/
diagnostics.rs
528 lines (499 loc) · 18.9 KB
/
diagnostics.rs
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use crate::ast;
use crate::ast::{BlockCheckMode, Expr, ExprKind, Item, ItemKind, Pat, PatKind, QSelf, Ty, TyKind};
use crate::parse::parser::{BlockMode, PathStyle, TokenType, SemiColonMode};
use crate::parse::token;
use crate::parse::PResult;
use crate::parse::Parser;
use crate::print::pprust;
use crate::ptr::P;
use crate::symbol::keywords;
use crate::ThinVec;
use errors::{Applicability, DiagnosticBuilder};
use syntax_pos::Span;
use log::debug;
pub trait RecoverQPath: Sized + 'static {
const PATH_STYLE: PathStyle = PathStyle::Expr;
fn to_ty(&self) -> Option<P<Ty>>;
fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self;
}
impl RecoverQPath for Ty {
const PATH_STYLE: PathStyle = PathStyle::Type;
fn to_ty(&self) -> Option<P<Ty>> {
Some(P(self.clone()))
}
fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
Self {
span: path.span,
node: TyKind::Path(qself, path),
id: ast::DUMMY_NODE_ID,
}
}
}
impl RecoverQPath for Pat {
fn to_ty(&self) -> Option<P<Ty>> {
self.to_ty()
}
fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
Self {
span: path.span,
node: PatKind::Path(qself, path),
id: ast::DUMMY_NODE_ID,
}
}
}
impl RecoverQPath for Expr {
fn to_ty(&self) -> Option<P<Ty>> {
self.to_ty()
}
fn recovered(qself: Option<QSelf>, path: ast::Path) -> Self {
Self {
span: path.span,
node: ExprKind::Path(qself, path),
attrs: ThinVec::new(),
id: ast::DUMMY_NODE_ID,
}
}
}
impl<'a> Parser<'a> {
crate fn maybe_report_ambiguous_plus(
&mut self,
allow_plus: bool,
impl_dyn_multi: bool,
ty: &Ty,
) {
if !allow_plus && impl_dyn_multi {
let sum_with_parens = format!("({})", pprust::ty_to_string(&ty));
self.struct_span_err(ty.span, "ambiguous `+` in a type")
.span_suggestion(
ty.span,
"use parentheses to disambiguate",
sum_with_parens,
Applicability::MachineApplicable,
)
.emit();
}
}
crate fn maybe_recover_from_bad_type_plus(
&mut self,
allow_plus: bool,
ty: &Ty,
) -> PResult<'a, ()> {
// Do not add `+` to expected tokens.
if !allow_plus || !self.token.is_like_plus() {
return Ok(());
}
self.bump(); // `+`
let bounds = self.parse_generic_bounds(None)?;
let sum_span = ty.span.to(self.prev_span);
let mut err = struct_span_err!(
self.sess.span_diagnostic,
sum_span,
E0178,
"expected a path on the left-hand side of `+`, not `{}`",
pprust::ty_to_string(ty)
);
match ty.node {
TyKind::Rptr(ref lifetime, ref mut_ty) => {
let sum_with_parens = pprust::to_string(|s| {
use crate::print::pprust::PrintState;
s.s.word("&")?;
s.print_opt_lifetime(lifetime)?;
s.print_mutability(mut_ty.mutbl)?;
s.popen()?;
s.print_type(&mut_ty.ty)?;
s.print_type_bounds(" +", &bounds)?;
s.pclose()
});
err.span_suggestion(
sum_span,
"try adding parentheses",
sum_with_parens,
Applicability::MachineApplicable,
);
}
TyKind::Ptr(..) | TyKind::BareFn(..) => {
err.span_label(sum_span, "perhaps you forgot parentheses?");
}
_ => {
err.span_label(sum_span, "expected a path");
}
}
err.emit();
Ok(())
}
/// Try to recover from associated item paths like `[T]::AssocItem`/`(T, U)::AssocItem`.
