Add SessionDiagnostic derive macro.
Co-authored-by: Oliver Scherer <github35764891676564198441@oli-obk.de>
This commit is contained in:
jumbatm
jumbatm
parent
6f1bbf5ee0
commit
93eaf15646
9 changed files with 1106 additions and 10 deletions
|
|
@ -1,3 +1,4 @@
|
|||
#![feature(proc_macro_diagnostic)]
|
||||
#![allow(rustc::default_hash_types)]
|
||||
#![recursion_limit = "128"]
|
||||
|
||||
|
|
@ -9,6 +10,7 @@ mod hash_stable;
|
|||
mod lift;
|
||||
mod query;
|
||||
mod serialize;
|
||||
mod session_diagnostic;
|
||||
mod symbols;
|
||||
mod type_foldable;
|
||||
|
||||
|
|
@ -36,3 +38,14 @@ decl_derive!([MetadataDecodable] => serialize::meta_decodable_derive);
|
|||
decl_derive!([MetadataEncodable] => serialize::meta_encodable_derive);
|
||||
decl_derive!([TypeFoldable, attributes(type_foldable)] => type_foldable::type_foldable_derive);
|
||||
decl_derive!([Lift, attributes(lift)] => lift::lift_derive);
|
||||
decl_derive!(
|
||||
[SessionDiagnostic, attributes(
|
||||
message,
|
||||
lint,
|
||||
error,
|
||||
label,
|
||||
suggestion,
|
||||
suggestion_short,
|
||||
suggestion_hidden,
|
||||
suggestion_verbose)] => session_diagnostic::session_diagnostic_derive
|
||||
);
|
||||
|
|
|
|||
665
compiler/rustc_macros/src/session_diagnostic.rs
Normal file
665
compiler/rustc_macros/src/session_diagnostic.rs
Normal file
|
|
@ -0,0 +1,665 @@
|
|||
#![deny(unused_must_use)]
|
||||
use quote::format_ident;
|
||||
use quote::quote;
|
||||
|
||||
use proc_macro::Diagnostic;
|
||||
use syn::spanned::Spanned;
|
||||
|
||||
use std::collections::{HashMap, HashSet};
|
||||
|
||||
/// Implements #[derive(SessionDiagnostic)], which allows for errors to be specified as a struct, independent
|
||||
/// from the actual diagnostics emitting code.
|
||||
/// ```ignore (pseudo-rust)
|
||||
/// # extern crate rustc_errors;
|
||||
/// # use rustc_errors::Applicability;
|
||||
/// # extern crate rustc_span;
|
||||
/// # use rustc_span::{symbol::Ident, Span};
|
||||
/// # extern crate rust_middle;
|
||||
/// # use rustc_middle::ty::Ty;
|
||||
/// #[derive(SessionDiagnostic)]
|
||||
/// #[code = "E0505"]
|
||||
/// #[error = "cannot move out of {name} because it is borrowed"]
|
||||
/// pub struct MoveOutOfBorrowError<'tcx> {
|
||||
/// pub name: Ident,
|
||||
/// pub ty: Ty<'tcx>,
|
||||
/// #[label = "cannot move out of borrow"]
|
||||
/// pub span: Span,
|
||||
/// #[label = "`{ty}` first borrowed here"]
|
||||
/// pub other_span: Span,
|
||||
/// #[suggestion(message = "consider cloning here", code = "{name}.clone()")]
|
||||
/// pub opt_sugg: Option<(Span, Applicability)>
|
||||
/// }
|
||||
/// ```
|
||||
/// Then, later, to emit the error:
|
||||
///
|
||||
/// ```ignore (pseudo-rust)
|
||||
/// sess.emit_err(MoveOutOfBorrowError {
|
||||
/// expected,
|
||||
/// actual,
|
||||
/// span,
|
||||
/// other_span,
|
||||
/// opt_sugg: Some(suggestion, Applicability::MachineApplicable),
|
||||
/// });
|
||||
/// ```
|
||||
pub fn session_diagnostic_derive(s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
|
||||
// Names for the diagnostic we build and the session we build it from.
