use std::rc::Rc;
use super::assumed_collections::CollectionAssumption;
use super::parameter_calls::ParameterCall;
use super::pinning::LiteralDefault;
use crate::core::{FieldLabel, Keyword};
use crate::diagnostic::{Counted, Diagnostic, DiagnosticCode, Label, Suggestion};
use crate::source::Span;
#[derive(Clone)]
pub enum MismatchContext {
Plain,
IfTest {
expanded_from: Option<Rc<str>>,
},
IfBranch {
first: Span,
expanded_from: Option<Rc<str>>,
},
Signature {
signature: Span,
},
Annotation {
annotation: Span,
},
}
pub struct TypeProblems;
#[derive(Default)]
pub struct ImplementorList {
pub entries: Vec<String>,
pub groups: Vec<ImplementorGroup>,
}
pub struct ProjectionNames<'a> {
pub projection: &'a str,
pub trait_name: &'a str,
pub owner: &'a str,
}
impl ProjectionNames<'_> {
fn needs(&self) -> String {
format!(
"`({} {})` needs `{}` to implement `{}`",
self.projection, self.owner, self.owner, self.trait_name
)
}
}
pub struct ImplementorGroup {
pub constructor: String,
pub parameter: String,
pub arguments: Vec<String>,
}
impl TypeProblems {
fn expansion_name(expanded_from: Option<Rc<str>>) -> String {
expanded_from.map_or_else(|| "if".to_string(), |name| name.to_string())
}
fn if_test_note(expanded_from: Option<Rc<str>>) -> String {
format!(
"the test of `{}` must be a `bool`",
Self::expansion_name(expanded_from)
)
}
fn if_branch_note(expanded_from: Option<Rc<str>>) -> String {
format!(
"both branches of `{}` must have the same type",
Self::expansion_name(expanded_from)
)
}
pub fn try_needs_value(found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRY_NOT_RESULT_OR_OPTION,
"`try` needs a result or an option",
Label::new(span, format!("this is {found}")),
)
.with_help("write `try` around a result or an option value")
}
pub fn try_needs_unknown_recursive(
called: &str,
group: &[String],
hides_prelude: bool,
span: Span,
) -> Diagnostic {
let names: Vec<String> = group.iter().map(|name| format!("`{name}`")).collect();
let diagnostic = Diagnostic::error(
DiagnosticCode::TRY_NOT_RESULT_OR_OPTION,
"`try` needs a result or an option",
Label::new(span, "the type of this call is not known yet"),
)
.with_help(format!(
"write a `type` signature for one of: {}",
names.join(", ")
));
if hides_prelude {
diagnostic.with_note(format!(
"this `{called}` is the program's own, and it hides the prelude's `{called}`"
))
} else {
diagnostic
}
}
pub fn try_cannot_return(needed: &str, found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRY_TARGET,
"`try` cannot return from this function",
Label::new(span, format!("this function returns {found}")),
)
.with_note(format!("`try` here needs a function that returns {needed}"))
.with_help(
"make the function return the value `try` needs, or handle this value without `try`",
)
}
pub fn try_ambiguous_conversion(
source: &str,
target: &str,
variants: &[(String, String)],
span: Span,
) -> Diagnostic {
let mut diagnostic = Diagnostic::error(
DiagnosticCode::TRY_NO_CONVERSION,
"`try` cannot choose an error variant",
Label::new(span, format!("this error is {source}")),
)
.with_note(format!(
"this function returns a result whose error is {target}"
))
.with_note("`try` converts an error through one variant of an error enum that holds it");
for (name, payload) in variants {
diagnostic = diagnostic.with_note(format!("variant `{name}` holds {payload}"));
}
diagnostic
.with_help("keep one variant for each error type, or convert the error with `map-err`")
}
pub fn try_no_conversion(source: &str, target: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRY_NO_CONVERSION,
"`try` cannot convert this error",
Label::new(span, format!("this error is {source}")),
)
.with_note(format!(
"this function returns a result whose error is {target}"
))
.with_note("`try` converts an error through one variant of an error enum that holds it")
.with_help(
"write the function's error type as an enum with one variant for each error it tries, or convert the error with `map-err`",
)
}
pub fn mismatch(
expected: &str,
found: &str,
span: Span,
context: MismatchContext,
) -> Diagnostic {
let diagnostic = Diagnostic::error(
DiagnosticCode::MISMATCHED_TYPES,
"mismatched types",
Label::new(span, format!("expected {expected}, found {found}")),
);
match context {
MismatchContext::Plain => diagnostic,
MismatchContext::IfTest { expanded_from } => {
diagnostic.with_note(Self::if_test_note(expanded_from))
}
MismatchContext::IfBranch {
first,
expanded_from,
} => diagnostic
.with_label(Label::new(first, format!("the first branch is {expected}")))
.with_note(Self::if_branch_note(expanded_from)),
MismatchContext::Signature { signature } => {
diagnostic.with_label(Label::new(signature, "expected because of this signature"))
}
