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Implement #[implicit] to automatically generate fields using the new ImplicitField trait

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This commit is contained in:
Carl Sverre 2024-12-19 11:40:24 -08:00
parent 2bd29821f4
commit 5195f7ccfa
8 changed files with 223 additions and 12 deletions
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36
impl/src/valid.rs
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@ -125,6 +125,12 @@ fn check_non_field_attrs(attrs: &Attrs) -> Result<()> {
"not expected here; the #[backtrace] attribute belongs on a specific field",
));
}
if let Some(implicit) = &attrs.implicit {
return Err(Error::new_spanned(
implicit,
"not expected here; the #[implicit] attribute belongs on a specific field",
));
}
if attrs.transparent.is_some() {
if let Some(display) = &attrs.display {
return Err(Error::new_spanned(
@ -152,7 +158,7 @@ fn check_field_attrs(fields: &[Field]) -> Result<()> {
let mut from_field = None;
let mut source_field = None;
let mut backtrace_field = None;
let mut has_backtrace = false;
let mut first_implicit_field = None;
for field in fields {
if let Some(from) = field.attrs.from {
if from_field.is_some() {
@ -180,7 +186,6 @@ fn check_field_attrs(fields: &[Field]) -> Result<()> {
));
}
backtrace_field = Some(field);
has_backtrace = true;
}
if let Some(transparent) = field.attrs.transparent {
return Err(Error::new_spanned(
@ -188,7 +193,9 @@ fn check_field_attrs(fields: &[Field]) -> Result<()> {
"#[error(transparent)] needs to go outside the enum or struct, not on an individual field",
));
}
has_backtrace |= field.is_backtrace();
if field.attrs.implicit.is_some() && first_implicit_field.is_none() {
first_implicit_field = Some(field);
}
}
if let (Some(from_field), Some(source_field)) = (from_field, source_field) {
if from_field.member != source_field.member {
@ -199,14 +206,17 @@ fn check_field_attrs(fields: &[Field]) -> Result<()> {
}
}
if let Some(from_field) = from_field {
let max_expected_fields = match backtrace_field {
Some(backtrace_field) => 1 + (from_field.member != backtrace_field.member) as usize,
None => 1 + has_backtrace as usize,
};
if fields.len() > max_expected_fields {
let has_unexpected_fields = fields.iter().any(|field| {
field.attrs.from.is_none()
&& field.attrs.source.is_none()
&& field.attrs.backtrace.is_none()
&& !field.is_backtrace()
&& !field.is_implicit()
});
if has_unexpected_fields {
return Err(Error::new_spanned(
from_field.attrs.from.unwrap().original,
"deriving From requires no fields other than source and backtrace",
"deriving From requires no fields other than source, backtrace, and implicit",
));
}
}
@ -218,6 +228,14 @@ fn check_field_attrs(fields: &[Field]) -> Result<()> {
));
}
}
if let Some(first_implicit_field) = first_implicit_field {
if from_field.is_none() {
return Err(Error::new_spanned(
first_implicit_field.original,
"implicit fields require a #[from] field",
));
}
}
Ok(())
}