Auto merge of rust-lang#114292 - estebank:issue-71039, r=<try>

More detail when expecting expression but encountering bad macro argument

Partially address rust-lang#71039.

```
error: expected expression, found `1 + 1`
  --> $DIR/trace_faulty_macros.rs:49:37
   |
LL |     (let $p:pat = $e:expr) => {test!(($p,$e))};
   |                                          -- this is interpreted as pattern `1 + 1` (in expansion #2)
...
LL |     (($p:pat, $e:pat)) => {let $p = $e;};
   |                                     ^^ expected expression
...
LL |     test!(let x = 1+1);
   |     ------------------
   |     |             |
   |     |             this is interpreted as expression `1 + 1` (in expansion #1)
   |     in this macro invocation
   |
   = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
```

Author: bors

compiler/rustc_ast/src/ast_traits.rs

@@ -231,29 +231,29 @@ impl HasTokens for Attribute {
 impl HasTokens for Nonterminal {
     fn tokens(&self) -> Option<&LazyAttrTokenStream> {
         match self {
-            Nonterminal::NtItem(item) => item.tokens(),
-            Nonterminal::NtStmt(stmt) => stmt.tokens(),
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens(),
-            Nonterminal::NtPat(pat) => pat.tokens(),
-            Nonterminal::NtTy(ty) => ty.tokens(),
-            Nonterminal::NtMeta(attr_item) => attr_item.tokens(),
-            Nonterminal::NtPath(path) => path.tokens(),
-            Nonterminal::NtVis(vis) => vis.tokens(),
-            Nonterminal::NtBlock(block) => block.tokens(),
+            Nonterminal::NtItem(item, _) => item.tokens(),
+            Nonterminal::NtStmt(stmt, _) => stmt.tokens(),
+            Nonterminal::NtExpr(expr, _) | Nonterminal::NtLiteral(expr, _) => expr.tokens(),
+            Nonterminal::NtPat(pat, _) => pat.tokens(),
+            Nonterminal::NtTy(ty, _) => ty.tokens(),
+            Nonterminal::NtMeta(attr_item, _) => attr_item.tokens(),
+            Nonterminal::NtPath(path, _) => path.tokens(),
+            Nonterminal::NtVis(vis, _) => vis.tokens(),
+            Nonterminal::NtBlock(block, _) => block.tokens(),
             Nonterminal::NtIdent(..) | Nonterminal::NtLifetime(..) => None,
         }
     }
     fn tokens_mut(&mut self) -> Option<&mut Option<LazyAttrTokenStream>> {
         match self {
-            Nonterminal::NtItem(item) => item.tokens_mut(),
-            Nonterminal::NtStmt(stmt) => stmt.tokens_mut(),
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens_mut(),
-            Nonterminal::NtPat(pat) => pat.tokens_mut(),
-            Nonterminal::NtTy(ty) => ty.tokens_mut(),
-            Nonterminal::NtMeta(attr_item) => attr_item.tokens_mut(),
-            Nonterminal::NtPath(path) => path.tokens_mut(),
-            Nonterminal::NtVis(vis) => vis.tokens_mut(),
-            Nonterminal::NtBlock(block) => block.tokens_mut(),
+            Nonterminal::NtItem(item, _) => item.tokens_mut(),
+            Nonterminal::NtStmt(stmt, _) => stmt.tokens_mut(),
+            Nonterminal::NtExpr(expr, _) | Nonterminal::NtLiteral(expr, _) => expr.tokens_mut(),
+            Nonterminal::NtPat(pat, _) => pat.tokens_mut(),
+            Nonterminal::NtTy(ty, _) => ty.tokens_mut(),
+            Nonterminal::NtMeta(attr_item, _) => attr_item.tokens_mut(),
+            Nonterminal::NtPath(path, _) => path.tokens_mut(),
+            Nonterminal::NtVis(vis, _) => vis.tokens_mut(),
+            Nonterminal::NtBlock(block, _) => block.tokens_mut(),
             Nonterminal::NtIdent(..) | Nonterminal::NtLifetime(..) => None,
         }
     }