/// Attempt to convert the base expression/pattern/type into a type, parse the `::AssocItem`
/// tail, and combine them into a `<Ty>::AssocItem` expression/pattern/type.
crate fn maybe_recover_from_bad_qpath<T: RecoverQPath>(
&mut self,
base: P<T>,
allow_recovery: bool,
) -> PResult<'a, P<T>> {
// Do not add `::` to expected tokens.
if allow_recovery && self.token == token::ModSep {
if let Some(ty) = base.to_ty() {
return self.maybe_recover_from_bad_qpath_stage_2(ty.span, ty);
}
}
Ok(base)
}
/// Given an already parsed `Ty` parse the `::AssocItem` tail and
/// combine them into a `<Ty>::AssocItem` expression/pattern/type.
crate fn maybe_recover_from_bad_qpath_stage_2<T: RecoverQPath>(
&mut self,
ty_span: Span,
ty: P<Ty>,
) -> PResult<'a, P<T>> {
self.expect(&token::ModSep)?;
let mut path = ast::Path {
segments: Vec::new(),
span: syntax_pos::DUMMY_SP,
};
self.parse_path_segments(&mut path.segments, T::PATH_STYLE)?;
path.span = ty_span.to(self.prev_span);
let ty_str = self
.sess
.source_map()
.span_to_snippet(ty_span)
.unwrap_or_else(|_| pprust::ty_to_string(&ty));
self.diagnostic()
.struct_span_err(path.span, "missing angle brackets in associated item path")
.span_suggestion(
// this is a best-effort recovery
path.span,
"try",
format!("<{}>::{}", ty_str, path),
Applicability::MaybeIncorrect,
)
.emit();
let path_span = ty_span.shrink_to_hi(); // use an empty path since `position` == 0
Ok(P(T::recovered(
Some(QSelf {
ty,
path_span,
position: 0,
}),
path,
)))
}
crate fn maybe_consume_incorrect_semicolon(&mut self, items: &[P<Item>]) -> bool {
if self.eat(&token::Semi) {
let mut err = self.struct_span_err(self.prev_span, "expected item, found `;`");
err.span_suggestion_short(
self.prev_span,
"remove this semicolon",
String::new(),
Applicability::MachineApplicable,
);
if !items.is_empty() {
let previous_item = &items[items.len() - 1];
let previous_item_kind_name = match previous_item.node {
// say "braced struct" because tuple-structs and
// braceless-empty-struct declarations do take a semicolon
ItemKind::Struct(..) => Some("braced struct"),
ItemKind::Enum(..) => Some("enum"),
ItemKind::Trait(..) => Some("trait"),
ItemKind::Union(..) => Some("union"),
_ => None,
};
if let Some(name) = previous_item_kind_name {
err.help(&format!(
"{} declarations are not followed by a semicolon",
name
));
}
}
err.emit();
true
} else {
false
}
}
/// Consume alternative await syntaxes like `await <expr>`, `await? <expr>`, `await(<expr>)`
/// and `await { <expr> }`.
crate fn parse_incorrect_await_syntax(
&mut self,
lo: Span,
await_sp: Span,
) -> PResult<'a, (Span, ExprKind)> {
let is_question = self.eat(&token::Question); // Handle `await? <expr>`.
let expr = if self.token == token::OpenDelim(token::Brace) {
// Handle `await { <expr> }`.
// This needs to be handled separatedly from the next arm to avoid
// interpreting `await { <expr> }?` as `<expr>?.await`.
self.parse_block_expr(
None,
self.span,
BlockCheckMode::Default,
ThinVec::new(),
)
} else {
self.parse_expr()
}.map_err(|mut err| {
err.span_label(await_sp, "while parsing this incorrect await expression");
err
})?;
let expr_str = self.sess.source_map().span_to_snippet(expr.span)
.unwrap_or_else(|_| pprust::expr_to_string(&expr));
let suggestion = format!("{}.await{}", expr_str, if is_question { "?" } else { "" });
let sp = lo.to(expr.span);
let app = match expr.node {
ExprKind::Try(_) => Applicability::MaybeIncorrect, // `await <expr>?`
_ => Applicability::MachineApplicable,
};
self.struct_span_err(sp, "incorrect use of `await`")
.span_suggestion(sp, "`await` is a postfix operation", suggestion, app)
.emit();
Ok((sp, ExprKind::Await(ast::AwaitOrigin::FieldLike, expr)))
}
/// If encountering `future.await()`, consume and emit error.
