diff options
Diffstat (limited to 'vendor/serde_derive/src/internals/check.rs')
| -rw-r--r-- | vendor/serde_derive/src/internals/check.rs | 477 |
1 files changed, 477 insertions, 0 deletions
diff --git a/vendor/serde_derive/src/internals/check.rs b/vendor/serde_derive/src/internals/check.rs new file mode 100644 index 0000000..52b0f37 --- /dev/null +++ b/vendor/serde_derive/src/internals/check.rs @@ -0,0 +1,477 @@ +use crate::internals::ast::{Container, Data, Field, Style}; +use crate::internals::attr::{Default, Identifier, TagType}; +use crate::internals::{ungroup, Ctxt, Derive}; +use syn::{Member, Type}; + +// Cross-cutting checks that require looking at more than a single attrs object. +// Simpler checks should happen when parsing and building the attrs. +pub fn check(cx: &Ctxt, cont: &mut Container, derive: Derive) { + check_default_on_tuple(cx, cont); + check_remote_generic(cx, cont); + check_getter(cx, cont); + check_flatten(cx, cont); + check_identifier(cx, cont); + check_variant_skip_attrs(cx, cont); + check_internal_tag_field_name_conflict(cx, cont); + check_adjacent_tag_conflict(cx, cont); + check_transparent(cx, cont, derive); + check_from_and_try_from(cx, cont); +} + +// If some field of a tuple struct is marked #[serde(default)] then all fields +// after it must also be marked with that attribute, or the struct must have a +// container-level serde(default) attribute. A field's default value is only +// used for tuple fields if the sequence is exhausted at that point; that means +// all subsequent fields will fail to deserialize if they don't have their own +// default. +fn check_default_on_tuple(cx: &Ctxt, cont: &Container) { + if let Default::None = cont.attrs.default() { + if let Data::Struct(Style::Tuple, fields) = &cont.data { + let mut first_default_index = None; + for (i, field) in fields.iter().enumerate() { + // Skipped fields automatically get the #[serde(default)] + // attribute. We are interested only on non-skipped fields here. + if field.attrs.skip_deserializing() { + continue; + } + if let Default::None = field.attrs.default() { + if let Some(first) = first_default_index { + cx.error_spanned_by( + field.ty, + format!("field must have #[serde(default)] because previous field {} has #[serde(default)]", first), + ); + } + continue; + } + if first_default_index.is_none() { + first_default_index = Some(i); + } + } + } + } +} + +// Remote derive definition type must have either all of the generics of the +// remote type: +// +// #[serde(remote = "Generic")] +// struct Generic<T> {…} +// +// or none of them, i.e. defining impls for one concrete instantiation of the +// remote type only: +// +// #[serde(remote = "Generic<T>")] +// struct ConcreteDef {…} +// +fn check_remote_generic(cx: &Ctxt, cont: &Container) { + if let Some(remote) = cont.attrs.remote() { + let local_has_generic = !cont.generics.params.is_empty(); + let remote_has_generic = !remote.segments.last().unwrap().arguments.is_none(); + if local_has_generic && remote_has_generic { + cx.error_spanned_by(remote, "remove generic parameters from this path"); + } + } +} + +// Getters are only allowed inside structs (not enums) with the `remote` +// attribute. +fn check_getter(cx: &Ctxt, cont: &Container) { + match cont.data { + Data::Enum(_) => { + if cont.data.has_getter() { + cx.error_spanned_by( + cont.original, + "#[serde(getter = \"...\")] is not allowed in an enum", + ); + } + } + Data::Struct(_, _) => { + if cont.data.has_getter() && cont.attrs.remote().is_none() { + cx.error_spanned_by( + cont.original, + "#[serde(getter = \"...\")] can only be used in structs that have #[serde(remote = \"...\")]", + ); + } + } + } +} + +// Flattening has some restrictions we can test. +fn check_flatten(cx: &Ctxt, cont: &Container) { + match &cont.data { + Data::Enum(variants) => { + for variant in variants { + for field in &variant.fields { + check_flatten_field(cx, variant.style, field); + } + } + } + Data::Struct(style, fields) => { + for field in fields { + check_flatten_field(cx, *style, field); + } + } + } +} + +fn check_flatten_field(cx: &Ctxt, style: Style, field: &Field) { + if !field.attrs.flatten() { + return; + } + match style { + Style::Tuple => { + cx.error_spanned_by( + field.original, + "#[serde(flatten)] cannot be used on tuple structs", + ); + } + Style::Newtype => { + cx.error_spanned_by( + field.original, + "#[serde(flatten)] cannot