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Properly handle attributes on statements

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We now collect tokens for the underlying node wrapped by `StmtKind`
instead of storing tokens directly in `Stmt`.

`LazyTokenStream` now supports capturing a trailing semicolon after it
is initially constructed. This allows us to avoid refactoring statement
parsing to wrap the parsing of the semicolon in `parse_tokens`.

Attributes on item statements
(e.g. `fn foo() { #[bar] struct MyStruct; }`) are now treated as
item attributes, not statement attributes, which is consistent with how
we handle attributes on other kinds of statements. The feature-gating
code is adjusted so that proc-macro attributes are still allowed on item
statements on stable.

Two built-in macros (`#[global_allocator]` and `#[test]`) needed to be
adjusted to support being passed `Annotatable::Stmt`.
This commit is contained in:
Aaron Hill 2020-11-17 14:27:44 -05:00
parent 72da5a9d85
commit de88bf148b
No known key found for this signature in database
GPG key ID: B4087E510E98B164
20 changed files with 485 additions and 187 deletions
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123
compiler/rustc_parse/src/parser/stmt.rs
View file

@ -7,8 +7,10 @@ use super::{BlockMode, Parser, Restrictions, SemiColonMode};
use crate::maybe_whole;
use rustc_ast as ast;
use rustc_ast::attr::HasAttrs;
use rustc_ast::ptr::P;
use rustc_ast::token::{self, TokenKind};
use rustc_ast::tokenstream::LazyTokenStream;
use rustc_ast::util::classify;
use rustc_ast::{AttrStyle, AttrVec, Attribute, MacCall, MacCallStmt, MacStmtStyle};
use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, Local, Stmt, StmtKind, DUMMY_NODE_ID};
@ -31,45 +33,75 @@ impl<'a> Parser<'a> {
}
fn parse_stmt_without_recovery(&mut self) -> PResult<'a, Option<Stmt>> {
maybe_whole!(self, NtStmt, |x| Some(x));
let attrs = self.parse_outer_attributes()?;
let mut attrs = self.parse_outer_attributes()?;
let has_attrs = !attrs.is_empty();
let lo = self.token.span;
let stmt = if self.eat_keyword(kw::Let) {
self.parse_local_mk(lo, attrs.into())?
} else if self.is_kw_followed_by_ident(kw::Mut) {
self.recover_stmt_local(lo, attrs.into(), "missing keyword", "let mut")?
} else if self.is_kw_followed_by_ident(kw::Auto) {
self.bump(); // `auto`
let msg = "write `let` instead of `auto` to introduce a new variable";
self.recover_stmt_local(lo, attrs.into(), msg, "let")?
} else if self.is_kw_followed_by_ident(sym::var) {
self.bump(); // `var`
let msg = "write `let` instead of `var` to introduce a new variable";
self.recover_stmt_local(lo, attrs.into(), msg, "let")?
} else if self.check_path() && !self.token.is_qpath_start() && !self.is_path_start_item() {
// We have avoided contextual keywords like `union`, items with `crate` visibility,
// or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
// that starts like a path (1 token), but it fact not a path.
// Also, we avoid stealing syntax from `parse_item_`.
self.parse_stmt_path_start(lo, attrs)?
} else if let Some(item) = self.parse_item_common(attrs.clone(), false, true, |_| true)? {
// FIXME: Bad copy of attrs
self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
} else if self.eat(&token::Semi) {
// Do not attempt to parse an expression if we're done here.
self.error_outer_attrs(&attrs);
self.mk_stmt(lo, StmtKind::Empty)
} else if self.token != token::CloseDelim(token::Brace) {
// Remainder are line-expr stmts.
let e = self.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs.into()))?;
self.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
} else {
self.error_outer_attrs(&attrs);
return Ok(None);
maybe_whole!(self, NtStmt, |stmt| {
let mut stmt = stmt;
stmt.visit_attrs(|stmt_attrs| {
mem::swap(stmt_attrs, &mut attrs);
stmt_attrs.extend(attrs);
});
Some(stmt)
});
let parse_stmt_inner = |this: &mut Self| {
let stmt = if this.eat_keyword(kw::Let) {
this.parse_local_mk(lo, attrs.into())?
} else if this.is_kw_followed_by_ident(kw::Mut) {
