Always fall back to PartialEq when a constant in a pattern is not recursively structural-eq

2 files changed, 53 insertions, 40 deletions

diff --git a/tests/ui/pattern/usefulness/consts-opaque.rs b/tests/ui/pattern/usefulness/consts-opaque.rs
index ca4fcd85bb6..c10c6205a08 100644
--- a/tests/ui/pattern/usefulness/consts-opaque.rs
+++ b/tests/ui/pattern/usefulness/consts-opaque.rs
@@ -20,11 +20,12 @@ const BAR: Bar = Bar;
 #[derive(PartialEq)]
 enum Baz {
     Baz1,
-    Baz2
+    Baz2,
 }
 impl Eq for Baz {}
 const BAZ: Baz = Baz::Baz1;
 
+#[rustfmt::skip]
 fn main() {
     match FOO {
         FOO => {}
@@ -124,8 +125,16 @@ fn main() {
 
     match WRAPQUUX {
         Wrap(_) => {}
-        WRAPQUUX => {} // detected unreachable because we do inspect the `Wrap` layer
-        //~^ ERROR unreachable pattern
+        WRAPQUUX => {}
+    }
+
+    match WRAPQUUX {
+        Wrap(_) => {}
+    }
+
+    match WRAPQUUX {
+        //~^ ERROR: non-exhaustive patterns: `Wrap(_)` not covered
+        WRAPQUUX => {}
     }
 
     #[derive(PartialEq, Eq)]
@@ -138,8 +147,7 @@ fn main() {
     match WHOKNOWSQUUX {
         WHOKNOWSQUUX => {}
         WhoKnows::Yay(_) => {}
-        WHOKNOWSQUUX => {} // detected unreachable because we do inspect the `WhoKnows` layer
-        //~^ ERROR unreachable pattern
+        WHOKNOWSQUUX => {}
         WhoKnows::Nope => {}
     }
 }
diff --git a/tests/ui/pattern/usefulness/consts-opaque.stderr b/tests/ui/pattern/usefulness/consts-opaque.stderr
index 3f0b4a9f26a..e01b06ccc82 100644
--- a/tests/ui/pattern/usefulness/consts-opaque.stderr
+++ b/tests/ui/pattern/usefulness/consts-opaque.stderr
@@ -1,5 +1,5 @@
 error: to use a constant of type `Foo` in a pattern, `Foo` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:30:9
+  --> $DIR/consts-opaque.rs:31:9
    |
 LL |         FOO => {}
    |         ^^^
@@ -8,7 +8,7 @@ LL |         FOO => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Foo` in a pattern, `Foo` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:37:9
+  --> $DIR/consts-opaque.rs:38:9
    |
 LL |         FOO_REF => {}
    |         ^^^^^^^
@@ -17,7 +17,7 @@ LL |         FOO_REF => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 warning: to use a constant of type `Foo` in a pattern, `Foo` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:45:9
+  --> $DIR/consts-opaque.rs:46:9
    |
 LL |         FOO_REF_REF => {}
    |         ^^^^^^^^^^^
@@ -29,7 +29,7 @@ LL |         FOO_REF_REF => {}
    = note: `#[warn(indirect_structural_match)]` on by default
 
