Change how anonymous associated types are printed.

nnethercote · nnethercote · commit cdf5b8d4e77d · 2025-04-11T20:13:16.000+10:00
Give them their own symbol `anon_assoc`, as is done for all the other
anonymous `DefPathData` variants.
diff --git a/compiler/rustc_hir/src/definitions.rs b/compiler/rustc_hir/src/definitions.rs
@@ -446,7 +446,7 @@ impl DefPathData {
             Ctor => DefPathDataName::Anon { namespace: sym::constructor },
             AnonConst => DefPathDataName::Anon { namespace: sym::constant },
             OpaqueTy => DefPathDataName::Anon { namespace: sym::opaque },
-            AnonAssocTy => DefPathDataName::Anon { namespace: sym::synthetic },
+            AnonAssocTy => DefPathDataName::Anon { namespace: sym::anon_assoc },
             SyntheticCoroutineBody => DefPathDataName::Anon { namespace: sym::synthetic },
         }
     }
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
@@ -454,6 +454,7 @@ symbols! {
         and_then,
         anon,
         anon_adt,
+        anon_assoc,
         anonymous_lifetime_in_impl_trait,
         any,
         append_const_msg,
diff --git a/tests/ui-fulldeps/stable-mir/check_assoc_items.rs b/tests/ui-fulldeps/stable-mir/check_assoc_items.rs
@@ -51,7 +51,7 @@ fn test_assoc_items() -> ControlFlow<()> {
     check_items(
         &trait_assoc_item_defs,
         &[
-            "ATrait::{synthetic#0}",
+            "ATrait::{anon_assoc#0}",
             "ATrait::rpitit",
             "ATrait::Assoc",
             "ATrait::assoc_fn_no_self",
@@ -64,7 +64,7 @@ fn test_assoc_items() -> ControlFlow<()> {
     check_items(
         &impl_assoc_item_defs,
         &[
-            "<AStruct as ATrait>::{synthetic#0}",
+            "<AStruct as ATrait>::{anon_assoc#0}",
             "<AStruct as ATrait>::rpitit",
             "<AStruct as ATrait>::Assoc",
             "<AStruct as ATrait>::assoc_fn_no_self",
diff --git a/tests/ui/delegation/unsupported.stderr b/tests/ui/delegation/unsupported.stderr
@@ -1,4 +1,4 @@
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`
   --> $DIR/unsupported.rs:22:25
    |
 LL |         reuse to_reuse::opaque_ret;
@@ -9,15 +9,15 @@ note: ...which requires comparing an impl and trait method signature, inferring
    |
 LL |         reuse to_reuse::opaque_ret;
    |                         ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`, completing the cycle
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`, completing the cycle
 note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>` is well-formed
   --> $DIR/unsupported.rs:21:5
    |
 LL |     impl ToReuse for u8 {
    |     ^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`
   --> $DIR/unsupported.rs:25:24
    |
 LL |         reuse ToReuse::opaque_ret;
@@ -28,7 +28,7 @@ note: ...which requires comparing an impl and trait method signature, inferring
    |
 LL |         reuse ToReuse::opaque_ret;
    |                        ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`, completing the cycle
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`, completing the cycle
 note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>` is well-formed
   --> $DIR/unsupported.rs:24:5
    |
diff --git a/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr b/tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr
@@ -6,11 +6,11 @@ LL |     fn bar() -> () {}
    |
    = help: the trait `std::fmt::Display` is not implemented for `()`
    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
-note: required by a bound in `Foo::{synthetic#0}`
+note: required by a bound in `Foo::{anon_assoc#0}`
   --> $DIR/doesnt-satisfy.rs:2:22
    |
 LL |     fn bar() -> impl std::fmt::Display;
-   |                      ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{synthetic#0}`
+   |                      ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/impl-trait/in-trait/dump.rs b/tests/ui/impl-trait/in-trait/dump.rs
@@ -8,7 +8,7 @@ trait Foo {
 }
 
 fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {
-//~^ ERROR <T as Foo>::{synthetic#0}<'s/#1>
+//~^ ERROR <T as Foo>::{anon_assoc#0}<'s/#1>
     x.hello()
 }
 
diff --git a/tests/ui/impl-trait/in-trait/dump.stderr b/tests/ui/impl-trait/in-trait/dump.stderr
@@ -1,4 +1,4 @@
-error: <T as Foo>::{synthetic#0}<'s/#1>
+error: <T as Foo>::{anon_assoc#0}<'s/#1>
   --> $DIR/dump.rs:10:35
    |
 LL | fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {
diff --git a/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr b/tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr
@@ -14,11 +14,11 @@ LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
    |                                  ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
    |
    = help: the trait `Foo<char>` is implemented for `Bar`
-note: required by a bound in `Foo::{synthetic#0}`
+note: required by a bound in `Foo::{anon_assoc#0}`
   --> $DIR/return-dont-satisfy-bounds.rs:2:30
    |
 LL |     fn foo<F2>(self) -> impl Foo<T>;
-   |                              ^^^^^^ required by this bound in `Foo::{synthetic#0}`
+   |                              ^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
 
 error[E0277]: the trait bound `Bar: Foo<u8>` is not satisfied
   --> $DIR/return-dont-satisfy-bounds.rs:8:34
diff --git a/tests/ui/rfcs/rfc-1937-termination-trait/issue-103052-2.stderr b/tests/ui/rfcs/rfc-1937-termination-trait/issue-103052-2.stderr
@@ -4,11 +4,11 @@ error[E0277]: the trait bound `Something: Termination` is not satisfied
 LL |         fn main() -> Something {
    |                      ^^^^^^^^^ the trait `Termination` is not implemented for `Something`
    |
-note: required by a bound in `Main::{synthetic#0}`
+note: required by a bound in `Main::{anon_assoc#0}`
   --> $DIR/issue-103052-2.rs:3:27
    |
 LL |         fn main() -> impl std::process::Termination;
-   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{synthetic#0}`
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{anon_assoc#0}`
 