|
||||
let diag = format_ident!("diag");
|
||||
let sess = format_ident!("sess");
|
||||
|
||||
SessionDiagnosticDerive::new(diag, sess, s).into_tokens()
|
||||
}
|
||||
|
||||
// Checks whether the type name of `ty` matches `name`.
|
||||
//
|
||||
// Given some struct at a::b::c::Foo, this will return true for c::Foo, b::c::Foo, or
|
||||
// a::b::c::Foo. This reasonably allows qualified names to be used in the macro.
|
||||
fn type_matches_path(ty: &syn::Type, name: &[&str]) -> bool {
|
||||
if let syn::Type::Path(ty) = ty {
|
||||
ty.path
|
||||
.segments
|
||||
.iter()
|
||||
.map(|s| s.ident.to_string())
|
||||
.rev()
|
||||
.zip(name.iter().rev())
|
||||
.all(|(x, y)| &x.as_str() == y)
|
||||
} else {
|
||||
false
|
||||
}
|
||||
}
|
||||
|
||||
/// The central struct for constructing the as_error method from an annotated struct.
|
||||
struct SessionDiagnosticDerive<'a> {
|
||||
structure: synstructure::Structure<'a>,
|
||||
builder: SessionDiagnosticDeriveBuilder<'a>,
|
||||
}
|
||||
|
||||
impl std::convert::From<syn::Error> for SessionDiagnosticDeriveError {
|
||||
fn from(e: syn::Error) -> Self {
|
||||
SessionDiagnosticDeriveError::SynError(e)
|
||||
}
|
||||
}
|
||||
|
||||
/// Equivalent to rustc:errors::diagnostic::DiagnosticId, except stores the quoted expression to
|
||||
/// initialise the code with.
|
||||
enum DiagnosticId {
|
||||
Error(proc_macro2::TokenStream),
|
||||
Lint(proc_macro2::TokenStream),
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
enum SessionDiagnosticDeriveError {
|
||||
SynError(syn::Error),
|
||||
ErrorHandled,
|
||||
}
|
||||
|
||||
impl SessionDiagnosticDeriveError {
|
||||
fn to_compile_error(self) -> proc_macro2::TokenStream {
|
||||
match self {
|
||||
SessionDiagnosticDeriveError::SynError(e) => e.to_compile_error(),
|
||||
SessionDiagnosticDeriveError::ErrorHandled => {
|
||||
// Return ! to avoid having to create a blank DiagnosticBuilder to return when an
|
||||
// error has already been emitted to the compiler.
|
||||
quote! {
|
||||
unreachable!()
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn span_err(span: impl proc_macro::MultiSpan, msg: &str) -> proc_macro::Diagnostic {
|
||||
Diagnostic::spanned(span, proc_macro::Level::Error, msg)
|
||||
}
|
||||
|
||||
/// For methods that return a Result<_, SessionDiagnosticDeriveError>: emit a diagnostic on
|
||||
/// span $span with msg $msg (and, optionally, perform additional decoration using the FnOnce
|
||||
/// passed in `diag`). Then, return Err(ErrorHandled).
|
||||
macro_rules! throw_span_err {
|
||||
($span:expr, $msg:expr) => {{ throw_span_err!($span, $msg, |diag| diag) }};
|
||||
($span:expr, $msg:expr, $f:expr) => {{
|
||||
return Err(_throw_span_err($span, $msg, $f));
|
||||
}};
|
||||
}
|
||||
|
||||
/// When possible, prefer using throw_span_err! over using this function directly. This only exists
|
||||
/// as a function to constrain `f` to an impl FnOnce.
|
||||
fn _throw_span_err(
|
||||
span: impl proc_macro::MultiSpan,
|
||||
msg: &str,
|
||||
f: impl FnOnce(proc_macro::Diagnostic) -> proc_macro::Diagnostic,
|
||||
) -> SessionDiagnosticDeriveError {
|
||||
let diag = span_err(span, msg);
|
||||
f(diag).emit();
|
||||
SessionDiagnosticDeriveError::ErrorHandled
|
||||
}
|
||||
|
||||
impl<'a> SessionDiagnosticDerive<'a> {
|
||||
fn new(diag: syn::Ident, sess: syn::Ident, structure: synstructure::Structure<'a>) -> Self {
|
||||
// Build the mapping of field names to fields. This allows attributes to peek values from
|
||||
// other fields.