be used on newtype structs", + ); + } + _ => {} + } +} + +// The `other` attribute must be used at most once and it must be the last +// variant of an enum. +// +// Inside a `variant_identifier` all variants must be unit variants. Inside a +// `field_identifier` all but possibly one variant must be unit variants. The +// last variant may be a newtype variant which is an implicit "other" case. +fn check_identifier(cx: &Ctxt, cont: &Container) { + let variants = match &cont.data { + Data::Enum(variants) => variants, + Data::Struct(_, _) => return, + }; + + for (i, variant) in variants.iter().enumerate() { + match ( + variant.style, + cont.attrs.identifier(), + variant.attrs.other(), + cont.attrs.tag(), + ) { + // The `other` attribute may not be used in a variant_identifier. + (_, Identifier::Variant, true, _) => { + cx.error_spanned_by( + variant.original, + "#[serde(other)] may not be used on a variant identifier", + ); + } + + // Variant with `other` attribute cannot appear in untagged enum + (_, Identifier::No, true, &TagType::None) => { + cx.error_spanned_by( + variant.original, + "#[serde(other)] cannot appear on untagged enum", + ); + } + + // Variant with `other` attribute must be the last one. + (Style::Unit, Identifier::Field, true, _) | (Style::Unit, Identifier::No, true, _) => { + if i < variants.len() - 1 { + cx.error_spanned_by( + variant.original, + "#[serde(other)] must be on the last variant", + ); + } + } + + // Variant with `other` attribute must be a unit variant. + (_, Identifier::Field, true, _) | (_, Identifier::No, true, _) => { + cx.error_spanned_by( + variant.original, + "#[serde(other)] must be on a unit variant", + ); + } + + // Any sort of variant is allowed if this is not an identifier. + (_, Identifier::No, false, _) => {} + + // Unit variant without `other` attribute is always fine. + (Style::Unit, _, false, _) => {} + + // The last field is allowed to be a newtype catch-all. + (Style::Newtype, Identifier::Field, false, _) => { + if i < variants.len() - 1 { + cx.error_spanned_by( + variant.original, + format!("`{}` must be the last variant", variant.ident), + ); + } + } + + (_, Identifier::Field, false, _) => { + cx.error_spanned_by( + variant.original, + "#[serde(field_identifier)] may only contain unit variants", + ); + } + + (_, Identifier::Variant, false, _) => { + cx.error_spanned_by( + variant.original, + "#[serde(variant_identifier)] may only contain unit variants", + ); + } + } + } +} + +// Skip-(de)serializing attributes are not allowed on variants marked +// (de)serialize_with. +fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) { + let variants = match &cont.data { + Data::Enum(variants) => variants, + Data::Struct(_, _) => return, + }; + + for variant in variants { + if variant.attrs.serialize_with().is_some() { + if variant.attrs.skip_serializing() { + cx.error_spanned_by( + variant.original, + format!( + "variant `{}` cannot have both #[serde(serialize_with)] and #[serde(skip_serializing)]", + variant.ident + ), + ); + } + + for field in &variant.fields { + let member = member_message(&field.member); + + if field.attrs.skip_serializing() { + cx.error_spanned_by( + variant.original, + format!( + "variant `{}` cannot have both #[serde(serialize_with)] and a field {} marked with #[serde(skip_serializing)]", + variant.ident, member + ), + ); + } + + if field.attrs.skip_serializing_if().is_some() { + cx.error_spanned_by( + variant.original, + format!( + "variant `{}` cannot have both #[serde(serialize_with)] and a field {} marked with #[serde(skip_serializing_if)]", + variant.ident, member + ), + ); + } + } + } + + if variant.attrs.deserialize_with().is_some() { + if variant.attrs.skip_deserializing() { + cx.error_spanned_by( + variant.original, + format!( + "variant `{}` cannot have both #[serde(deserialize_with)] and #[serde(skip_deserializing)]", + variant.ident + ), + ); + } + + for field in &variant.fields { + if field.attrs.skip_deserializing() { + let member = member_message(&field.member); + + cx.error_spanned_by( + variant.original, + format!