compiler/rustc_ast/src/attr/mod.rs

@@ -343,8 +343,8 @@ impl MetaItem {
                 Path { span, segments, tokens: None }
             }
             Some(TokenTree::Token(Token { kind: token::Interpolated(nt), .. }, _)) => match &**nt {
-                token::Nonterminal::NtMeta(item) => return item.meta(item.path.span),
-                token::Nonterminal::NtPath(path) => (**path).clone(),
+                token::Nonterminal::NtMeta(item, _) => return item.meta(item.path.span),
+                token::Nonterminal::NtPath(path, _) => (**path).clone(),
                 _ => return None,
             },
             _ => return None,

compiler/rustc_ast/src/mut_visit.rs

@@ -793,33 +793,33 @@ pub fn visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
 // multiple items there....
 pub fn visit_nonterminal<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
     match nt {
-        token::NtItem(item) => visit_clobber(item, |item| {
+        token::NtItem(item, _) => visit_clobber(item, |item| {
             // This is probably okay, because the only visitors likely to
             // peek inside interpolated nodes will be renamings/markings,
             // which map single items to single items.
             vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
         }),
-        token::NtBlock(block) => vis.visit_block(block),
-        token::NtStmt(stmt) => visit_clobber(stmt, |stmt| {
+        token::NtBlock(block, _) => vis.visit_block(block),
+        token::NtStmt(stmt, _) => visit_clobber(stmt, |stmt| {
             // See reasoning above.
             stmt.map(|stmt| {
                 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
             })
         }),
-        token::NtPat(pat) => vis.visit_pat(pat),
-        token::NtExpr(expr) => vis.visit_expr(expr),
-        token::NtTy(ty) => vis.visit_ty(ty),
-        token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
-        token::NtLifetime(ident) => vis.visit_ident(ident),
-        token::NtLiteral(expr) => vis.visit_expr(expr),
-        token::NtMeta(item) => {
+        token::NtPat(pat, _) => vis.visit_pat(pat),
+        token::NtExpr(expr, _) => vis.visit_expr(expr),
+        token::NtTy(ty, _) => vis.visit_ty(ty),
+        token::NtIdent(ident, _is_raw, _) => vis.visit_ident(ident),
+        token::NtLifetime(ident, _) => vis.visit_ident(ident),
+        token::NtLiteral(expr, _) => vis.visit_expr(expr),
+        token::NtMeta(item, _) => {
             let AttrItem { path, args, tokens } = item.deref_mut();
             vis.visit_path(path);
             visit_attr_args(args, vis);
             visit_lazy_tts(tokens, vis);
         }
-        token::NtPath(path) => vis.visit_path(path),
-        token::NtVis(visib) => vis.visit_vis(visib),
+        token::NtPath(path, _) => vis.visit_path(path),
+        token::NtVis(visib, _) => vis.visit_vis(visib),
     }
 }
 

