for generated arguments.
+pub const DEFAULT_CASING: CasingStyle = CasingStyle::Kebab;
+
+/// Default casing style for environment variables
+pub const DEFAULT_ENV_CASING: CasingStyle = CasingStyle::ScreamingSnake;
+
+#[derive(Clone)]
+pub struct Attrs {
+    name: Name,
+    casing: Sp<CasingStyle>,
+    env_casing: Sp<CasingStyle>,
+    ty: Option<Type>,
+    doc_comment: Vec<Method>,
+    methods: Vec<Method>,
+    parser: Sp<Parser>,
+    verbatim_doc_comment: Option<Ident>,
+    next_display_order: Option<Method>,
+    next_help_heading: Option<Method>,
+    help_heading: Option<Method>,
+    is_enum: bool,
+    has_custom_parser: bool,
+    kind: Sp<Kind>,
+}
+
+impl Attrs {
+    pub fn from_struct(
+        span: Span,
+        attrs: &[Attribute],
+        name: Name,
+        argument_casing: Sp<CasingStyle>,
+        env_casing: Sp<CasingStyle>,
+    ) -> Self {
+        let mut res = Self::new(span, name, None, argument_casing, env_casing);
+        res.push_attrs(attrs);
+        res.push_doc_comment(attrs, "about");
+
+        if res.has_custom_parser {
+            abort!(
+                res.parser.span(),
+                "`parse` attribute is only allowed on fields"
+            );
+        }
+        match &*res.kind {
+            Kind::Subcommand(_) => abort!(res.kind.span(), "subcommand is only allowed on fields"),
+            Kind::Skip(_) => abort!(res.kind.span(), "skip is only allowed on fields"),
+            Kind::Arg(_) => res,
+            Kind::FromGlobal(_) => abort!(res.kind.span(), "from_global is only allowed on fields"),
+            Kind::Flatten => abort!(res.kind.span(), "flatten is only allowed on fields"),
+            Kind::ExternalSubcommand => abort!(
+                res.kind.span(),
+                "external_subcommand is only allowed on fields"
+            ),
+        }
+    }
+
+    pub fn from_variant(
+        variant: &Variant,
+        struct_casing: Sp<CasingStyle>,
+        env_casing: Sp<CasingStyle>,
+    ) -> Self {
+        let name = variant.ident.clone();
+        let mut res = Self::new(
+            variant.span(),
+            Name::Derived(name),
+            None,
+            struct_casing,
+            env_casing,
+        );
+        res.push_attrs(&variant.attrs);
+        res.push_doc_comment(&variant.attrs, "about");
+
+        match &*res.kind {
+            Kind::Flatten => {
+                if res.has_custom_parser {
+                    abort!(
+                        res.parser.span(),
+                        "parse attribute is not allowed for flattened entry"
+                    );
+                }
+                if res.has_explicit_methods() {
+                    abort!(
+                        res.kind.span(),
+                        "methods are not allowed for flattened entry"
+                    );
+                }
+
+                // ignore doc comments
+                res.doc_comment = vec![];
+            }
+
+            Kind::ExternalSubcommand => (),
+
+            Kind::Subcommand(_) => {
+                if res.has_custom_parser {
+                    abort!(
+                        res.parser.span(),
+                        "parse attribute is not allowed for subcommand"
+                    );
+                }
+
+                use syn::Fields::*;
+                use syn::FieldsUnnamed;
+                let field_ty = match variant.fields {
+                    Named(_) => {
+                        abort!(variant.span(), "structs are not allowed for subcommand");
+                    }
+                    Unit => abort!(variant.span(), "unit-type is not allowed for subcommand"),
+                    Unnamed(FieldsUnnamed { ref unnamed, .. }) if unnamed.len() == 1 => {
+                        &unnamed[0].ty
+                    }
+                    Unnamed(..) => {
+                        abort!(
+                            variant,
+                            "non single-typed tuple is not allowed for subcommand"
+                        )
+                    }
+                };
+                let ty = Ty::from_syn_ty(field_ty);
+                match *ty {
+                    Ty::OptionOption => {
+                        abort!(
+                            field_ty,