|
||||
let mut fields_map = HashMap::new();
|
||||
|
||||
// Convenience bindings.
|
||||
let ast = structure.ast();
|
||||
|
||||
if let syn::Data::Struct(syn::DataStruct { fields, .. }) = &ast.data {
|
||||
for field in fields.iter() {
|
||||
if let Some(ident) = &field.ident {
|
||||
fields_map.insert(ident.to_string(), field);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Self {
|
||||
builder: SessionDiagnosticDeriveBuilder { diag, sess, fields: fields_map, kind: None },
|
||||
structure,
|
||||
}
|
||||
}
|
||||
fn into_tokens(self) -> proc_macro2::TokenStream {
|
||||
let SessionDiagnosticDerive { structure, mut builder } = self;
|
||||
|
||||
let ast = structure.ast();
|
||||
let attrs = &ast.attrs;
|
||||
|
||||
let implementation = {
|
||||
if let syn::Data::Struct(..) = ast.data {
|
||||
let preamble = {
|
||||
let preamble = attrs.iter().map(|attr| {
|
||||
builder
|
||||
.generate_structure_code(attr)
|
||||
.unwrap_or_else(|v| v.to_compile_error())
|
||||
});
|
||||
quote! {
|
||||
#(#preamble)*;
|
||||
}
|
||||
};
|
||||
|
||||
let body = structure.each(|field_binding| {
|
||||
let field = field_binding.ast();
|
||||
let result = field.attrs.iter().map(|attr| {
|
||||
builder
|
||||
.generate_field_code(
|
||||
attr,
|
||||
FieldInfo {
|
||||
vis: &field.vis,
|
||||
binding: field_binding,
|
||||
ty: &field.ty,
|
||||
span: &field.span(),
|
||||
},
|
||||
)
|
||||
.unwrap_or_else(|v| v.to_compile_error())
|
||||
});
|
||||
return quote! {
|
||||
#(#result);*
|
||||
};
|
||||
});
|
||||
// Finally, putting it altogether.
|
||||
match builder.kind {
|
||||
None => {
|
||||
span_err(ast.span().unwrap(), "`code` not specified")
|
||||
.help("use the [code = \"...\"] attribute to set this diagnostic's error code ")
|
||||
.emit();
|
||||
SessionDiagnosticDeriveError::ErrorHandled.to_compile_error()
|
||||
}
|
||||
Some((kind, _)) => match kind {
|
||||
DiagnosticId::Lint(_lint) => todo!(),
|
||||
DiagnosticId::Error(code) => {
|
||||
let (diag, sess) = (&builder.diag, &builder.sess);
|
||||
quote! {
|
||||
let mut #diag = #sess.struct_err_with_code("", rustc_errors::DiagnosticId::Error(#code));
|
||||
#preamble
|
||||
match self {
|
||||
#body
|
||||
}
|
||||
#diag
|
||||
}
|
||||
}
|
||||
},
|
||||
}
|
||||
} else {
|
||||
span_err(
|
||||
ast.span().unwrap(),
|
||||
"`#[derive(SessionDiagnostic)]` can only be used on structs",
|
||||
)
|
||||
.emit();
|
||||
SessionDiagnosticDeriveError::ErrorHandled.to_compile_error()
|
||||
}
|
||||
};
|
||||
|
||||
let sess = &builder.sess;
|
||||
structure.gen_impl(quote! {
|
||||
gen impl<'__session_diagnostic_sess> rustc_session::SessionDiagnostic<'__session_diagnostic_sess>
|
||||
for @Self
|
||||
{
|
||||
fn into_diagnostic(
|
||||
self,
|
||||
#sess: &'__session_diagnostic_sess rustc_session::Session
|
||||
) -> rustc_errors::DiagnosticBuilder<'__session_diagnostic_sess> {
|
||||
#implementation
|
||||
}
|
||||
}
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
/// Field information passed to the builder. Deliberately omits attrs to discourage the generate_*
|
||||
/// methods from walking the attributes themselves.