compiler/rustc_ast/src/token.rs

@@ -112,7 +112,7 @@ impl Lit {
             }
             Literal(token_lit) => Some(token_lit),
             Interpolated(ref nt)
-                if let NtExpr(expr) | NtLiteral(expr) = &**nt
+                if let NtExpr(expr, _) | NtLiteral(expr, _) = &**nt
                 && let ast::ExprKind::Lit(token_lit) = expr.kind =>
             {
                 Some(token_lit)
@@ -395,7 +395,7 @@ impl Token {
     /// if they keep spans or perform edition checks.
     pub fn uninterpolated_span(&self) -> Span {
         match &self.kind {
-            Interpolated(nt) => nt.span(),
+            Interpolated(nt) => nt.use_span(),
             _ => self.span,
         }
     }
@@ -551,8 +551,8 @@ impl Token {
             Literal(..) | BinOp(Minus) => true,
             Ident(name, false) if name.is_bool_lit() => true,
             Interpolated(ref nt) => match &**nt {
-                NtLiteral(_) => true,
-                NtExpr(e) => match &e.kind {
+                NtLiteral(..) => true,
+                NtExpr(e, _) => match &e.kind {
                     ast::ExprKind::Lit(_) => true,
                     ast::ExprKind::Unary(ast::UnOp::Neg, e) => {
                         matches!(&e.kind, ast::ExprKind::Lit(_))
@@ -572,10 +572,10 @@ impl Token {
     pub fn uninterpolate(&self) -> Cow<'_, Token> {
         match &self.kind {
             Interpolated(nt) => match **nt {
-                NtIdent(ident, is_raw) => {
+                NtIdent(ident, is_raw, _) => {
                     Cow::Owned(Token::new(Ident(ident.name, is_raw), ident.span))
                 }
-                NtLifetime(ident) => Cow::Owned(Token::new(Lifetime(ident.name), ident.span)),
+                NtLifetime(ident, _) => Cow::Owned(Token::new(Lifetime(ident.name), ident.span)),
                 _ => Cow::Borrowed(self),
             },
             _ => Cow::Borrowed(self),
@@ -589,7 +589,7 @@ impl Token {
         match &self.kind {
             &Ident(name, is_raw) => Some((Ident::new(name, self.span), is_raw)),
             Interpolated(nt) => match **nt {
-                NtIdent(ident, is_raw) => Some((ident, is_raw)),
+                NtIdent(ident, is_raw, _) => Some((ident, is_raw)),
                 _ => None,
             },
             _ => None,
@@ -603,7 +603,7 @@ impl Token {
         match &self.kind {
             &Lifetime(name) => Some(Ident::new(name, self.span)),
             Interpolated(nt) => match **nt {
-                NtLifetime(ident) => Some(ident),
+                NtLifetime(ident, _) => Some(ident),
                 _ => None,
             },
             _ => None,
@@ -640,7 +640,7 @@ impl Token {
     /// (which happens while parsing the result of macro expansion)?
     pub fn is_whole_expr(&self) -> bool {
         if let Interpolated(nt) = &self.kind
-            && let NtExpr(_) | NtLiteral(_) | NtPath(_) | NtBlock(_) = **nt
+            && let NtExpr(..) | NtLiteral(..) | NtPath(..) | NtBlock(..) = **nt
         {
             return true;
         }
@@ -803,19 +803,19 @@ impl PartialEq<TokenKind> for Token {
 #[derive(Clone, Encodable, Decodable)]
 /// For interpolation during macro expansion.
 pub enum Nonterminal {
-    NtItem(P<ast::Item>),
-    NtBlock(P<ast::Block>),
-    NtStmt(P<ast::Stmt>),
-    NtPat(P<ast::Pat>),
-    NtExpr(P<ast::Expr>),
-    NtTy(P<ast::Ty>),
-    NtIdent(Ident, /* is_raw */ bool),
-    NtLifetime(Ident),
-    NtLiteral(P<ast::Expr>),
+    NtItem(P<ast::Item>, Span),
+    NtBlock(P<ast::Block>, Span),
+    NtStmt(P<ast::Stmt>, Span),
+    NtPat(P<ast::Pat>, Span),
+    NtExpr(P<ast::Expr>, Span),
+    NtTy(P<ast::Ty>, Span),
+    NtIdent(Ident, /* is_raw */ bool, Span),
+    NtLifetime(Ident, Span),
+    NtLiteral(P<ast::Expr>, Span),
     /// Stuff inside brackets for attributes
-    NtMeta(P<ast::AttrItem>),
-    NtPath(P<ast::Path>),
-    NtVis(P<ast::Visibility>),
+    NtMeta(P<ast::AttrItem>, Span),
+    NtPath(P<ast::Path>, Span),
+    NtVis(P<ast::Visibility>, Span),
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Encodable, Decodable)]
@@ -897,29 +897,63 @@ impl fmt::Display for NonterminalKind {
 }
 