+                            "Option<Option<T>> type is not allowed for subcommand"
+                        );
+                    }
+                    Ty::OptionVec => {
+                        abort!(
+                            field_ty,
+                            "Option<Vec<T>> type is not allowed for subcommand"
+                        );
+                    }
+                    _ => (),
+                }
+
+                res.kind = Sp::new(Kind::Subcommand(ty), res.kind.span());
+            }
+            Kind::Skip(_) => (),
+            Kind::FromGlobal(_) => {
+                abort!(res.kind.span(), "from_global is not supported on variants");
+            }
+            Kind::Arg(_) => (),
+        }
+
+        res
+    }
+
+    pub fn from_arg_enum_variant(
+        variant: &Variant,
+        argument_casing: Sp<CasingStyle>,
+        env_casing: Sp<CasingStyle>,
+    ) -> Self {
+        let mut res = Self::new(
+            variant.span(),
+            Name::Derived(variant.ident.clone()),
+            None,
+            argument_casing,
+            env_casing,
+        );
+        res.push_attrs(&variant.attrs);
+        res.push_doc_comment(&variant.attrs, "help");
+
+        if res.has_custom_parser {
+            abort!(
+                res.parser.span(),
+                "`parse` attribute is only allowed on fields"
+            );
+        }
+        match &*res.kind {
+            Kind::Subcommand(_) => abort!(res.kind.span(), "subcommand is only allowed on fields"),
+            Kind::Skip(_) => res,
+            Kind::Arg(_) => res,
+            Kind::FromGlobal(_) => abort!(res.kind.span(), "from_global is only allowed on fields"),
+            Kind::Flatten => abort!(res.kind.span(), "flatten is only allowed on fields"),
+            Kind::ExternalSubcommand => abort!(
+                res.kind.span(),
+                "external_subcommand is only allowed on fields"
+            ),
+        }
+    }
+
+    pub fn from_field(
+        field: &Field,
+        struct_casing: Sp<CasingStyle>,
+        env_casing: Sp<CasingStyle>,
+    ) -> Self {
+        let name = field.ident.clone().unwrap();
+        let mut res = Self::new(
+            field.span(),
+            Name::Derived(name),
+            Some(field.ty.clone()),
+            struct_casing,
+            env_casing,
+        );
+        res.push_attrs(&field.attrs);
+        res.push_doc_comment(&field.attrs, "help");
+
+        match &*res.kind {
+            Kind::Flatten => {
+                if res.has_custom_parser {
+                    abort!(
+                        res.parser.span(),
+                        "parse attribute is not allowed for flattened entry"
+                    );
+                }
+                if res.has_explicit_methods() {
+                    abort!(
+                        res.kind.span(),
+                        "methods are not allowed for flattened entry"
+                    );
+                }
+
+                // ignore doc comments
+                res.doc_comment = vec![];
+            }
+
+            Kind::ExternalSubcommand => {
+                abort! { res.kind.span(),
+                    "`external_subcommand` can be used only on enum variants"
+                }
+            }
+
+            Kind::Subcommand(_) => {
+                if res.has_custom_parser {
+                    abort!(
+                        res.parser.span(),
+                        "parse attribute is not allowed for subcommand"
+                    );
+                }
+                if res.has_explicit_methods() {
+                    abort!(
+                        res.kind.span(),
+                        "methods in attributes are not allowed for subcommand"
+                    );
+                }
+
+                let ty = Ty::from_syn_ty(&field.ty);
+                match *ty {
+                    Ty::OptionOption => {
+                        abort!(
+                            field.ty,
+                            "Option<Option<T>> type is not allowed for subcommand"
+                        );
+                    }
+                    Ty::OptionVec => {
+                        abort!(
+                            field.ty,
