Overhaul token collection.
This commit does the following. - Renames `collect_tokens_trailing_token` as `collect_tokens`, because (a) it's annoying long, and (b) the `_trailing_token` bit is less accurate now that its types have changed. - In `collect_tokens`, adds a `Option<CollectPos>` argument and a `UsePreAttrPos` in the return type of `f`. These are used in `parse_expr_force_collect` (for vanilla expressions) and in `parse_stmt_without_recovery` (for two different cases of expression statements). Together these ensure are enough to fix all the problems with token collection and assoc expressions. The changes to the `stringify.rs` test demonstrate some of these. - Adds a new test. The code in this test was causing an assertion failure prior to this commit, due to an invalid `NodeRange`. The extra complexity is annoying, but necessary to fix the existing problems.
This commit is contained in:
Nicholas Nethercote
parent
fe460ac28b
commit
9d31f86f0d
12 changed files with 414 additions and 292 deletions
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@ -7,7 +7,7 @@ use rustc_span::symbol::{kw, Ident};
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use rustc_span::Span;
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use thin_vec::ThinVec;
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use super::{ForceCollect, Parser, Trailing};
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use super::{ForceCollect, Parser, Trailing, UsePreAttrPos};
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use crate::errors::{
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self, MultipleWhereClauses, UnexpectedDefaultValueForLifetimeInGenericParameters,
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UnexpectedSelfInGenericParameters, WhereClauseBeforeTupleStructBody,
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@ -169,94 +169,88 @@ impl<'a> Parser<'a> {
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let mut done = false;
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while !done {
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let attrs = self.parse_outer_attributes()?;
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let param =
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self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
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if this.eat_keyword_noexpect(kw::SelfUpper) {
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// `Self` as a generic param is invalid. Here we emit the diagnostic and continue parsing
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// as if `Self` never existed.
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this.dcx().emit_err(UnexpectedSelfInGenericParameters {
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span: this.prev_token.span,
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});
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let param = self.collect_tokens(None, attrs, ForceCollect::No, |this, attrs| {
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if this.eat_keyword_noexpect(kw::SelfUpper) {
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// `Self` as a generic param is invalid. Here we emit the diagnostic and continue parsing
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// as if `Self` never existed.
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this.dcx()
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.emit_err(UnexpectedSelfInGenericParameters { span: this.prev_token.span });
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// Eat a trailing comma, if it exists.
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let _ = this.eat(&token::Comma);
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}
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// Eat a trailing comma, if it exists.
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let _ = this.eat(&token::Comma);
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}
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let param = if this.check_lifetime() {
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let lifetime = this.expect_lifetime();
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// Parse lifetime parameter.
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let (colon_span, bounds) = if this.eat(&token::Colon) {
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(Some(this.prev_token.span), this.parse_lt_param_bounds())
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} else {
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(None, Vec::new())
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};
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if this.check_noexpect(&token::Eq)
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&& this.look_ahead(1, |t| t.is_lifetime())
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{
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let lo = this.token.span;
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// Parse `= 'lifetime`.
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this.bump(); // `=`
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this.bump(); // `'lifetime`
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let span = lo.to(this.prev_token.span);
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this.dcx().emit_err(
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UnexpectedDefaultValueForLifetimeInGenericParameters { span },
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);
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}
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Some(ast::GenericParam {
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ident: lifetime.ident,
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id: lifetime.id,
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attrs,
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bounds,
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kind: ast::GenericParamKind::Lifetime,
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is_placeholder: false,
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colon_span,
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})
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} else if this.check_keyword(kw::Const) {
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// Parse const parameter.
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Some(this.parse_const_param(attrs)?)
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} else if this.check_ident() {
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// Parse type parameter.
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Some(this.parse_ty_param(attrs)?)
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} else if this.token.can_begin_type() {
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// Trying to write an associated type bound? (#26271)
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let snapshot = this.create_snapshot_for_diagnostic();
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match this.parse_ty_where_predicate() {
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Ok(where_predicate) => {
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this.dcx().emit_err(errors::BadAssocTypeBounds {
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span: where_predicate.span(),
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});
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// FIXME - try to continue parsing other generics?
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return Ok((None, Trailing::No));
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}
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Err(err) => {
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err.cancel();
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// FIXME - maybe we should overwrite 'self' outside of `collect_tokens`?
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this.restore_snapshot(snapshot);
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return Ok((None, Trailing::No));
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}
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}
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let param = if this.check_lifetime() {
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let lifetime = this.expect_lifetime();
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// Parse lifetime parameter.
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let (colon_span, bounds) = if this.eat(&token::Colon) {
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(Some(this.prev_token.span), this.parse_lt_param_bounds())
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} else {
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// Check for trailing attributes and stop parsing.
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if !attrs.is_empty() {
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if !params.is_empty() {
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this.dcx()
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.emit_err(errors::AttrAfterGeneric { span: attrs[0].span });
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} else {
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this.dcx()
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.emit_err(errors::AttrWithoutGenerics { span: attrs[0].span });
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}
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}
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return Ok((None, Trailing::No));
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(None, Vec::new())
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};
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if !this.eat(&token::Comma) {
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done = true;
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if this.check_noexpect(&token::Eq) && this.look_ahead(1, |t| t.is_lifetime()) {
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let lo = this.token.span;
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// Parse `= 'lifetime`.
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this.bump(); // `=`
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this.bump(); // `'lifetime`
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let span = lo.to(this.prev_token.span);
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this.dcx().emit_err(UnexpectedDefaultValueForLifetimeInGenericParameters {
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span,
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});
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}
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// We just ate the comma, so no need to capture the trailing token.
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Ok((param, Trailing::No))
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})?;
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Some(ast::GenericParam {
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ident: lifetime.ident,
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id: lifetime.id,
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attrs,
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bounds,
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kind: ast::GenericParamKind::Lifetime,
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is_placeholder: false,
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colon_span,
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})
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} else if this.check_keyword(kw::Const) {
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// Parse const parameter.
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Some(this.parse_const_param(attrs)?)
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} else if this.check_ident() {
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// Parse type parameter.
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Some(this.parse_ty_param(attrs)?)
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} else if this.token.can_begin_type() {
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// Trying to write an associated type bound? (#26271)
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let snapshot = this.create_snapshot_for_diagnostic();
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match this.parse_ty_where_predicate() {
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Ok(where_predicate) => {
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this.dcx().emit_err(errors::BadAssocTypeBounds {
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span: where_predicate.span(),
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});
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// FIXME - try to continue parsing other generics?
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}
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Err(err) => {
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err.cancel();
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// FIXME - maybe we should overwrite 'self' outside of `collect_tokens`?
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this.restore_snapshot(snapshot);
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}
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}
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return Ok((None, Trailing::No, UsePreAttrPos::No));
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} else {
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// Check for trailing attributes and stop parsing.
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if !attrs.is_empty() {
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if !params.is_empty() {
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this.dcx().emit_err(errors::AttrAfterGeneric { span: attrs[0].span });
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} else {
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this.dcx()
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.emit_err(errors::AttrWithoutGenerics { span: attrs[0].span });
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}
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}
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return Ok((None, Trailing::No, UsePreAttrPos::No));
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};
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if !this.eat(&token::Comma) {
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done = true;
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}
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// We just ate the comma, so no need to capture the trailing token.
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Ok((param, Trailing::No, UsePreAttrPos::No))
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})?;
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if let Some(param) = param {
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params.push(param);
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