Improve dead code analysis for structs and traits defined locally

Author: mu001999

compiler/rustc_incremental/messages.ftl

@@ -99,6 +99,4 @@ incremental_unrecognized_depnode = unrecognized `DepNode` variant: {$name}
 
 incremental_unrecognized_depnode_label = dep-node label `{$label}` not recognized
 
-incremental_write_dep_graph = failed to write dependency graph to `{$path}`: {$err}
-
 incremental_write_new = failed to write {$name} to `{$path}`: {$err}

compiler/rustc_incremental/src/errors.rs

@@ -272,13 +272,6 @@ pub struct LoadDepGraph {
     pub err: std::io::Error,
 }
 
-#[derive(Diagnostic)]
-#[diag(incremental_write_dep_graph)]
-pub struct WriteDepGraph<'a> {
-    pub path: &'a Path,
-    pub err: std::io::Error,
-}
-
 #[derive(Diagnostic)]
 #[diag(incremental_move_dep_graph)]
 pub struct MoveDepGraph<'a> {

compiler/rustc_passes/src/dead.rs

@@ -4,7 +4,6 @@ use crate::layout;
 pub(crate) trait QueryContext {
     type Def: layout::Def;
     type Ref: layout::Ref;
-    type Scope: Copy;
 }
 
 #[cfg(test)]
@@ -28,7 +27,6 @@ pub(crate) mod test {
     impl QueryContext for UltraMinimal {
         type Def = Def;
         type Ref = !;
-        type Scope = ();
     }
 }
 
@@ -41,7 +39,5 @@ mod rustc {
     impl<'tcx> super::QueryContext for TyCtxt<'tcx> {
         type Def = layout::rustc::Def<'tcx>;
         type Ref = layout::rustc::Ref<'tcx>;
-
-        type Scope = Ty<'tcx>;
     }
 }

compiler/rustc_transmute/src/maybe_transmutable/query_context.rs

@@ -103,7 +103,6 @@ use crate::ascii::Char as AsciiChar;
 /// ```
 #[cfg_attr(not(test), rustc_diagnostic_item = "Default")]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg_attr(not(bootstrap), rustc_trivial_field_reads)]
 pub trait Default: Sized {
     /// Returns the "default value" for a type.
     ///

library/core/src/default.rs

@@ -4,7 +4,7 @@
 
 trait Tr1: Copy { type As1: Copy; }
 trait Tr2: Copy { type As2: Copy; }
-trait Tr3: Copy { type As3: Copy; }
+trait Tr3: Copy { #[allow(dead_code)] type As3: Copy; }
 trait Tr4<'a>: Copy { type As4: Copy; }
 trait Tr5: Copy { type As5: Copy; }
 

tests/ui/associated-type-bounds/union-bounds.rs

@@ -11,6 +11,7 @@ impl Fiz for bool {}
 
 trait Grault {
     type A;
+    #[allow(dead_code)]
     type B;
 }
 

tests/ui/associated-types/impl-wf-cycle-5.fixed

@@ -11,6 +11,7 @@ impl Fiz for bool {}
 
 trait Grault {
     type A;
+    #[allow(dead_code)]
     type B;
 }
 

tests/ui/associated-types/impl-wf-cycle-5.rs

@@ -1,5 +1,5 @@
 error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
-  --> $DIR/impl-wf-cycle-5.rs:22:1
+  --> $DIR/impl-wf-cycle-5.rs:23:1
    |
 LL | / impl<T> Grault for (T,)
 LL | |
@@ -12,7 +12,7 @@ LL |       type A = ();
    |       ------ associated type `<(T,) as Grault>::A` is specified here
    |
 note: required for `(T,)` to implement `Grault`
-  --> $DIR/impl-wf-cycle-5.rs:22:9
+  --> $DIR/impl-wf-cycle-5.rs:23:9
    |
 LL | impl<T> Grault for (T,)
    |         ^^^^^^     ^^^^

tests/ui/associated-types/impl-wf-cycle-5.stderr

@@ -11,6 +11,7 @@ impl Fiz for bool {}
 
 trait Grault {
     type A;
+    #[allow(dead_code)]
     type B;
 }