rustc_errors/diagnostic.rs
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use std::borrow::Cow;
use std::fmt::{self, Debug};
use std::hash::{Hash, Hasher};
use std::marker::PhantomData;
use std::ops::{Deref, DerefMut};
use std::panic;
use std::thread::panicking;
use rustc_data_structures::fx::FxIndexMap;
use rustc_error_messages::{FluentValue, fluent_value_from_str_list_sep_by_and};
use rustc_lint_defs::Applicability;
use rustc_macros::{Decodable, Encodable};
use rustc_span::source_map::Spanned;
use rustc_span::symbol::Symbol;
use rustc_span::{DUMMY_SP, Span};
use tracing::debug;
use crate::snippet::Style;
use crate::{
CodeSuggestion, DiagCtxtHandle, DiagMessage, ErrCode, ErrorGuaranteed, ExplicitBug, Level,
MultiSpan, StashKey, SubdiagMessage, Substitution, SubstitutionPart, SuggestionStyle,
Suggestions,
};
/// Simplified version of `FluentArg` that can implement `Encodable` and `Decodable`. Collection of
/// `DiagArg` are converted to `FluentArgs` (consuming the collection) at the start of diagnostic
/// emission.
pub type DiagArg<'iter> = (&'iter DiagArgName, &'iter DiagArgValue);
/// Name of a diagnostic argument.
pub type DiagArgName = Cow<'static, str>;
/// Simplified version of `FluentValue` that can implement `Encodable` and `Decodable`. Converted
/// to a `FluentValue` by the emitter to be used in diagnostic translation.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
pub enum DiagArgValue {
Str(Cow<'static, str>),
// This gets converted to a `FluentNumber`, which is an `f64`. An `i32`
// safely fits in an `f64`. Any integers bigger than that will be converted
// to strings in `into_diag_arg` and stored using the `Str` variant.
Number(i32),
StrListSepByAnd(Vec<Cow<'static, str>>),
}
pub type DiagArgMap = FxIndexMap<DiagArgName, DiagArgValue>;
/// Trait for types that `Diag::emit` can return as a "guarantee" (or "proof")
/// token that the emission happened.
pub trait EmissionGuarantee: Sized {
/// This exists so that bugs and fatal errors can both result in `!` (an
/// abort) when emitted, but have different aborting behaviour.
type EmitResult = Self;
/// Implementation of `Diag::emit`, fully controlled by each `impl` of
/// `EmissionGuarantee`, to make it impossible to create a value of
/// `Self::EmitResult` without actually performing the emission.
#[track_caller]
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult;
}
impl EmissionGuarantee for ErrorGuaranteed {
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult {
diag.emit_producing_error_guaranteed()
}
}
impl EmissionGuarantee for () {
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult {
diag.emit_producing_nothing();
}
}
/// Marker type which enables implementation of `create_bug` and `emit_bug` functions for
/// bug diagnostics.
#[derive(Copy, Clone)]
pub struct BugAbort;
impl EmissionGuarantee for BugAbort {
type EmitResult = !;
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult {
diag.emit_producing_nothing();
panic::panic_any(ExplicitBug);
}
}
/// Marker type which enables implementation of `create_fatal` and `emit_fatal` functions for
/// fatal diagnostics.
#[derive(Copy, Clone)]
pub struct FatalAbort;
impl EmissionGuarantee for FatalAbort {
type EmitResult = !;
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult {
diag.emit_producing_nothing();
crate::FatalError.raise()
}
}
impl EmissionGuarantee for rustc_span::fatal_error::FatalError {
fn emit_producing_guarantee(diag: Diag<'_, Self>) -> Self::EmitResult {
diag.emit_producing_nothing();
rustc_span::fatal_error::FatalError
}
}
/// Trait implemented by error types. This is rarely implemented manually. Instead, use
/// `#[derive(Diagnostic)]` -- see [rustc_macros::Diagnostic].
///
/// When implemented manually, it should be generic over the emission
/// guarantee, i.e.:
/// ```ignore (fragment)
/// impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for Foo { ... }
/// ```
/// rather than being specific:
/// ```ignore (fragment)
/// impl<'a> Diagnostic<'a> for Bar { ... } // the default type param is `ErrorGuaranteed`
/// impl<'a> Diagnostic<'a, ()> for Baz { ... }
/// ```
/// There are two reasons for this.
/// - A diagnostic like `Foo` *could* be emitted at any level -- `level` is
/// passed in to `into_diag` from outside. Even if in practice it is
/// always emitted at a single level, we let the diagnostic creation/emission
/// site determine the level (by using `create_err`, `emit_warn`, etc.)
/// rather than the `Diagnostic` impl.
/// - Derived impls are always generic, and it's good for the hand-written
/// impls to be consistent with them.
#[rustc_diagnostic_item = "Diagnostic"]
pub trait Diagnostic<'a, G: EmissionGuarantee = ErrorGuaranteed> {
/// Write out as a diagnostic out of `DiagCtxt`.
#[must_use]
fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G>;
}
impl<'a, T, G> Diagnostic<'a, G> for Spanned<T>
where
T: Diagnostic<'a, G>,
G: EmissionGuarantee,
{
fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
self.node.into_diag(dcx, level).with_span(self.span)
}
}
/// Converts a value of a type into a `DiagArg` (typically a field of an `Diag` struct).
