Reject invalid literal suffixes in tuple indexing, tuple struct indexing, and struct field name position

compiler/rustc_parse/messages.ftl

@@ -473,9 +473,6 @@ parse_invalid_label =
 
 parse_invalid_literal_suffix_on_tuple_index = suffixes on a tuple index are invalid
     .label = invalid suffix `{$suffix}`
-    .tuple_exception_line_1 = `{$suffix}` is *temporarily* accepted on tuple index fields as it was incorrectly accepted on stable for a few releases
-    .tuple_exception_line_2 = on proc macros, you'll want to use `syn::Index::from` or `proc_macro::Literal::*_unsuffixed` for code that will desugar to tuple field access
-    .tuple_exception_line_3 = see issue #60210 <https://github.com/rust-lang/rust/issues/60210> for more information
 
 parse_invalid_logical_operator = `{$incorrect}` is not a logical operator
     .note = unlike in e.g., Python and PHP, `&&` and `||` are used for logical operators

compiler/rustc_parse/src/errors.rs

@@ -1016,10 +1016,6 @@ pub(crate) struct InvalidLiteralSuffixOnTupleIndex {
     #[label]
     pub span: Span,
     pub suffix: Symbol,
-    #[help(parse_tuple_exception_line_1)]
-    #[help(parse_tuple_exception_line_2)]
-    #[help(parse_tuple_exception_line_3)]
-    pub exception: bool,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_parse/src/parser/expr.rs

@@ -1163,7 +1163,10 @@ impl<'a> Parser<'a> {
                         suffix,
                     }) => {
                         if let Some(suffix) = suffix {
-                            self.expect_no_tuple_index_suffix(current.span, suffix);
+                            self.dcx().emit_err(errors::InvalidLiteralSuffixOnTupleIndex {
+                                span: current.span,
+                                suffix,
+                            });
                         }
                         match self.break_up_float(symbol, current.span) {
                             // 1e2
@@ -1239,7 +1242,8 @@ impl<'a> Parser<'a> {
         suffix: Option<Symbol>,
     ) -> Box<Expr> {
         if let Some(suffix) = suffix {
-            self.expect_no_tuple_index_suffix(ident_span, suffix);
+            self.dcx()
+                .emit_err(errors::InvalidLiteralSuffixOnTupleIndex { span: ident_span, suffix });
         }
         self.mk_expr(lo.to(ident_span), ExprKind::Field(base, Ident::new(field, ident_span)))
     }
@@ -2225,24 +2229,6 @@ impl<'a> Parser<'a> {
         })
     }
 
-    pub(super) fn expect_no_tuple_index_suffix(&self, span: Span, suffix: Symbol) {
-        if [sym::i32, sym::u32, sym::isize, sym::usize].contains(&suffix) {
-            // #59553: warn instead of reject out of hand to allow the fix to percolate
-            // through the ecosystem when people fix their macros
-            self.dcx().emit_warn(errors::InvalidLiteralSuffixOnTupleIndex {
-                span,
-                suffix,
-                exception: true,
-            });
-        } else {
-            self.dcx().emit_err(errors::InvalidLiteralSuffixOnTupleIndex {
-                span,
-                suffix,
-                exception: false,
-            });
-        }
-    }
-
     /// Matches `'-' lit | lit` (cf. `ast_validation::AstValidator::check_expr_within_pat`).
     /// Keep this in sync with `Token::can_begin_literal_maybe_minus`.
     pub fn parse_literal_maybe_minus(&mut self) -> PResult<'a, Box<Expr>> {

compiler/rustc_parse/src/parser/mod.rs

@@ -1333,7 +1333,10 @@ impl<'a> Parser<'a> {
         if let token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) = self.token.kind
         {
             if let Some(suffix) = suffix {
-                self.expect_no_tuple_index_suffix(self.token.span, suffix);
+                self.dcx().emit_err(errors::InvalidLiteralSuffixOnTupleIndex {
+                    span: self.token.span,
+                    suffix,
+                });
             }
             self.bump();
             Ok(Ident::new(symbol, self.prev_token.span))

