Rollup merge of rust-lang#128425 - tgross35:missing-fragment-specifier-unconditional, r=petrochenkov,traviscross

matthiaskrgr · web-flow · commit 8002683e9957 · 2025-06-13T05:19:13.000+02:00
Make `missing_fragment_specifier` an unconditional error This was attempted in [1] then reverted in [2] because of fallout. Recently, this was made an edition-dependent error in [3]. Make missing fragment specifiers an unconditional error again, across all editions. More context: rust-lang#128006 Most recent crater: rust-lang#128425 (comment) Fixes: rust-lang#40107 [1]: rust-lang#75516 [2]: rust-lang#80210 [3]: rust-lang#128006
diff --git a/compiler/rustc_expand/messages.ftl b/compiler/rustc_expand/messages.ftl
@@ -113,7 +113,7 @@ expand_meta_var_expr_unrecognized_var =
     variable `{$key}` is not recognized in meta-variable expression
 
 expand_missing_fragment_specifier = missing fragment specifier
-    .note = fragment specifiers must be specified in the 2024 edition
+    .note = fragment specifiers must be provided
     .suggestion_add_fragspec = try adding a specifier here
     .valid = {$valid}
 
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -112,9 +112,8 @@ use rustc_ast::{DUMMY_NODE_ID, NodeId};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::MultiSpan;
 use rustc_lint_defs::BuiltinLintDiag;
-use rustc_session::lint::builtin::{META_VARIABLE_MISUSE, MISSING_FRAGMENT_SPECIFIER};
+use rustc_session::lint::builtin::META_VARIABLE_MISUSE;
 use rustc_session::parse::ParseSess;
-use rustc_span::edition::Edition;
 use rustc_span::{ErrorGuaranteed, MacroRulesNormalizedIdent, Span, kw};
 use smallvec::SmallVec;
 
@@ -266,23 +265,11 @@ fn check_binders(
         // Similarly, this can only happen when checking a toplevel macro.
         TokenTree::MetaVarDecl(span, name, kind) => {
             if kind.is_none() && node_id != DUMMY_NODE_ID {
-                // FIXME: Report this as a hard error eventually and remove equivalent errors from
-                // `parse_tt_inner` and `nameize`. Until then the error may be reported twice, once
-                // as a hard error and then once as a buffered lint.
-                if span.edition() >= Edition::Edition2024 {
-                    psess.dcx().emit_err(errors::MissingFragmentSpecifier {
-                        span,
-                        add_span: span.shrink_to_hi(),
-                        valid: VALID_FRAGMENT_NAMES_MSG,
-                    });
-                } else {
-                    psess.buffer_lint(
-                        MISSING_FRAGMENT_SPECIFIER,
-                        span,
-                        node_id,
-                        BuiltinLintDiag::MissingFragmentSpecifier,
-                    );
-                }
+                psess.dcx().emit_err(errors::MissingFragmentSpecifier {
+                    span,
+                    add_span: span.shrink_to_hi(),
+                    valid: VALID_FRAGMENT_NAMES_MSG,
+                });
             }
             if !macros.is_empty() {
                 psess.dcx().span_bug(span, "unexpected MetaVarDecl in nested lhs");
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
@@ -533,8 +533,6 @@ lint_mismatched_lifetime_syntaxes_suggestion_implicit =
 lint_mismatched_lifetime_syntaxes_suggestion_mixed =
     one option is to remove the lifetime for references and use the anonymous lifetime for paths
 
-lint_missing_fragment_specifier = missing fragment specifier
-
 lint_missing_unsafe_on_extern = extern blocks should be unsafe
     .suggestion = needs `unsafe` before the extern keyword
 
diff --git a/compiler/rustc_lint/src/early/diagnostics.rs b/compiler/rustc_lint/src/early/diagnostics.rs
@@ -432,9 +432,6 @@ pub fn decorate_builtin_lint(
         BuiltinLintDiag::CfgAttrNoAttributes => {
             lints::CfgAttrNoAttributes.decorate_lint(diag);
         }
-        BuiltinLintDiag::MissingFragmentSpecifier => {
-            lints::MissingFragmentSpecifier.decorate_lint(diag);
-        }
         BuiltinLintDiag::MetaVariableStillRepeating(name) => {
             lints::MetaVariableStillRepeating { name }.decorate_lint(diag);
         }
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
@@ -619,6 +619,11 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, \
          see <https://github.com/rust-lang/rust/issues/116558> for more information",
     );
+    store.register_removed(
+        "missing_fragment_specifier",
+        "converted into hard error, \
+         see <https://github.com/rust-lang/rust/issues/40107> for more information",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
@@ -2616,10 +2616,6 @@ pub(crate) struct DuplicateMacroAttribute;
 #[diag(lint_cfg_attr_no_attributes)]
 pub(crate) struct CfgAttrNoAttributes;
 