/// Implemented as a custom trait rather than `From` so that it is implemented on the type being
/// converted rather than on `DiagArgValue`, which enables types from other `rustc_*` crates to
/// implement this.
pub trait IntoDiagArg {
fn into_diag_arg(self) -> DiagArgValue;
}
impl IntoDiagArg for DiagArgValue {
fn into_diag_arg(self) -> DiagArgValue {
self
}
}
impl Into<FluentValue<'static>> for DiagArgValue {
fn into(self) -> FluentValue<'static> {
match self {
DiagArgValue::Str(s) => From::from(s),
DiagArgValue::Number(n) => From::from(n),
DiagArgValue::StrListSepByAnd(l) => fluent_value_from_str_list_sep_by_and(l),
}
}
}
/// Trait implemented by error types. This should not be implemented manually. Instead, use
/// `#[derive(Subdiagnostic)]` -- see [rustc_macros::Subdiagnostic].
#[rustc_diagnostic_item = "Subdiagnostic"]
pub trait Subdiagnostic
where
Self: Sized,
{
/// Add a subdiagnostic to an existing diagnostic.
fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
self.add_to_diag_with(diag, &|_, m| m);
}
/// Add a subdiagnostic to an existing diagnostic where `f` is invoked on every message used
/// (to optionally perform eager translation).
fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
self,
diag: &mut Diag<'_, G>,
f: &F,
);
}
pub trait SubdiagMessageOp<G: EmissionGuarantee> =
Fn(&mut Diag<'_, G>, SubdiagMessage) -> SubdiagMessage;
/// Trait implemented by lint types. This should not be implemented manually. Instead, use
/// `#[derive(LintDiagnostic)]` -- see [rustc_macros::LintDiagnostic].
#[rustc_diagnostic_item = "LintDiagnostic"]
pub trait LintDiagnostic<'a, G: EmissionGuarantee> {
/// Decorate and emit a lint.
fn decorate_lint<'b>(self, diag: &'b mut Diag<'a, G>);
}
#[derive(Clone, Debug, Encodable, Decodable)]
pub(crate) struct DiagLocation {
file: Cow<'static, str>,
line: u32,
col: u32,
}
impl DiagLocation {
#[track_caller]
fn caller() -> Self {
let loc = panic::Location::caller();
DiagLocation { file: loc.file().into(), line: loc.line(), col: loc.column() }
}
}
impl fmt::Display for DiagLocation {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}:{}:{}", self.file, self.line, self.col)
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
pub struct IsLint {
/// The lint name.
pub(crate) name: String,
/// Indicates whether this lint should show up in cargo's future breakage report.
has_future_breakage: bool,
}
#[derive(Debug, PartialEq, Eq)]
pub struct DiagStyledString(pub Vec<StringPart>);
impl DiagStyledString {
pub fn new() -> DiagStyledString {
DiagStyledString(vec![])
}
pub fn push_normal<S: Into<String>>(&mut self, t: S) {
self.0.push(StringPart::normal(t));
}
pub fn push_highlighted<S: Into<String>>(&mut self, t: S) {
self.0.push(StringPart::highlighted(t));
}
pub fn push<S: Into<String>>(&mut self, t: S, highlight: bool) {
if highlight {
self.push_highlighted(t);
} else {
self.push_normal(t);
}
}
pub fn normal<S: Into<String>>(t: S) -> DiagStyledString {
DiagStyledString(vec![StringPart::normal(t)])
}
pub fn highlighted<S: Into<String>>(t: S) -> DiagStyledString {
DiagStyledString(vec![StringPart::highlighted(t)])
}
pub fn content(&self) -> String {
self.0.iter().map(|x| x.content.as_str()).collect::<String>()
}
}
#[derive(Debug, PartialEq, Eq)]
pub struct StringPart {
content: String,
style: Style,
}
impl StringPart {
pub fn normal<S: Into<String>>(content: S) -> StringPart {
StringPart { content: content.into(), style: Style::NoStyle }
}
pub fn highlighted<S: Into<String>>(content: S) -> StringPart {
StringPart { content: content.into(), style: Style::Highlight }
}
}
/// The main part of a diagnostic. Note that `Diag`, which wraps this type, is
/// used for most operations, and should be used instead whenever possible.
/// This type should only be used when `Diag`'s lifetime causes difficulties,
/// e.g. when storing diagnostics within `DiagCtxt`.
#[must_use]
#[derive(Clone, Debug, Encodable, Decodable)]
pub struct DiagInner {
// NOTE(eddyb) this is private to disallow arbitrary after-the-fact changes,
// outside of what methods in this crate themselves allow.
pub(crate) level: Level,
pub messages: Vec<(DiagMessage, Style)>,
pub code: Option<ErrCode>,
pub span: MultiSpan,
pub children: Vec<Subdiag>,
pub suggestions: Suggestions,
pub args: DiagArgMap,
/// This is not used for highlighting or rendering any error message. Rather, it can be used
/// as a sort key to sort a buffer of diagnostics. By default, it is the primary span of
/// `span` if there is one. Otherwise, it is `DUMMY_SP`.
pub sort_span: Span,
pub is_lint: Option<IsLint>,
/// With `-Ztrack_diagnostics` enabled,
/// we print where in rustc this error was emitted.
