diff options
Diffstat (limited to 'compiler/rustc_parse/src/parser/stmt.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/stmt.rs | 129 |
1 files changed, 112 insertions, 17 deletions
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index 2fa6520f2a4..ad5ab6e6b77 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -4,9 +4,9 @@ use std::ops::Bound; use ast::Label; use rustc_ast as ast; -use rustc_ast::ptr::P; use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, TokenKind}; use rustc_ast::util::classify::{self, TrailingBrace}; +use rustc_ast::visit::{Visitor, walk_expr}; use rustc_ast::{ AttrStyle, AttrVec, Block, BlockCheckMode, DUMMY_NODE_ID, Expr, ExprKind, HasAttrs, Local, LocalKind, MacCall, MacCallStmt, MacStmtStyle, Recovered, Stmt, StmtKind, @@ -20,8 +20,8 @@ use super::diagnostics::AttemptLocalParseRecovery; use super::pat::{PatternLocation, RecoverComma}; use super::path::PathStyle; use super::{ - AttrWrapper, BlockMode, FnParseMode, ForceCollect, Parser, Restrictions, SemiColonMode, - Trailing, UsePreAttrPos, + AttrWrapper, BlockMode, FnContext, FnParseMode, ForceCollect, Parser, Restrictions, + SemiColonMode, Trailing, UsePreAttrPos, }; use crate::errors::{self, MalformedLoopLabel}; use crate::exp; @@ -154,10 +154,10 @@ impl<'a> Parser<'a> { attrs.clone(), // FIXME: unwanted clone of attrs false, true, - FnParseMode { req_name: |_| true, req_body: true }, + FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: true }, force_collect, )? { - self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item))) + self.mk_stmt(lo.to(item.span), StmtKind::Item(Box::new(item))) } else if self.eat(exp!(Semi)) { // Do not attempt to parse an expression if we're done here. self.error_outer_attrs(attrs); @@ -246,7 +246,7 @@ impl<'a> Parser<'a> { _ => MacStmtStyle::NoBraces, }; - let mac = P(MacCall { path, args }); + let mac = Box::new(MacCall { path, args }); let kind = if (style == MacStmtStyle::Braces && !matches!(self.token.kind, token::Dot | token::Question)) @@ -256,7 +256,7 @@ impl<'a> Parser<'a> { | token::Eof | token::CloseInvisible(InvisibleOrigin::MetaVar(MetaVarKind::Stmt)) ) { - StmtKind::MacCall(P(MacCallStmt { mac, style, attrs, tokens: None })) + StmtKind::MacCall(Box::new(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)); @@ -307,7 +307,7 @@ impl<'a> Parser<'a> { } /// Parses a local variable declaration. - fn parse_local(&mut self, super_: Option<Span>, attrs: AttrVec) -> PResult<'a, P<Local>> { + fn parse_local(&mut self, super_: Option<Span>, attrs: AttrVec) -> PResult<'a, Box<Local>> { let lo = super_.unwrap_or(self.prev_token.span); if self.token.is_keyword(kw::Const) && self.look_ahead(1, |t| t.is_ident()) { @@ -409,7 +409,7 @@ impl<'a> Parser<'a> { } }; let hi = if self.token == token::Semi { self.token.span } else { self.prev_token.span }; - Ok(P(ast::Local { + Ok(Box::new(ast::Local { super_, ty, pat, @@ -463,7 +463,7 @@ impl<'a> Parser<'a> { } /// Parses the RHS of a local variable declaration (e.g., `= 14;`). - fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> { + fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<Box<Expr>>> { let eq_consumed = match self.token.kind { token::PlusEq | token::MinusEq @@ -494,7 +494,7 @@ impl<'a> Parser<'a> { } /// Parses a block. No inner attributes are allowed. - pub fn parse_block(&mut self) -> PResult<'a, P<Block>> { + pub fn parse_block(&mut self) -> PResult<'a, Box<Block>> { let (attrs, block) = self.parse_inner_attrs_and_block(None)?; if let [.., last] = &*attrs { let suggest_to_outer = match &last.kind { @@ -679,7 +679,7 @@ impl<'a> Parser<'a> { pub(super) fn parse_inner_attrs_and_block( &mut self, loop_header: Option<Span>, - ) -> PResult<'a, (AttrVec, P<Block>)> { + ) -> PResult<'a, (AttrVec, Box<Block>)> { self.parse_block_common(self.token.span, BlockCheckMode::Default, loop_header) } @@ -692,7 +692,7 @@ impl<'a> Parser<'a> { lo: Span, blk_mode: BlockCheckMode, loop_header: Option<Span>, - ) -> PResult<'a, (AttrVec, P<Block>)> { + ) -> PResult<'a, (AttrVec, Box<Block>)> { if let Some(block) = self.eat_metavar_seq(MetaVarKind::Block, |this| this.parse_block()) { return Ok((AttrVec::new(), block)); } @@ -718,7 +718,7 @@ impl<'a> Parser<'a> { lo: Span, s: BlockCheckMode, recover: AttemptLocalParseRecovery, - ) -> PResult<'a, P<Block>> { + ) -> PResult<'a, Box<Block>> { let mut stmts = ThinVec::new(); let mut snapshot = None; while !self.eat(exp!