add def-ids from nominal types into TraitSelect

This way we distinguish, in particular, `Foo: Sized`
and `Bar: Sized`, which fixes #33850.

Author: nikomatsakis

src/librustc/ty/mod.rs

@@ -946,7 +946,28 @@ impl<'tcx> TraitPredicate<'tcx> {
 
     /// Creates the dep-node for selecting/evaluating this trait reference.
     fn dep_node(&self) -> DepNode<DefId> {
-        DepNode::TraitSelect(self.def_id(), vec![])
+        // Ideally, the dep-node would just have all the input types
+        // in it.  But they are limited to including def-ids. So as an
+        // approximation we include the def-ids for all nominal types
+        // found somewhere. This means that we will e.g. conflate the
+        // dep-nodes for `u32: SomeTrait` and `u64: SomeTrait`, but we
+        // would have distinct dep-nodes for `Vec<u32>: SomeTrait`,
+        // `Rc<u32>: SomeTrait`, and `(Vec<u32>, Rc<u32>): SomeTrait`.
+        // Note that it's always sound to conflate dep-nodes, it jus
+        // leads to more recompilation.
+        let def_ids: Vec<_> =
+            self.input_types()
+                .iter()
+                .flat_map(|t| t.walk())
+                .filter_map(|t| match t.sty {
+                    ty::TyStruct(adt_def, _) |
+                    ty::TyEnum(adt_def, _) =>
+                        Some(adt_def.did),
+                    _ =>
+                        None
+                })
+                .collect();
+        DepNode::TraitSelect(self.def_id(), def_ids)
     }
 
     pub fn input_types(&self) -> &[Ty<'tcx>] {

src/test/incremental/struct_add_field.rs

@@ -40,7 +40,7 @@ pub fn use_EmbedX(embed: EmbedX) -> u32 {
     embed.x.x as u32
 }
 
-#[rustc_dirty(label="TypeckItemBody", cfg="rpass2")] // FIXME(#33850) should be clean
+#[rustc_clean(label="TypeckItemBody", cfg="rpass2")]
 pub fn use_Y() {
     let x: Y = Y { y: 'c' };
 }

src/test/incremental/struct_change_field_name.rs

@@ -47,7 +47,7 @@ pub fn use_EmbedX(embed: EmbedX) -> u32 {
     //[cfail2]~^ ERROR attempted access of field `x`
 }
 
-#[rustc_dirty(label="TypeckItemBody", cfg="cfail2")] // FIXME(#33850) should be clean
+#[rustc_clean(label="TypeckItemBody", cfg="cfail2")]
 pub fn use_Y() {
     let x: Y = Y { y: 'c' };
 }

src/test/incremental/struct_change_field_type.rs

@@ -45,7 +45,7 @@ pub fn use_EmbedX(x: EmbedX) -> u32 {
     x.x as u32
 }
 
-#[rustc_dirty(label="TypeckItemBody", cfg="rpass2")] // FIXME(#33850) should be clean
+#[rustc_clean(label="TypeckItemBody", cfg="rpass2")]
 pub fn use_Y() {
     let x: Y = Y { y: 'c' };
 }

src/test/incremental/struct_change_field_type_cross_crate/b.rs

@@ -28,7 +28,7 @@ pub fn use_EmbedX(embed: EmbedX) -> u32 {
     embed.x.x as u32
 }
 
-#[rustc_dirty(label="TypeckItemBody", cfg="rpass2")] // FIXME(#33850) should be clean
+#[rustc_clean(label="TypeckItemBody", cfg="rpass2")]
 pub fn use_Y() {
     let x: Y = Y { y: 'c' };
 }

src/test/incremental/struct_remove_field.rs

@@ -44,7 +44,7 @@ pub fn use_EmbedX(embed: EmbedX) -> u32 {
     embed.x.x as u32
 }
 
-#[rustc_dirty(label="TypeckItemBody", cfg="rpass2")] // FIXME(#33850) should be clean
+#[rustc_clean(label="TypeckItemBody", cfg="rpass2")]
 pub fn use_Y() {
     let x: Y = Y { y: 'c' };
 }