pub(crate) emitted_at: DiagLocation,
}
impl DiagInner {
#[track_caller]
pub fn new<M: Into<DiagMessage>>(level: Level, message: M) -> Self {
DiagInner::new_with_messages(level, vec![(message.into(), Style::NoStyle)])
}
#[track_caller]
pub fn new_with_messages(level: Level, messages: Vec<(DiagMessage, Style)>) -> Self {
DiagInner {
level,
messages,
code: None,
span: MultiSpan::new(),
children: vec![],
suggestions: Suggestions::Enabled(vec![]),
args: Default::default(),
sort_span: DUMMY_SP,
is_lint: None,
emitted_at: DiagLocation::caller(),
}
}
#[inline(always)]
pub fn level(&self) -> Level {
self.level
}
pub fn is_error(&self) -> bool {
match self.level {
Level::Bug | Level::Fatal | Level::Error | Level::DelayedBug => true,
Level::ForceWarning(_)
| Level::Warning
| Level::Note
| Level::OnceNote
| Level::Help
| Level::OnceHelp
| Level::FailureNote
| Level::Allow
| Level::Expect(_) => false,
}
}
/// Indicates whether this diagnostic should show up in cargo's future breakage report.
pub(crate) fn has_future_breakage(&self) -> bool {
matches!(self.is_lint, Some(IsLint { has_future_breakage: true, .. }))
}
pub(crate) fn is_force_warn(&self) -> bool {
match self.level {
Level::ForceWarning(_) => {
assert!(self.is_lint.is_some());
true
}
_ => false,
}
}
// See comment on `Diag::subdiagnostic_message_to_diagnostic_message`.
pub(crate) fn subdiagnostic_message_to_diagnostic_message(
&self,
attr: impl Into<SubdiagMessage>,
) -> DiagMessage {
let msg =
self.messages.iter().map(|(msg, _)| msg).next().expect("diagnostic with no messages");
msg.with_subdiagnostic_message(attr.into())
}
pub(crate) fn sub(
&mut self,
level: Level,
message: impl Into<SubdiagMessage>,
span: MultiSpan,
) {
let sub = Subdiag {
level,
messages: vec![(
self.subdiagnostic_message_to_diagnostic_message(message),
Style::NoStyle,
)],
span,
};
self.children.push(sub);
}
pub(crate) fn arg(&mut self, name: impl Into<DiagArgName>, arg: impl IntoDiagArg) {
self.args.insert(name.into(), arg.into_diag_arg());
}
/// Fields used for Hash, and PartialEq trait.
fn keys(
&self,
) -> (
&Level,
&[(DiagMessage, Style)],
&Option<ErrCode>,
&MultiSpan,
&[Subdiag],
&Suggestions,
Vec<(&DiagArgName, &DiagArgValue)>,
&Option<IsLint>,
) {
(
&self.level,
&self.messages,
&self.code,
&self.span,
&self.children,
&self.suggestions,
self.args.iter().collect(),
// omit self.sort_span
&self.is_lint,
// omit self.emitted_at
)
}
}
impl Hash for DiagInner {
fn hash<H>(&self, state: &mut H)
where
H: Hasher,
{
self.keys().hash(state);
}
}
impl PartialEq for DiagInner {
fn eq(&self, other: &Self) -> bool {
self.keys() == other.keys()
}
}
/// A "sub"-diagnostic attached to a parent diagnostic.
/// For example, a note attached to an error.
#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
pub struct Subdiag {
pub level: Level,
pub messages: Vec<(DiagMessage, Style)>,
pub span: MultiSpan,
}
/// Used for emitting structured error messages and other diagnostic information.
/// Wraps a `DiagInner`, adding some useful things.
/// - The `dcx` field, allowing it to (a) emit itself, and (b) do a drop check
/// that it has been emitted or cancelled.
/// - The `EmissionGuarantee`, which determines the type returned from `emit`.
///
/// Each constructed `Diag` must be consumed by a function such as `emit`,
/// `cancel`, `delay_as_bug`, or `into_diag`. A panic occurs if a `Diag`
/// is dropped without being consumed by one of these functions.
///
/// If there is some state in a downstream crate you would like to access in
/// the methods of `Diag` here, consider extending `DiagCtxtFlags`.
#[must_use]
pub struct Diag<'a, G: EmissionGuarantee = ErrorGuaranteed> {
pub dcx: DiagCtxtHandle<'a>,
/// Why the `Option`? It is always `Some` until the `Diag` is consumed via
/// `emit`, `cancel`, etc. At that point it is consumed and replaced with
/// `None`. Then `drop` checks that it is `None`; if not, it panics because
/// a diagnostic was built but not used.
///
/// Why the Box? `DiagInner` is a large type, and `Diag` is often used as a
/// return value, especially within the frequently-used `PResult` type. In
/// theory, return value optimization (RVO) should avoid unnecessary
/// copying. In practice, it does not (at the time of writing).
diag: Option<Box<DiagInner>>,
_marker: PhantomData<G>,
}
// Cloning a `Diag` is a recipe for a diagnostic being emitted twice, which
// would be bad.
impl<G> !Clone for Diag<'_, G> {}
rustc_data_structures::static_assert_size!(Diag<'_, ()>, 3 * std::mem::size_of::<usize>());
impl<G: EmissionGuarantee> Deref for Diag<'_, G> {
type Target = DiagInner;
fn deref(&self) -> &DiagInner {
self.diag.as_ref().unwrap()
}
}
impl<G: EmissionGuarantee> DerefMut for Diag<'_, G> {
fn deref_mut(&mut self) -> &mut DiagInner {
self.diag.as_mut().unwrap()
}
}
impl<G: EmissionGuarantee> Debug for Diag<'_, G> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.diag.fmt(f)
}
}
/// `Diag` impls many `&mut self -> &mut Self` methods. Each one modifies an
/// existing diagnostic, either in a standalone fashion, e.g.