+                            "Option<Vec<T>> type is not allowed for subcommand"
+                        );
+                    }
+                    _ => (),
+                }
+
+                res.kind = Sp::new(Kind::Subcommand(ty), res.kind.span());
+            }
+            Kind::Skip(_) => {
+                if res.has_explicit_methods() {
+                    abort!(
+                        res.kind.span(),
+                        "methods are not allowed for skipped fields"
+                    );
+                }
+            }
+            Kind::FromGlobal(orig_ty) => {
+                let ty = Ty::from_syn_ty(&field.ty);
+                res.kind = Sp::new(Kind::FromGlobal(ty), orig_ty.span());
+            }
+            Kind::Arg(orig_ty) => {
+                let mut ty = Ty::from_syn_ty(&field.ty);
+                if res.has_custom_parser {
+                    match *ty {
+                        Ty::Option | Ty::Vec | Ty::OptionVec => (),
+                        _ => ty = Sp::new(Ty::Other, ty.span()),
+                    }
+                }
+
+                match *ty {
+                    Ty::Bool => {
+                        if res.is_positional() && !res.has_custom_parser {
+                            abort!(field.ty,
+                                "`bool` cannot be used as positional parameter with default parser";
+                                help = "if you want to create a flag add `long` or `short`";
+                                help = "If you really want a boolean parameter \
+                                    add an explicit parser, for example `parse(try_from_str)`";
+                                note = "see also https://github.com/clap-rs/clap/blob/master/examples/derive_ref/custom-bool.md";
+                            )
+                        }
+                        if res.is_enum {
+                            abort!(field.ty, "`arg_enum` is meaningless for bool")
+                        }
+                        if let Some(m) = res.find_default_method() {
+                            abort!(m.name, "default_value is meaningless for bool")
+                        }
+                        if let Some(m) = res.find_method("required") {
+                            abort!(m.name, "required is meaningless for bool")
+                        }
+                    }
+                    Ty::Option => {
+                        if let Some(m) = res.find_default_method() {
+                            abort!(m.name, "default_value is meaningless for Option")
+                        }
+                    }
+                    Ty::OptionOption => {
+                        if res.is_positional() {
+                            abort!(
+                                field.ty,
+                                "Option<Option<T>> type is meaningless for positional argument"
+                            )
+                        }
+                    }
+                    Ty::OptionVec => {
+                        if res.is_positional() {
+                            abort!(
+                                field.ty,
+                                "Option<Vec<T>> type is meaningless for positional argument"
+                            )
+                        }
+                    }
+
+                    _ => (),
+                }
+                res.kind = Sp::new(Kind::Arg(ty), orig_ty.span());
+            }
+        }
+
+        res
+    }
+
+    fn new(
+        default_span: Span,
+        name: Name,
+        ty: Option<Type>,
+        casing: Sp<CasingStyle>,
+        env_casing: Sp<CasingStyle>,
+    ) -> Self {
+        Self {
+            name,
+            ty,
+            casing,
+            env_casing,
+            doc_comment: vec![],
+            methods: vec![],
+            parser: Parser::default_spanned(default_span),
+            verbatim_doc_comment: None,
+            next_display_order: None,
+            next_help_heading: None,
+            help_heading: None,
+            is_enum: false,
+            has_custom_parser: false,
+            kind: Sp::new(Kind::Arg(Sp::new(Ty::Other, default_span)), default_span),
+        }
+    }
+
+    fn push_method(&mut self, name: Ident, arg: impl ToTokens) {