this.recover_stmt_local(lo, attrs.into(), "missing keyword", "let mut")?
} else if this.is_kw_followed_by_ident(kw::Auto) {
this.bump(); // `auto`
let msg = "write `let` instead of `auto` to introduce a new variable";
this.recover_stmt_local(lo, attrs.into(), msg, "let")?
} else if this.is_kw_followed_by_ident(sym::var) {
this.bump(); // `var`
let msg = "write `let` instead of `var` to introduce a new variable";
this.recover_stmt_local(lo, attrs.into(), msg, "let")?
} else if this.check_path()
&& !this.token.is_qpath_start()
&& !this.is_path_start_item()
{
// We have avoided contextual keywords like `union`, items with `crate` visibility,
// or `auto trait` items. We aim to parse an arbitrary path `a::b` but not something
// that starts like a path (1 token), but it fact not a path.
// Also, we avoid stealing syntax from `parse_item_`.
this.parse_stmt_path_start(lo, attrs)?
} else if let Some(item) =
this.parse_item_common(attrs.clone(), false, true, |_| true)?
{
// FIXME: Bad copy of attrs
this.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
} else if this.eat(&token::Semi) {
// Do not attempt to parse an expression if we're done here.
this.error_outer_attrs(&attrs);
this.mk_stmt(lo, StmtKind::Empty)
} else if this.token != token::CloseDelim(token::Brace) {
// Remainder are line-expr stmts.
let e = this.parse_expr_res(Restrictions::STMT_EXPR, Some(attrs.into()))?;
this.mk_stmt(lo.to(e.span), StmtKind::Expr(e))
} else {
this.error_outer_attrs(&attrs);
return Ok(None);
};
Ok(Some(stmt))
};
Ok(Some(stmt))
let stmt = if has_attrs {
let (mut stmt, tokens) = self.collect_tokens(parse_stmt_inner)?;
if let Some(stmt) = &mut stmt {
// If we already have tokens (e.g. due to encounting an `NtStmt`),
// use those instead.
if stmt.tokens().is_none() {
stmt.set_tokens(tokens);
}
}
stmt
} else {
parse_stmt_inner(self)?
};
Ok(stmt)
}
fn parse_stmt_path_start(&mut self, lo: Span, attrs: Vec<Attribute>) -> PResult<'a, Stmt> {
@ -107,7 +139,7 @@ impl<'a> Parser<'a> {
let kind = if delim == token::Brace || self.token == token::Semi || self.token == token::Eof
{
StmtKind::MacCall(P(MacCallStmt { mac, style, attrs }))
StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None }))
} else {
// Since none of the above applied, this is an expression statement macro.
let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac), AttrVec::new());
@ -219,7 +251,7 @@ impl<'a> Parser<'a> {
}
};
let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span };
Ok(P(ast::Local { ty, pat, init, id: DUMMY_NODE_ID, span: lo.to(hi), attrs }))
Ok(P(ast::Local { ty, pat, init, id: DUMMY_NODE_ID, span: lo.to(hi), attrs, tokens: None }))
}
/// Parses the RHS of a local variable declaration (e.g., '= 14;').
@ -376,6 +408,12 @@ impl<'a> Parser<'a> {
None => return Ok(None),
};
let add_semi_token = |tokens: Option<&mut LazyTokenStream>| {
if let Some(tokens) = tokens {
*tokens = tokens.add_trailing_semi();
}
};
let mut eat_semi = true;
match stmt.kind {
// Expression without semicolon.
@ -417,6 +455,7 @@ impl<'a> Parser<'a> {
*expr = self.mk_expr_err(sp);
}
}
StmtKind::Expr(_) | StmtKind::MacCall(_) => {}
StmtKind::Local(ref mut local) => {
if let Err(e) = self.expect_semi() {
// We might be at the `,` in `let x = foo<bar, baz>;`. Try to recover.
@ -430,6 +469,9 @@ impl<'a> Parser<'a> {
}
}
eat_semi = false;
// We just checked that there's a semicolon in the tokenstream,
// so capture it
add_semi_token(local.tokens.as_mut());
}
StmtKind::Empty => eat_semi = false,
_ => {}
@ -437,6 +479,9 @@ impl<'a> Parser<'a> {
if eat_semi && self.eat(&token::Semi) {
stmt = stmt.add_trailing_semicolon();
// We just checked that we have a semicolon in the tokenstream,
// so capture it
add_semi_token(stmt.tokens_mut());
}
stmt.span = stmt.span.to(self.prev_token.span);
Ok(Some(stmt))
@ -447,7 +492,7 @@ impl<'a> Parser<'a> {
}
pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt {
Stmt { id: DUMMY_NODE_ID, kind, span, tokens: None }
Stmt { id: DUMMY_NODE_ID, kind, span }
}
pub(super) fn mk_stmt_err(&self, span: Span) -> Stmt {