 impl Nonterminal {
-    pub fn span(&self) -> Span {
+    pub fn use_span(&self) -> Span {
         match self {
-            NtItem(item) => item.span,
-            NtBlock(block) => block.span,
-            NtStmt(stmt) => stmt.span,
-            NtPat(pat) => pat.span,
-            NtExpr(expr) | NtLiteral(expr) => expr.span,
-            NtTy(ty) => ty.span,
-            NtIdent(ident, _) | NtLifetime(ident) => ident.span,
-            NtMeta(attr_item) => attr_item.span(),
-            NtPath(path) => path.span,
-            NtVis(vis) => vis.span,
+            NtItem(item, _) => item.span,
+            NtBlock(block, _) => block.span,
+            NtStmt(stmt, _) => stmt.span,
+            NtPat(pat, _) => pat.span,
+            NtExpr(expr, _) | NtLiteral(expr, _) => expr.span,
+            NtTy(ty, _) => ty.span,
+            NtIdent(ident, _, _) | NtLifetime(ident, _) => ident.span,
+            NtMeta(attr_item, _) => attr_item.span(),
+            NtPath(path, _) => path.span,
+            NtVis(vis, _) => vis.span,
+        }
+    }
+
+    pub fn def_span(&self) -> Span {
+        match self {
+            NtItem(_, span)
+            | NtBlock(_, span)
+            | NtStmt(_, span)
+            | NtPat(_, span)
+            | NtExpr(_, span)
+            | NtLiteral(_, span)
+            | NtTy(_, span)
+            | NtIdent(_, _, span)
+            | NtLifetime(_, span)
+            | NtMeta(_, span)
+            | NtPath(_, span)
+            | NtVis(_, span) => *span,
+        }
+    }
+
+    pub fn descr(&self) -> &'static str {
+        match self {
+            NtItem(..) => "item",
+            NtBlock(..) => "block",
+            NtStmt(..) => "statement",
+            NtPat(..) => "pattern",
+            NtExpr(..) => "expression",
+            NtLiteral(..) => "literal",
+            NtTy(..) => "type",
+            NtIdent(..) => "identifier",
+            NtLifetime(..) => "lifetime",
+            NtMeta(..) => "attribute",
+            NtPath(..) => "path",
+            NtVis(..) => "visibility",
         }
     }
 }
 
 impl PartialEq for Nonterminal {
     fn eq(&self, rhs: &Self) -> bool {
         match (self, rhs) {
-            (NtIdent(ident_lhs, is_raw_lhs), NtIdent(ident_rhs, is_raw_rhs)) => {
+            (NtIdent(ident_lhs, is_raw_lhs, _), NtIdent(ident_rhs, is_raw_rhs, _)) => {
                 ident_lhs == ident_rhs && is_raw_lhs == is_raw_rhs
             }
-            (NtLifetime(ident_lhs), NtLifetime(ident_rhs)) => ident_lhs == ident_rhs,
+            (NtLifetime(ident_lhs, _), NtLifetime(ident_rhs, _)) => ident_lhs == ident_rhs,
             // FIXME: Assume that all "complex" nonterminal are not equal, we can't compare them
             // correctly based on data from AST. This will prevent them from matching each other
             // in macros. The comparison will become possible only when each nonterminal has an
@@ -965,7 +999,7 @@ mod size_asserts {
     // tidy-alphabetical-start
     static_assert_size!(Lit, 12);
     static_assert_size!(LitKind, 2);
-    static_assert_size!(Nonterminal, 16);
+    static_assert_size!(Nonterminal, 24);
     static_assert_size!(Token, 24);
     static_assert_size!(TokenKind, 16);
     // tidy-alphabetical-end