crate fn recover_from_await_method_call(&mut self) {
if self.token == token::OpenDelim(token::Paren) &&
self.look_ahead(1, |t| t == &token::CloseDelim(token::Paren))
{
// future.await()
let lo = self.span;
self.bump(); // (
let sp = lo.to(self.span);
self.bump(); // )
let mut err = self.struct_span_err(sp, "incorrect use of `await`");
err.span_suggestion(
sp,
"`await` is not a method call, remove the parentheses",
String::new(),
Applicability::MachineApplicable,
);
err.emit()
}
}
crate fn could_ascription_be_path(&self, node: &ast::ExprKind) -> bool {
self.token.is_ident() &&
if let ast::ExprKind::Path(..) = node { true } else { false } &&
!self.token.is_reserved_ident() && // v `foo:bar(baz)`
self.look_ahead(1, |t| t == &token::OpenDelim(token::Paren)) ||
self.look_ahead(1, |t| t == &token::Lt) && // `foo:bar<baz`
self.look_ahead(2, |t| t.is_ident()) ||
self.look_ahead(1, |t| t == &token::Colon) && // `foo:bar:baz`
self.look_ahead(2, |t| t.is_ident()) ||
self.look_ahead(1, |t| t == &token::ModSep) && // `foo:bar::baz`
self.look_ahead(2, |t| t.is_ident())
}
crate fn bad_type_ascription(
&self,
err: &mut DiagnosticBuilder<'a>,
lhs_span: Span,
cur_op_span: Span,
next_sp: Span,
maybe_path: bool,
) {
err.span_label(self.span, "expecting a type here because of type ascription");
let cm = self.sess.source_map();
let next_pos = cm.lookup_char_pos(next_sp.lo());
let op_pos = cm.lookup_char_pos(cur_op_span.hi());
if op_pos.line != next_pos.line {
err.span_suggestion(
cur_op_span,
"try using a semicolon",
";".to_string(),
Applicability::MaybeIncorrect,
);
} else {
if maybe_path {
err.span_suggestion(
cur_op_span,
"maybe you meant to write a path separator here",
"::".to_string(),
Applicability::MaybeIncorrect,
);
} else {
err.note("type ascription is a nightly-only feature that lets \
you annotate an expression with a type: `<expr>: <type>`");
err.span_note(
lhs_span,
"this expression expects an ascribed type after the colon",
);
err.help("this might be indicative of a syntax error elsewhere");
}
}
}
crate fn recover_seq_parse_error(
&mut self,
delim: token::DelimToken,
lo: Span,
result: PResult<'a, P<Expr>>,
) -> P<Expr> {
match result {
Ok(x) => x,
Err(mut err) => {
err.emit();
// recover from parse error
self.consume_block(delim);
self.mk_expr(lo.to(self.prev_span), ExprKind::Err, ThinVec::new())
}
}
}
crate fn recover_closing_delimiter(
&mut self,
tokens: &[token::Token],
mut err: DiagnosticBuilder<'a>,
) -> PResult<'a, bool> {
let mut pos = None;
// we want to use the last closing delim that would apply
for (i, unmatched) in self.unclosed_delims.iter().enumerate().rev() {
if tokens.contains(&token::CloseDelim(unmatched.expected_delim))
&& Some(self.span) > unmatched.unclosed_span
{
pos = Some(i);
}
}
match pos {
Some(pos) => {
// Recover and assume that the detected unclosed delimiter was meant for
// this location. Emit the diagnostic and act as if the delimiter was
// present for the parser's sake.