 error: to use a constant of type `Bar` in a pattern, `Bar` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:53:9
+  --> $DIR/consts-opaque.rs:54:9
    |
 LL |         BAR => {} // should not be emitting unreachable warning
    |         ^^^
@@ -38,7 +38,7 @@ LL |         BAR => {} // should not be emitting unreachable warning
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Bar` in a pattern, `Bar` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:61:9
+  --> $DIR/consts-opaque.rs:62:9
    |
 LL |         BAR => {}
    |         ^^^
@@ -47,7 +47,7 @@ LL |         BAR => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Bar` in a pattern, `Bar` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:70:9
+  --> $DIR/consts-opaque.rs:71:9
    |
 LL |         BAR => {}
    |         ^^^
@@ -56,7 +56,7 @@ LL |         BAR => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Bar` in a pattern, `Bar` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:72:9
+  --> $DIR/consts-opaque.rs:73:9
    |
 LL |         BAR => {} // should not be emitting unreachable warning
    |         ^^^
@@ -65,7 +65,7 @@ LL |         BAR => {} // should not be emitting unreachable warning
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:80:9
+  --> $DIR/consts-opaque.rs:81:9
    |
 LL |         BAZ => {}
    |         ^^^
@@ -74,7 +74,7 @@ LL |         BAZ => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:90:9
+  --> $DIR/consts-opaque.rs:91:9
    |
 LL |         BAZ => {}
    |         ^^^
@@ -83,7 +83,7 @@ LL |         BAZ => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
-  --> $DIR/consts-opaque.rs:97:9
+  --> $DIR/consts-opaque.rs:98:9
    |
 LL |         BAZ => {}
    |         ^^^
@@ -92,7 +92,7 @@ LL |         BAZ => {}
    = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralEq.html for details
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:32:9
+  --> $DIR/consts-opaque.rs:33:9
    |
 LL |         FOO => {}
    |         --- matches any value
@@ -107,7 +107,7 @@ LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:39:9
+  --> $DIR/consts-opaque.rs:40:9
    |
 LL |         FOO_REF => {}
    |         ------- matches any value
@@ -116,7 +116,7 @@ LL |         Foo(_) => {} // should not be emitting unreachable warning
    |         ^^^^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:53:9
+  --> $DIR/consts-opaque.rs:54:9
    |
 LL |         Bar => {}
    |         --- matches any value
@@ -124,7 +124,7 @@ LL |         BAR => {} // should not be emitting unreachable warning
    |         ^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:56:9
+  --> $DIR/consts-opaque.rs:57:9
    |
 LL |         Bar => {}
    |         --- matches any value
@@ -133,7 +133,7 @@ LL |         _ => {}
    |         ^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:63:9
+  --> $DIR/consts-opaque.rs:64:9
    |
 LL |         BAR => {}
    |         --- matches any value
@@ -142,7 +142,7 @@ LL |         Bar => {} // should not be emitting unreachable warning
    |         ^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:65:9
+  --> $DIR/consts-opaque.rs:66:9
    |
 LL |         BAR => {}
    |         --- matches any value
@@ -151,7 +151,7 @@ LL |         _ => {}
    |         ^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:72:9
+  --> $DIR/consts-opaque.rs:73:9
    |
 LL |         BAR => {}
    |         --- matches any value
@@ -160,7 +160,7 @@ LL |         BAR => {} // should not be emitting unreachable warning
    |         ^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:75:9
+  --> $DIR/consts-opaque.rs:76:9
    |
 LL |         BAR => {}
    |         --- matches any value
@@ -169,7 +169,7 @@ LL |         _ => {} // should not be emitting unreachable warning
    |         ^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:82:9
+  --> $DIR/consts-opaque.rs:83:9
    |
 LL |         BAZ => {}
    |         --- matches any value
@@ -178,7 +178,7 @@ LL |         Baz::Baz1 => {} // should not be emitting unreachable warning
    |         ^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:84:9
+  --> $DIR/consts-opaque.rs:85:9
    |
 LL |         BAZ => {}
    |         --- matches any value
@@ -187,7 +187,7 @@ LL |         _ => {}
    |         ^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:92:9
+  --> $DIR/consts-opaque.rs:93:9
    |
 LL |         BAZ => {}
    |         --- matches any value
@@ -196,7 +196,7 @@ LL |         _ => {}
    |         ^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:99:9
+  --> $DIR/consts-opaque.rs:100:9
    |
 LL |         BAZ => {}
    |         --- matches any value
@@ -205,7 +205,7 @@ LL |         Baz::Baz2 => {} // should not be emitting unreachable warning
    |         ^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
-  --> $DIR/consts-opaque.rs:101:9
+  --> $DIR/consts-opaque.rs:102:9
    |
 LL |         BAZ => {}
    |         --- matches any value
@@ -213,19 +213,24 @@ LL |         BAZ => {}
 LL |         _ => {} // should not be emitting unreachable warning
    |         ^ unreachable pattern
 
-error: unreachable pattern
-  --> $DIR/consts-opaque.rs:127:9
+error[E0004]: non-exhaustive patterns: `Wrap(_)` not covered
+  --> $DIR/consts-opaque.rs:135:11
    |
-LL |         Wrap(_) => {}
-   |         ------- matches any value
-LL |         WRAPQUUX => {} // detected unreachable because we do inspect the `Wrap` layer
-   |         ^^^^^^^^ unreachable pattern
-
-error: unreachable pattern
-  --> $DIR/consts-opaque.rs:141:9
+LL |     match WRAPQUUX {
+   |           ^^^^^^^^ pattern `Wrap(_)` not covered
+   |
+note: `Wrap<fn(usize, usize) -> usize>` defined here
+  --> $DIR/consts-opaque.rs:117:12
+   |
+LL |     struct Wrap<T>(T);
+   |            ^^^^
+   = note: the matched value is of type `Wrap<fn(usize, usize) -> usize>`
+help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
+   |
+LL ~         WRAPQUUX => {},
+LL +         Wrap(_) => todo!()
    |
-LL |         WHOKNOWSQUUX => {} // detected unreachable because we do inspect the `WhoKnows` layer
-   |         ^^^^^^^^^^^^
 
-error: aborting due to 24 previous errors; 1 warning emitted
+error: aborting due to 23 previous errors; 1 warning emitted
 
+For more information about this error, try `rustc --explain E0004`.