MismatchContext::Annotation { annotation } => diagnostic.with_label(Label::new(
annotation,
"expected because of this annotation",
)),
}
}
pub fn parameter_call(
diagnostic: Diagnostic,
function: &str,
call: &ParameterCall,
) -> Diagnostic {
let parameter = &call.parameter;
let diagnostic = diagnostic.with_label(Label::new(
call.span,
format!(
"`{function}` calls its parameter `{parameter}` here, so it expects a function"
),
));
if !call.shadows_function {
return diagnostic;
}
Self::parameter_shadows_function(diagnostic, call)
}
fn parameter_shadows_function(diagnostic: Diagnostic, call: &ParameterCall) -> Diagnostic {
let parameter = &call.parameter;
if call.arguments > 0 {
return diagnostic.with_help(format!(
"the parameter `{parameter}` shadows the function `{parameter}`, so to call the function, rename the parameter"
));
}
diagnostic.with_suggestion(
format!(
"the parameter `{parameter}` shadows the function `{parameter}`, so to use the parameter's value, write it without parentheses"
),
Suggestion::new(call.span, parameter.to_string()),
)
}
pub fn iter_needs_collection(found: &str, span: Span) -> Diagnostic {
Self::mismatch(
"a vector, a slice or a map",
found,
span,
MismatchContext::Plain,
)
}
pub fn assumed_collection_help(
assumption: CollectionAssumption,
function: &str,
signature: &str,
) -> String {
format!(
"`{}` reads {}, so write a `type` signature for `{function}`, such as `(type {function} {signature})`",
assumption.operation(),
assumption.reading(),
)
}
pub fn string_push_item(found: &str, span: Span) -> Diagnostic {
Self::string_push_mismatch(found, span)
.with_help("pass the item's text as `(ref (str ...))`")
}
pub fn owned_string_push_item(span: Span) -> Diagnostic {
Self::string_push_mismatch("`string`", span).with_help("borrow the item with `(ref ...)`")
}
fn string_push_mismatch(found: &str, span: Span) -> Diagnostic {
Self::mismatch(
"a `char` or a `(ref str)`",
found,
span,
MismatchContext::Plain,
)
}
pub fn generic_mismatch(generic: &str, found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISMATCHED_TYPES,
"mismatched types",
Label::new(span, format!("expected `{generic}`, found {found}")),
)
.with_note(format!(
"`{generic}` is a type parameter, so this code must work for every type `{generic}` stands for"
))
}
pub fn literal_default_note(default: &LiteralDefault, function: &str) -> String {
format!(
"`{}` defaulted to `{}`, because `{function}` is {}",
default.parameter,
default.default,
Self::literal_uses(default)
)
}
fn literal_uses(default: &LiteralDefault) -> String {
let calls = (!default.calls.is_empty())
.then(|| format!("called with {}", Self::listed_types(&default.calls)));
let values = (!default.values.is_empty()).then(|| {
format!(
"passed as a value with {}",
Self::listed_types(&default.values)
)
});
calls
.into_iter()
.chain(values)
.collect::<Vec<_>>()
.join(" and ")
}
fn listed_types(types: &[String]) -> String {
types
.iter()
.map(|ty| format!("`{ty}`"))
.collect::<Vec<_>>()
.join(" and with ")
}
pub fn literal_default_help(default: &LiteralDefault, function: &str) -> String {
if default.values.is_empty() {
return format!(
"give `{function}` one parameter type with a `type` signature, such as `(type {function} {})`, and pass that type at every call",
default.signature
);
}
format!(
"give `{function}` a type parameter with a `type` signature, such as `(type {function} {})`, so that each use takes its own type",
default.generic_signature
)
}
pub fn borrowed_items_help(function: &str, signature: &str) -> String {
format!(
"`{function}` takes owned items, but the argument yields borrowed items: write `(type {function} {signature})` to take borrowed items"
)
}
pub fn infinite(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::INFINITE_TYPE,
"this value's type would contain itself",
Label::new(span, "here"),
)
.with_help("a function cannot be called with itself as its own argument type")
}
pub fn wrong_argument_count(expected: usize, found: usize, span: Span) -> Diagnostic {
let expected = Counted::noun(expected, "argument");
Diagnostic::error(
DiagnosticCode::WRONG_ARGUMENT_COUNT,
format!(
"this function takes {expected} but {found} {} given",
Counted::was_or_were(found)
),
Label::new(span, format!("expected {expected}")),
)
}
pub fn not_a_function(found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::NOT_A_FUNCTION,
format!("expected a function, found {found}"),
Label::new(span, "this is called but is not a function"),
)
}
pub fn missing_trait(
trait_name: &str,
found: &str,
span: Span,
implementors: ImplementorList,
) -> Diagnostic {
let diagnostic = Diagnostic::error(
DiagnosticCode::MISSING_TRAIT,
format!("`{found}` does not implement `{trait_name}`"),
Label::new(span, format!("this needs `{trait_name}`")),
)
.with_note(format!(