-#[derive(LintDiagnostic)]
-#[diag(lint_missing_fragment_specifier)]
-pub(crate) struct MissingFragmentSpecifier;
-
 #[derive(LintDiagnostic)]
 #[diag(lint_metavariable_still_repeating)]
 pub(crate) struct MetaVariableStillRepeating {
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
@@ -65,7 +65,6 @@ declare_lint_pass! {
         MACRO_USE_EXTERN_CRATE,
         META_VARIABLE_MISUSE,
         MISSING_ABI,
-        MISSING_FRAGMENT_SPECIFIER,
         MISSING_UNSAFE_ON_EXTERN,
         MUST_NOT_SUSPEND,
         NAMED_ARGUMENTS_USED_POSITIONALLY,
@@ -1417,51 +1416,6 @@ declare_lint! {
     };
 }
 
-declare_lint! {
-    /// The `missing_fragment_specifier` lint is issued when an unused pattern in a
-    /// `macro_rules!` macro definition has a meta-variable (e.g. `$e`) that is not
-    /// followed by a fragment specifier (e.g. `:expr`).
-    ///
-    /// This warning can always be fixed by removing the unused pattern in the
-    /// `macro_rules!` macro definition.
-    ///
-    /// ### Example
-    ///
-    /// ```rust,compile_fail,edition2021
-    /// macro_rules! foo {
-    ///    () => {};
-    ///    ($name) => { };
-    /// }
-    ///
-    /// fn main() {
-    ///    foo!();
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// To fix this, remove the unused pattern from the `macro_rules!` macro definition:
-    ///
-    /// ```rust
-    /// macro_rules! foo {
-    ///     () => {};
-    /// }
-    /// fn main() {
-    ///     foo!();
-    /// }
-    /// ```
-    pub MISSING_FRAGMENT_SPECIFIER,
-    Deny,
-    "detects missing fragment specifiers in unused `macro_rules!` patterns",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseError,
-        reference: "issue #40107 <https://github.com/rust-lang/rust/issues/40107>",
-        report_in_deps: true,
-    };
-}
-
 declare_lint! {
     /// The `late_bound_lifetime_arguments` lint detects generic lifetime
     /// arguments in path segments with late bound lifetime parameters.
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
@@ -778,7 +778,6 @@ pub enum BuiltinLintDiag {
     UnnameableTestItems,
     DuplicateMacroAttribute,
     CfgAttrNoAttributes,
-    MissingFragmentSpecifier,
     MetaVariableStillRepeating(MacroRulesNormalizedIdent),
     MetaVariableWrongOperator,
     DuplicateMatcherBinding,
diff --git a/tests/rustdoc/macro/macro-generated-macro.macro_morestuff_pre.html b/tests/rustdoc/macro/macro-generated-macro.macro_morestuff_pre.html
@@ -1,7 +1,7 @@
 macro_rules! morestuff {
     (
-        <= "space between most kinds of tokens" : 1 $x + @ :: >>= 'static
-        "no space inside paren or bracket" : (2 a) [2 a] $(2 $a:tt)*
+        <= "space between most kinds of tokens" : 1 $x:ident + @ :: >>=
+        'static "no space inside paren or bracket" : (2 a) [2 a] $(2 $a:tt)*
         "space inside curly brace" : { 2 a }
         "no space inside empty delimiters" : () [] {}
         "no space before comma or semicolon" : a, (a), { a }, a; [T; 0];
diff --git a/tests/rustdoc/macro/macro-generated-macro.rs b/tests/rustdoc/macro/macro-generated-macro.rs
@@ -25,7 +25,7 @@ make_macro!(linebreak 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
 
 //@ snapshot macro_morestuff_pre macro_generated_macro/macro.morestuff.html //pre/text()
 make_macro!(morestuff
-    "space between most kinds of tokens": 1 $x + @ :: >>= 'static
+    "space between most kinds of tokens": 1 $x:ident + @ :: >>= 'static
     "no space inside paren or bracket": (2 a) [2 a] $(2 $a:tt)*
     "space inside curly brace": { 2 a }
     "no space inside empty delimiters": () [] {}
diff --git a/tests/ui/lint/expansion-time.rs b/tests/ui/lint/expansion-time.rs
@@ -5,10 +5,6 @@ macro_rules! foo {
     ( $($i:ident)* ) => { $($i)+ }; //~ WARN meta-variable repeats with different Kleene operator
 }
 
-#[warn(missing_fragment_specifier)]
-macro_rules! m { ($i) => {} } //~ WARN missing fragment specifier
-                              //~| WARN this was previously accepted
-
 #[deprecated = "reason"]
 macro_rules! deprecated {
     () => {}
diff --git a/tests/ui/lint/expansion-time.stderr b/tests/ui/lint/expansion-time.stderr
@@ -12,46 +12,17 @@ note: the lint level is defined here
 LL | #[warn(meta_variable_misuse)]
    |        ^^^^^^^^^^^^^^^^^^^^
 
-warning: missing fragment specifier
-  --> $DIR/expansion-time.rs:9:19
-   |
-LL | macro_rules! m { ($i) => {} }
-   |                   ^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
-note: the lint level is defined here
-  --> $DIR/expansion-time.rs:8:8
-   |
-LL | #[warn(missing_fragment_specifier)]
-   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 warning: include macro expected single expression in source
   --> $DIR/expansion-time-include.rs:4:1
    |
 LL | 2
    | ^
    |
 note: the lint level is defined here
-  --> $DIR/expansion-time.rs:22:8
+  --> $DIR/expansion-time.rs:18:8
    |
 LL | #[warn(incomplete_include)]
    |        ^^^^^^^^^^^^^^^^^^
 
-warning: 3 warnings emitted
-
-Future incompatibility report: Future breakage diagnostic:
-warning: missing fragment specifier
-  --> $DIR/expansion-time.rs:9:19
-   |
-LL | macro_rules! m { ($i) => {} }
-   |                   ^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
-note: the lint level is defined here
-  --> $DIR/expansion-time.rs:8:8
-   |
-LL | #[warn(missing_fragment_specifier)]
-   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^
+warning: 2 warnings emitted
 
diff --git a/tests/ui/lint/future-incompatible-lint-group.rs b/tests/ui/lint/future-incompatible-lint-group.rs
@@ -4,14 +4,23 @@
 // lints for changes that are not tied to an edition
 #![deny(future_incompatible)]
 
-// Error since this is a `future_incompatible` lint
-macro_rules! m {
-    ($i) => {};
-    //~^ ERROR missing fragment specifier
+enum E { V }
+
+trait Tr1 {
+    type V;
+    fn foo() -> Self::V;
+}
+
+impl Tr1 for E {
+    type V = u8;
+
+    // Error since this is a `future_incompatible` lint
+    fn foo() -> Self::V { 0 }
+    //~^ ERROR ambiguous associated item
     //~| WARN this was previously accepted
 }
 
-trait Tr {
+trait Tr2 {
     // Warn only since this is not a `future_incompatible` lint
     fn f(u8) {}
     //~^ WARN anonymous parameters are deprecated
diff --git a/tests/ui/lint/future-incompatible-lint-group.stderr b/tests/ui/lint/future-incompatible-lint-group.stderr
@@ -1,20 +1,5 @@
-error: missing fragment specifier
-  --> $DIR/future-incompatible-lint-group.rs:9:6
-   |
-LL |     ($i) => {};
-   |      ^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
-note: the lint level is defined here
-  --> $DIR/future-incompatible-lint-group.rs:5:9
-   |
-LL | #![deny(future_incompatible)]
-   |         ^^^^^^^^^^^^^^^^^^^
-   = note: `#[deny(missing_fragment_specifier)]` implied by `#[deny(future_incompatible)]`
-
 warning: anonymous parameters are deprecated and will be removed in the next edition
-  --> $DIR/future-incompatible-lint-group.rs:16:10
+  --> $DIR/future-incompatible-lint-group.rs:25:10
    |
 LL |     fn f(u8) {}
    |          ^^ help: try naming the parameter or explicitly ignoring it: `_: u8`
@@ -23,21 +8,30 @@ LL |     fn f(u8) {}
    = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
    = note: `#[warn(anonymous_parameters)]` on by default
 
-error: aborting due to 1 previous error; 1 warning emitted
-
-Future incompatibility report: Future breakage diagnostic:
-error: missing fragment specifier
-  --> $DIR/future-incompatible-lint-group.rs:9:6
+error: ambiguous associated item
+  --> $DIR/future-incompatible-lint-group.rs:18:17
    |
-LL |     ($i) => {};
-   |      ^^
+LL |     fn foo() -> Self::V { 0 }
+   |                 ^^^^^^^ help: use fully-qualified syntax: `<E as Tr1>::V`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
+   = note: for more information, see issue #57644 <https://github.com/rust-lang/rust/issues/57644>
+note: `V` could refer to the variant defined here
+  --> $DIR/future-incompatible-lint-group.rs:7:10
+   |
+LL | enum E { V }
+   |          ^
+note: `V` could also refer to the associated type defined here
+  --> $DIR/future-incompatible-lint-group.rs:10:5
+   |
+LL |     type V;
+   |     ^^^^^^
 note: the lint level is defined here
   --> $DIR/future-incompatible-lint-group.rs:5:9
    |
 LL | #![deny(future_incompatible)]
    |         ^^^^^^^^^^^^^^^^^^^
-   = note: `#[deny(missing_fragment_specifier)]` implied by `#[deny(future_incompatible)]`
+   = note: `#[deny(ambiguous_associated_items)]` implied by `#[deny(future_incompatible)]`
+
+error: aborting due to 1 previous error; 1 warning emitted
 
diff --git a/tests/ui/macros/issue-39404.rs b/tests/ui/macros/issue-39404.rs
@@ -1,7 +1,7 @@
 #![allow(unused)]
 
-macro_rules! m { ($i) => {} }
-//~^ ERROR missing fragment specifier
-//~| WARN previously accepted
+macro_rules! m {
+    ($i) => {}; //~ ERROR missing fragment specifier
+}
 
 fn main() {}
diff --git a/tests/ui/macros/issue-39404.stderr b/tests/ui/macros/issue-39404.stderr
@@ -1,23 +1,15 @@
 error: missing fragment specifier
-  --> $DIR/issue-39404.rs:3:19
+  --> $DIR/issue-39404.rs:4:6
    |
-LL | macro_rules! m { ($i) => {} }
-   |                   ^^
+LL |     ($i) => {};
+   |      ^^
    |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
-   = note: `#[deny(missing_fragment_specifier)]` on by default
+   = note: fragment specifiers must be provided
+   = help: valid fragment specifiers are `ident`, `block`, `stmt`, `expr`, `pat`, `ty`, `lifetime`, `literal`, `path`, `meta`, `tt`, `item` and `vis`, along with `expr_2021` and `pat_param` for edition compatibility
+help: try adding a specifier here
+   |
+LL |     ($i:spec) => {};
+   |        +++++
 
 error: aborting due to 1 previous error
 
-Future incompatibility report: Future breakage diagnostic:
-error: missing fragment specifier
-  --> $DIR/issue-39404.rs:3:19
-   |
-LL | macro_rules! m { ($i) => {} }
-   |                   ^^
-   |
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
-   = note: `#[deny(missing_fragment_specifier)]` on by default
-
diff --git a/tests/ui/macros/macro-match-nonterminal.rs b/tests/ui/macros/macro-match-nonterminal.rs
@@ -3,8 +3,6 @@ macro_rules! test {
         //~^ ERROR missing fragment
         //~| ERROR missing fragment
         //~| ERROR missing fragment
-        //~| WARN this was previously accepted
-        //~| WARN this was previously accepted
         ()
     };
 }
diff --git a/tests/ui/macros/macro-match-nonterminal.stderr b/tests/ui/macros/macro-match-nonterminal.stderr
diff --git a/tests/ui/macros/macro-missing-fragment-deduplication.rs b/tests/ui/macros/macro-missing-fragment-deduplication.rs
diff --git a/tests/ui/macros/macro-missing-fragment-deduplication.stderr b/tests/ui/macros/macro-missing-fragment-deduplication.stderr
diff --git a/tests/ui/macros/macro-missing-fragment.e2015.stderr b/tests/ui/macros/macro-missing-fragment.e2015.stderr
diff --git a/tests/ui/macros/macro-missing-fragment.rs b/tests/ui/macros/macro-missing-fragment.rs
diff --git a/tests/ui/macros/macro-missing-fragment.stderr b/tests/ui/macros/macro-missing-fragment.stderr
diff --git a/tests/ui/parser/macro/issue-33569.rs b/tests/ui/parser/macro/issue-33569.rs
diff --git a/tests/ui/parser/macro/issue-33569.stderr b/tests/ui/parser/macro/issue-33569.stderr

Original file line number	Diff line number	Diff line change
`@@ -432,9 +432,6 @@ pub fn decorate_builtin_lint(`
`432`	`432`	`BuiltinLintDiag::CfgAttrNoAttributes => {`
`433`	`433`	`lints::CfgAttrNoAttributes.decorate_lint(diag);`
`434`	`434`	`}`
`435`		`- BuiltinLintDiag::MissingFragmentSpecifier => {`
`436`		`- lints::MissingFragmentSpecifier.decorate_lint(diag);`
`437`		`- }`
`438`	`435`	`BuiltinLintDiag::MetaVariableStillRepeating(name) => {`
`439`	`436`	`lints::MetaVariableStillRepeating { name }.decorate_lint(diag);`
`440`	`437`	`}`