rust/compiler/rustc_errors/src/diagnostic_builder.rs
2020-08-30 18:45:07 +03:00

453 lines
14 KiB
Rust

use crate::{Applicability, Handler, Level, StashKey};
use crate::{Diagnostic, DiagnosticId, DiagnosticStyledString};
use rustc_span::{MultiSpan, Span};
use std::fmt::{self, Debug};
use std::ops::{Deref, DerefMut};
use std::thread::panicking;
use tracing::debug;
/// Used for emitting structured error messages and other diagnostic information.
///
/// If there is some state in a downstream crate you would like to
/// access in the methods of `DiagnosticBuilder` here, consider
/// extending `HandlerFlags`, accessed via `self.handler.flags`.
#[must_use]
#[derive(Clone)]
pub struct DiagnosticBuilder<'a>(Box<DiagnosticBuilderInner<'a>>);
/// This is a large type, and 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). The split between `DiagnosticBuilder` and
/// `DiagnosticBuilderInner` exists to avoid many `memcpy` calls.
#[must_use]
#[derive(Clone)]
struct DiagnosticBuilderInner<'a> {
handler: &'a Handler,
diagnostic: Diagnostic,
allow_suggestions: bool,
}
/// In general, the `DiagnosticBuilder` uses deref to allow access to
/// the fields and methods of the embedded `diagnostic` in a
/// transparent way. *However,* many of the methods are intended to
/// be used in a chained way, and hence ought to return `self`. In
/// that case, we can't just naively forward to the method on the
/// `diagnostic`, because the return type would be a `&Diagnostic`
/// instead of a `&DiagnosticBuilder<'a>`. This `forward!` macro makes
/// it easy to declare such methods on the builder.
macro_rules! forward {
// Forward pattern for &self -> &Self
(
$(#[$attrs:meta])*
pub fn $n:ident(&self, $($name:ident: $ty:ty),* $(,)?) -> &Self
) => {
$(#[$attrs])*
pub fn $n(&self, $($name: $ty),*) -> &Self {
self.diagnostic.$n($($name),*);
self
}
};
// Forward pattern for &mut self -> &mut Self
(
$(#[$attrs:meta])*
pub fn $n:ident(&mut self, $($name:ident: $ty:ty),* $(,)?) -> &mut Self
) => {
$(#[$attrs])*
pub fn $n(&mut self, $($name: $ty),*) -> &mut Self {
self.0.diagnostic.$n($($name),*);
self
}
};
// Forward pattern for &mut self -> &mut Self, with S: Into<MultiSpan>
// type parameter. No obvious way to make this more generic.
(
$(#[$attrs:meta])*
pub fn $n:ident<S: Into<MultiSpan>>(
&mut self,
$($name:ident: $ty:ty),*
$(,)?
) -> &mut Self
) => {
$(#[$attrs])*
pub fn $n<S: Into<MultiSpan>>(&mut self, $($name: $ty),*) -> &mut Self {
self.0.diagnostic.$n($($name),*);
self
}
};
}
impl<'a> Deref for DiagnosticBuilder<'a> {
type Target = Diagnostic;
fn deref(&self) -> &Diagnostic {
&self.0.diagnostic
}
}
impl<'a> DerefMut for DiagnosticBuilder<'a> {
fn deref_mut(&mut self) -> &mut Diagnostic {
&mut self.0.diagnostic
}
}
impl<'a> DiagnosticBuilder<'a> {
/// Emit the diagnostic.
pub fn emit(&mut self) {
self.0.handler.emit_diagnostic(&self);
self.cancel();
}
/// 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.
pub fn emit_unless(&mut self, delay: bool) {
if delay {
self.delay_as_bug();
} else {
self.emit();
}
}
/// Stashes diagnostic for possible later improvement in a different,
/// later stage of the compiler. The diagnostic can be accessed with
/// the provided `span` and `key` through `.steal_diagnostic` on `Handler`.