"`{trait_name}` is implemented for: {}",
implementors.entries.join(", ")
));
implementors
.groups
.into_iter()
.fold(diagnostic, |diagnostic, group| {
diagnostic.with_note(Self::implementor_group_note(trait_name, &group))
})
}
fn implementor_group_note(trait_name: &str, group: &ImplementorGroup) -> String {
format!(
"`{trait_name}` is implemented for `({} {})` for each `{}` in: {}",
group.constructor,
group.parameter,
group.parameter,
group.arguments.join(", ")
)
}
pub fn missing_associated_value(trait_name: &str, projection: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISSING_ASSOCIATED_VALUE,
format!("this entry of `{trait_name}` does not give `{projection}`"),
Label::new(
span,
format!("`{trait_name}` declares the associated type `{projection}`"),
),
)
.with_help(format!(
"end the entry with `({projection} type)`, as in `(where () i64 ({projection} type))`"
))
}
pub fn undeclared_associated_value(
trait_name: &str,
projection: &str,
span: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNDECLARED_ASSOCIATED_VALUE,
format!("`{trait_name}` does not declare `{projection}`"),
Label::new(
span,
format!("`{projection}` is not an associated type of `{trait_name}`"),
),
)
.with_help(format!(
"remove the clause, or declare it with `(associated ({projection} owner) \"Name\")`"
))
}
pub fn projection_without_implementor(names: &ProjectionNames<'_>, span: Span) -> Diagnostic {
let ProjectionNames {
projection,
trait_name,
owner,
} = names;
Diagnostic::error(
DiagnosticCode::PROJECTION_WITHOUT_IMPLEMENTOR,
format!("`{owner}` does not implement `{trait_name}`"),
Label::new(span, names.needs()),
)
.with_note(format!(
"`{projection}` is an associated type of `{trait_name}`"
))
}
pub fn projection_without_bound(names: &ProjectionNames<'_>, span: Span) -> Diagnostic {
let ProjectionNames {
trait_name, owner, ..
} = names;
Diagnostic::error(
DiagnosticCode::PROJECTION_WITHOUT_BOUND,
format!("`{owner}` might not implement `{trait_name}`"),
Label::new(span, names.needs()),
)
.with_help(format!(
"add the trait to the `where` that binds `{owner}`: `({owner} {trait_name})`"
))
}
pub fn second_impl(
implementor: &str,
trait_name: &str,
span: Span,
first: Label,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::SECOND_IMPL,
format!("`{implementor}` already implements `{trait_name}`"),
Label::new(span, format!("this implements `{trait_name}` again")),
)
.with_label(first)
.with_help("remove one of the two")
}
pub fn inferred_impl_clash(
implementor: &str,
trait_name: &str,
written_trait: &str,
path: &str,
span: Span,
written: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::SECOND_IMPL,
format!("`{implementor}` already implements `{path}` through `{written_trait}`"),
Label::new(
span,
format!("this needs the inferred `{trait_name}`, a second impl of `{path}`"),
),
)
.with_label(Label::new(
written,
format!("`{written_trait}` implements `{path}` here"),
))
.with_help(format!(
"use `{written_trait}` here, or remove one of the two"
))
}
pub fn replacing_impl(span: Span, trait_name: &str, head: &str) -> Label {
Label::new(
span,
format!("this `{trait_name}` replaces the inferred one for every `{head}`"),
)
}
pub fn first_impl(span: Span) -> Label {
Label::new(span, "first implemented here")
}
pub fn derive_lists(span: Span, trait_name: &str) -> Label {
Label::new(span, format!("this `derive` lists `{trait_name}`"))
}
pub fn foreign_implementor(trait_name: &str, found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::FOREIGN_IMPLEMENTOR,
format!("`{found}` cannot implement `{trait_name}`"),
Label::new(
span,
format!("only a struct or enum of this program can implement `{trait_name}`"),
),
)
.with_note("Rust implements a trait only for a type in the crate that defines the trait or the type")
.with_help("implement it for a struct or enum this program defines")
}
pub fn missing_supertrait(
trait_name: &str,
supertrait_name: &str,
implementor: &str,
span: Span,
help: Option<Rc<str>>,
) -> Diagnostic {
let diagnostic = Diagnostic::error(
DiagnosticCode::SUPERTRAIT,
format!(
"`{implementor}` does not implement `{supertrait_name}`, a supertrait of `{trait_name}`"
),
Label::new(
span,
format!("`{implementor}` does not implement `{supertrait_name}`"),
),
);
match help {
Some(help) => diagnostic.with_help(help.to_string()),
None => {
diagnostic.with_help(format!("implement `{supertrait_name}` for `{implementor}`"))
}
}
}
pub fn missing_trait_on_struct(trait_name: &str, found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISSING_TRAIT,
format!("`{found}` does not implement `{trait_name}`"),
Label::new(span, format!("this needs `{trait_name}`")),
)
}
pub fn missing_trait_on_box(trait_name: &str, found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISSING_TRAIT,