 error: aborting due to 1 previous error
 

Original file line number	Diff line number	Diff line change
`@@ -446,7 +446,7 @@ impl DefPathData {`
`446`	`446`	`Ctor => DefPathDataName::Anon { namespace: sym::constructor },`
`447`	`447`	`AnonConst => DefPathDataName::Anon { namespace: sym::constant },`
`448`	`448`	`OpaqueTy => DefPathDataName::Anon { namespace: sym::opaque },`
`449`		`- AnonAssocTy => DefPathDataName::Anon { namespace: sym::synthetic },`
	`449`	`+ AnonAssocTy => DefPathDataName::Anon { namespace: sym::anon_assoc },`
`450`	`450`	`SyntheticCoroutineBody => DefPathDataName::Anon { namespace: sym::synthetic },`
`451`	`451`	`}`
`452`	`452`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`
	`1`	+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`
`2`	`2`	`--> $DIR/unsupported.rs:22:25`
`3`	`3`	`\|`
`4`	`4`	`LL \| reuse to_reuse::opaque_ret;`
`@@ -9,15 +9,15 @@ note: ...which requires comparing an impl and trait method signature, inferring`
`9`	`9`	`\|`
`10`	`10`	`LL \| reuse to_reuse::opaque_ret;`
`11`	`11`	`\| ^^^^^^^^^^`
`12`		- = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`, completing the cycle
	`12`	+ = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`, completing the cycle
`13`	`13`	note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>` is well-formed
`14`	`14`	`--> $DIR/unsupported.rs:21:5`
`15`	`15`	`\|`
`16`	`16`	`LL \| impl ToReuse for u8 {`
`17`	`17`	`\| ^^^^^^^^^^^^^^^^^^^`
`18`	`18`	`= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information`
`19`	`19`
`20`		-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`
	`20`	+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`
`21`	`21`	`--> $DIR/unsupported.rs:25:24`
`22`	`22`	`\|`
`23`	`23`	`LL \| reuse ToReuse::opaque_ret;`
`@@ -28,7 +28,7 @@ note: ...which requires comparing an impl and trait method signature, inferring`
`28`	`28`	`\|`
`29`	`29`	`LL \| reuse ToReuse::opaque_ret;`
`30`	`30`	`\| ^^^^^^^^^^`
`31`		- = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`, completing the cycle
	`31`	+ = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`, completing the cycle
`32`	`32`	note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>` is well-formed
`33`	`33`	`--> $DIR/unsupported.rs:24:5`
`34`	`34`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -6,11 +6,11 @@ LL \| fn bar() -> () {}`
`6`	`6`	`\|`
`7`	`7`	= help: the trait `std::fmt::Display` is not implemented for `()`
`8`	`8`	= note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
`9`		-note: required by a bound in `Foo::{synthetic#0}`
	`9`	+note: required by a bound in `Foo::{anon_assoc#0}`
`10`	`10`	`--> $DIR/doesnt-satisfy.rs:2:22`
`11`	`11`	`\|`
`12`	`12`	`LL \| fn bar() -> impl std::fmt::Display;`
`13`		- \| ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{synthetic#0}`
	`13`	+ \| ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
`14`	`14`
`15`	`15`	`error: aborting due to 1 previous error`
`16`	`16`
Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@ trait Foo {`
`8`	`8`	`}`
`9`	`9`
`10`	`10`	`fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {`
`11`		`-//~^ ERROR <T as Foo>::{synthetic#0}<'s/#1>`
	`11`	`+//~^ ERROR <T as Foo>::{anon_assoc#0}<'s/#1>`
`12`	`12`	`x.hello()`
`13`	`13`	`}`
`14`	`14`
Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-error: <T as Foo>::{synthetic#0}<'s/#1>`
	`1`	`+error: <T as Foo>::{anon_assoc#0}<'s/#1>`
`2`	`2`	`--> $DIR/dump.rs:10:35`
`3`	`3`	`\|`
`4`	`4`	`LL \| fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {`
Original file line number	Diff line number	Diff line change
`@@ -14,11 +14,11 @@ LL \| fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {`
`14`	`14`	\| ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
`15`	`15`	`\|`
`16`	`16`	= help: the trait `Foo<char>` is implemented for `Bar`
`17`		-note: required by a bound in `Foo::{synthetic#0}`
	`17`	+note: required by a bound in `Foo::{anon_assoc#0}`
`18`	`18`	`--> $DIR/return-dont-satisfy-bounds.rs:2:30`
`19`	`19`	`\|`
`20`	`20`	`LL \| fn foo<F2>(self) -> impl Foo<T>;`
`21`		- \| ^^^^^^ required by this bound in `Foo::{synthetic#0}`
	`21`	+ \| ^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
`22`	`22`
`23`	`23`	error[E0277]: the trait bound `Bar: Foo<u8>` is not satisfied
`24`	`24`	`--> $DIR/return-dont-satisfy-bounds.rs:8:34`
Original file line number	Diff line number	Diff line change
@@ -4,11 +4,11 @@ error[E0277]: the trait bound `Something: Termination` is not satisfied
`4`	`4`	`LL \| fn main() -> Something {`
`5`	`5`	\| ^^^^^^^^^ the trait `Termination` is not implemented for `Something`
`6`	`6`	`\|`
`7`		-note: required by a bound in `Main::{synthetic#0}`
	`7`	+note: required by a bound in `Main::{anon_assoc#0}`
`8`	`8`	`--> $DIR/issue-103052-2.rs:3:27`
`9`	`9`	`\|`
`10`	`10`	`LL \| fn main() -> impl std::process::Termination;`
`11`		- \| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{synthetic#0}`
	`11`	+ \| ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{anon_assoc#0}`
`12`	`12`
`13`	`13`	`error: aborting due to 1 previous error`
`14`	`14`