///
/// As with `buffer`, this is unless the handler has disabled such buffering.
pub fn stash(self, span: Span, key: StashKey) {
if let Some((diag, handler)) = self.into_diagnostic() {
handler.stash_diagnostic(span, key, diag);
}
}
/// Converts the builder to a `Diagnostic` for later emission,
/// unless handler has disabled such buffering.
pub fn into_diagnostic(mut self) -> Option<(Diagnostic, &'a Handler)> {
if self.0.handler.flags.dont_buffer_diagnostics
|| self.0.handler.flags.treat_err_as_bug.is_some()
{
self.emit();
return None;
}
let handler = self.0.handler;
// We must use `Level::Cancelled` for `dummy` to avoid an ICE about an
// unused diagnostic.
let dummy = Diagnostic::new(Level::Cancelled, "");
let diagnostic = std::mem::replace(&mut self.0.diagnostic, dummy);
// Logging here is useful to help track down where in logs an error was
// actually emitted.
debug!("buffer: diagnostic={:?}", diagnostic);
Some((diagnostic, handler))
}
/// Buffers the diagnostic for later emission,
/// unless handler has disabled such buffering.
pub fn buffer(self, buffered_diagnostics: &mut Vec<Diagnostic>) {
buffered_diagnostics.extend(self.into_diagnostic().map(|(diag, _)| diag));
}
/// Convenience function for internal use, clients should use one of the
/// span_* methods instead.
pub fn sub<S: Into<MultiSpan>>(
&mut self,
level: Level,
message: &str,
span: Option<S>,
) -> &mut Self {
let span = span.map(|s| s.into()).unwrap_or_else(MultiSpan::new);
self.0.diagnostic.sub(level, message, span, None);
self
}
/// 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.
pub fn delay_as_bug(&mut self) {
self.level = Level::Bug;
self.0.handler.delay_as_bug(self.0.diagnostic.clone());
self.cancel();
}
/// Adds a span/label to be included in the resulting snippet.
///
/// This is pushed onto the [`MultiSpan`] that was created when the diagnostic
/// was first built. That means it will be shown together with the original
/// span/label, *not* a span added by one of the `span_{note,warn,help,suggestions}` methods.
///
/// This span is *not* considered a ["primary span"][`MultiSpan`]; only
/// the `Span` supplied when creating the diagnostic is primary.
///
/// [`MultiSpan`]: ../rustc_span/struct.MultiSpan.html
pub fn span_label(&mut self, span: Span, label: impl Into<String>) -> &mut Self {
self.0.diagnostic.span_label(span, label);
self
}
/// Labels all the given spans with the provided label.
/// See `span_label` for more information.
pub fn span_labels(
&mut self,
spans: impl IntoIterator<Item = Span>,
label: impl AsRef<str>,
) -> &mut Self {
let label = label.as_ref();
for span in spans {
self.0.diagnostic.span_label(span, label);
}
self
}
forward!(pub fn note_expected_found(
&mut self,
expected_label: &dyn fmt::Display,
expected: DiagnosticStyledString,
found_label: &dyn fmt::Display,
found: DiagnosticStyledString,
) -> &mut Self);
forward!(pub fn note_expected_found_extra(
&mut self,
expected_label: &dyn fmt::Display,
expected: DiagnosticStyledString,
found_label: &dyn fmt::Display,
found: DiagnosticStyledString,
expected_extra: &dyn fmt::Display,
found_extra: &dyn fmt::Display,
) -> &mut Self);
forward!(pub fn note_unsuccessfull_coercion(
&mut self,
expected: DiagnosticStyledString,
found: DiagnosticStyledString,
) -> &mut Self);
forward!(pub fn note(&mut self, msg: &str) -> &mut Self);
forward!(pub fn span_note<S: Into<MultiSpan>>(
&mut self,
sp: S,
msg: &str,
) -> &mut Self);
forward!(pub fn warn(&mut self, msg: &str) -> &mut Self);
forward!(pub fn span_warn<S: Into<MultiSpan>>(&mut self, sp: S, msg: &str) -> &mut Self);
forward!(pub fn help(&mut self, msg: &str) -> &mut Self);
forward!(pub fn span_help<S: Into<MultiSpan>>(
&mut self,
sp: S,
msg: &str,
) -> &mut Self);
pub fn multipart_suggestion(
&mut self,
msg: &str,