|
||||
struct FieldInfo<'a> {
|
||||
vis: &'a syn::Visibility,
|
||||
binding: &'a synstructure::BindingInfo<'a>,
|
||||
ty: &'a syn::Type,
|
||||
span: &'a proc_macro2::Span,
|
||||
}
|
||||
|
||||
/// Tracks persistent information required for building up the individual calls to diagnostic
|
||||
/// methods for the final generated method. This is a separate struct to SessionDerive only to be
|
||||
/// able to destructure and split self.builder and the self.structure up to avoid a double mut
|
||||
/// borrow later on.
|
||||
struct SessionDiagnosticDeriveBuilder<'a> {
|
||||
/// Name of the session parameter that's passed in to the as_error method.
|
||||
sess: syn::Ident,
|
||||
|
||||
/// Store a map of field name to its corresponding field. This is built on construction of the
|
||||
/// derive builder.
|
||||
fields: HashMap<String, &'a syn::Field>,
|
||||
|
||||
/// The identifier to use for the generated DiagnosticBuilder instance.
|
||||
diag: syn::Ident,
|
||||
|
||||
/// Whether this is a lint or an error. This dictates how the diag will be initialised. Span
|
||||
/// stores at what Span the kind was first set at (for error reporting purposes, if the kind
|
||||
/// was multiply specified).
|
||||
kind: Option<(DiagnosticId, proc_macro2::Span)>,
|
||||
}
|
||||
|
||||
impl<'a> SessionDiagnosticDeriveBuilder<'a> {
|
||||
fn generate_structure_code(
|
||||
&mut self,
|
||||
attr: &syn::Attribute,
|
||||
) -> Result<proc_macro2::TokenStream, SessionDiagnosticDeriveError> {
|
||||
Ok(match attr.parse_meta()? {
|
||||
syn::Meta::NameValue(syn::MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
|
||||
let formatted_str = self.build_format(&s.value(), attr.span());
|
||||
let name = attr.path.segments.last().unwrap().ident.to_string();
|
||||
let name = name.as_str();
|
||||
match name {
|
||||
"message" => {
|
||||
let diag = &self.diag;
|
||||
quote! {
|
||||
#diag.set_primary_message(#formatted_str);
|
||||
}
|
||||
}
|
||||
attr @ "error" | attr @ "lint" => {
|
||||
self.set_kind_once(
|
||||
if attr == "error" {
|
||||
DiagnosticId::Error(formatted_str)
|
||||
} else if attr == "lint" {
|
||||
DiagnosticId::Lint(formatted_str)
|
||||
} else {
|
||||
unreachable!()
|
||||
},
|
||||
s.span(),
|
||||
)?;
|
||||
// This attribute is only allowed to be applied once, and the attribute
|
||||
// will be set in the initialisation code.
|
||||
quote! {}
|
||||
}
|
||||
other => throw_span_err!(
|
||||
attr.span().unwrap(),
|
||||
&format!(
|
||||
"`#[{} = ...]` is not a valid SessionDiagnostic struct attribute",
|
||||
other
|
||||
)
|
||||
),
|
||||
}
|
||||
}
|
||||
_ => todo!("unhandled meta kind"),
|
||||
})
|
||||
}
|
||||
|
||||
#[must_use]
|
||||
fn set_kind_once(
|
||||
&mut self,
|
||||
kind: DiagnosticId,
|
||||
span: proc_macro2::Span,
|
||||
) -> Result<(), SessionDiagnosticDeriveError> {
|
||||
if self.kind.is_none() {
|
||||
self.kind = Some((kind, span));
|
||||
Ok(())
|
||||
} else {
|
||||
let kind_str = |kind: &DiagnosticId| match kind {
|
||||
DiagnosticId::Lint(..) => "lint",
|
||||
DiagnosticId::Error(..) => "error",
|
||||
};
|
||||
|
||||
let existing_kind = kind_str(&self.kind.as_ref().unwrap().0);
|
||||
let this_kind = kind_str(&kind);
