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Migrate out from proc macro error (#920)
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Implement `Result<T, E>` based proc macro error handling instead of out
of fashion `proc_macro_error` that still is in _syn_ `1.0`. This allows
us to remove the need for `proc_macro_error` crate and makes our
dependency tree leaner.

The error handling is implemented with custom `ToTokensDiagnostics` trait
that is used instead of the `ToTokens` when there is a possibility for
error. Error is passed up in the call stack via `Diagnostics` struct
that converts to compile error token stream at root of the macro call.

The result based approach is the recommended way of handling compile
errors in proc macros.

Resolves #854
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@juhaku
juhaku committed May 14, 2024
1 parent 272ceb8 commit f03e7d5
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Showing 20 changed files with 1,725 additions and 1,117 deletions.
1 change: 0 additions & 1 deletion utoipa-gen/Cargo.toml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@ proc-macro = true
proc-macro2 = "1.0"
syn = { version = "2.0", features = ["full", "extra-traits"] }
quote = "1.0"
proc-macro-error = "1.0"
regex = { version = "1.7", optional = true }
uuid = { version = "1", features = ["serde"], optional = true }
ulid = { version = "1", optional = true, default-features = false }
Expand Down
257 changes: 151 additions & 106 deletions utoipa-gen/src/component.rs
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,14 @@
use std::borrow::Cow;

use proc_macro2::{Ident, Span, TokenStream};
use proc_macro_error::{abort, abort_call_site};
use quote::{quote, quote_spanned, ToTokens};
use syn::spanned::Spanned;
use syn::{Attribute, GenericArgument, Path, PathArguments, PathSegment, Type, TypePath};

use crate::doc_comment::CommentAttributes;
use crate::schema_type::SchemaFormat;
use crate::{schema_type::SchemaType, Deprecated};
use crate::{Diagnostics, OptionExt};

use self::features::{
pop_feature, Feature, FeaturesExt, IsInline, Minimum, Nullable, ToTokensExt, Validatable,
Expand Down Expand Up @@ -104,27 +104,31 @@ pub struct TypeTree<'t> {
}

impl<'t> TypeTree<'t> {
pub fn from_type(ty: &'t Type) -> TypeTree<'t> {
Self::convert_types(Self::get_type_tree_values(ty))
.next()
.expect("TypeTree from type should have one TypeTree parent")
pub fn from_type(ty: &'t Type) -> Result<TypeTree<'t>, Diagnostics> {
Self::convert_types(Self::get_type_tree_values(ty)?).map(|mut type_tree| {
type_tree
.next()
.expect("TypeTree from type should have one TypeTree parent")
})
}

fn get_type_tree_values(ty: &'t Type) -> Vec<TypeTreeValue> {
match ty {
fn get_type_tree_values(ty: &'t Type) -> Result<Vec<TypeTreeValue>, Diagnostics> {
let type_tree_values = match ty {
Type::Path(path) => {
vec![TypeTreeValue::TypePath(path)]
},
Type::Reference(reference) => Self::get_type_tree_values(reference.elem.as_ref()),
Type::Reference(reference) => Self::get_type_tree_values(reference.elem.as_ref())?,
Type::Tuple(tuple) => {
// Detect unit type ()
if tuple.elems.is_empty() { return vec![TypeTreeValue::UnitType] }

vec![TypeTreeValue::Tuple(tuple.elems.iter().flat_map(Self::get_type_tree_values).collect(), tuple.span())]
if tuple.elems.is_empty() { return Ok(vec![TypeTreeValue::UnitType]) }
vec![TypeTreeValue::Tuple(
tuple.elems.iter().map(Self::get_type_tree_values).collect::<Result<Vec<_>, Diagnostics>>()?.into_iter().flatten().collect(),
tuple.span()
)]
},
Type::Group(group) => Self::get_type_tree_values(group.elem.as_ref()),
Type::Slice(slice) => vec![TypeTreeValue::Array(Self::get_type_tree_values(&slice.elem), slice.bracket_token.span.join())],
Type::Array(array) => vec![TypeTreeValue::Array(Self::get_type_tree_values(&array.elem), array.bracket_token.span.join())],
Type::Group(group) => Self::get_type_tree_values(group.elem.as_ref())?,
Type::Slice(slice) => vec![TypeTreeValue::Array(Self::get_type_tree_values(&slice.elem)?, slice.bracket_token.span.join())],
Type::Array(array) => vec![TypeTreeValue::Array(Self::get_type_tree_values(&array.elem)?, array.bracket_token.span.join())],
Type::TraitObject(trait_object) => {
trait_object
.bounds
Expand All @@ -139,68 +143,83 @@ impl<'t> TypeTree<'t> {
})
.map(|path| vec![TypeTreeValue::Path(path)]).unwrap_or_else(Vec::new)
}
_ => abort_call_site!(
"unexpected type in component part get type path, expected one of: Path, Tuple, Reference, Group, Array, Slice, TraitObject"
),
}
unexpected => return Err(Diagnostics::with_span(unexpected.span(), "unexpected type in component part get type path, expected one of: Path, Tuple, Reference, Group, Array, Slice, TraitObject")),
};