+        if name == "name" {
+            self.name = Name::Assigned(quote!(#arg));
+        } else {
+            self.methods.push(Method::new(name, quote!(#arg)));
+        }
+    }
+
+    fn push_attrs(&mut self, attrs: &[Attribute]) {
+        use ClapAttr::*;
+
+        let parsed = parse_clap_attributes(attrs);
+        for attr in &parsed {
+            let attr = attr.clone();
+            match attr {
+                Short(ident) => {
+                    self.push_method(ident, self.name.clone().translate_char(*self.casing));
+                }
+
+                Long(ident) => {
+                    self.push_method(ident, self.name.clone().translate(*self.casing));
+                }
+
+                Env(ident) => {
+                    self.push_method(ident, self.name.clone().translate(*self.env_casing));
+                }
+
+                ArgEnum(_) => self.is_enum = true,
+
+                FromGlobal(ident) => {
+                    let ty = Sp::call_site(Ty::Other);
+                    let kind = Sp::new(Kind::FromGlobal(ty), ident.span());
+                    self.set_kind(kind);
+                }
+
+                Subcommand(ident) => {
+                    let ty = Sp::call_site(Ty::Other);
+                    let kind = Sp::new(Kind::Subcommand(ty), ident.span());
+                    self.set_kind(kind);
+                }
+
+                ExternalSubcommand(ident) => {
+                    let kind = Sp::new(Kind::ExternalSubcommand, ident.span());
+                    self.set_kind(kind);
+                }
+
+                Flatten(ident) => {
+                    let kind = Sp::new(Kind::Flatten, ident.span());
+                    self.set_kind(kind);
+                }
+
+                Skip(ident, expr) => {
+                    let kind = Sp::new(Kind::Skip(expr), ident.span());
+                    self.set_kind(kind);
+                }
+
+                VerbatimDocComment(ident) => self.verbatim_doc_comment = Some(ident),
+
+                DefaultValueT(ident, expr) => {
+                    let ty = if let Some(ty) = self.ty.as_ref() {
+                        ty
+                    } else {
+                        abort!(
+                            ident,
+                            "#[clap(default_value_t)] (without an argument) can be used \
+                            only on field level";
+
+                            note = "see \
+                                https://github.com/clap-rs/clap/blob/master/examples/derive_ref/README.md#magic-attributes")
+                    };
+
+                    let val = if let Some(expr) = expr {
+                        quote!(#expr)
+                    } else {
+                        quote!(<#ty as ::std::default::Default>::default())
+                    };
+
+                    let val = if parsed.iter().any(|a| matches!(a, ArgEnum(_))) {
+                        quote_spanned!(ident.span()=> {
+                            {
+                                let val: #ty = #val;
+                                clap::ArgEnum::to_possible_value(&val).unwrap().get_name()
+                            }
+                        })
+                    } else {
+                        quote_spanned!(ident.span()=> {
+                            clap::lazy_static::lazy_static! {
+                                static ref DEFAULT_VALUE: &'static str = {
+                                    let val: #ty = #val;
+                                    let s = ::std::string::ToString::to_string(&val);
+                                    ::std::boxed::Box::leak(s.into_boxed_str())
+                                };
+                            }
+                            *DEFAULT_VALUE
+                        })
+                    };
+
+                    let raw_ident = Ident::new("default_value", ident.span());
+                    self.methods.push(Method::new(raw_ident, val));
+                }
+
+                DefaultValueOsT(ident, expr) => {
+                    let ty = if let Some(ty) = self.ty.as_ref() {
+                        ty
+                    } else {
+                        abort!(
+                            ident,
+                            "#[clap(default_value_os_t)] (without an argument) can be used \