|
||||
|
||||
let msg = if this_kind == existing_kind {
|
||||
format!("`{}` specified multiple times", existing_kind)
|
||||
} else {
|
||||
format!("`{}` specified when `{}` was already specified", this_kind, existing_kind)
|
||||
};
|
||||
throw_span_err!(span.unwrap(), &msg);
|
||||
}
|
||||
}
|
||||
|
||||
fn generate_field_code(
|
||||
&mut self,
|
||||
attr: &syn::Attribute,
|
||||
info: FieldInfo<'_>,
|
||||
) -> Result<proc_macro2::TokenStream, SessionDiagnosticDeriveError> {
|
||||
let field_binding = &info.binding.binding;
|
||||
|
||||
let option_ty = option_inner_ty(&info.ty);
|
||||
|
||||
let generated_code = self.generate_non_option_field_code(
|
||||
attr,
|
||||
FieldInfo {
|
||||
vis: info.vis,
|
||||
binding: info.binding,
|
||||
ty: option_ty.unwrap_or(&info.ty),
|
||||
span: info.span,
|
||||
},
|
||||
)?;
|
||||
Ok(if option_ty.is_none() {
|
||||
quote! { #generated_code }
|
||||
} else {
|
||||
quote! {
|
||||
if let Some(#field_binding) = #field_binding {
|
||||
#generated_code
|
||||
}
|
||||
}
|
||||
})
|
||||
}
|
||||
|
||||
fn generate_non_option_field_code(
|
||||
&mut self,
|
||||
attr: &syn::Attribute,
|
||||
info: FieldInfo<'_>,
|
||||
) -> Result<proc_macro2::TokenStream, SessionDiagnosticDeriveError> {
|
||||
let diag = &self.diag;
|
||||
let field_binding = &info.binding.binding;
|
||||
let name = attr.path.segments.last().unwrap().ident.to_string();
|
||||
let name = name.as_str();
|
||||
// At this point, we need to dispatch based on the attribute key + the
|
||||
// type.
|
||||
let meta = attr.parse_meta()?;
|
||||
Ok(match meta {
|
||||
syn::Meta::NameValue(syn::MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
|
||||
let formatted_str = self.build_format(&s.value(), attr.span());
|
||||
match name {
|
||||
"message" => {
|
||||
if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
|
||||
quote! {
|
||||
#diag.set_span(*#field_binding);
|
||||
#diag.set_primary_message(#formatted_str);
|
||||
}
|
||||
} else {
|
||||
throw_span_err!(
|
||||
attr.span().unwrap(),
|
||||
"the `#[message = \"...\"]` attribute can only be applied to fields of type Span"
|
||||
);
|
||||
}
|
||||
}
|
||||
"label" => {
|
||||
if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
|
||||
quote! {
|
||||
#diag.span_label(*#field_binding, #formatted_str);
|
||||
}
|
||||
} else {
|
||||
throw_span_err!(
|
||||
attr.span().unwrap(),
|
||||
"The `#[label = ...]` attribute can only be applied to fields of type Span"
|
||||
);
|
||||
}
|
||||
}
|
||||
other => throw_span_err!(
|
||||
attr.span().unwrap(),
|
||||
&format!(
|
||||
"`#[{} = ...]` is not a valid SessionDiagnostic field attribute",
|
||||
other
|
||||
)
|
||||
),
|
||||
}
|
||||
}
|
||||
syn::Meta::List(list) => {
|
||||
match list.path.segments.iter().last().unwrap().ident.to_string().as_str() {
|
||||
suggestion_kind @ "suggestion"
|
||||
| suggestion_kind @ "suggestion_short"
|
||||
| suggestion_kind @ "suggestion_hidden"
|
||||
| suggestion_kind @ "suggestion_verbose" => {
|
||||
// For suggest, we need to ensure we are running on a (Span,
|
||||
// Applicability) pair.
|
||||
let (span, applicability) = (|| match &info.ty {
|
||||
ty @ syn::Type::Path(..)