format!("`{found}` does not implement `{trait_name}`"),
Label::new(span, format!("this needs `{trait_name}`")),
)
.with_help(format!(
"write the type `(box {trait_name})` where the box is made, such as `(local (shapes (vec (box {trait_name}))) ...)`"
))
}
pub fn order_not_inferred_note(trait_name: &str) -> String {
format!(
"`{trait_name}` is never inferred for a struct, so the struct needs a written `derive`"
)
}
pub fn order_derive_help(struct_name: &str, derives: &[String], fields: &[Rc<str>]) -> String {
format!(
"add `(derive {struct_name} {})` to compare fields in this order: {}",
derives.join(" "),
Self::field_order(fields)
)
}
pub fn order_blocked_note(
struct_name: &str,
field: &str,
field_type: &str,
trait_name: &str,
) -> String {
format!("`{struct_name}` cannot derive `{trait_name}`: field `{field}` is `{field_type}`")
}
pub fn sort_by_help(field: Option<&str>) -> String {
match field {
Some(field) => format!(
"to sort by one field instead, use `sort-by!` with the field keyword `{}{field}`",
Keyword::MARKER
),
None => "to sort by one field instead, use `sort-by!`".to_string(),
}
}
fn field_order(fields: &[Rc<str>]) -> String {
let names: Vec<String> = fields.iter().map(|field| format!("`{field}`")).collect();
match names.split_last() {
None => "no fields".to_string(),
Some((last, [])) => last.clone(),
Some((last, rest)) => format!("{}, then {last}", rest.join(", ")),
}
}
pub fn blocked_derive_note(
struct_name: &str,
trait_name: &str,
field: &str,
field_type: &str,
) -> String {
format!("`{struct_name}` cannot derive `{trait_name}`: field `{field}` is `{field_type}`")
}
pub fn missing_bound(trait_name: &str, generic: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISSING_BOUND,
format!("`{generic}` might not implement `{trait_name}`"),
Label::new(span, format!("this needs `{trait_name}`")),
)
.with_help(format!(
"add the trait to the signature's `where`: `({generic} {trait_name})`"
))
}
pub fn covered_clause(clause: Span, earlier: Span) -> Diagnostic {
Self::unreachable_clause(clause, earlier, "an earlier clause covers this target")
.with_help("move the narrower clause first")
}
pub fn repeated_clause(clause: Span, earlier: Span) -> Diagnostic {
Self::unreachable_clause(clause, earlier, "an earlier clause has this target")
.with_help("remove the repeated clause")
}
fn unreachable_clause(clause: Span, earlier: Span, reason: &str) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::COVERED_CLAUSE,
"this clause can never be chosen",
Label::new(clause, reason),
)
.with_label(Label::new(earlier, "this clause comes first"))
}
pub fn requirement_cycle(trait_name: &str, required: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::REQUIREMENT_CYCLE,
format!("`{trait_name}` requires itself"),
Label::new(span, format!("`{required}` leads back to `{trait_name}`")),
)
.with_help("remove this requirement: Rust rejects a trait that is its own supertrait")
}
pub fn out_of_range(literal: &str, type_name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::LITERAL_OUT_OF_RANGE,
format!("the literal `{literal}` does not fit in `{type_name}`"),
Label::new(span, format!("out of range for `{type_name}`")),
)
}
pub fn literal_of_any_type(literal: &str, parameter: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::LITERAL_TYPE_PARAMETER,
format!("`{literal}` cannot have type `{parameter}`"),
Label::new(span, format!("this literal has type `{parameter}`")),
)
.with_note(format!(
"`{parameter}` has no trait, so it can be any type, including `string`"
))
.with_help(format!(
"give `{parameter}` a numeric trait in the signature"
))
}
pub fn literal_misfit(
literal: &str,
parameter: &str,
misfit: &str,
admissible: &[String],
span: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::LITERAL_MISFIT,
format!("`{literal}` does not fit every type `{parameter}` can be"),
Label::new(
span,
format!("`{parameter}` can be `{misfit}`, which cannot hold this value"),
),
)
.with_note(format!(
"`{parameter}` can be any of: {}",
admissible.join(", ")
))
.with_help(format!(
"narrow `{parameter}` with a trait whose types all hold this value"
))
}
pub fn cannot_infer(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::CANNOT_INFER,
"type annotations needed",
Label::new(span, "cannot infer the type of this value"),
)
.with_help(
"write the type with `the`, as in `(the (vec i64) (vec))`, or add a `type` signature",
)
}
pub fn unprintable_value(shown_type: &str, missing_trait: &str, span: Span) -> Diagnostic {
Diagnostic::note(
format!(
"the value has type `{shown_type}`, which does not implement `{missing_trait}`"
),
Label::new(span, "this value does not print"),
)
}
pub fn cannot_infer_bound(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::CANNOT_INFER,