+                            only on field level";
+
+                            note = "see \
+                                https://github.com/clap-rs/clap/blob/master/examples/derive_ref/README.md#magic-attributes")
+                    };
+
+                    let val = if let Some(expr) = expr {
+                        quote!(#expr)
+                    } else {
+                        quote!(<#ty as ::std::default::Default>::default())
+                    };
+
+                    let val = if parsed.iter().any(|a| matches!(a, ArgEnum(_))) {
+                        quote_spanned!(ident.span()=> {
+                            {
+                                let val: #ty = #val;
+                                clap::ArgEnum::to_possible_value(&val).unwrap().get_name()
+                            }
+                        })
+                    } else {
+                        quote_spanned!(ident.span()=> {
+                            clap::lazy_static::lazy_static! {
+                                static ref DEFAULT_VALUE: &'static ::std::ffi::OsStr = {
+                                    let val: #ty = #val;
+                                    let s: ::std::ffi::OsString = val.into();
+                                    ::std::boxed::Box::leak(s.into_boxed_os_str())
+                                };
+                            }
+                            *DEFAULT_VALUE
+                        })
+                    };
+
+                    let raw_ident = Ident::new("default_value_os", ident.span());
+                    self.methods.push(Method::new(raw_ident, val));
+                }
+
+                NextDisplayOrder(ident, expr) => {
+                    self.next_display_order = Some(Method::new(ident, quote!(#expr)));
+                }
+
+                HelpHeading(ident, expr) => {
+                    self.help_heading = Some(Method::new(ident, quote!(#expr)));
+                }
+                NextHelpHeading(ident, expr) => {
+                    self.next_help_heading = Some(Method::new(ident, quote!(#expr)));
+                }
+
+                About(ident) => {
+                    if let Some(method) = Method::from_env(ident, "CARGO_PKG_DESCRIPTION") {
+                        self.methods.push(method);
+                    }
+                }
+
+                Author(ident) => {
+                    if let Some(method) = Method::from_env(ident, "CARGO_PKG_AUTHORS") {
+                        self.methods.push(method);
+                    }
+                }
+
+                Version(ident) => {
+                    if let Some(method) = Method::from_env(ident, "CARGO_PKG_VERSION") {
+                        self.methods.push(method);
+                    }
+                }
+
+                NameLitStr(name, lit) => {
+                    self.push_method(name, lit);
+                }
+
+                NameExpr(name, expr) => {
+                    self.push_method(name, expr);
+                }
+
+                MethodCall(name, args) => self.push_method(name, quote!(#(#args),*)),
+
+                RenameAll(_, casing_lit) => {
+                    self.casing = CasingStyle::from_lit(casing_lit);
+                }
+
+                RenameAllEnv(_, casing_lit) => {
+                    self.env_casing = CasingStyle::from_lit(casing_lit);
+                }
+
+                Parse(ident, spec) => {
+                    self.has_custom_parser = true;
+                    self.parser = Parser::from_spec(ident, spec);
+                }
+            }
+        }
+    }
+
+    fn push_doc_comment(&mut self, attrs: &[Attribute], name: &str) {
+        use syn::Lit::*;
+        use syn::Meta::*;
+
+        let comment_parts: Vec<_> = attrs
+            .iter()
+            .filter(|attr| attr.path.is_ident("doc"))
+            .filter_map(|attr| {
+                if let Ok(NameValue(MetaNameValue { lit: Str(s), .. })) = attr.parse_meta() {
+                    Some(s.value())
+                } else {
+                    // non #[doc = "..."] attributes are not our concern
+                    // we leave them for rustc to handle
+                    None
+                }