src/tools/tidy/src/issues.txt

@@ -2021,7 +2021,6 @@ ui/parser/issues/issue-5806.rs
 ui/parser/issues/issue-58094-missing-right-square-bracket.rs
 ui/parser/issues/issue-58856-1.rs
 ui/parser/issues/issue-58856-2.rs
-ui/parser/issues/issue-59418.rs
 ui/parser/issues/issue-60075.rs
 ui/parser/issues/issue-61858.rs
 ui/parser/issues/issue-62524.rs

tests/ui/parser/auxiliary/tuple-index-suffix-proc-macro-aux.rs

@@ -0,0 +1,33 @@
+#![feature(proc_macro_quote, proc_macro_span)]
+
+extern crate proc_macro;
+
+use proc_macro::{Ident, Literal, Span, TokenStream, TokenTree, quote};
+
+#[proc_macro]
+pub fn bad_tup_indexing(input: TokenStream) -> TokenStream {
+    let tt = input.into_iter().next().unwrap();
+    let TokenTree::Literal(indexing_expr) = tt else {
+        unreachable!();
+    };
+    quote! { (42,).$indexing_expr }
+}
+
+// Expects {IDENT, COMMA, LITERAL}
+#[proc_macro]
+pub fn bad_tup_struct_indexing(input: TokenStream) -> TokenStream {
+    let mut input = input.into_iter();
+
+    let ident = input.next().unwrap();
+    let _comma = input.next().unwrap();
+    let lit = input.next().unwrap();
+
+    let TokenTree::Ident(ident) = ident else {
+        unreachable!("id");
+    };
+    let TokenTree::Literal(indexing_expr) = lit else {
+        unreachable!("lit");
+    };
+
+    quote! { $ident.$indexing_expr }
+}

tests/ui/parser/tuple-index-suffix-proc-macro.rs

@@ -0,0 +1,32 @@
+//! See #59418.
+//!
+//! Like `tuple-index-suffix.rs`, but exercises the proc-macro interaction.
+
+//@ proc-macro: tuple-index-suffix-proc-macro-aux.rs
+
+extern crate tuple_index_suffix_proc_macro_aux;
+use tuple_index_suffix_proc_macro_aux as aux;
+
+fn main() {
+    struct TupStruct(i32);
+    let tup_struct = TupStruct(42);
+
+    // Previously, #60186 had carve outs for `{i,u}{32,usize}` as non-lint pseudo-FCW warnings. Now,
+    // they all hard error.
+
+    aux::bad_tup_indexing!(0usize);
+    //~^ ERROR suffixes on a tuple index are invalid
+    aux::bad_tup_struct_indexing!(tup_struct, 0isize);
+    //~^ ERROR suffixes on a tuple index are invalid
+
+    // Not part of the #60186 carve outs.
+
+    aux::bad_tup_indexing!(0u8);
+    //~^ ERROR suffixes on a tuple index are invalid
+    aux::bad_tup_struct_indexing!(tup_struct, 0u64);
+    //~^ ERROR suffixes on a tuple index are invalid
+
+    // NOTE: didn't bother with trying to figure out how to generate `struct P { 0u32: u32 }` using
+    // *only* `proc_macro` without help with `syn`/`quote`, looks like you can't with just
+    // `proc_macro::quote`?
+}

tests/ui/parser/tuple-index-suffix-proc-macro.stderr

@@ -0,0 +1,26 @@
+error: suffixes on a tuple index are invalid
+  --> $DIR/tuple-index-suffix-proc-macro.rs:17:28
+   |
+LL |     aux::bad_tup_indexing!(0usize);
+   |                            ^^^^^^ invalid suffix `usize`
+
+error: suffixes on a tuple index are invalid
+  --> $DIR/tuple-index-suffix-proc-macro.rs:19:47
+   |
+LL |     aux::bad_tup_struct_indexing!(tup_struct, 0isize);
+   |                                               ^^^^^^ invalid suffix `isize`
+
+error: suffixes on a tuple index are invalid
+  --> $DIR/tuple-index-suffix-proc-macro.rs:24:28
+   |
+LL |     aux::bad_tup_indexing!(0u8);
+   |                            ^^^ invalid suffix `u8`
+
+error: suffixes on a tuple index are invalid
+  --> $DIR/tuple-index-suffix-proc-macro.rs:26:47
+   |
+LL |     aux::bad_tup_struct_indexing!(tup_struct, 0u64);
+   |                                               ^^^^ invalid suffix `u64`
+
+error: aborting due to 4 previous errors
+

