diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_ast/src/util/classify.rs | 95 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/stmt.rs | 28 |
2 files changed, 108 insertions, 15 deletions
diff --git a/compiler/rustc_ast/src/util/classify.rs b/compiler/rustc_ast/src/util/classify.rs index f6e9e1a87c4..382c903625f 100644 --- a/compiler/rustc_ast/src/util/classify.rs +++ b/compiler/rustc_ast/src/util/classify.rs @@ -81,8 +81,17 @@ pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool { } } +pub enum TrailingBrace<'a> { + /// Trailing brace in a macro call, like the one in `x as *const brace! {}`. + /// We will suggest changing the macro call to a different delimiter. + MacCall(&'a ast::MacCall), + /// Trailing brace in any other expression, such as `a + B {}`. We will + /// suggest wrapping the innermost expression in parentheses: `a + (B {})`. + Expr(&'a ast::Expr), +} + /// If an expression ends with `}`, returns the innermost expression ending in the `}` -pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> { +pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<TrailingBrace<'_>> { loop { match &expr.kind { AddrOf(_, _, e) @@ -111,10 +120,14 @@ pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> { | Struct(..) | TryBlock(..) | While(..) - | ConstBlock(_) => break Some(expr), + | ConstBlock(_) => break Some(TrailingBrace::Expr(expr)), + + Cast(_, ty) => { + break type_trailing_braced_mac_call(ty).map(TrailingBrace::MacCall); + } MacCall(mac) => { - break (mac.args.delim == Delimiter::Brace).then_some(expr); + break (mac.args.delim == Delimiter::Brace).then_some(TrailingBrace::MacCall(mac)); } InlineAsm(_) | OffsetOf(_, _) | IncludedBytes(_) | FormatArgs(_) => { @@ -131,7 +144,6 @@ pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> { | MethodCall(_) | Tup(_) | Lit(_) - | Cast(_, _) | Type(_, _) | Await(_, _) | Field(_, _) @@ -148,3 +160,78 @@ pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> { } } } + +/// If the type's last token is `}`, it must be due to a braced macro call, such +/// as in `*const brace! { ... }`. Returns that trailing macro call. +fn type_trailing_braced_mac_call(mut ty: &ast::Ty) -> Option<&ast::MacCall> { + loop { + match &ty.kind { + ast::TyKind::MacCall(mac) => { + break (mac.args.delim == Delimiter::Brace).then_some(mac); + } + + ast::TyKind::Ptr(mut_ty) | ast::TyKind::Ref(_, mut_ty) => { + ty = &mut_ty.ty; + } + + ast::TyKind::BareFn(fn_ty) => match &fn_ty.decl.output { + ast::FnRetTy::Default(_) => break None, + ast::FnRetTy::Ty(ret) => ty = ret, + }, + + ast::TyKind::Path(_, path) => match path_return_type(path) { + Some(trailing_ty) => ty = trailing_ty, + None => break None, + }, + + ast::TyKind::TraitObject(bounds, _) | ast::TyKind::ImplTrait(_, bounds, _) => { + match bounds.last() { + Some(ast::GenericBound::Trait(bound, _)) => { + match path_return_type(&bound.trait_ref.path) { + Some(trailing_ty) => ty = trailing_ty, + None => break None, + } + } + Some(ast::GenericBound::Outlives(_)) | None => break None, + } + } + + ast::TyKind::Slice(..) + | ast::TyKind::Array(..) + | ast::TyKind::Never + | ast::TyKind::Tup(..) + | ast::TyKind::Paren(..) + | ast::TyKind::Typeof(..) + | ast::TyKind::Infer + | ast::TyKind::ImplicitSelf + | ast::TyKind::CVarArgs + | ast::TyKind::Pat(..) + | ast::TyKind::Dummy + | ast::TyKind::Err(..) => break None, + + // These end in brace, but cannot occur in a let-else statement. + // They are only parsed as fields of a data structure. For the + // purpose of denying trailing braces in the expression of a + // let-else, we can disregard these. + ast::TyKind::AnonStruct(..) | ast::TyKind::AnonUnion(..) => break None, + } + } +} + +/// Returns the trailing return type in the given path, if it has one. +/// +/// ```ignore (illustrative) +/// ::std::ops::FnOnce(&str) -> fn() -> *const c_void +/// ^^^^^^^^^^^^^^^^^^^^^ +/// ``` +fn path_return_type(path: &ast::Path) -> Option<&ast::Ty> { + let last_segment = path.segments.last()?; + let args = last_segment.args.as_ref()?; + match &**args { + ast::GenericArgs::Parenthesized(args) => match &args.output { + ast::FnRetTy::Default(_) => None, + ast::FnRetTy::Ty(ret) => Some(ret), + }, + ast::GenericArgs::AngleBracketed(_) => None, + } +} diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index d70afebf1b2..941b145e2db 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -15,7 +15,7 @@ use ast::Label; use rustc_ast as ast; use rustc_ast::ptr::P; use rustc_ast::token::{self, Delimiter, TokenKind}; -use rustc_ast::util::classify; +use rustc_ast::util::classify::{self, TrailingBrace}; use rustc_ast::{AttrStyle, AttrVec, LocalKind, MacCall, MacCallStmt, MacStmtStyle}; use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, HasAttrs, Local, Recovered, Stmt}; use rustc_ast::{StmtKind, DUMMY_NODE_ID}; @@ -407,18 +407,24 @@ impl<'a> Parser<'a> { fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) { if let Some(trailing) = classify::expr_trailing_brace(init) { - let sugg = match &trailing.kind { - ExprKind::MacCall(mac) => errors::WrapInParentheses::MacroArgs { - left: mac.args.dspan.open, - right: mac.args.dspan.close, - }, - _ => errors::WrapInParentheses::Expression { - left: trailing.span.shrink_to_lo(), - right: trailing.span.shrink_to_hi(), - }, + let (span, sugg) = match trailing { + TrailingBrace::MacCall(mac) => ( + mac.span(), + errors::WrapInParentheses::MacroArgs { + left: mac.args.dspan.open, + right: mac.args.dspan.close, + }, + ), + TrailingBrace::Expr(expr) => ( + expr.span, + errors::WrapInParentheses::Expression { + left: expr.span.shrink_to_lo(), + right: expr.span.shrink_to_hi(), + }, + ), }; self.dcx().emit_err(errors::InvalidCurlyInLetElse { - span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)), + span: span.with_lo(span.hi() - BytePos(1)), sugg, }); } |