+            })
+            .collect();
+
+        self.doc_comment =
+            process_doc_comment(comment_parts, name, self.verbatim_doc_comment.is_none());
+    }
+
+    fn set_kind(&mut self, kind: Sp<Kind>) {
+        if let Kind::Arg(_) = *self.kind {
+            self.kind = kind;
+        } else {
+            abort!(
+                kind.span(),
+                "`subcommand`, `flatten`, `external_subcommand` and `skip` cannot be used together"
+            );
+        }
+    }
+
+    pub fn find_method(&self, name: &str) -> Option<&Method> {
+        self.methods.iter().find(|m| m.name == name)
+    }
+
+    pub fn find_default_method(&self) -> Option<&Method> {
+        self.methods
+            .iter()
+            .find(|m| m.name == "default_value" || m.name == "default_value_os")
+    }
+
+    /// generate methods from attributes on top of struct or enum
+    pub fn initial_top_level_methods(&self) -> TokenStream {
+        let next_display_order = self.next_display_order.as_ref().into_iter();
+        let next_help_heading = self.next_help_heading.as_ref().into_iter();
+        let help_heading = self.help_heading.as_ref().into_iter();
+        quote!(
+            #(#next_display_order)*
+            #(#next_help_heading)*
+            #(#help_heading)*
+        )
+    }
+
+    pub fn final_top_level_methods(&self) -> TokenStream {
+        let methods = &self.methods;
+        let doc_comment = &self.doc_comment;
+
+        quote!( #(#doc_comment)* #(#methods)*)
+    }
+
+    /// generate methods on top of a field
+    pub fn field_methods(&self, supports_long_help: bool) -> proc_macro2::TokenStream {
+        let methods = &self.methods;
+        let help_heading = self.help_heading.as_ref().into_iter();
+        match supports_long_help {
+            true => {
+                let doc_comment = &self.doc_comment;
+                quote!( #(#doc_comment)* #(#help_heading)* #(#methods)* )
+            }
+            false => {
+                let doc_comment = self
+                    .doc_comment
+                    .iter()
+                    .filter(|mth| mth.name != "long_help");
+                quote!( #(#doc_comment)* #(#help_heading)* #(#methods)* )
+            }
+        }
+    }
+
+    pub fn next_display_order(&self) -> TokenStream {
+        let next_display_order = self.next_display_order.as_ref().into_iter();
+        quote!( #(#next_display_order)* )
+    }
+
+    pub fn next_help_heading(&self) -> TokenStream {
+        let next_help_heading = self.next_help_heading.as_ref().into_iter();
+        let help_heading = self.help_heading.as_ref().into_iter();
+        quote!( #(#next_help_heading)*  #(#help_heading)* )
+    }
+
+    #[cfg(feature = "unstable-v4")]
+    pub fn id(&self) -> TokenStream {
+        self.name.clone().raw()
+    }
+
+    #[cfg(not(feature = "unstable-v4"))]
+    pub fn id(&self) -> TokenStream {
+        self.cased_name()
+    }
+
+    pub fn cased_name(&self) -> TokenStream {
+        self.name.clone().translate(*self.casing)
+    }
+
+    pub fn value_name(&self) -> TokenStream {
+        self.name.clone().translate(CasingStyle::ScreamingSnake)
+    }
+
+    pub fn parser(&self) -> &Sp<Parser> {
+        &self.parser
+    }
+
+    pub fn kind(&self) -> Sp<Kind> {
+        self.kind.clone()
+    }
+
+    pub fn is_enum(&self) -> bool {
+        self.is_enum
+    }
+
+    pub fn ignore_case(&self) -> TokenStream {
+        let method = self.find_method("ignore_case");
+
+        if let Some(method) = method {
+            method.args.clone()
+        } else {
+            quote! { false }
+        }
+    }
+
+    pub fn casing(&self) -> Sp<CasingStyle> {
+        self.casing.clone()
+    }
+
+    pub fn env_casing(&self) -> Sp<CasingStyle> {
+        self.env_casing.clone()
+    }
+
+    pub fn is_positional(&self) -> bool {
+        self.methods
+            .iter()
+            .all(|m| m.name != "long" && m.name != "short")
+    }
+
+    pub fn has_explicit_methods(&self) -> bool {
+        self.methods
+            .iter()
+            .any(|m| m.name != "help" && m.name != "long_help")
+    }
+}
+
+#[allow(clippy::large_enum_variant)]
+#[derive(Clone)]
+pub enum Kind {
+    Arg(Sp<Ty>),
+    FromGlobal(Sp<Ty>),
+    Subcommand(Sp<Ty>),
