Fix ICE #102878

compiler/rustc_error_messages/src/lib.rs

@@ -336,19 +336,6 @@ impl DiagnosticMessage {
  }
  }
  }
-
- /// Returns the `String` contained within the `DiagnosticMessage::Str` variant, assuming that
- /// this diagnostic message is of the legacy, non-translatable variety. Panics if this
- /// assumption does not hold.
- ///
- /// Don't use this - it exists to support some places that do comparison with diagnostic
- /// strings.
- pub fn expect_str(&self) -> &str {
- match self {
- DiagnosticMessage::Str(s) => s,
- _ => panic!("expected non-translatable diagnostic message"),
- }
- }
 }
 
 /// `From` impl that enables existing diagnostic calls to functions which now take

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -14,7 +14,7 @@ use rustc_ast::{NodeId, DUMMY_NODE_ID};
 use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, TransparencyError};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder};
+use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage};
 use rustc_feature::Features;
 use rustc_lint_defs::builtin::{
  RUST_2021_INCOMPATIBLE_OR_PATTERNS, SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
@@ -68,19 +68,22 @@ fn emit_frag_parse_err(
  kind: AstFragmentKind,
 ) {
  // FIXME(davidtwco): avoid depending on the error message text
- if parser.token == token::Eof && e.message[0].0.expect_str().ends_with(", found `<eof>`") {
- if !e.span.is_dummy() {
- // early end of macro arm (#52866)
- e.replace_span_with(parser.sess.source_map().next_point(parser.token.span));
- }
+ if parser.token == token::Eof
+ && let DiagnosticMessage::Str(message) = &e.message[0].0
+ && message.ends_with(", found `<eof>`")
+ {
  let msg = &e.message[0];
  e.message[0] = (
- rustc_errors::DiagnosticMessage::Str(format!(
+ DiagnosticMessage::Str(format!(
  "macro expansion ends with an incomplete expression: {}",
- msg.0.expect_str().replace(", found `<eof>`", ""),
+ message.replace(", found `<eof>`", ""),
  )),
  msg.1,
  );
+ if !e.span.is_dummy() {
+ // early end of macro arm (#52866)
+ e.replace_span_with(parser.sess.source_map().next_point(parser.token.span));
+ }
  }
  if e.span.is_dummy() {
  // Get around lack of span in error (#30128)

src/test/ui/macros/issue-102878.rs

@@ -0,0 +1,10 @@
+macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+//~^ ERROR mismatched closing delimiter: `)`
+//~| ERROR invalid fragment specifier `r`
+//~| ERROR expected identifier, found keyword `const`
+//~| ERROR expected identifier, found keyword `const`
+//~| ERROR expected identifier, found `:`
+
+fn s(){test!(1,i)}
+
+fn main() {}

src/test/ui/macros/issue-102878.stderr

@@ -0,0 +1,60 @@
+error: mismatched closing delimiter: `)`
+ --> $DIR/issue-102878.rs:1:35
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+ | -^ ^ mismatched closing delimiter
+ | ||
+ | |unclosed delimiter
+ | closing delimiter possibly meant for this
+
+error: invalid fragment specifier `r`
+ --> $DIR/issue-102878.rs:1:27
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+ | ^^^^
+ |
+ = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`
+
+error: expected identifier, found keyword `const`
+ --> $DIR/issue-102878.rs:1:36
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+ | ^^^^^ expected identifier, found keyword
+...
+LL | fn s(){test!(1,i)}
+ | ---------- in this macro invocation
+ |
+ = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: escape `const` to use it as an identifier
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({r#const:y y)}
+ | ++
+
+error: expected identifier, found keyword `const`
+ --> $DIR/issue-102878.rs:1:36
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+ | ^^^^^ expected identifier, found keyword
+...
+LL | fn s(){test!(1,i)}
+ | ---------- in this macro invocation
+ |
+ = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: escape `const` to use it as an identifier
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({r#const:y y)}
+ | ++
+
+error: expected identifier, found `:`
+ --> $DIR/issue-102878.rs:1:41
+ |
+LL | macro_rules!test{($l:expr,$_:r)=>({const:y y)}
+ | ^ expected identifier
+...
+LL | fn s(){test!(1,i)}
+ | ---------- in this macro invocation
+ |
+ = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 5 previous errors
+