( + "variant `{}` cannot have both #[serde(deserialize_with)] and a field {} marked with #[serde(skip_deserializing)]", + variant.ident, member + ), + ); + } + } + } + } +} + +// The tag of an internally-tagged struct variant must not be the same as either +// one of its fields, as this would result in duplicate keys in the serialized +// output and/or ambiguity in the to-be-deserialized input. +fn check_internal_tag_field_name_conflict(cx: &Ctxt, cont: &Container) { + let variants = match &cont.data { + Data::Enum(variants) => variants, + Data::Struct(_, _) => return, + }; + + let tag = match cont.attrs.tag() { + TagType::Internal { tag } => tag.as_str(), + TagType::External | TagType::Adjacent { .. } | TagType::None => return, + }; + + let diagnose_conflict = || { + cx.error_spanned_by( + cont.original, + format!("variant field name `{}` conflicts with internal tag", tag), + ); + }; + + for variant in variants { + match variant.style { + Style::Struct => { + if variant.attrs.untagged() { + continue; + } + for field in &variant.fields { + let check_ser = + !(field.attrs.skip_serializing() || variant.attrs.skip_serializing()); + let check_de = + !(field.attrs.skip_deserializing() || variant.attrs.skip_deserializing()); + let name = field.attrs.name(); + let ser_name = name.serialize_name(); + + if check_ser && ser_name == tag { + diagnose_conflict(); + return; + } + + for de_name in field.attrs.aliases() { + if check_de && de_name == tag { + diagnose_conflict(); + return; + } + } + } + } + Style::Unit | Style::Newtype | Style::Tuple => {} + } + } +} + +// In the case of adjacently-tagged enums, the type and the contents tag must +// differ, for the same reason. +fn check_adjacent_tag_conflict(cx: &Ctxt, cont: &Container) { + let (type_tag, content_tag) = match cont.attrs.tag() { + TagType::Adjacent { tag, content } => (tag, content), + TagType::Internal { .. } | TagType::External | TagType::None => return, + }; + + if type_tag == content_tag { + cx.error_spanned_by( + cont.original, + format!( + "enum tags `{}` for type and content conflict with each other", + type_tag + ), + ); + } +} + +// Enums and unit structs cannot be transparent. +fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) { + if !cont.attrs.transparent() { + return; + } + + if cont.attrs.type_from().is_some() { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] is not allowed with #[serde(from = \"...\")]", + ); + } + + if cont.attrs.type_try_from().is_some() { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] is not allowed with #[serde(try_from = \"...\")]", + ); + } + + if cont.attrs.type_into().is_some() { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] is not allowed with #[serde(into = \"...\")]", + ); + } + + let fields = match &mut cont.data { + Data::Enum(_) => { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] is not allowed on an enum", + ); + return; + } + Data::Struct(Style::Unit, _) => { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] is not allowed on a unit struct", + ); + return; + } + Data::Struct(_, fields) => fields, + }; + + let mut transparent_field = None; + + for field in fields { + if allow_transparent(field, derive) { + if transparent_field.is_some() { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] requires struct to have at most one transparent field", + ); + return; + } + transparent_field = Some(field); + } + } + + match transparent_field { + Some(transparent_field) => transparent_field.attrs.mark_transparent(), + None => match derive { + Derive::Serialize => { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] requires at least one field that is not skipped", + ); + } + Derive::Deserialize => { + cx.error_spanned_by( + cont.original, + "#[serde(transparent)] requires at least one field that is neither skipped nor has a default", + ); + } + }, + } +} + +fn member_message(member: &Member) -> String { + match member { + Member::Named(ident) => format!("`{}`", ident), + Member::Unnamed(i) => format!("#{}", i.index), + } +} + +fn allow_transparent(field: &Field, derive: Derive) -> bool { + if let Type::Path(ty) = ungroup(field.ty) { + if let Some(seg) = ty.path.segments.last() { + if seg.ident == "PhantomData" { + return false; + } + } + } + + match derive { + Derive::Serialize => !field.attrs.skip_serializing(), + Derive::Deserialize => !field.attrs.skip_deserializing() && field.attrs.default().is_none(), + } +} + +fn check_from_and_try_from(cx: &Ctxt, cont: &mut Container) { + if cont.attrs.type_from().is_some() && cont.attrs.type_try_from().is_some() { + cx.error_spanned_by( + cont.original, + "#[serde(from = \"...\")] and #[serde(try_from = \"...\")] conflict with each other", + ); + } +} |