/// `err.code(code);`, or in a chained fashion to make multiple modifications,
/// e.g. `err.code(code).span(span);`.
///
/// This macro creates an equivalent `self -> Self` method, with a `with_`
/// prefix. This can be used in a chained fashion when making a new diagnostic,
/// e.g. `let err = struct_err(msg).with_code(code);`, or emitting a new
/// diagnostic, e.g. `struct_err(msg).with_code(code).emit();`.
///
/// Although the latter method can be used to modify an existing diagnostic,
/// e.g. `err = err.with_code(code);`, this should be avoided because the former
/// method gives shorter code, e.g. `err.code(code);`.
///
/// Note: the `with_` methods are added only when needed. If you want to use
/// one and it's not defined, feel free to add it.
///
/// Note: any doc comments must be within the `with_fn!` call.
macro_rules! with_fn {
{
$with_f:ident,
$(#[$attrs:meta])*
pub fn $f:ident(&mut $self:ident, $($name:ident: $ty:ty),* $(,)?) -> &mut Self {
$($body:tt)*
}
} => {
// The original function.
$(#[$attrs])*
#[doc = concat!("See [`Diag::", stringify!($f), "()`].")]
pub fn $f(&mut $self, $($name: $ty),*) -> &mut Self {
$($body)*
}
// The `with_*` variant.
$(#[$attrs])*
#[doc = concat!("See [`Diag::", stringify!($f), "()`].")]
pub fn $with_f(mut $self, $($name: $ty),*) -> Self {
$self.$f($($name),*);
$self
}
};
}
impl<'a, G: EmissionGuarantee> Diag<'a, G> {
#[rustc_lint_diagnostics]
#[track_caller]
pub fn new(dcx: DiagCtxtHandle<'a>, level: Level, message: impl Into<DiagMessage>) -> Self {
Self::new_diagnostic(dcx, DiagInner::new(level, message))
}
/// Allow moving diagnostics between different error tainting contexts
pub fn with_dcx(mut self, dcx: DiagCtxtHandle<'_>) -> Diag<'_, G> {
Diag { dcx, diag: self.diag.take(), _marker: PhantomData }
}
/// Creates a new `Diag` with an already constructed diagnostic.
#[track_caller]
pub(crate) fn new_diagnostic(dcx: DiagCtxtHandle<'a>, diag: DiagInner) -> Self {
debug!("Created new diagnostic");
Self { dcx, diag: Some(Box::new(diag)), _marker: PhantomData }
}
/// Delay emission of this diagnostic as a bug.
///
/// This can be useful in contexts where an error indicates a bug but
/// typically this only happens when other compilation errors have already
/// happened. In those cases this can be used to defer emission of this
/// diagnostic as a bug in the compiler only if no other errors have been
/// emitted.
///
/// In the meantime, though, callsites are required to deal with the "bug"
/// locally in whichever way makes the most sense.
#[rustc_lint_diagnostics]
#[track_caller]
pub fn downgrade_to_delayed_bug(&mut self) {
assert!(
matches!(self.level, Level::Error | Level::DelayedBug),
"downgrade_to_delayed_bug: cannot downgrade {:?} to DelayedBug: not an error",
self.level
);
self.level = Level::DelayedBug;
}
with_fn! { with_span_label,
/// Appends a labeled span to the diagnostic.
///
/// Labels are used to convey additional context for the diagnostic's primary span. They will
/// be shown together with the original diagnostic's span, *not* with spans added by
/// `span_note`, `span_help`, etc. Therefore, if the primary span is not displayable (because
/// the span is `DUMMY_SP` or the source code isn't found), labels will not be displayed
/// either.
///
/// Implementation-wise, the label span is pushed onto the [`MultiSpan`] that was created when
/// the diagnostic was constructed. However, the label span is *not* considered a
/// ["primary span"][`MultiSpan`]; only the `Span` supplied when creating the diagnostic is
/// primary.
#[rustc_lint_diagnostics]
pub fn span_label(&mut self, span: Span, label: impl Into<SubdiagMessage>) -> &mut Self {
let msg = self.subdiagnostic_message_to_diagnostic_message(label);
self.span.push_span_label(span, msg);
self
} }
with_fn! { with_span_labels,
/// Labels all the given spans with the provided label.
/// See [`Self::span_label()`] for more information.
#[rustc_lint_diagnostics]
pub fn span_labels(&mut self, spans: impl IntoIterator<Item = Span>, label: &str) -> &mut Self {
for span in spans {
self.span_label(span, label.to_string());
}
self
} }
#[rustc_lint_diagnostics]
pub fn replace_span_with(&mut self, after: Span, keep_label: bool) -> &mut Self {
let before = self.span.clone();
self.span(after);
for span_label in before.span_labels() {
if let Some(label) = span_label.label {
if span_label.is_primary && keep_label {
self.span.push_span_label(after, label);
} else {
self.span.push_span_label(span_label.span, label);
}
}
}
self
}
#[rustc_lint_diagnostics]
pub fn note_expected_found(
&mut self,
expected_label: &dyn fmt::Display,
expected: DiagStyledString,
found_label: &dyn fmt::Display,
found: DiagStyledString,
) -> &mut Self {
self.note_expected_found_extra(expected_label, expected, found_label, found, &"", &"")
}
#[rustc_lint_diagnostics]
pub fn note_expected_found_extra(
&mut self,
expected_label: &dyn fmt::Display,
expected: DiagStyledString,
found_label: &dyn fmt::Display,
found: DiagStyledString,
expected_extra: &dyn fmt::Display,
found_extra: &dyn fmt::Display,
) -> &mut Self {
let expected_label = expected_label.to_string();
let expected_label = if expected_label.is_empty() {
"expected".to_string()
} else {
format!("expected {expected_label}")
};
let found_label = found_label.to_string();
let found_label = if found_label.is_empty() {
"found".to_string()
} else {
format!("found {found_label}")
};
let (found_padding, expected_padding) = if expected_label.len() > found_label.len() {
(expected_label.len() - found_label.len(), 0)
} else {
(0, found_label.len() - expected_label.len())
};
let mut msg = vec![StringPart::normal(format!(
"{}{} `",
" ".repeat(expected_padding),
expected_label
))];
msg.extend(expected.0);
msg.push(StringPart::normal(format!("`{expected_extra}\n")));
msg.push(StringPart::normal(format!("{}{} `", " ".repeat(found_padding), found_label)));
msg.extend(found.0);
msg.push(StringPart::normal(format!("`{found_extra}")));
// For now, just attach these as notes.