"type annotations needed",
Label::new(span, "cannot infer a type that a bound of this function names"),
)
.with_help(
"a bound of this function names a type that no argument or result holds, so its signature must change",
)
}
pub fn cannot_infer_value(open_type: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::CANNOT_INFER,
"type annotations needed",
Label::new(
span,
format!("cannot infer the type `{open_type}` of this value"),
),
)
.with_suggestion(
"write the type with `the`, and replace each `_` with a type",
Suggestion::wrapping(span, format!("(the {open_type} "), ")"),
)
}
pub fn unnameable_type(opaque: &str, span: Span) -> Diagnostic {
let label = Label::new(
span,
format!("this holds `{opaque}` inside a function type"),
);
Self::unnameable(opaque, label).with_help(
"pass a value whose type Rust can name instead, such as the collection the items come from",
)
}
pub fn stored_unnameable_type(opaque: &str, span: Span) -> Diagnostic {
let label = Label::new(span, format!("this stores `{opaque}`"));
Self::unnameable(opaque, label).with_help(
"store the collection the items come from instead, and call `iter` on it where the items are used",
)
}
pub fn closure_receiver_unnameable_type(opaque: &str, span: Span) -> Diagnostic {
let label = Label::new(
span,
format!("this parameter holds `{opaque}`, and the closure calls a method on it"),
);
Self::unnameable(opaque, label)
.with_note(
"Rust must know a closure parameter's type before the closure calls a method on it",
)
.with_help("define the function with `defn`, whose parameters can take an `iterator`")
}
fn unnameable(opaque: &str, label: Label) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNNAMEABLE_TYPE,
format!("Rust cannot name the type `{opaque}` here"),
label,
)
.with_note("Rust names this type only as the type of a function's own parameter or result")
}
pub fn unknown_collection(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNKNOWN_COLLECTION,
"type annotations needed",
Label::new(span, "cannot tell whether this is a vector or a map"),
)
.with_help("add a `type` signature that names the collection's type")
}
pub fn ambiguous_variant(name: &str, enums: &[String], span: Span) -> Diagnostic {
let diagnostic = Diagnostic::error(
DiagnosticCode::AMBIGUOUS_VARIANT,
"cannot tell which enum this pattern matches",
Label::new(span, "this variant name fits more than one enum"),
)
.with_note(format!(
"this variant name fits {}",
enums
.iter()
.map(|enum_name| format!("`{enum_name}`"))
.collect::<Vec<_>>()
.join(" and ")
));
match enums.first() {
Some(enum_name) if !name.is_empty() => diagnostic.with_help(format!(
"qualify one pattern with its enum's name, as in `({enum_name}/{name} ...)`"
)),
_ => diagnostic.with_help("qualify one pattern with its enum's name"),
}
}
pub fn variant_arm_value(name: &str, variant: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::VARIANT_ARM_VALUE,
format!("`{name}` names a variant in this arm, not a value"),
Label::new(span, "names the variant, not a value"),
)
.with_help(format!("write `{variant}` for the variant's value"))
}
pub fn unknown_variant(
enum_name: &str,
variant: &str,
variants: &[Rc<str>],
span: Span,
) -> Diagnostic {
let names: Vec<String> = variants.iter().map(|name| format!("`{name}`")).collect();
Diagnostic::error(
DiagnosticCode::UNKNOWN_VARIANT,
format!("`{enum_name}` has no variant `{variant}`"),
Label::new(span, format!("not a variant of `{enum_name}`")),
)
.with_help(format!("write one of: {}", names.join(", ")))
}
pub fn non_exhaustive_match(cases: &[String], span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::NON_EXHAUSTIVE_MATCH,
"non-exhaustive `match`",
Label::new(span, "this `match` does not cover every value"),
)
.with_note(format!(
"missing {}: {}",
Counted::noun(cases.len(), "case"),
cases
.iter()
.map(|case| format!("`{case}`"))
.collect::<Vec<_>>()
.join(", ")
))
.with_help("add an arm for each missing case")
}
pub fn unreachable_arm(span: Span, covered_by: Option<Span>) -> Diagnostic {
let diagnostic = Diagnostic::warning(
DiagnosticCode::UNREACHABLE_ARM,
"unreachable `match` arm",
Label::new(span, "this arm can never match"),
);
match covered_by {
Some(covered_by) => diagnostic.with_label(Label::new(covered_by, "this arm covers it")),
None => {
diagnostic.with_note("the earlier arms together cover every value this arm matches")
}
}
}
pub fn pattern_count(name: &str, expected: usize, found: usize, span: Span) -> Diagnostic {
let expected = Counted::noun(expected, "part");
Diagnostic::error(
DiagnosticCode::WRONG_PATTERN_COUNT,
format!(
"`{name}` takes {expected} in a pattern but {found} {} given",
Counted::was_or_were(found)
),
Label::new(span, "this pattern has the wrong number of parts"),