// Don't attempt to recover from this unclosed delimiter more than once.
let unmatched = self.unclosed_delims.remove(pos);
let delim = TokenType::Token(token::CloseDelim(unmatched.expected_delim));
// We want to suggest the inclusion of the closing delimiter where it makes
// the most sense, which is immediately after the last token:
//
// {foo(bar {}}
// - ^
// | |
// | help: `)` may belong here (FIXME: #58270)
// |
// unclosed delimiter
if let Some(sp) = unmatched.unclosed_span {
err.span_label(sp, "unclosed delimiter");
}
err.span_suggestion_short(
self.sess.source_map().next_point(self.prev_span),
&format!("{} may belong here", delim.to_string()),
delim.to_string(),
Applicability::MaybeIncorrect,
);
err.emit();
self.expected_tokens.clear(); // reduce errors
Ok(true)
}
_ => Err(err),
}
}
/// Recover from `pub` keyword in places where it seems _reasonable_ but isn't valid.
crate fn eat_bad_pub(&mut self) {
if self.token.is_keyword(keywords::Pub) {
match self.parse_visibility(false) {
Ok(vis) => {
let mut err = self.diagnostic()
.struct_span_err(vis.span, "unnecessary visibility qualifier");
err.span_label(vis.span, "`pub` not permitted here");
err.emit();
}
Err(mut err) => err.emit(),
}
}
}
// Eat tokens until we can be relatively sure we reached the end of the
// statement. This is something of a best-effort heuristic.
//
// We terminate when we find an unmatched `}` (without consuming it).
crate fn recover_stmt(&mut self) {
self.recover_stmt_(SemiColonMode::Ignore, BlockMode::Ignore)
}
// If `break_on_semi` is `Break`, then we will stop consuming tokens after
// finding (and consuming) a `;` outside of `{}` or `[]` (note that this is
// approximate - it can mean we break too early due to macros, but that
// should only lead to sub-optimal recovery, not inaccurate parsing).
//
// If `break_on_block` is `Break`, then we will stop consuming tokens
// after finding (and consuming) a brace-delimited block.
crate fn recover_stmt_(&mut self, break_on_semi: SemiColonMode, break_on_block: BlockMode) {
let mut brace_depth = 0;
let mut bracket_depth = 0;
let mut in_block = false;
debug!("recover_stmt_ enter loop (semi={:?}, block={:?})",
break_on_semi, break_on_block);
loop {
debug!("recover_stmt_ loop {:?}", self.token);
match self.token {
token::OpenDelim(token::DelimToken::Brace) => {
brace_depth += 1;
self.bump();
if break_on_block == BlockMode::Break &&
brace_depth == 1 &&
bracket_depth == 0 {
in_block = true;
}
}
token::OpenDelim(token::DelimToken::Bracket) => {
bracket_depth += 1;
self.bump();
}
token::CloseDelim(token::DelimToken::Brace) => {
if brace_depth == 0 {
debug!("recover_stmt_ return - close delim {:?}", self.token);
break;
}
brace_depth -= 1;
self.bump();
if in_block && bracket_depth == 0 && brace_depth == 0 {
debug!("recover_stmt_ return - block end {:?}", self.token);
break;
}
}
token::CloseDelim(token::DelimToken::Bracket) => {
bracket_depth -= 1;
if bracket_depth < 0 {
bracket_depth = 0;
}
self.bump();
}
token::Eof => {
debug!("recover_stmt_ return - Eof");
break;
}
token::Semi => {
self.bump();
if break_on_semi == SemiColonMode::Break &&
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
break;
}
}
token::Comma => {
if break_on_semi == SemiColonMode::Comma &&
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
break;
} else {
self.bump();
}
}
_ => {
self.bump()
}
}
}
}
crate fn consume_block(&mut self, delim: token::DelimToken) {
let mut brace_depth = 0;
loop {
if self.eat(&token::OpenDelim(delim)) {
brace_depth += 1;
} else if self.eat(&token::CloseDelim(delim)) {
if brace_depth == 0 {
return;
} else {
brace_depth -= 1;
continue;
}
} else if self.token == token::Eof || self.eat(&token::CloseDelim(token::NoDelim)) {
return;
} else {
self.bump();
}
}
}
}