|
||||
if type_matches_path(ty, &["rustc_span", "Span"]) =>
|
||||
{
|
||||
let binding = &info.binding.binding;
|
||||
Ok((
|
||||
quote!(*#binding),
|
||||
quote!(rustc_errors::Applicability::Unspecified),
|
||||
))
|
||||
}
|
||||
syn::Type::Tuple(tup) => {
|
||||
let mut span_idx = None;
|
||||
let mut applicability_idx = None;
|
||||
for (idx, elem) in tup.elems.iter().enumerate() {
|
||||
if type_matches_path(elem, &["rustc_span", "Span"]) {
|
||||
if span_idx.is_none() {
|
||||
span_idx = Some(syn::Index::from(idx));
|
||||
} else {
|
||||
throw_span_err!(
|
||||
info.span.clone().unwrap(),
|
||||
"type of field annotated with `#[suggestion(...)]` contains more than one Span"
|
||||
);
|
||||
}
|
||||
} else if type_matches_path(
|
||||
elem,
|
||||
&["rustc_errors", "Applicability"],
|
||||
) {
|
||||
if applicability_idx.is_none() {
|
||||
applicability_idx = Some(syn::Index::from(idx));
|
||||
} else {
|
||||
throw_span_err!(
|
||||
info.span.clone().unwrap(),
|
||||
"type of field annotated with `#[suggestion(...)]` contains more than one Applicability"
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
if let Some(span_idx) = span_idx {
|
||||
let binding = &info.binding.binding;
|
||||
let span = quote!(#binding.#span_idx);
|
||||
let applicability = applicability_idx
|
||||
.map(
|
||||
|applicability_idx| quote!(#binding.#applicability_idx),
|
||||
)
|
||||
.unwrap_or(quote!(
|
||||
rustc_errors::Applicability::Unspecified
|
||||
));
|
||||
return Ok((span, applicability));
|
||||
}
|
||||
throw_span_err!(
|
||||
info.span.clone().unwrap(),
|
||||
"wrong types for suggestion",
|
||||
|diag| {
|
||||
diag.help("#[suggestion(...)] on a tuple field must be applied to fields of type (Span, Applicability)")
|
||||
}
|
||||
);
|
||||
}
|
||||
_ => throw_span_err!(
|
||||
info.span.clone().unwrap(),
|
||||
"wrong field type for suggestion",
|
||||
|diag| {
|
||||
diag.help("#[suggestion(...)] should be applied to fields of type Span or (Span, Applicability)")
|
||||
}
|
||||
),
|
||||
})()?;
|
||||
// Now read the key-value pairs.
|
||||
let mut msg = None;
|
||||
let mut code = None;
|
||||
|
||||
for arg in list.nested.iter() {
|
||||
if let syn::NestedMeta::Meta(syn::Meta::NameValue(arg_name_value)) = arg
|
||||
{
|
||||
if let syn::MetaNameValue { lit: syn::Lit::Str(s), .. } =
|
||||
arg_name_value
|
||||
{
|
||||
let name = arg_name_value
|
||||
.path
|
||||
.segments
|
||||
.last()
|
||||
.unwrap()
|
||||
.ident
|
||||
.to_string();
|
||||
let name = name.as_str();
|
||||
let formatted_str = self.build_format(&s.value(), arg.span());
|
||||
match name {
|
||||
"message" => {
|
||||
msg = Some(formatted_str);
|
||||
}
|
||||
"code" => {
|
||||
code = Some(formatted_str);
|
||||
}
|
||||
other => throw_span_err!(
|
||||
arg.span().unwrap(),
|
||||
&format!(
|
||||
"`{}` is not a valid key for `#[suggestion(...)]`",
|
||||
other
|
||||
)
|
||||
),
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
let msg = if let Some(msg) = msg {
|
||||
quote!(#msg.as_str())
|
||||
} else {
|
||||
throw_span_err!(
|
||||
list.span().unwrap(),
|
||||
"missing suggestion message",
|
||||
|diag| {
|
||||
diag.help("provide a suggestion message using #[suggestion(message = \"...\")]")
|
||||
}
|
||||
);
|
||||
};
|
||||
let code = code.unwrap_or_else(|| quote! { String::new() });
|
||||
// Now build it out:
|
||||
let suggestion_method = format_ident!("span_{}", suggestion_kind);
|
||||
quote! {
|
||||
#diag.#suggestion_method(#span, #msg, #code, #applicability);
|
||||
}
|
||||
}
|
||||
other => throw_span_err!(
|
||||
list.span().unwrap(),
|
||||
&format!("invalid annotation list `#[{}(...)]`", other)
|
||||
),
|
||||
}
|
||||
}
|
||||
_ => panic!("unhandled meta kind"),
|
||||
})
|
||||
}
|
||||
|
||||
/// In the strings in the attributes supplied to this macro, we want callers to be able to
|
||||
/// reference fields in the format string. Take this, for example:
|
||||
/// ```ignore (not-usage-example)
|
||||
/// struct Point {
|
||||
/// #[error = "Expected a point greater than ({x}, {y})"]
|
||||
/// x: i32,
|
||||
/// y: i32,
|
||||
/// }
|
||||
/// ```
|
||||
/// We want to automatically pick up that {x} refers `self.x` and {y} refers to `self.y`, then
|
||||
/// generate this call to format!:
|
||||
/// ```ignore (not-usage-example)
|
||||
/// format!("Expected a point greater than ({x}, {y})", x = self.x, y = self.y)
|
||||
/// ```
|
||||
/// This function builds the entire call to format!.
