Auto merge of #66994 - Centril:stmt-polish, r=estebank

refactor expr & stmt parsing + improve recovery

Summary of important changes (best read commit-by-commit, ignoring whitespace changes):

- `AttrVec` is introduces as an alias for `ThinVec<Attribute>`
- `parse_expr_bottom` and `parse_stmt` are thoroughly refactored.
- Extract diagnostics logic for `vec![...]` in a pattern context.
- Recovery is added for `do catch { ... }`
- Recovery is added for `'label: non_block_expr`
- Recovery is added for `var $local`, `auto $local`, and `mut $local`. Fixes #65257.
- Recovery is added for `e1 and e2` and `e1 or e2`.
- ~~`macro_legacy_warnings` is turned into an error (has been a warning for 3 years!)~~
- Fixes #63396 by forward-porting #64105 which now works thanks to added recovery.
- `ui-fulldeps/ast_stmt_expr_attr.rs` is turned into UI and pretty tests.
- Recovery is fixed for `#[attr] if expr {}`

r? @estebank

4 files changed, 14 insertions, 14 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index cf54fd2887a..c1458236788 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -338,7 +338,7 @@ pub enum GenericParamKind {
 pub struct GenericParam {
     pub id: NodeId,
     pub ident: Ident,
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
     pub bounds: GenericBounds,
     pub is_placeholder: bool,
     pub kind: GenericParamKind,
@@ -599,7 +599,7 @@ pub struct FieldPat {
     /// The pattern the field is destructured to
     pub pat: P<Pat>,
     pub is_shorthand: bool,
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
     pub id: NodeId,
     pub span: Span,
     pub is_placeholder: bool,
@@ -911,7 +911,7 @@ pub enum StmtKind {
     /// Expr with a trailing semi-colon.
     Semi(P<Expr>),
     /// Macro.
-    Mac(P<(Mac, MacStmtStyle, ThinVec<Attribute>)>),
+    Mac(P<(Mac, MacStmtStyle, AttrVec)>),
 }
 
 #[derive(Clone, Copy, PartialEq, RustcEncodable, RustcDecodable, Debug)]
@@ -936,7 +936,7 @@ pub struct Local {
     /// Initializer expression to set the value, if any.
     pub init: Option<P<Expr>>,
     pub span: Span,
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
 }
 
 /// An arm of a 'match'.
@@ -966,7 +966,7 @@ pub struct Arm {
 /// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct field.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Field {
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
     pub id: NodeId,
     pub span: Span,
     pub ident: Ident,
@@ -1004,7 +1004,7 @@ pub struct Expr {
     pub id: NodeId,
     pub kind: ExprKind,
     pub span: Span,
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
 }
 
 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
@@ -1961,7 +1961,7 @@ pub struct InlineAsm {
 /// E.g., `bar: usize` as in `fn foo(bar: usize)`.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Param {
-    pub attrs: ThinVec<Attribute>,
+    pub attrs: AttrVec,
     pub ty: P<Ty>,
     pub pat: P<Pat>,
     pub id: NodeId,
@@ -2014,7 +2014,7 @@ impl Param {
     }
 
     /// Builds a `Param` object from `ExplicitSelf`.
-    pub fn from_self(attrs: ThinVec<Attribute>, eself: ExplicitSelf, eself_ident: Ident) -> Param {
+    pub fn from_self(attrs: AttrVec, eself: ExplicitSelf, eself_ident: Ident) -> Param {
         let span = eself.span.to(eself_ident.span);
         let infer_ty = P(Ty {
             id: DUMMY_NODE_ID,
@@ -2332,6 +2332,9 @@ pub struct AttrItem {
     pub args: MacArgs,
 }
 
+/// A list of attributes.
+pub type AttrVec = ThinVec<Attribute>;
+
 /// Metadata associated with an item.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Attribute {
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
index 13a9ed5f215..ae6d50ba083 100644
--- a/src/libsyntax/attr/mod.rs
+++ b/src/libsyntax/attr/mod.rs
@@ -9,7 +9,7 @@ pub use StabilityLevel::*;
 pub use crate::ast::Attribute;
 
 use crate::ast;
-use crate::ast::{AttrItem, AttrId, AttrKind, AttrStyle, Name, Ident, Path, PathSegment};
+use crate::ast::{AttrVec, AttrItem, AttrId, AttrKind, AttrStyle, Name, Ident, Path, PathSegment};
 use crate::ast::{MacArgs, MacDelimiter, MetaItem, MetaItemKind, NestedMetaItem};
 use crate::ast::{Lit, LitKind, Expr, Item, Local, Stmt, StmtKind, GenericParam};
 use crate::mut_visit::visit_clobber;
@@ -17,7 +17,6 @@ use crate::source_map::{BytePos, Spanned};
 use crate::token::{self, Token};
 use crate::ptr::P;
 use crate::symbol::{sym, Symbol};
-use crate::ThinVec;
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
 use crate::GLOBALS;
 
@@ -665,7 +664,7 @@ impl HasAttrs for Vec<Attribute> {
     }
 }
 
-impl HasAttrs for ThinVec<Attribute> {
+impl HasAttrs for AttrVec {
     fn attrs(&self) -> &[Attribute] {
         self
     }
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 36173801eae..30fd23ea909 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -24,7 +24,6 @@
 pub use errors;
 use rustc_data_structures::sync::Lock;
 use rustc_index::bit_set::GrowableBitSet;
-pub use rustc_data_structures::thin_vec::ThinVec;
 use ast::AttrId;
 use syntax_pos::edition::Edition;
 
diff --git a/src/libsyntax/mut_visit.rs b/src/libsyntax/mut_visit.rs
index 2a6cff5971c..1d27f70f5a5 100644
--- a/src/libsyntax/mut_visit.rs
+++ b/src/libsyntax/mut_visit.rs
@@ -11,7 +11,6 @@ use crate::ast::*;
 use crate::source_map::{Spanned, respan};
 use crate::token::{self, Token};
 use crate::ptr::P;
-use crate::ThinVec;
 use crate::tokenstream::*;
 use crate::util::map_in_place::MapInPlace;
 
@@ -337,7 +336,7 @@ pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
 }
 
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
-pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut ThinVec<Attribute>, vis: &mut T) {
+pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut AttrVec, vis: &mut T) {
     for attr in attrs.iter_mut() {
         vis.visit_attribute(attr);
     }