Ok(type_tree_values)
}

fn convert_types(paths: Vec<TypeTreeValue<'t>>) -> impl Iterator<Item = TypeTree<'t>> {
paths.into_iter().map(|value| {
let path = match value {
TypeTreeValue::TypePath(type_path) => &type_path.path,
TypeTreeValue::Path(path) => path,
TypeTreeValue::Array(value, span) => {
let array: Path = Ident::new("Array", span).into();
return TypeTree {
path: Some(Cow::Owned(array)),
span: Some(span),
value_type: ValueType::Object,
generic_type: Some(GenericType::Vec),
children: Some(Self::convert_types(value).collect()),
};
}
TypeTreeValue::Tuple(tuple, span) => {
return TypeTree {
path: None,
span: Some(span),
children: Some(Self::convert_types(tuple).collect()),
generic_type: None,
value_type: ValueType::Tuple,
fn convert_types(
paths: Vec<TypeTreeValue<'t>>,
) -> Result<impl Iterator<Item = TypeTree<'t>>, Diagnostics> {
paths
.into_iter()
.map(|value| {
let path = match value {
TypeTreeValue::TypePath(type_path) => &type_path.path,
TypeTreeValue::Path(path) => path,
TypeTreeValue::Array(value, span) => {
let array: Path = Ident::new("Array", span).into();
return Ok(TypeTree {
path: Some(Cow::Owned(array)),
span: Some(span),
value_type: ValueType::Object,
generic_type: Some(GenericType::Vec),
children: Some(match Self::convert_types(value) {
Ok(converted_values) => converted_values.collect(),
Err(diagnostics) => return Err(diagnostics),
}),
});
}
}
TypeTreeValue::UnitType => {
return TypeTree {
path: None,
span: None,
value_type: ValueType::Tuple,
generic_type: None,
children: None,
TypeTreeValue::Tuple(tuple, span) => {
return Ok(TypeTree {
path: None,
span: Some(span),
children: Some(match Self::convert_types(tuple) {
Ok(converted_values) => converted_values.collect(),
Err(diagnostics) => return Err(diagnostics),
}),
generic_type: None,
value_type: ValueType::Tuple,
})
}
}
};
TypeTreeValue::UnitType => {
return Ok(TypeTree {
path: None,
span: None,
value_type: ValueType::Tuple,
generic_type: None,
children: None,
})
}
};

// there will always be one segment at least
let last_segment = path
.segments
.last()
.expect("at least one segment within path in TypeTree::convert_types");
// there will always be one segment at least
let last_segment = path
.segments
.last()
.expect("at least one segment within path in TypeTree::convert_types");

if last_segment.arguments.is_empty() {
Self::convert(path, last_segment)
} else {
Self::resolve_schema_type(path, last_segment)
}
})
if last_segment.arguments.is_empty() {
Ok(Self::convert(path, last_segment))
} else {
Self::resolve_schema_type(path, last_segment)
}
})
.collect::<Result<Vec<TypeTree<'t>>, Diagnostics>>()
.map(IntoIterator::into_iter)
}