+    Flatten,
+    Skip(Option<Expr>),
+    ExternalSubcommand,
+}
+
+#[derive(Clone)]
+pub struct Method {
+    name: Ident,
+    args: TokenStream,
+}
+
+impl Method {
+    pub fn new(name: Ident, args: TokenStream) -> Self {
+        Method { name, args }
+    }
+
+    fn from_env(ident: Ident, env_var: &str) -> Option<Self> {
+        let mut lit = match env::var(env_var) {
+            Ok(val) => {
+                if val.is_empty() {
+                    return None;
+                }
+                LitStr::new(&val, ident.span())
+            }
+            Err(_) => {
+                abort!(ident,
+                    "cannot derive `{}` from Cargo.toml", ident;
+                    note = "`{}` environment variable is not set", env_var;
+                    help = "use `{} = \"...\"` to set {} manually", ident, ident;
+                );
+            }
+        };
+
+        if ident == "author" {
+            let edited = process_author_str(&lit.value());
+            lit = LitStr::new(&edited, lit.span());
+        }
+
+        Some(Method::new(ident, quote!(#lit)))
+    }
+}
+
+impl ToTokens for Method {
+    fn to_tokens(&self, ts: &mut proc_macro2::TokenStream) {
+        let Method { ref name, ref args } = self;
+
+        let tokens = quote!( .#name(#args) );
+
+        tokens.to_tokens(ts);
+    }
+}
+
+/// replace all `:` with `, ` when not inside the `<>`
+///
+/// `"author1:author2:author3" => "author1, author2, author3"`
+/// `"author1 <http://website1.com>:author2" => "author1 <http://website1.com>, author2"
+fn process_author_str(author: &str) -> String {
+    let mut res = String::with_capacity(author.len());
+    let mut inside_angle_braces = 0usize;
+
+    for ch in author.chars() {
+        if inside_angle_braces > 0 && ch == '>' {
+            inside_angle_braces -= 1;
+            res.push(ch);
+        } else if ch == '<' {
+            inside_angle_braces += 1;
+            res.push(ch);
+        } else if inside_angle_braces == 0 && ch == ':' {
+            res.push_str(", ");
+        } else {
+            res.push(ch);
+        }
+    }
+
+    res
+}
+
+#[derive(Clone)]
+pub struct Parser {
+    pub kind: Sp<ParserKind>,
+    pub func: TokenStream,
+}
+
+impl Parser {
+    fn default_spanned(span: Span) -> Sp<Self> {
+        let kind = Sp::new(ParserKind::TryFromStr, span);
+        let func = quote_spanned!(span=> ::std::str::FromStr::from_str);
+        Sp::new(Parser { kind, func }, span)
+    }
+
+    fn from_spec(parse_ident: Ident, spec: ParserSpec) -> Sp<Self> {
+        use self::ParserKind::*;
+
+        let kind = match &*spec.kind.to_string() {
+            "from_str" => FromStr,
+            "try_from_str" => TryFromStr,
+            "from_os_str" => FromOsStr,
+            "try_from_os_str" => TryFromOsStr,
+            "from_occurrences" => FromOccurrences,
+            "from_flag" => FromFlag,
+            s => abort!(spec.kind.span(), "unsupported parser `{}`", s),
+        };
+
+        let func = match spec.parse_func {
+            None => match kind {
+                FromStr | FromOsStr => {
+                    quote_spanned!(spec.kind.span()=> ::std::convert::From::from)
+                }
+                TryFromStr => quote_spanned!(spec.kind.span()=> ::std::str::FromStr::from_str),
+                TryFromOsStr => abort!(
+                    spec.kind.span(),
+                    "you must set parser for `try_from_os_str` explicitly"
+                ),
+                FromOccurrences => quote_spanned!(spec.kind.span()=> { |v| v as _ }),
+                FromFlag => quote_spanned!(spec.kind.span()=> ::std::convert::From::from),
+            },
+
+            Some(func) => match func {
+                Expr::Path(_) => quote!(#func),
+                _ => abort!(func, "`parse` argument must be a function path"),
+            },
+        };
+
+        let kind = Sp::new(kind, spec.kind.span());
+        let parser = Parser { kind, func };
+        Sp::new(parser, parse_ident.span())
+    }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum ParserKind {
+    FromStr,
+    TryFromStr,
+    FromOsStr,
+    TryFromOsStr,
+    FromOccurrences,
+    FromFlag,
+}
+
+/// Defines the casing for the attributes long representation.