self.highlighted_note(msg);
self
}
#[rustc_lint_diagnostics]
pub fn note_trait_signature(&mut self, name: Symbol, signature: String) -> &mut Self {
self.highlighted_note(vec![
StringPart::normal(format!("`{name}` from trait: `")),
StringPart::highlighted(signature),
StringPart::normal("`"),
]);
self
}
with_fn! { with_note,
/// Add a note attached to this diagnostic.
#[rustc_lint_diagnostics]
pub fn note(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
self.sub(Level::Note, msg, MultiSpan::new());
self
} }
#[rustc_lint_diagnostics]
pub fn highlighted_note(&mut self, msg: Vec<StringPart>) -> &mut Self {
self.sub_with_highlights(Level::Note, msg, MultiSpan::new());
self
}
#[rustc_lint_diagnostics]
pub fn highlighted_span_note(
&mut self,
span: impl Into<MultiSpan>,
msg: Vec<StringPart>,
) -> &mut Self {
self.sub_with_highlights(Level::Note, msg, span.into());
self
}
/// This is like [`Diag::note()`], but it's only printed once.
#[rustc_lint_diagnostics]
pub fn note_once(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
self.sub(Level::OnceNote, msg, MultiSpan::new());
self
}
with_fn! { with_span_note,
/// Prints the span with a note above it.
/// This is like [`Diag::note()`], but it gets its own span.
#[rustc_lint_diagnostics]
pub fn span_note(
&mut self,
sp: impl Into<MultiSpan>,
msg: impl Into<SubdiagMessage>,
) -> &mut Self {
self.sub(Level::Note, msg, sp.into());
self
} }
/// Prints the span with a note above it.
/// This is like [`Diag::note_once()`], but it gets its own span.
#[rustc_lint_diagnostics]
pub fn span_note_once<S: Into<MultiSpan>>(
&mut self,
sp: S,
msg: impl Into<SubdiagMessage>,
) -> &mut Self {
self.sub(Level::OnceNote, msg, sp.into());
self
}
with_fn! { with_warn,
/// Add a warning attached to this diagnostic.
#[rustc_lint_diagnostics]
pub fn warn(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
self.sub(Level::Warning, msg, MultiSpan::new());
self
} }
/// Prints the span with a warning above it.
/// This is like [`Diag::warn()`], but it gets its own span.
#[rustc_lint_diagnostics]
pub fn span_warn<S: Into<MultiSpan>>(
&mut self,
sp: S,
msg: impl Into<SubdiagMessage>,
) -> &mut Self {
self.sub(Level::Warning, msg, sp.into());
self
}
with_fn! { with_help,
/// Add a help message attached to this diagnostic.
#[rustc_lint_diagnostics]
pub fn help(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
self.sub(Level::Help, msg, MultiSpan::new());
self
} }
/// This is like [`Diag::help()`], but it's only printed once.
#[rustc_lint_diagnostics]
pub fn help_once(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
self.sub(Level::OnceHelp, msg, MultiSpan::new());
self
}
/// Add a help message attached to this diagnostic with a customizable highlighted message.
#[rustc_lint_diagnostics]
pub fn highlighted_help(&mut self, msg: Vec<StringPart>) -> &mut Self {
self.sub_with_highlights(Level::Help, msg, MultiSpan::new());
self
}
/// Add a help message attached to this diagnostic with a customizable highlighted message.
#[rustc_lint_diagnostics]
pub fn highlighted_span_help(
&mut self,
span: impl Into<MultiSpan>,
msg: Vec<StringPart>,
) -> &mut Self {
self.sub_with_highlights(Level::Help, msg, span.into());
self
}
/// Prints the span with some help above it.
/// This is like [`Diag::help()`], but it gets its own span.
#[rustc_lint_diagnostics]
pub fn span_help<S: Into<MultiSpan>>(
&mut self,
sp: S,
msg: impl Into<SubdiagMessage>,
) -> &mut Self {
self.sub(Level::Help, msg, sp.into());
self
}
/// Disallow attaching suggestions to this diagnostic.
/// Any suggestions attached e.g. with the `span_suggestion_*` methods
/// (before and after the call to `disable_suggestions`) will be ignored.
#[rustc_lint_diagnostics]
pub fn disable_suggestions(&mut self) -> &mut Self {
self.suggestions = Suggestions::Disabled;
self
}
/// Prevent new suggestions from being added to this diagnostic.
///
/// Suggestions added before the call to `.seal_suggestions()` will be preserved
/// and new suggestions will be ignored.