// Only when type is a generic type we get to this function.
fn resolve_schema_type(path: &'t Path, last_segment: &'t PathSegment) -> TypeTree<'t> {
fn resolve_schema_type(
path: &'t Path,
last_segment: &'t PathSegment,
) -> Result<TypeTree<'t>, Diagnostics> {
if last_segment.arguments.is_empty() {
abort!(
last_segment.ident,
"expected at least one angle bracket argument but was 0"
);
return Err(Diagnostics::with_span(
last_segment.ident.span(),
"expected at least one angle bracket argument but was 0",
));
};

let mut generic_schema_type = Self::convert(path, last_segment);
Expand All @@ -227,26 +246,32 @@ impl<'t> TypeTree<'t> {
)
})
.map(|arg| match arg {
GenericArgument::Type(arg) => arg,
_ => abort!(
arg,
"expected generic argument type or generic argument lifetime"
),
}),
GenericArgument::Type(arg) => Ok(arg),
unexpected => Err(Diagnostics::with_span(
unexpected.span(),
"expected generic argument type or generic argument lifetime",
)),
})
.collect::<Result<Vec<_>, Diagnostics>>()?
.into_iter(),
)
}
}
_ => abort!(
last_segment.ident,
"unexpected path argument, expected angle bracketed path argument"
),
_ => {
return Err(Diagnostics::with_span(
last_segment.ident.span(),
"unexpected path argument, expected angle bracketed path argument",
))
}
};

generic_schema_type.children = generic_types
.as_mut()
.map(|generic_type| generic_type.map(Self::from_type).collect());
generic_schema_type.children = generic_types.as_mut().map_try(|generic_type| {
generic_type
.map(Self::from_type)
.collect::<Result<Vec<_>, Diagnostics>>()
})?;

generic_schema_type
Ok(generic_schema_type)
}

fn convert(path: &'t Path, last_segment: &'t PathSegment) -> TypeTree<'t> {
Expand Down Expand Up @@ -489,6 +514,12 @@ impl<'c> ComponentSchema {
let deprecated_stream = ComponentSchema::get_deprecated(deprecated);
let description_stream = ComponentSchema::get_description(description);

let match_diagnostics =
|result: Result<(), Diagnostics>, tokens: &mut TokenStream| match result {
Err(diagnostics) => diagnostics.to_tokens(tokens),
_ => (),
};

match type_tree.generic_type {
Some(GenericType::Map) => ComponentSchema::map_to_tokens(
&mut tokens,
Expand All @@ -498,38 +529,50 @@ impl<'c> ComponentSchema {
description_stream,
deprecated_stream,
),
Some(GenericType::Vec) => ComponentSchema::vec_to_tokens(
Some(GenericType::Vec) => match_diagnostics(
ComponentSchema::vec_to_tokens(
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
Some(GenericType::LinkedList) => ComponentSchema::vec_to_tokens(
Some(GenericType::LinkedList) => match_diagnostics(
ComponentSchema::vec_to_tokens(
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
Some(GenericType::Set) => ComponentSchema::vec_to_tokens(
Some(GenericType::Set) => match_diagnostics(
ComponentSchema::vec_to_tokens(
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
#[cfg(feature = "smallvec")]
Some(GenericType::SmallVec) => ComponentSchema::vec_to_tokens(
Some(GenericType::SmallVec) => match_diagnostics(
ComponentSchema::vec_to_tokens(
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
&mut tokens,
features,
type_tree,
object_name,
description_stream,
deprecated_stream,
),
Some(GenericType::Option) => {
// Add nullable feature if not already exists. Option is always nullable
Expand Down Expand Up @@ -658,9 +701,9 @@ impl<'c> ComponentSchema {
object_name: &str,
description_stream: Option<TokenStream>,
deprecated_stream: Option<TokenStream>,
) {
) -> Result<(), Diagnostics> {
let example = pop_feature!(features => Feature::Example(_));
let xml = features.extract_vec_xml_feature(type_tree);
let xml = features.extract_vec_xml_feature(type_tree)?;
let max_items = pop_feature!(features => Feature::MaxItems(_));
let min_items = pop_feature!(features => Feature::MinItems(_));
let nullable = pop_feature!(features => Feature::Nullable(_));
Expand Down Expand Up @@ -753,6 +796,8 @@ impl<'c> ComponentSchema {
example.to_tokens(tokens);
xml.to_tokens(tokens);
nullable.to_tokens(tokens);

Ok(())
}

fn non_generic_to_tokens(
Expand Down
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