tests/ui/parser/tuple-index-suffix.rs

@@ -0,0 +1,79 @@
+//! Regression test for both the original regression in #59418 where invalid suffixes in indexing
+//! positions were accidentally accepted, and also for the removal of the temporary carve out that
+//! mitigated ecosystem impact following trying to reject #59418 (this was implemented as a FCW
+//! tracked in #60210).
+//!
+//! Check that we hard error on invalid suffixes in tuple indexing subexpressions and struct numeral
+//! field names.
+
+struct X(i32,i32,i32);
+
+fn main() {
+    let tup_struct = X(1, 2, 3);
+    let invalid_tup_struct_suffix = tup_struct.0suffix;
+    //~^ ERROR suffixes on a tuple index are invalid
+    let previous_carve_out_tup_struct_suffix = tup_struct.0i32;
+    //~^ ERROR suffixes on a tuple index are invalid
+
+    let tup = (1, 2, 3);
+    let invalid_tup_suffix = tup.0suffix;
+    //~^ ERROR suffixes on a tuple index are invalid
+    let previous_carve_out_tup_suffix = tup.0u32;
+    //~^ ERROR suffixes on a tuple index are invalid
+
+    numeral_struct_field_name_suffix_invalid();
+    numeral_struct_field_name_suffix_previous_carve_out();
+}
+
+// Previously, there were very limited carve outs as a ecosystem impact mitigation implemented in
+// #60186. *Only* `{i,u}{32,usize}` suffixes were temporarily accepted. Now, they all hard error.
+fn previous_carve_outs() {
+    // Previously temporarily accepted by a pseudo-FCW (#60210), now hard error.
+
+    let previous_carve_out_i32 = (42,).0i32;     //~ ERROR suffixes on a tuple index are invalid
+    let previous_carve_out_i32 = (42,).0u32;     //~ ERROR suffixes on a tuple index are invalid
+    let previous_carve_out_isize = (42,).0isize; //~ ERROR suffixes on a tuple index are invalid
+    let previous_carve_out_usize = (42,).0usize; //~ ERROR suffixes on a tuple index are invalid
+
+    // Not part of the carve outs!
+    let error_i8 = (42,).0i8;      //~ ERROR suffixes on a tuple index are invalid
+    let error_u8 = (42,).0u8;      //~ ERROR suffixes on a tuple index are invalid
+    let error_i16 = (42,).0i16;    //~ ERROR suffixes on a tuple index are invalid
+    let error_u16 = (42,).0u16;    //~ ERROR suffixes on a tuple index are invalid
+    let error_i64 = (42,).0i64;    //~ ERROR suffixes on a tuple index are invalid
+    let error_u64 = (42,).0u64;    //~ ERROR suffixes on a tuple index are invalid
+    let error_i128 = (42,).0i128;  //~ ERROR suffixes on a tuple index are invalid
+    let error_u128 = (42,).0u128;  //~ ERROR suffixes on a tuple index are invalid
+}
+
+fn numeral_struct_field_name_suffix_invalid() {
+    let invalid_struct_name = X { 0suffix: 0, 1: 1, 2: 2 };
+    //~^ ERROR suffixes on a tuple index are invalid
+    match invalid_struct_name {
+        X { 0suffix: _, .. } => {}
+        //~^ ERROR suffixes on a tuple index are invalid
+    }
+}
+
+fn numeral_struct_field_name_suffix_previous_carve_out() {
+    let carve_out_struct_name = X { 0u32: 0, 1: 1, 2: 2 };
+    //~^ ERROR suffixes on a tuple index are invalid
+    match carve_out_struct_name {
+        X { 0u32: _, .. } => {}
+        //~^ ERROR suffixes on a tuple index are invalid
+    }
+}
+
+// Unfortunately, it turns out `std::mem::offset_of!` uses the same expect suffix code path.
+fn offset_of_suffix() {
+    #[repr(C)]
+    pub struct Struct<T>(u8, T);
+
+    // Previous pseudo-FCW carve outs
+    assert_eq!(std::mem::offset_of!(Struct<u32>, 0usize), 0);
+    //~^ ERROR suffixes on a tuple index are invalid
+
+    // Not part of carve outs
+    assert_eq!(std::mem::offset_of!(Struct<u32>, 0u8), 0);
+    //~^ ERROR suffixes on a tuple index are invalid
+}