Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 34 insertions, 11 deletions

diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index f469b2dae..355722922 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -1,12 +1,10 @@
-use std::borrow::Cow;
-
 use crate::base::{DummyResult, ExtCtxt, MacResult};
 use crate::expand::{parse_ast_fragment, AstFragmentKind};
 use crate::mbe::{
     macro_parser::{MatcherLoc, NamedParseResult, ParseResult::*, TtParser},
     macro_rules::{try_match_macro, Tracker},
 };
-use rustc_ast::token::{self, Token};
+use rustc_ast::token::{self, Token, TokenKind};
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast_pretty::pprust;
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage};
@@ -14,6 +12,7 @@ use rustc_parse::parser::{Parser, Recovery};
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
+use std::borrow::Cow;
 
 use super::macro_rules::{parser_from_cx, NoopTracker};
 
@@ -63,6 +62,18 @@ pub(super) fn failed_to_match_macro<'cx>(
         err.note(format!("while trying to match {remaining_matcher}"));
     }
 
+    if let MatcherLoc::Token { token: expected_token } = &remaining_matcher
+        && (matches!(expected_token.kind, TokenKind::Interpolated(_))
+            || matches!(token.kind, TokenKind::Interpolated(_)))
+    {
+        err.note("captured metavariables except for `:tt`, `:ident` and `:lifetime` cannot be compared to other tokens");
+        err.note("see <https://doc.rust-lang.org/nightly/reference/macros-by-example.html#forwarding-a-matched-fragment> for more information");
+
+        if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
+            err.help("try using `:tt` instead in the macro definition");
+        }
+    }
+
     // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
     if let Some((arg, comma_span)) = arg.add_comma() {
         for lhs in lhses {
@@ -239,12 +250,24 @@ pub(super) fn emit_frag_parse_err(
                 e.note(
                     "the macro call doesn't expand to an expression, but it can expand to a statement",
                 );
-                e.span_suggestion_verbose(
-                    site_span.shrink_to_hi(),
-                    "add `;` to interpret the expansion as a statement",
-                    ";",
-                    Applicability::MaybeIncorrect,
-                );
+
+                if parser.token == token::Semi {
+                    if let Ok(snippet) = parser.sess.source_map().span_to_snippet(site_span) {
+                        e.span_suggestion_verbose(
+                            site_span,
+                            "surround the macro invocation with `{}` to interpret the expansion as a statement",
+                            format!("{{ {}; }}", snippet),
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                } else {
+                    e.span_suggestion_verbose(
+                        site_span.shrink_to_hi(),
+                        "add `;` to interpret the expansion as a statement",
+                        ";",
+                        Applicability::MaybeIncorrect,
+                    );
+                }
             }
         },
         _ => annotate_err_with_kind(&mut e, kind, site_span),
diff --git a/compiler/rustc_expand/src/mbe/metavar_expr.rs b/compiler/rustc_expand/src/mbe/metavar_expr.rs
index de34df011..fb3a00d86 100644
--- a/compiler/rustc_expand/src/mbe/metavar_expr.rs
+++ b/compiler/rustc_expand/src/mbe/metavar_expr.rs
@@ -41,7 +41,7 @@ impl MetaVarExpr {
         };
         check_trailing_token(&mut tts, sess)?;
         let mut iter = args.trees();
-        let rslt = match &*ident.as_str() {
+        let rslt = match ident.as_str() {
             "count" => parse_count(&mut iter, sess, ident.span)?,
             "ignore" => MetaVarExpr::Ignore(parse_ident(&mut iter, sess, ident.span)?),
             "index" => MetaVarExpr::Index(parse_depth(&mut iter, sess, ident.span)?),
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index 47a8b4bc4..a07cb6517 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -367,7 +367,7 @@ impl LockstepIterSize {
 ///
 /// Example: `$($($x $y)+*);+` -- we need to make sure that `x` and `y` repeat the same amount as
 /// each other at the given depth when the macro was invoked. If they don't it might mean they were
-/// declared at unequal depths or there was a compile bug. For example, if we have 3 repetitions of
+/// declared at depths which weren't equal or there was a compiler bug. For example, if we have 3 repetitions of
 /// the outer sequence and 4 repetitions of the inner sequence for `x`, we should have the same for
 /// `y`; otherwise, we can't transcribe them both at the given depth.
 fn lockstep_iter_size(