suggestion: Vec<(Span, String)>,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.multipart_suggestion(msg, suggestion, applicability);
self
}
pub fn multipart_suggestions(
&mut self,
msg: &str,
suggestions: Vec<Vec<(Span, String)>>,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.multipart_suggestions(msg, suggestions, applicability);
self
}
pub fn tool_only_multipart_suggestion(
&mut self,
msg: &str,
suggestion: Vec<(Span, String)>,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.tool_only_multipart_suggestion(msg, suggestion, applicability);
self
}
pub fn span_suggestion(
&mut self,
sp: Span,
msg: &str,
suggestion: String,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.span_suggestion(sp, msg, suggestion, applicability);
self
}
pub fn span_suggestions(
&mut self,
sp: Span,
msg: &str,
suggestions: impl Iterator<Item = String>,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.span_suggestions(sp, msg, suggestions, applicability);
self
}
pub fn span_suggestion_short(
&mut self,
sp: Span,
msg: &str,
suggestion: String,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.span_suggestion_short(sp, msg, suggestion, applicability);
self
}
pub fn span_suggestion_verbose(
&mut self,
sp: Span,
msg: &str,
suggestion: String,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.span_suggestion_verbose(sp, msg, suggestion, applicability);
self
}
pub fn span_suggestion_hidden(
&mut self,
sp: Span,
msg: &str,
suggestion: String,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.span_suggestion_hidden(sp, msg, suggestion, applicability);
self
}
pub fn tool_only_span_suggestion(
&mut self,
sp: Span,
msg: &str,
suggestion: String,
applicability: Applicability,
) -> &mut Self {
if !self.0.allow_suggestions {
return self;
}
self.0.diagnostic.tool_only_span_suggestion(sp, msg, suggestion, applicability);
self
}
forward!(pub fn set_span<S: Into<MultiSpan>>(&mut self, sp: S) -> &mut Self);
forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);
pub fn allow_suggestions(&mut self, allow: bool) -> &mut Self {
self.0.allow_suggestions = allow;
self
}
/// Convenience function for internal use, clients should use one of the
/// struct_* methods on Handler.
crate fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
DiagnosticBuilder::new_with_code(handler, level, None, message)
}
/// Convenience function for internal use, clients should use one of the
/// struct_* methods on Handler.
crate fn new_with_code(
handler: &'a Handler,
level: Level,
code: Option<DiagnosticId>,
message: &str,
) -> DiagnosticBuilder<'a> {
let diagnostic = Diagnostic::new_with_code(level, code, message);
DiagnosticBuilder::new_diagnostic(handler, diagnostic)
}
/// Creates a new `DiagnosticBuilder` with an already constructed
/// diagnostic.
crate fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic) -> DiagnosticBuilder<'a> {
debug!("Created new diagnostic");
DiagnosticBuilder(Box::new(DiagnosticBuilderInner {
handler,
diagnostic,
allow_suggestions: true,
}))
}
}
impl<'a> Debug for DiagnosticBuilder<'a> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.diagnostic.fmt(f)
}
}
/// Destructor bomb - a `DiagnosticBuilder` must be either emitted or canceled
/// or we emit a bug.
impl<'a> Drop for DiagnosticBuilder<'a> {
fn drop(&mut self) {
if !panicking() && !self.cancelled() {
let mut db = DiagnosticBuilder::new(
self.0.handler,
Level::Bug,
"the following error was constructed but not emitted",
);
db.emit();
self.emit();
panic!();
}
}
}
#[macro_export]
macro_rules! struct_span_err {
($session:expr, $span:expr, $code:ident, $($message:tt)*) => ({
$session.struct_span_err_with_code(
$span,
&format!($($message)*),
$crate::error_code!($code),
)
})
}
#[macro_export]
macro_rules! error_code {
($code:ident) => {{ $crate::DiagnosticId::Error(stringify!($code).to_owned()) }};
}