Remove `NtPat`.

The one notable test change is `tests/ui/macros/trace_faulty_macros.rs`.
This commit removes the complicated `Interpolated` handling in
`expected_expression_found` that results in a longer error message. But
I think the new, shorter message is actually an improvement.

The original complaint was in #71039, when the error message started
with "error: expected expression, found `1 + 1`". That was confusing
because `1 + 1` is an expression. Other than that, the reporter said
"the whole error message is not too bad if you ignore the first line".

Subsequently, extra complexity and wording was added to the error
message. But I don't think the extra wording actually helps all that
much. In particular, it still says of the `1+1` that "this is expected
to be expression". This repeats the problem from the original complaint!

This commit removes the extra complexity, reverting to a simpler error
message. This is primarily because the traversal is a pain without
`Interpolated` tokens. Nonetheless, I think the error message is
*improved*. It now starts with "expected expression, found `pat`
metavariable", which is much clearer and the real problem. It also
doesn't say anything specific about `1+1`, which is good, because the
`1+1` isn't really relevant to the error -- it's the `$e:pat` that's
important.

4 files changed, 0 insertions, 9 deletions

diff --git a/compiler/rustc_ast/src/ast_traits.rs b/compiler/rustc_ast/src/ast_traits.rs
index 346edc87c86..8b94d65c44e 100644
--- a/compiler/rustc_ast/src/ast_traits.rs
+++ b/compiler/rustc_ast/src/ast_traits.rs
@@ -202,7 +202,6 @@ impl HasTokens for Nonterminal {
             Nonterminal::NtItem(item) => item.tokens(),
             Nonterminal::NtStmt(stmt) => stmt.tokens(),
             Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens(),
-            Nonterminal::NtPat(pat) => pat.tokens(),
             Nonterminal::NtMeta(attr_item) => attr_item.tokens(),
             Nonterminal::NtPath(path) => path.tokens(),
             Nonterminal::NtBlock(block) => block.tokens(),
@@ -213,7 +212,6 @@ impl HasTokens for Nonterminal {
             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::NtMeta(attr_item) => attr_item.tokens_mut(),
             Nonterminal::NtPath(path) => path.tokens_mut(),
             Nonterminal::NtBlock(block) => block.tokens_mut(),
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 40b29fdba25..6ebe52738b9 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -905,7 +905,6 @@ fn visit_nonterminal<T: MutVisitor>(vis: &mut T, nt: &mut token::Nonterminal) {
                 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::NtLiteral(expr) => vis.visit_expr(expr),
         token::NtMeta(item) => {
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 97d121909f8..ff8a68ff711 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -659,7 +659,6 @@ impl Token {
                     | NtExpr(..)
                     | NtLiteral(..)
                     | NtMeta(..)
-                    | NtPat(..)
                     | NtPath(..)
                 ),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
@@ -1075,7 +1074,6 @@ pub enum Nonterminal {
     NtItem(P<ast::Item>),
     NtBlock(P<ast::Block>),
     NtStmt(P<ast::Stmt>),
-    NtPat(P<ast::Pat>),
     NtExpr(P<ast::Expr>),
     NtLiteral(P<ast::Expr>),
     /// Stuff inside brackets for attributes
@@ -1172,7 +1170,6 @@ impl Nonterminal {
             NtItem(item) => item.span,
             NtBlock(block) => block.span,
             NtStmt(stmt) => stmt.span,
-            NtPat(pat) => pat.span,
             NtExpr(expr) | NtLiteral(expr) => expr.span,
             NtMeta(attr_item) => attr_item.span(),
             NtPath(path) => path.span,
@@ -1184,7 +1181,6 @@ impl Nonterminal {
             NtItem(..) => "item",
             NtBlock(..) => "block",
             NtStmt(..) => "statement",
-            NtPat(..) => "pattern",
             NtExpr(..) => "expression",
             NtLiteral(..) => "literal",
             NtMeta(..) => "attribute",
@@ -1209,7 +1205,6 @@ impl fmt::Debug for Nonterminal {
             NtItem(..) => f.pad("NtItem(..)"),
             NtBlock(..) => f.pad("NtBlock(..)"),
             NtStmt(..) => f.pad("NtStmt(..)"),
-            NtPat(..) => f.pad("NtPat(..)"),
             NtExpr(..) => f.pad("NtExpr(..)"),
             NtLiteral(..) => f.pad("NtLiteral(..)"),
             NtMeta(..) => f.pad("NtMeta(..)"),
diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index 1123ea3a449..2b4c818fc32 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -468,7 +468,6 @@ impl TokenStream {
                 TokenStream::token_alone(token::Semi, stmt.span)
             }
             Nonterminal::NtStmt(stmt) => TokenStream::from_ast(stmt),
-            Nonterminal::NtPat(pat) => TokenStream::from_ast(pat),
             Nonterminal::NtMeta(attr) => TokenStream::from_ast(attr),
             Nonterminal::NtPath(path) => TokenStream::from_ast(path),
             Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => TokenStream::from_ast(expr),