)
}
pub fn unknown_field(
struct_name: &str,
label: &FieldLabel,
similar: Option<Rc<str>>,
) -> Diagnostic {
let absent = Self::absent_field(DiagnosticCode::UNKNOWN_FIELD, struct_name, label);
Self::with_similar_field(absent, label, similar)
}
pub fn unknown_pattern_field(
owner: &str,
label: &FieldLabel,
similar: Option<Rc<str>>,
) -> Diagnostic {
let absent = Self::absent_field(DiagnosticCode::UNKNOWN_PATTERN_FIELD, owner, label);
Self::with_similar_field(absent, label, similar)
}
pub fn label_on_positional_payload(
owner: &str,
label: &FieldLabel,
parts: usize,
) -> Diagnostic {
Self::absent_field(DiagnosticCode::UNKNOWN_PATTERN_FIELD, owner, label)
.with_help(Self::positional_payload_help(owner, parts))
}
fn positional_payload_help(owner: &str, parts: usize) -> String {
if parts == 0 {
return format!("`{owner}` has no payload: write `{owner}`");
}
let parts = Counted::noun(parts, "part");
format!("`{owner}` takes {parts} by position, without a label")
}
fn absent_field(code: DiagnosticCode, owner: &str, label: &FieldLabel) -> Diagnostic {
Diagnostic::error(
code,
format!("`{owner}` has no field `{}`", label.spelled(&label.name)),
Label::new(label.span, "unknown field"),
)
}
fn with_similar_field(
diagnostic: Diagnostic,
label: &FieldLabel,
similar: Option<Rc<str>>,
) -> Diagnostic {
match similar {
Some(similar) => diagnostic.with_suggestion(
"a field with a similar name exists",
Suggestion::new(label.span, label.spelled(&similar)),
),
None => diagnostic,
}
}
pub fn main_returns_value(shown: &str, returned: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MAIN_RETURNS_VALUE,
format!("`main` returns a value of type `{shown}`"),
Label::new(returned, format!("this `{shown}` is returned from `main`")),
)
.with_note("`main` returns `unit` or a `result`")
.with_help(
"end the body of `main` with a print, such as `(println value)`, or return a `result`",
)
}
pub fn selfless_method_call(
trait_name: &str,
method: &str,
replacement: &str,
call: Span,
signature: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::SELFLESS_METHOD_CALL,
format!("cannot choose which implementor of `{trait_name}` runs `{method}`"),
Label::new(
call,
format!("no type here picks an implementor of `{trait_name}`"),
),
)
.with_label(Label::new(
signature,
"this signature never mentions `self`",
))
.with_note(
"a call picks an implementor from the type of a parameter or result that is `self`",
)
.with_help(format!(
"add `(ref self)` as the first parameter of `{method}`, as in `{replacement}`"
))
}
pub fn repeated_field(struct_name: &str, label: &FieldLabel, first: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::REPEATED_FIELD,
format!(
"`{}` is given twice in `{struct_name}`",
label.spelled(&label.name)
),
Label::new(label.span, "given again here"),
)
.with_label(Label::new(first, "first given here"))
.with_help(format!(
"remove the second `{}` and its value",
label.spelled(&label.name)
))
}
pub fn repeated_pattern_field(owner: &str, label: &FieldLabel, first: Span) -> Diagnostic {
let keyword = label.spelled(&label.name);
Diagnostic::error(
DiagnosticCode::REPEATED_PATTERN_FIELD,
format!("`{keyword}` is given twice in this pattern of `{owner}`"),
Label::new(label.span, "given again here"),
)
.with_label(Label::new(first, "first given here"))
.with_help(format!("remove the second `{keyword}` and its pattern"))
}
pub fn keyword_without_pattern(label: &FieldLabel) -> Diagnostic {
let keyword = label.spelled(&label.name);
Diagnostic::error(
DiagnosticCode::KEYWORD_WITHOUT_PATTERN,
format!("`{keyword}` has no pattern after it"),
Label::new(label.span, "this field keyword needs a pattern"),
)
.with_help(format!("write a pattern after `{keyword}`, or remove it"))
}
pub fn mixed_named_pattern(owner: &str, labeled: Span, positional: Span) -> Diagnostic {
Self::mixed_pattern_forms(owner, labeled, positional)
.with_help("label every part, or write one pattern for each field in order")
}
pub fn mixed_positional_pattern(
owner: &str,
labeled: Span,
positional: Span,
parts: usize,
) -> Diagnostic {
Self::mixed_pattern_forms(owner, labeled, positional)
.with_help(Self::positional_payload_help(owner, parts))
}
fn mixed_pattern_forms(owner: &str, labeled: Span, positional: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MIXED_PATTERN_FORMS,
format!("this pattern of `{owner}` mixes positions and field labels"),
Label::new(labeled, "this part names a field"),
)
.with_label(Label::new(positional, "this part goes by position"))
}
pub fn missing_fields(struct_name: &str, missing: &[Rc<str>], span: Span) -> Diagnostic {
let noun = if missing.len() == 1 {
"field"
} else {
"fields"
};
let names: Vec<String> = missing.iter().map(|field| format!("`{field}`")).collect();