(CloseBrace)) { @@ -784,6 +784,100 @@ impl<'a> Parser<'a> { Ok(self.mk_block(stmts, s, lo.to(self.prev_token.span))) } + fn recover_missing_let_else(&mut self, err: &mut Diag<'_>, pat: &ast::Pat, stmt_span: Span) { + if self.token.kind != token::OpenBrace { + return; + } + match pat.kind { + ast::PatKind::Ident(..) | ast::PatKind::Missing | ast::PatKind::Wild => { + // Not if let or let else + return; + } + _ => {} + } + let snapshot = self.create_snapshot_for_diagnostic(); + let block_span = self.token.span; + let (if_let, let_else) = match self.parse_block() { + Ok(block) => { + let mut idents = vec![]; + pat.walk(&mut |pat: &ast::Pat| { + if let ast::PatKind::Ident(_, ident, _) = pat.kind { + idents.push(ident); + } + true + }); + + struct IdentFinder { + idents: Vec<Ident>, + /// If a block references one of the bindings introduced by the let pattern, + /// we likely meant to use `if let`. + /// This is pre-expansion, so if we encounter + /// `let Some(x) = foo() { println!("{x}") }` we won't find it. + references_ident: bool = false, + /// If a block has a `return`, then we know with high certainty that it was + /// meant to be let-else. + has_return: bool = false, + } + + impl<'a> Visitor<'a> for IdentFinder { + fn visit_ident(&mut self, ident: &Ident) { + for i in &self.idents { + if ident.name == i.name { + self.references_ident = true; + } + } + } + fn visit_expr(&mut self, node: &'a Expr) { + if let ExprKind::Ret(..) = node.kind { + self.has_return = true; + } + walk_expr(self, node); + } + } + + // Collect all bindings in pattern and see if they appear in the block. Likely meant + // to write `if let`. See if the block has a return. Likely meant to write + // `let else`. + let mut visitor = IdentFinder { idents, .. }; + visitor.visit_block(&block); + + (visitor.references_ident, visitor.has_return) + } + Err(e) => { + e.cancel(); + self.restore_snapshot(snapshot); + (false, false) + } + }; + + let mut alternatively = ""; + if if_let || !let_else { + alternatively = "alternatively, "; + err.span_suggestion_verbose( + stmt_span.shrink_to_lo(), + "you might have meant to use `if let`", + "if ".to_string(), + if if_let { + Applicability::MachineApplicable + } else { + Applicability::MaybeIncorrect + }, + ); + } + if let_else || !if_let { + err.span_suggestion_verbose( + block_span.shrink_to_lo(), + format!("{alternatively}you might have meant to use `let else`"), + "else ".to_string(), + if let_else { + Applicability::MachineApplicable + } else { + Applicability::MaybeIncorrect + }, + ); + } + } + fn recover_missing_dot(&mut self, err: &mut Diag<'_>) { let Some((ident, _)) = self.token.ident() else { return; @@ -978,6 +1072,7 @@ impl<'a> Parser<'a> { self.check_mistyped_turbofish_with_multiple_type_params(e, expr).map_err( |mut e| { self.recover_missing_dot(&mut e); + self.recover_missing_let_else(&mut e, &local.pat, stmt.span); e }, )?; @@ -1050,8 +1145,8 @@ impl<'a> Parser<'a> { stmts: ThinVec<Stmt>, rules: BlockCheckMode, span: Span, - ) -> P<Block> { - P(Block { stmts, id: DUMMY_NODE_ID, rules, span, tokens: None }) + ) -> Box<Block> { + Box::new(Block { stmts, id: DUMMY_NODE_ID, rules, span, tokens: None }) } pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt { @@ -1062,7 +1157,7 @@ impl<'a> Parser<'a> { self.mk_stmt(span, StmtKind::Expr(self.mk_expr_err(span, guar))) } - pub(super) fn mk_block_err(&self, span: Span, guar: ErrorGuaranteed) -> P<Block> { + pub(super) fn mk_block_err(&self, span: Span, guar: ErrorGuaranteed) -> Box<Block> { self.mk_block(thin_vec![self.mk_stmt_err(span, guar)], BlockCheckMode::Default, span) } } |