customize debug impl for assoc ty

could be better

Author: nikomatsakis

crates/formality-types/src/grammar/ty.rs

@@ -188,7 +188,7 @@ pub enum ScalarId {
 }
 
 #[term((alias $name $*parameters))]
-#[customize(parse)]
+#[customize(parse, debug)]
 pub struct AliasTy {
     pub name: AliasName,
     pub parameters: Parameters,

crates/formality-types/src/grammar/ty/debug_impls.rs

@@ -1 +1,24 @@
+use super::{AliasName, AliasTy, AssociatedTyName};
+use std::fmt::Debug;
 
+impl Debug for AliasTy {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let AliasTy { name, parameters } = self;
+        match name {
+            AliasName::AssociatedTyId(AssociatedTyName { trait_id, item_id }) => {
+                // Grr, wish we would remember the number of parameters assigned to each position.
+                write!(
+                    f,
+                    "({:?}::{:?})<{}>",
+                    trait_id,
+                    item_id,
+                    parameters
+                        .iter()
+                        .map(|p| format!("{p:?}"))
+                        .collect::<Vec<String>>()
+                        .join(","),
+                )
+            }
+        }
+    }
+}

tests/associated_type_normalization.rs

@@ -39,7 +39,7 @@ fn test_mirror_normalizes_u32_to_u32() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_1 => (alias (Mirror :: Assoc) (rigid (scalar u32))),
+                        ?ty_1 => (Mirror::Assoc)<(rigid (scalar u32))>,
                     },
                 },
             },

tests/coherence_overlap.rs

@@ -51,10 +51,11 @@ fn test_overlap_normalize_alias_to_LocalType() {
     // ...but it's an error if LocalType implements Iterator (figuring *this* out also
     // requires normalizing).
 
-    expect_test::expect![[r#"Err(
-    "impls may overlap:\nimpl <ty> LocalTrait < > for ^ty0_0 where [^ty0_0 : Iterator < >] { }\nimpl <> LocalTrait < > for (alias (Mirror :: T) (rigid (adt LocalType))) where [] { }",
-)
-"#]]
+    expect_test::expect![[r#"
+        Err(
+            "impls may overlap:\nimpl <ty> LocalTrait < > for ^ty0_0 where [^ty0_0 : Iterator < >] { }\nimpl <> LocalTrait < > for (Mirror::T)<(rigid (adt LocalType))> where [] { }",
+        )
+    "#]]
     .assert_debug_eq(&test_program_ok(&gen_program(
         "impl<> Iterator<> for LocalType<> where [] {}",
     )));
@@ -111,10 +112,11 @@ fn test_overlap_alias_not_normalizable() {
 
     // ...as long as there is at least one Iterator impl, however, we do flag an error.
 
-    expect_test::expect![[r#"Err(
-    "impls may overlap:\nimpl <ty> LocalTrait < > for ^ty0_0 where [^ty0_0 : Iterator < >] { }\nimpl <ty> LocalTrait < > for (alias (Mirror :: T) ^ty0_0) where [^ty0_0 : Mirror < >] { }",
-)
-"#]] // FIXME
+    expect_test::expect![[r#"
+        Err(
+            "impls may overlap:\nimpl <ty> LocalTrait < > for ^ty0_0 where [^ty0_0 : Iterator < >] { }\nimpl <ty> LocalTrait < > for (Mirror::T)<^ty0_0> where [^ty0_0 : Mirror < >] { }",
+        )
+    "#]] // FIXME
     .assert_debug_eq(&test_program_ok(&gen_program(
         "impl<> Iterator<> for u32 where[] {}",
     )));

tests/projection.rs

@@ -31,7 +31,7 @@ fn normalize_basic() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_2 => (alias (Iterator :: Item) (rigid (adt Vec) !ty_1)),
+                        ?ty_2 => (Iterator::Item)<(rigid (adt Vec) !ty_1)>,
                     },
                 },
                 Constraints {
@@ -110,7 +110,7 @@ fn normalize_basic() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_2 => (alias (Iterator :: Item) !ty_1),
+                        ?ty_2 => (Iterator::Item)<!ty_1>,
                     },
                 },
             },
@@ -169,8 +169,8 @@ fn normalize_basic() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_2 => (rigid (adt Vec) (alias (Iterator :: Item) !ty_1)),
-                        ?ty_3 => (alias (Iterator :: Item) !ty_1),
+                        ?ty_2 => (rigid (adt Vec) (Iterator::Item)<!ty_1>),
+                        ?ty_3 => (Iterator::Item)<!ty_1>,
                     },
                 },
             },
@@ -221,7 +221,7 @@ fn normalize_into_iterator() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_2 => (alias (IntoIterator :: Item) (rigid (adt Vec) !ty_1)),
+                        ?ty_2 => (IntoIterator::Item)<(rigid (adt Vec) !ty_1)>,
                     },
                 },
                 Constraints {
@@ -286,7 +286,7 @@ fn projection_equality() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_1 => (alias (Trait1 :: Type) (rigid (adt S))),
+                        ?ty_1 => (Trait1::Type)<(rigid (adt S))>,
                     },
                 },
             },
@@ -321,7 +321,7 @@ fn projection_equality() {
                     },
                     known_true: true,
                     substitution: {
-                        ?ty_1 => (alias (Trait1 :: Type) (rigid (adt S))),
+                        ?ty_1 => (Trait1::Type)<(rigid (adt S))>,
                     },
                 },
             },

tests/ui/coherence_orphan/alias_to_unit.stderr

@@ -1,4 +1,4 @@
-Error: orphan_check(impl <> CoreTrait < > for (alias (Unit :: Assoc) (rigid (adt FooStruct))) where [] { })
+Error: orphan_check(impl <> CoreTrait < > for (Unit::Assoc)<(rigid (adt FooStruct))> where [] { })
 
 Caused by:
-    failed to prove {@ IsLocal(CoreTrait((alias (Unit :: Assoc) (rigid (adt FooStruct)))))} given {}, got {}
+    failed to prove {@ IsLocal(CoreTrait((Unit::Assoc)<(rigid (adt FooStruct))>))} given {}, got {}

tests/ui/coherence_orphan/mirror_CoreStruct.stderr

@@ -1,4 +1,4 @@
-Error: orphan_check(impl <> CoreTrait < > for (alias (Mirror :: Assoc) (rigid (adt CoreStruct))) where [] { })
+Error: orphan_check(impl <> CoreTrait < > for (Mirror::Assoc)<(rigid (adt CoreStruct))> where [] { })
 
 Caused by:
-    failed to prove {@ IsLocal(CoreTrait((alias (Mirror :: Assoc) (rigid (adt CoreStruct)))))} given {}, got {}
+    failed to prove {@ IsLocal(CoreTrait((Mirror::Assoc)<(rigid (adt CoreStruct))>))} given {}, got {}