#[rustc_lint_diagnostics]
pub fn seal_suggestions(&mut self) -> &mut Self {
if let Suggestions::Enabled(suggestions) = &mut self.suggestions {
let suggestions_slice = std::mem::take(suggestions).into_boxed_slice();
self.suggestions = Suggestions::Sealed(suggestions_slice);
}
self
}
/// Helper for pushing to `self.suggestions`.
///
/// A new suggestion is added if suggestions are enabled for this diagnostic.
/// Otherwise, they are ignored.
#[rustc_lint_diagnostics]
fn push_suggestion(&mut self, suggestion: CodeSuggestion) {
for subst in &suggestion.substitutions {
for part in &subst.parts {
let span = part.span;
let call_site = span.ctxt().outer_expn_data().call_site;
if span.in_derive_expansion() && span.overlaps_or_adjacent(call_site) {
// Ignore if spans is from derive macro.
return;
}
}
}
if let Suggestions::Enabled(suggestions) = &mut self.suggestions {
suggestions.push(suggestion);
}
}
with_fn! { with_multipart_suggestion,
/// Show a suggestion that has multiple parts to it.
/// In other words, multiple changes need to be applied as part of this suggestion.
#[rustc_lint_diagnostics]
pub fn multipart_suggestion(
&mut self,
msg: impl Into<SubdiagMessage>,
suggestion: Vec<(Span, String)>,
applicability: Applicability,
) -> &mut Self {
self.multipart_suggestion_with_style(
msg,
suggestion,
applicability,
SuggestionStyle::ShowCode,
)
} }
/// Show a suggestion that has multiple parts to it, always as it's own subdiagnostic.
/// In other words, multiple changes need to be applied as part of this suggestion.
#[rustc_lint_diagnostics]
pub fn multipart_suggestion_verbose(
&mut self,
msg: impl Into<SubdiagMessage>,
suggestion: Vec<(Span, String)>,
applicability: Applicability,
) -> &mut Self {
self.multipart_suggestion_with_style(
msg,
suggestion,
applicability,
SuggestionStyle::ShowAlways,
)
}
/// [`Diag::multipart_suggestion()`] but you can set the [`SuggestionStyle`].
#[rustc_lint_diagnostics]
pub fn multipart_suggestion_with_style(
&mut self,
msg: impl Into<SubdiagMessage>,
mut suggestion: Vec<(Span, String)>,
applicability: Applicability,
style: SuggestionStyle,
) -> &mut Self {
let mut seen = crate::FxHashSet::default();
suggestion.retain(|(span, msg)| seen.insert((span.lo(), span.hi(), msg.clone())));
let parts = suggestion
.into_iter()
.map(|(span, snippet)| SubstitutionPart { snippet, span })
.collect::<Vec<_>>();
assert!(!parts.is_empty());
debug_assert_eq!(
parts.iter().find(|part| part.span.is_empty() && part.snippet.is_empty()),
None,
"Span must not be empty and have no suggestion",
);
debug_assert_eq!(
parts.array_windows().find(|[a, b]| a.span.overlaps(b.span)),
None,
"suggestion must not have overlapping parts",
);
self.push_suggestion(CodeSuggestion {
substitutions: vec![Substitution { parts }],
msg: self.subdiagnostic_message_to_diagnostic_message(msg),
style,
applicability,
});
self
}
/// Prints out a message with for a multipart suggestion without showing the suggested code.
///
/// This is intended to be used for suggestions that are obvious in what the changes need to
/// be from the message, showing the span label inline would be visually unpleasant
/// (marginally overlapping spans or multiline spans) and showing the snippet window wouldn't
/// improve understandability.
#[rustc_lint_diagnostics]
pub fn tool_only_multipart_suggestion(
&mut self,
msg: impl Into<SubdiagMessage>,
suggestion: Vec<(Span, String)>,
applicability: Applicability,
) -> &mut Self {
self.multipart_suggestion_with_style(
msg,
suggestion,
applicability,
SuggestionStyle::CompletelyHidden,
)
}
with_fn! { with_span_suggestion,
/// Prints out a message with a suggested edit of the code.
///
/// In case of short messages and a simple suggestion, rustc displays it as a label:
///
/// ```text
/// try adding parentheses: `(tup.0).1`
/// ```
///
/// The message
///
/// * should not end in any punctuation (a `:` is added automatically)
/// * should not be a question (avoid language like "did you mean")
/// * should not contain any phrases like "the following", "as shown", etc.
/// * may look like "to do xyz, use" or "to do xyz, use abc"
/// * may contain a name of a function, variable, or type, but not whole expressions
///
/// See `CodeSuggestion` for more information.
#[rustc_lint_diagnostics]
pub fn span_suggestion(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
) -> &mut Self {
self.span_suggestion_with_style(
sp,
msg,
suggestion,
applicability,
SuggestionStyle::ShowCode,
);
self
} }
/// [`Diag::span_suggestion()`] but you can set the [`SuggestionStyle`].
#[rustc_lint_diagnostics]
pub fn span_suggestion_with_style(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
style: SuggestionStyle,
) -> &mut Self {
debug_assert!(
!(sp.is_empty() && suggestion.to_string().is_empty()),
"Span must not be empty and have no suggestion"
);
self.push_suggestion(CodeSuggestion {
substitutions: vec![Substitution {
parts: vec![SubstitutionPart { snippet: suggestion.to_string(), span: sp }],
}],
msg: self.subdiagnostic_message_to_diagnostic_message(msg),
style,
applicability,
});
self
}
with_fn! { with_span_suggestion_verbose,
/// Always show the suggested change.