|
||||
fn build_format(&self, input: &String, span: proc_macro2::Span) -> proc_macro2::TokenStream {
|
||||
let mut referenced_fields: HashSet<String> = HashSet::new();
|
||||
|
||||
// At this point, we can start parsing the format string.
|
||||
let mut it = input.chars().peekable();
|
||||
// Once the start of a format string has been found, process the format string and spit out
|
||||
// the referenced fields. Leaves `it` sitting on the closing brace of the format string, so the
|
||||
// next call to `it.next()` retrieves the next character.
|
||||
while let Some(c) = it.next() {
|
||||
if c == '{' && *it.peek().unwrap_or(&'\0') != '{' {
|
||||
#[must_use]
|
||||
let mut eat_argument = || -> Option<String> {
|
||||
let mut result = String::new();
|
||||
// Format specifiers look like
|
||||
// format := '{' [ argument ] [ ':' format_spec ] '}' .
|
||||
// Therefore, we only need to eat until ':' or '}' to find the argument.
|
||||
while let Some(c) = it.next() {
|
||||
result.push(c);
|
||||
let next = *it.peek().unwrap_or(&'\0');
|
||||
if next == '}' {
|
||||
break;
|
||||
} else if next == ':' {
|
||||
// Eat the ':' character.
|
||||
assert_eq!(it.next().unwrap(), ':');
|
||||
break;
|
||||
}
|
||||
}
|
||||
// Eat until (and including) the matching '}'
|
||||
while it.next()? != '}' {
|
||||
continue;
|
||||
}
|
||||
Some(result)
|
||||
};
|
||||
|
||||
if let Some(referenced_field) = eat_argument() {
|
||||
referenced_fields.insert(referenced_field);
|
||||
}
|
||||
}
|
||||
}
|
||||
// At this point, `referenced_fields` contains a set of the unique fields that were
|
||||
// referenced in the format string. Generate the corresponding "x = self.x" format
|
||||
// string parameters:
|
||||
let args = referenced_fields.into_iter().map(|field: String| {
|
||||
let field_ident = format_ident!("{}", field);
|
||||
let value = if self.fields.contains_key(&field) {
|
||||
quote! {
|
||||
&self.#field_ident
|
||||
}
|
||||
} else {
|
||||
// This field doesn't exist. Emit a diagnostic.
|
||||
Diagnostic::spanned(
|
||||
span.unwrap(),
|
||||
proc_macro::Level::Error,
|
||||
format!("`{}` doesn't refer to a field on this type", field),
|
||||
)
|
||||
.emit();
|
||||
quote! {
|
||||
"{#field}"
|
||||
}
|
||||
};
|
||||
quote! {
|
||||
#field_ident = #value
|
||||
}
|
||||
});
|
||||
quote! {
|
||||
format!(#input #(,#args)*)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// If `ty` is an Option, returns Some(inner type). Else, returns None.
|
||||
fn option_inner_ty(ty: &syn::Type) -> Option<&syn::Type> {
|
||||
if type_matches_path(ty, &["std", "option", "Option"]) {
|
||||
if let syn::Type::Path(ty_path) = ty {
|
||||
let path = &ty_path.path;
|
||||
let ty = path.segments.iter().last().unwrap();
|
||||
if let syn::PathArguments::AngleBracketed(bracketed) = &ty.arguments {
|
||||
if bracketed.args.len() == 1 {
|
||||
if let syn::GenericArgument::Type(ty) = &bracketed.args[0] {
|
||||
return Some(ty);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
None
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue