Also disallow ref/ref mut overriding the binding mode

rust-lang · Oct 7, 2024 · 575033c · 575033c
1 parent 4107322
commit 575033c
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Showing 6 changed files with 67 additions and 20 deletions.
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs
@@ -691,7 +691,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
                     BindingMode(def_br, Mutability::Mut)
                 } else {
-                    // `mut` resets binding mode on edition <= 2021
+                    // `mut` resets the binding mode on edition <= 2021
                     *self
                         .typeck_results
                         .borrow_mut()
@@ -702,7 +702,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             }
             BindingMode(ByRef::No, mutbl) => BindingMode(def_br, mutbl),
-            BindingMode(ByRef::Yes(_), _) => user_bind_annot,
+            BindingMode(ByRef::Yes(_), _) => {
+                if matches!(def_br, ByRef::Yes(_)) {
+                    // `ref`/`ref mut` overrides the binding mode on edition <= 2021
+                    *self
+                        .typeck_results
+                        .borrow_mut()
+                        .rust_2024_migration_desugared_pats_mut()
+                        .entry(pat_info.top_info.hir_id)
+                        .or_default() |= pat.span.at_least_rust_2024();
+                }
+                user_bind_annot
+            }
         };
 
         if bm.0 == ByRef::Yes(Mutability::Mut)

diff --git a/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.fixed b/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.fixed
@@ -30,10 +30,12 @@ fn main() {
     //~^ ERROR: the semantics of this pattern will change in edition 2024
     assert_type_eq(x, 0u8);
 
-    let Foo(ref x) = &Foo(0);
+    let &Foo(ref x) = &Foo(0);
+    //~^ ERROR: the semantics of this pattern will change in edition 2024
     assert_type_eq(x, &0u8);
 
-    let Foo(ref x) = &mut Foo(0);
+    let &mut Foo(ref x) = &mut Foo(0);
+    //~^ ERROR: the semantics of this pattern will change in edition 2024
     assert_type_eq(x, &0u8);
 
     let &Foo(x) = &Foo(0);

diff --git a/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.rs b/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.rs
@@ -31,9 +31,11 @@ fn main() {
     assert_type_eq(x, 0u8);
 
     let Foo(ref x) = &Foo(0);
+    //~^ ERROR: the semantics of this pattern will change in edition 2024
     assert_type_eq(x, &0u8);
 
     let Foo(ref x) = &mut Foo(0);
+    //~^ ERROR: the semantics of this pattern will change in edition 2024
     assert_type_eq(x, &0u8);
 
     let &Foo(x) = &Foo(0);

diff --git a/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.stderr b/tests/ui/pattern/rfc-3627-match-ergonomics-2024/migration_lint.stderr
@@ -21,63 +21,79 @@ LL |     let Foo(mut x) = &mut Foo(0);
    |         help: desugar the match ergonomics: `&mut`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:51:9
+  --> $DIR/migration_lint.rs:33:9
+   |
+LL |     let Foo(ref x) = &Foo(0);
+   |         -^^^^^^^^^
+   |         |
+   |         help: desugar the match ergonomics: `&`
+
+error: the semantics of this pattern will change in edition 2024
+  --> $DIR/migration_lint.rs:37:9
+   |
+LL |     let Foo(ref x) = &mut Foo(0);
+   |         -^^^^^^^^^
+   |         |
+   |         help: desugar the match ergonomics: `&mut`
+
+error: the semantics of this pattern will change in edition 2024
+  --> $DIR/migration_lint.rs:53:9
    |
 LL |     let Foo(&x) = &Foo(&0);
    |         -^^^^^^
    |         |
    |         help: desugar the match ergonomics: `&`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:55:9
+  --> $DIR/migration_lint.rs:57:9
    |
 LL |     let Foo(&mut x) = &Foo(&mut 0);
    |         -^^^^^^^^^^
    |         |
    |         help: desugar the match ergonomics: `&`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:59:9
+  --> $DIR/migration_lint.rs:61:9
    |
 LL |     let Foo(&x) = &mut Foo(&0);
    |         -^^^^^^
    |         |
    |         help: desugar the match ergonomics: `&mut`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:63:9
+  --> $DIR/migration_lint.rs:65:9
    |
 LL |     let Foo(&mut x) = &mut Foo(&mut 0);
    |         -^^^^^^^^^^
    |         |
    |         help: desugar the match ergonomics: `&mut`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:71:12
+  --> $DIR/migration_lint.rs:73:12
    |
 LL |     if let Some(&x) = &&&&&Some(&0u8) {
    |            -^^^^^^^
    |            |
    |            help: desugar the match ergonomics: `&&&&&`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:76:12
+  --> $DIR/migration_lint.rs:78:12
    |
 LL |     if let Some(&mut x) = &&&&&Some(&mut 0u8) {
    |            -^^^^^^^^^^^
    |            |
    |            help: desugar the match ergonomics: `&&&&&`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:81:12
+  --> $DIR/migration_lint.rs:83:12
    |
 LL |     if let Some(&x) = &&&&&mut Some(&0u8) {
    |            -^^^^^^^
    |            |
    |            help: desugar the match ergonomics: `&&&&&mut`
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:86:12
+  --> $DIR/migration_lint.rs:88:12
    |
 LL |     if let Some(&mut Some(Some(x))) = &mut Some(&mut Some(&mut Some(0u8))) {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -88,7 +104,7 @@ LL |     if let &mut Some(&mut Some(&mut Some(ref mut x))) = &mut Some(&mut Some
    |            ++++                ++++      +++++++
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:97:9
+  --> $DIR/migration_lint.rs:99:9
    |
 LL |     let Struct { a, mut b, c } = &Struct { a: 0, b: 0, c: 0 };
    |         ^^^^^^^^^^^^^^^^^^^^^^
@@ -99,7 +115,7 @@ LL |     let &Struct { ref a, mut b, ref c } = &Struct { a: 0, b: 0, c: 0 };
    |         +         +++           +++
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:102:9
+  --> $DIR/migration_lint.rs:104:9
    |
 LL |     let Struct { a: &a, b, ref c } = &Struct { a: &0, b: &0, c: &0 };
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -110,7 +126,7 @@ LL |     let &Struct { a: &a, ref b, ref c } = &Struct { a: &0, b: &0, c: &0 };
    |         +                +++
 
 error: the semantics of this pattern will change in edition 2024
-  --> $DIR/migration_lint.rs:108:12
+  --> $DIR/migration_lint.rs:110:12
    |
 LL |     if let Struct { a: &Some(a), b: Some(&b), c: Some(c) } =
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -121,12 +137,12 @@ LL |     if let &Struct { a: &Some(a), b: &Some(&b), c: &Some(ref c) } =
    |            +                         +             +     +++
 
 error: patterns are not allowed to reset the default binding mode in rust 2024
-  --> $DIR/migration_lint.rs:120:9
+  --> $DIR/migration_lint.rs:122:9
    |
 LL |         (Some(mut x), migration_lint_macros::mixed_edition_pat!(y)) => {
    |         -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |         |
    |         help: desugar the match ergonomics: `&`
 
-error: aborting due to 14 previous errors
+error: aborting due to 16 previous errors
 
diff --git a/tests/ui/pattern/rfc-3627-match-ergonomics-2024/min_match_ergonomics_fail.rs b/tests/ui/pattern/rfc-3627-match-ergonomics-2024/min_match_ergonomics_fail.rs
@@ -34,8 +34,8 @@ test_pat_on_type![Foo { f: (&x,) }: Foo]; //~ ERROR mismatched types
 test_pat_on_type![Foo { f: (&x,) }: &mut Foo]; //~ ERROR mismatched types
 test_pat_on_type![Foo { f: &(x,) }: &Foo]; //~ ERROR patterns are not allowed to reset the default binding mode
 test_pat_on_type![(mut x,): &(T,)]; //~ ERROR patterns are not allowed to reset the default binding mode
-test_pat_on_type![(ref x,): &(T,)];
-test_pat_on_type![(ref mut x,): &mut (T,)];
+test_pat_on_type![(ref x,): &(T,)]; //~ ERROR patterns are not allowed to reset the default binding mode
+test_pat_on_type![(ref mut x,): &mut (T,)]; //~ ERROR patterns are not allowed to reset the default binding mode
 
 fn get<X>() -> X {
     unimplemented!()

diff --git a/tests/ui/pattern/rfc-3627-match-ergonomics-2024/min_match_ergonomics_fail.stderr b/tests/ui/pattern/rfc-3627-match-ergonomics-2024/min_match_ergonomics_fail.stderr
@@ -131,6 +131,22 @@ LL | test_pat_on_type![(mut x,): &(T,)];
    |                   |
    |                   help: desugar the match ergonomics: `&`
 
+error: patterns are not allowed to reset the default binding mode in rust 2024
+  --> $DIR/min_match_ergonomics_fail.rs:37:19
+   |
+LL | test_pat_on_type![(ref x,): &(T,)];
+   |                   -^^^^^^^
+   |                   |
+   |                   help: desugar the match ergonomics: `&`
+
+error: patterns are not allowed to reset the default binding mode in rust 2024
+  --> $DIR/min_match_ergonomics_fail.rs:38:19
+   |
+LL | test_pat_on_type![(ref mut x,): &mut (T,)];
+   |                   -^^^^^^^^^^^
+   |                   |
+   |                   help: desugar the match ergonomics: `&mut`
+
 error: patterns are not allowed to reset the default binding mode in rust 2024
   --> $DIR/min_match_ergonomics_fail.rs:47:9
    |
@@ -139,6 +155,6 @@ LL |         (&x,) => x,
    |         |
    |         help: desugar the match ergonomics: `&`
 
-error: aborting due to 11 previous errors
+error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0308`.