compiler/rustc_ast/src/tokenstream.rs

@@ -453,31 +453,31 @@ impl TokenStream {
 
     pub fn from_nonterminal_ast(nt: &Nonterminal) -> TokenStream {
         match nt {
-            Nonterminal::NtIdent(ident, is_raw) => {
+            Nonterminal::NtIdent(ident, is_raw, _) => {
                 TokenStream::token_alone(token::Ident(ident.name, *is_raw), ident.span)
             }
-            Nonterminal::NtLifetime(ident) => {
+            Nonterminal::NtLifetime(ident, _) => {
                 TokenStream::token_alone(token::Lifetime(ident.name), ident.span)
             }
-            Nonterminal::NtItem(item) => TokenStream::from_ast(item),
-            Nonterminal::NtBlock(block) => TokenStream::from_ast(block),
-            Nonterminal::NtStmt(stmt) if let StmtKind::Empty = stmt.kind => {
+            Nonterminal::NtItem(item, _) => TokenStream::from_ast(item),
+            Nonterminal::NtBlock(block, _) => TokenStream::from_ast(block),
+            Nonterminal::NtStmt(stmt, _) if let StmtKind::Empty = stmt.kind => {
                 // FIXME: Properly collect tokens for empty statements.
                 TokenStream::token_alone(token::Semi, stmt.span)
             }
-            Nonterminal::NtStmt(stmt) => TokenStream::from_ast(stmt),
-            Nonterminal::NtPat(pat) => TokenStream::from_ast(pat),
-            Nonterminal::NtTy(ty) => TokenStream::from_ast(ty),
-            Nonterminal::NtMeta(attr) => TokenStream::from_ast(attr),
-            Nonterminal::NtPath(path) => TokenStream::from_ast(path),
-            Nonterminal::NtVis(vis) => TokenStream::from_ast(vis),
-            Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => TokenStream::from_ast(expr),
+            Nonterminal::NtStmt(stmt, _) => TokenStream::from_ast(stmt),
+            Nonterminal::NtPat(pat, _) => TokenStream::from_ast(pat),
+            Nonterminal::NtTy(ty, _) => TokenStream::from_ast(ty),
+            Nonterminal::NtMeta(attr, _) => TokenStream::from_ast(attr),
+            Nonterminal::NtPath(path, _) => TokenStream::from_ast(path),
+            Nonterminal::NtVis(vis, _) => TokenStream::from_ast(vis),
+            Nonterminal::NtExpr(expr, _) | Nonterminal::NtLiteral(expr, _) => TokenStream::from_ast(expr),
         }
     }
 
     fn flatten_token(token: &Token, spacing: Spacing) -> TokenTree {
         match &token.kind {
-            token::Interpolated(nt) if let token::NtIdent(ident, is_raw) = **nt => {
+            token::Interpolated(nt) if let token::NtIdent(ident, is_raw, _) = **nt => {
                 TokenTree::Token(Token::new(token::Ident(ident.name, is_raw), ident.span), spacing)
             }
             token::Interpolated(nt) => TokenTree::Delimited(

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -731,18 +731,18 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
 
     fn nonterminal_to_string(&self, nt: &Nonterminal) -> String {
         match nt {
-            token::NtExpr(e) => self.expr_to_string(e),
-            token::NtMeta(e) => self.attr_item_to_string(e),
-            token::NtTy(e) => self.ty_to_string(e),
-            token::NtPath(e) => self.path_to_string(e),
-            token::NtItem(e) => self.item_to_string(e),
-            token::NtBlock(e) => self.block_to_string(e),
-            token::NtStmt(e) => self.stmt_to_string(e),
-            token::NtPat(e) => self.pat_to_string(e),
-            token::NtIdent(e, is_raw) => IdentPrinter::for_ast_ident(*e, *is_raw).to_string(),
-            token::NtLifetime(e) => e.to_string(),
-            token::NtLiteral(e) => self.expr_to_string(e),
-            token::NtVis(e) => self.vis_to_string(e),
+            token::NtExpr(e, _) => self.expr_to_string(e),
+            token::NtMeta(e, _) => self.attr_item_to_string(e),
+            token::NtTy(e, _) => self.ty_to_string(e),
+            token::NtPath(e, _) => self.path_to_string(e),
+            token::NtItem(e, _) => self.item_to_string(e),
+            token::NtBlock(e, _) => self.block_to_string(e),
+            token::NtStmt(e, _) => self.stmt_to_string(e),
+            token::NtPat(e, _) => self.pat_to_string(e),
+            token::NtIdent(e, is_raw, _) => IdentPrinter::for_ast_ident(*e, *is_raw).to_string(),
+            token::NtLifetime(e, _) => e.to_string(),
+            token::NtLiteral(e, _) => self.expr_to_string(e),
+            token::NtVis(e, _) => self.vis_to_string(e),
         }
     }
 

compiler/rustc_expand/src/base.rs

@@ -1498,8 +1498,8 @@ pub(crate) fn ann_pretty_printing_compatibility_hack(ann: &Annotatable, sess: &P
 
 pub(crate) fn nt_pretty_printing_compatibility_hack(nt: &Nonterminal, sess: &ParseSess) -> bool {
     let item = match nt {
-        Nonterminal::NtItem(item) => item,
-        Nonterminal::NtStmt(stmt) => match &stmt.kind {
+        Nonterminal::NtItem(item, _) => item,
+        Nonterminal::NtStmt(stmt, _) => match &stmt.kind {
             ast::StmtKind::Item(item) => item,
             _ => return false,
         },