#[rustc_lint_diagnostics]
pub fn span_suggestion_verbose(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
) -> &mut Self {
self.span_suggestion_with_style(
sp,
msg,
suggestion,
applicability,
SuggestionStyle::ShowAlways,
);
self
} }
with_fn! { with_span_suggestions,
/// Prints out a message with multiple suggested edits of the code.
/// See also [`Diag::span_suggestion()`].
#[rustc_lint_diagnostics]
pub fn span_suggestions(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestions: impl IntoIterator<Item = String>,
applicability: Applicability,
) -> &mut Self {
self.span_suggestions_with_style(
sp,
msg,
suggestions,
applicability,
SuggestionStyle::ShowCode,
)
} }
#[rustc_lint_diagnostics]
pub fn span_suggestions_with_style(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestions: impl IntoIterator<Item = String>,
applicability: Applicability,
style: SuggestionStyle,
) -> &mut Self {
let substitutions = suggestions
.into_iter()
.map(|snippet| {
debug_assert!(
!(sp.is_empty() && snippet.is_empty()),
"Span must not be empty and have no suggestion"
);
Substitution { parts: vec![SubstitutionPart { snippet, span: sp }] }
})
.collect();
self.push_suggestion(CodeSuggestion {
substitutions,
msg: self.subdiagnostic_message_to_diagnostic_message(msg),
style,
applicability,
});
self
}
/// Prints out a message with multiple suggested edits of the code, where each edit consists of
/// multiple parts.
/// See also [`Diag::multipart_suggestion()`].
#[rustc_lint_diagnostics]
pub fn multipart_suggestions(
&mut self,
msg: impl Into<SubdiagMessage>,
suggestions: impl IntoIterator<Item = Vec<(Span, String)>>,
applicability: Applicability,
) -> &mut Self {
let substitutions = suggestions
.into_iter()
.map(|sugg| {
let mut parts = sugg
.into_iter()
.map(|(span, snippet)| SubstitutionPart { snippet, span })
.collect::<Vec<_>>();
parts.sort_unstable_by_key(|part| part.span);
assert!(!parts.is_empty());
debug_assert_eq!(
parts.iter().find(|part| part.span.is_empty() && part.snippet.is_empty()),
None,
"Span must not be empty and have no suggestion",
);
debug_assert_eq!(
parts.array_windows().find(|[a, b]| a.span.overlaps(b.span)),
None,
"suggestion must not have overlapping parts",
);
Substitution { parts }
})
.collect();
self.push_suggestion(CodeSuggestion {
substitutions,
msg: self.subdiagnostic_message_to_diagnostic_message(msg),
style: SuggestionStyle::ShowCode,
applicability,
});
self
}
with_fn! { with_span_suggestion_short,
/// Prints out a message with a suggested edit of the code. If the suggestion is presented
/// inline, it will only show the message and not the suggestion.
///
/// See `CodeSuggestion` for more information.
#[rustc_lint_diagnostics]
pub fn span_suggestion_short(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
) -> &mut Self {
self.span_suggestion_with_style(
sp,
msg,
suggestion,
applicability,
SuggestionStyle::HideCodeInline,
);
self
} }
/// Prints out a message for a suggestion without showing the suggested code.
///
/// This is intended to be used for suggestions that are obvious in what the changes need to
/// be from the message, showing the span label inline would be visually unpleasant
/// (marginally overlapping spans or multiline spans) and showing the snippet window wouldn't
/// improve understandability.
#[rustc_lint_diagnostics]
pub fn span_suggestion_hidden(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
) -> &mut Self {
self.span_suggestion_with_style(
sp,
msg,
suggestion,
applicability,
SuggestionStyle::HideCodeAlways,
);
self
}
with_fn! { with_tool_only_span_suggestion,
/// Adds a suggestion to the JSON output that will not be shown in the CLI.
///
/// This is intended to be used for suggestions that are *very* obvious in what the changes
/// need to be from the message, but we still want other tools to be able to apply them.
#[rustc_lint_diagnostics]
pub fn tool_only_span_suggestion(
&mut self,
sp: Span,
msg: impl Into<SubdiagMessage>,
suggestion: impl ToString,
applicability: Applicability,
) -> &mut Self {
self.span_suggestion_with_style(
sp,
msg,
suggestion,
applicability,
SuggestionStyle::CompletelyHidden,
);
self
} }
/// Add a subdiagnostic from a type that implements `Subdiagnostic` (see
/// [rustc_macros::Subdiagnostic]). Performs eager translation of any translatable messages
/// used in the subdiagnostic, so suitable for use with repeated messages (i.e. re-use of
/// interpolated variables).
#[rustc_lint_diagnostics]
pub fn subdiagnostic(&mut self, subdiagnostic: impl Subdiagnostic) -> &mut Self {
let dcx = self.dcx;
subdiagnostic.add_to_diag_with(self, &|diag, msg| {
let args = diag.args.iter();
let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
dcx.eagerly_translate(msg, args)
});
self
}
with_fn! { with_span,
/// Add a span.
#[rustc_lint_diagnostics]
pub fn span(&mut self, sp: impl Into<MultiSpan>) -> &mut Self {
self.span = sp.into();
if let Some(span) = self.span.primary_span() {
self.sort_span = span;
}
self
} }
#[rustc_lint_diagnostics]
pub fn is_lint(&mut self, name: String, has_future_breakage: bool) -> &mut Self {
self.is_lint = Some(IsLint { name, has_future_breakage });
self
}
with_fn! { with_code,
/// Add an error code.