Diagnostic::error(
DiagnosticCode::MISSING_FIELDS,
format!("missing {noun} {} in `{struct_name}`", names.join(", ")),
Label::new(span, "each missing field needs a value"),
)
}
pub fn no_fields(found: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::NO_FIELDS,
format!("`{found}` has no fields"),
Label::new(span, "only structs have fields"),
)
}
pub fn borrowed_update_base(struct_name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::NO_FIELDS,
format!("cannot update a borrowed `{struct_name}`"),
Label::new(span, format!("this `{struct_name}` is borrowed")),
)
.with_help(format!(
"bind an owned `{struct_name}` first, as in `(local owned (clone base))`, and update `owned`"
))
}
pub fn struct_base_help() -> String {
format!(
"a struct is not a collection, so update a field with a keyword key, such as `{}field`",
Keyword::MARKER
)
}
pub fn ambiguous_field(field: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::CANNOT_INFER,
"type annotations needed",
Label::new(
span,
format!("cannot tell which struct's `{field}` this is"),
),
)
.with_help("name the struct in a signature, as in `(fn ((ref point)) _)`")
}
pub fn compile_time_only(name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::COMPILE_TIME_ONLY,
format!("`{name}` only exists at compile time"),
Label::new(span, "used in code that runs in the program"),
)
.with_note("definitions that use the `code` module or `quote` can only be used by macros")
}
pub fn quote_at_runtime(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::QUOTE_AT_RUNTIME,
"quoted code only exists at compile time",
Label::new(span, "used in code that runs in the program"),
)
.with_help("use `quote` inside macros, or write a string if you want text")
}
pub fn wrong_type_argument_count(
name: &str,
expected: usize,
found: usize,
span: Span,
) -> Diagnostic {
let expected = Counted::noun(expected, "type argument");
Diagnostic::error(
DiagnosticCode::WRONG_TYPE_ARGUMENT_COUNT,
format!(
"`{name}` takes {expected} but {found} {} given",
Counted::was_or_were(found)
),
Label::new(span, format!("expected {expected}")),
)
}
pub fn bare_implementor(trait_name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::BARE_IMPLEMENTOR,
"a type parameter alone cannot implement a trait",
Label::new(span, "this would match every type"),
)
.with_help(format!(
"wrap the parameter in a type, as in `(where ((a {trait_name})) (ref a))`"
))
}
pub fn unsized_implementor(implementor: &str, method: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNSIZABLE_IMPLEMENTOR,
format!("`{implementor}` has no size, so `{method}` cannot take `self` by value"),
Label::new(span, format!("`{implementor}` has no size")),
)
.with_help("take the receiver by reference, as in `(fn ((ref self)) ...)`")
}
pub fn unused_type_parameter(name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNUSED_TYPE_PARAMETER,
format!("no field uses the type parameter `{name}`"),
Label::new(span, "declared here"),
)
.with_help(format!("use `{name}` in a field's type, or remove it"))
}
pub fn unused_enum_parameter(name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::UNUSED_ENUM_PARAMETER,
format!("no payload uses the type parameter `{name}`"),
Label::new(span, "declared here"),
)
.with_help(format!("use `{name}` in a variant payload, or remove it"))
}
pub fn recursively_used_enum_parameter(
name: &str,
enum_name: &str,
binder: Span,
recursive_use: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::RECURSIVELY_USED_TYPE_PARAMETER,
format!("type parameter `{name}` is only used recursively"),
Label::new(binder, "declared here"),
)
.with_label(Label::new(recursive_use, "first recursive use"))
.with_help(format!(
"use `{name}` in a payload outside `{enum_name}`, or remove it"
))
}
pub fn bounded_type_parameter(name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::BOUNDED_TYPE_PARAMETER,
format!("the type parameter `{name}` cannot require traits here"),
Label::new(span, "traits given here"),
)
.with_help(format!(
"write `{name}` alone, and require the traits in the `where` of each function that needs them"
))
}
pub fn mut_borrow_of_copy(span: Span, place: Option<String>) -> Diagnostic {
let help = match place {
Some(place) => format!("pass the field as a place: `{place}`"),
None => "pass a local or a field, because a call returns a copy".to_string(),
};
Diagnostic::error(
DiagnosticCode::MUT_BORROW_OF_COPY,
"this argument is a copy, so changing it changes nothing",
Label::new(span, "this is a copy, not a place"),
)
.with_help(help)
}
pub fn trait_claim_on_struct(
definer: &str,
struct_name: &str,
trait_name: &str,
span: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRAIT_CLAIM_ON_STRUCT,
format!("`{struct_name}` does not derive `{trait_name}`"),