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum CasingStyle {
+    /// Indicate word boundaries with uppercase letter, excluding the first word.
+    Camel,
+    /// Keep all letters lowercase and indicate word boundaries with hyphens.
+    Kebab,
+    /// Indicate word boundaries with uppercase letter, including the first word.
+    Pascal,
+    /// Keep all letters uppercase and indicate word boundaries with underscores.
+    ScreamingSnake,
+    /// Keep all letters lowercase and indicate word boundaries with underscores.
+    Snake,
+    /// Keep all letters lowercase and remove word boundaries.
+    Lower,
+    /// Keep all letters uppercase and remove word boundaries.
+    Upper,
+    /// Use the original attribute name defined in the code.
+    Verbatim,
+}
+
+impl CasingStyle {
+    fn from_lit(name: LitStr) -> Sp<Self> {
+        use self::CasingStyle::*;
+
+        let normalized = name.value().to_upper_camel_case().to_lowercase();
+        let cs = |kind| Sp::new(kind, name.span());
+
+        match normalized.as_ref() {
+            "camel" | "camelcase" => cs(Camel),
+            "kebab" | "kebabcase" => cs(Kebab),
+            "pascal" | "pascalcase" => cs(Pascal),
+            "screamingsnake" | "screamingsnakecase" => cs(ScreamingSnake),
+            "snake" | "snakecase" => cs(Snake),
+            "lower" | "lowercase" => cs(Lower),
+            "upper" | "uppercase" => cs(Upper),
+            "verbatim" | "verbatimcase" => cs(Verbatim),
+            s => abort!(name, "unsupported casing: `{}`", s),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub enum Name {
+    Derived(Ident),
+    Assigned(TokenStream),
+}
+
+impl Name {
+    #[cfg(feature = "unstable-v4")]
+    pub fn raw(self) -> TokenStream {
+        match self {
+            Name::Assigned(tokens) => tokens,
+            Name::Derived(ident) => {
+                let s = ident.unraw().to_string();
+                quote_spanned!(ident.span()=> #s)
+            }
+        }
+    }
+
+    pub fn translate(self, style: CasingStyle) -> TokenStream {
+        use CasingStyle::*;
+
+        match self {
+            Name::Assigned(tokens) => tokens,
+            Name::Derived(ident) => {
+                let s = ident.unraw().to_string();
+                let s = match style {
+                    Pascal => s.to_upper_camel_case(),
+                    Kebab => s.to_kebab_case(),
+                    Camel => s.to_lower_camel_case(),
+                    ScreamingSnake => s.to_shouty_snake_case(),
+                    Snake => s.to_snake_case(),
+                    Lower => s.to_snake_case().replace('_', ""),
+                    Upper => s.to_shouty_snake_case().replace('_', ""),
+                    Verbatim => s,
+                };
+                quote_spanned!(ident.span()=> #s)
+            }
+        }
+    }
+
+    pub fn translate_char(self, style: CasingStyle) -> TokenStream {
+        use CasingStyle::*;
+
+        match self {
+            Name::Assigned(tokens) => quote!( (#tokens).chars().next().unwrap() ),
+            Name::Derived(ident) => {
+                let s = ident.unraw().to_string();
+                let s = match style {
+                    Pascal => s.to_upper_camel_case(),
+                    Kebab => s.to_kebab_case(),
+                    Camel => s.to_lower_camel_case(),
+                    ScreamingSnake => s.to_shouty_snake_case(),
+                    Snake => s.to_snake_case(),
+                    Lower => s.to_snake_case(),
+                    Upper => s.to_shouty_snake_case(),
+                    Verbatim => s,
+                };
+
+                let s = s.chars().next().unwrap();
+                quote_spanned!(ident.span()=> #s)
+            }
+        }
+    }
+}