#[rustc_lint_diagnostics]
pub fn code(&mut self, code: ErrCode) -> &mut Self {
self.code = Some(code);
self
} }
with_fn! { with_primary_message,
/// Add a primary message.
#[rustc_lint_diagnostics]
pub fn primary_message(&mut self, msg: impl Into<DiagMessage>) -> &mut Self {
self.messages[0] = (msg.into(), Style::NoStyle);
self
} }
with_fn! { with_arg,
/// Add an argument.
#[rustc_lint_diagnostics]
pub fn arg(
&mut self,
name: impl Into<DiagArgName>,
arg: impl IntoDiagArg,
) -> &mut Self {
self.deref_mut().arg(name, arg);
self
} }
/// Helper function that takes a `SubdiagMessage` and returns a `DiagMessage` by
/// combining it with the primary message of the diagnostic (if translatable, otherwise it just
/// passes the user's string along).
pub(crate) fn subdiagnostic_message_to_diagnostic_message(
&self,
attr: impl Into<SubdiagMessage>,
) -> DiagMessage {
self.deref().subdiagnostic_message_to_diagnostic_message(attr)
}
/// Convenience function for internal use, clients should use one of the
/// public methods above.
///
/// Used by `proc_macro_server` for implementing `server::Diagnostic`.
pub fn sub(&mut self, level: Level, message: impl Into<SubdiagMessage>, span: MultiSpan) {
self.deref_mut().sub(level, message, span);
}
/// Convenience function for internal use, clients should use one of the
/// public methods above.
fn sub_with_highlights(&mut self, level: Level, messages: Vec<StringPart>, span: MultiSpan) {
let messages = messages
.into_iter()
.map(|m| (self.subdiagnostic_message_to_diagnostic_message(m.content), m.style))
.collect();
let sub = Subdiag { level, messages, span };
self.children.push(sub);
}
/// Takes the diagnostic. For use by methods that consume the Diag: `emit`,
/// `cancel`, etc. Afterwards, `drop` is the only code that will be run on
/// `self`.
fn take_diag(&mut self) -> DiagInner {
Box::into_inner(self.diag.take().unwrap())
}
/// Most `emit_producing_guarantee` functions use this as a starting point.
fn emit_producing_nothing(mut self) {
let diag = self.take_diag();
self.dcx.emit_diagnostic(diag);
}
/// `ErrorGuaranteed::emit_producing_guarantee` uses this.
fn emit_producing_error_guaranteed(mut self) -> ErrorGuaranteed {
let diag = self.take_diag();
// The only error levels that produce `ErrorGuaranteed` are
// `Error` and `DelayedBug`. But `DelayedBug` should never occur here
// because delayed bugs have their level changed to `Bug` when they are
// actually printed, so they produce an ICE.
//
// (Also, even though `level` isn't `pub`, the whole `DiagInner` could
// be overwritten with a new one thanks to `DerefMut`. So this assert
// protects against that, too.)
assert!(
matches!(diag.level, Level::Error | Level::DelayedBug),
"invalid diagnostic level ({:?})",
diag.level,
);
let guar = self.dcx.emit_diagnostic(diag);
guar.unwrap()
}
/// Emit and consume the diagnostic.
#[track_caller]
pub fn emit(self) -> G::EmitResult {
G::emit_producing_guarantee(self)
}
/// Emit the diagnostic unless `delay` is true,
/// in which case the emission will be delayed as a bug.
///
/// See `emit` and `delay_as_bug` for details.
#[track_caller]
pub fn emit_unless(mut self, delay: bool) -> G::EmitResult {
if delay {
self.downgrade_to_delayed_bug();
}
self.emit()
}
/// Cancel and consume the diagnostic. (A diagnostic must either be emitted or
/// cancelled or it will panic when dropped).
pub fn cancel(mut self) {
self.diag = None;
drop(self);
}
/// See `DiagCtxt::stash_diagnostic` for details.
pub fn stash(mut self, span: Span, key: StashKey) -> Option<ErrorGuaranteed> {
let diag = self.take_diag();
self.dcx.stash_diagnostic(span, key, diag)
}
/// Delay emission of this diagnostic as a bug.
///
/// This can be useful in contexts where an error indicates a bug but
/// typically this only happens when other compilation errors have already
/// happened. In those cases this can be used to defer emission of this
/// diagnostic as a bug in the compiler only if no other errors have been
/// emitted.
///
/// In the meantime, though, callsites are required to deal with the "bug"
/// locally in whichever way makes the most sense.
#[track_caller]
pub fn delay_as_bug(mut self) -> G::EmitResult {
self.downgrade_to_delayed_bug();
self.emit()
}
}
/// Destructor bomb: every `Diag` must be consumed (emitted, cancelled, etc.)
/// or we emit a bug.
impl<G: EmissionGuarantee> Drop for Diag<'_, G> {
fn drop(&mut self) {
match self.diag.take() {
Some(diag) if !panicking() => {
self.dcx.emit_diagnostic(DiagInner::new(
Level::Bug,
DiagMessage::from("the following error was constructed but not emitted"),
));
self.dcx.emit_diagnostic(*diag);
panic!("error was constructed but not emitted");
}
_ => {}
}
}
}
#[macro_export]
macro_rules! struct_span_code_err {
($dcx:expr, $span:expr, $code:expr, $($message:tt)*) => ({
$dcx.struct_span_err($span, format!($($message)*)).with_code($code)
})
}