Label::new(span, format!("this struct does not derive `{trait_name}`")),
)
.with_help(format!(
"remove `{struct_name}` from this `{definer}`, or list a type that Rust implements `{trait_name}` for"
))
}
pub fn not_derivable(trait_name: &str, derivable: &[String], span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::NOT_DERIVABLE,
format!("`{trait_name}` cannot be derived"),
Label::new(span, "not a derivable trait"),
)
.with_help(format!("a `derive` lists any of: {}", derivable.join(", ")))
}
pub fn blocked_enum_derive(
enum_name: &str,
trait_name: &str,
variant: &str,
payload_type: &str,
span: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::BLOCKED_DERIVE,
format!("`{enum_name}` cannot derive `{trait_name}`"),
Label::new(
span,
format!("variant `{variant}` holds `{payload_type}`, which is not `{trait_name}`"),
),
)
.with_help(format!(
"change the payload of variant `{variant}`, or leave this trait out of the `derive`"
))
}
pub fn blocked_enum_derive_note(
enum_name: &str,
trait_name: &str,
variant: &str,
payload_type: &str,
) -> String {
format!(
"`{enum_name}` cannot derive `{trait_name}`: variant `{variant}` holds `{payload_type}`"
)
}
pub fn order_not_inferred_enum_note(trait_name: &str) -> String {
format!(
"`{trait_name}` is never inferred for an enum, so the enum needs a written `derive`"
)
}
pub fn enum_order_help(enum_name: &str, derives: &[String], variants: &[Rc<str>]) -> String {
format!(
"add `(derive {enum_name} {})` to compare variants in declared order: {}",
derives.join(" "),
Self::field_order(variants)
)
}
pub fn add_to_enum_derive_help(trait_name: &str) -> String {
format!("add `{trait_name}` to the enum's `derive`")
}
pub fn order_blocked_enum_note(
enum_name: &str,
variant: &str,
payload_type: &str,
trait_name: &str,
) -> String {
format!(
"`{enum_name}` cannot derive `{trait_name}`: variant `{variant}` holds `{payload_type}`"
)
}
pub fn blocked_derive(
struct_name: &str,
trait_name: &str,
field: &str,
field_type: &str,
span: Span,
) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::BLOCKED_DERIVE,
format!("`{struct_name}` cannot derive `{trait_name}`"),
Label::new(
span,
format!("field `{field}` is `{field_type}`, which is not `{trait_name}`"),
),
)
.with_help(format!(
"change the type of field `{field}`, or leave this trait out of the `derive`"
))
}
pub fn derive_on_rust_type(enum_name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::DERIVE_ON_RUST_TYPE,
format!("`{enum_name}` is a Rust type, so it has no `derive`"),
Label::new(span, format!("`{enum_name}` names a Rust type")),
)
.with_help("the traits of a Rust type come from the Rust traits that list it")
}
pub fn duplicate_derive(struct_name: &str, span: Span, first: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::DUPLICATE_DERIVE,
format!("`{struct_name}` has a second `derive`"),
Label::new(span, "second `derive`"),
)
.with_label(Label::new(first, "first `derive`"))
.with_help("merge the two trait lists into one `derive`")
}
pub fn derive_leaves_out(span: Span, trait_name: &str) -> Label {
Label::new(span, format!("this `derive` leaves out `{trait_name}`"))
}
pub fn borrow_copied(span: Span) -> Label {
Label::new(span, "this copies the borrowed value")
}
pub fn clone_copied_help() -> String {
"to copy a value that is not `copy`, write `(clone ...)` around it".to_string()
}
pub fn add_to_derive_help(trait_name: &str) -> String {
format!("add `{trait_name}` to the struct's `derive`")
}
pub fn trait_takes_no_argument(trait_name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRAIT_NO_SECOND_TYPE,
format!("`{trait_name}` takes no second type"),
Label::new(span, "this gives it a second type"),
)
.with_help(format!("write `{trait_name}` alone, without a second type"))
}
pub fn misplaced_with(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISPLACED_WITH,
"`with` is only allowed in a Rust trait's list of implementors",
Label::new(span, "not allowed here"),
)
.with_help("write `(with type type)` in the list of a Rust trait's implementors")
}
pub fn not_boxable(trait_name: &str, blocker: String, help: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::OBJECT_SAFETY,
format!("`{trait_name}` cannot be a trait object"),
Label::new(span, blocker),
)
.with_help(help)
}
pub fn trait_outside_box(name: &str, span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::TRAIT_OUTSIDE_BOX,
"a trait is a type only inside `(box ...)`",
Label::new(span, format!("`{name}` is a trait")),
)
.with_help(format!("write `(box {name})` to box it as a trait object"))
}
pub fn misplaced_where(span: Span) -> Diagnostic {
Diagnostic::error(
DiagnosticCode::MISPLACED_WHERE,
"`where` must wrap a whole signature",
Label::new(span, "not allowed inside another type"),
)
}
}