Unrolled build for rust-lang#124381

Rollup merge of rust-lang#124381 - compiler-errors:derived-for-wf, r=lcnr

Renamed `DerivedObligation` to `WellFormedDeriveObligation`

It's used when computing `WellFormed` obligations, so let's give it a less ambiguous name.

Author: rust-timer

compiler/rustc_middle/src/traits/mod.rs

@@ -328,11 +328,16 @@ pub enum ObligationCauseCode<'tcx> {
     /// `static` items must have `Sync` type.
     SharedStatic,
 
+    /// Derived obligation (i.e. theoretical `where` clause) on a built-in
+    /// implementation like `Copy` or `Sized`.
     BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
 
+    /// Derived obligation (i.e. `where` clause) on an user-provided impl
+    /// or a trait alias.
     ImplDerivedObligation(Box<ImplDerivedObligationCause<'tcx>>),
 
-    DerivedObligation(DerivedObligationCause<'tcx>),
+    /// Derived obligation for WF goals.
+    WellFormedDerivedObligation(DerivedObligationCause<'tcx>),
 
     FunctionArgumentObligation {
         /// The node of the relevant argument in the function call.
@@ -534,7 +539,7 @@ impl<'tcx> ObligationCauseCode<'tcx> {
         match self {
             FunctionArgumentObligation { parent_code, .. } => Some((parent_code, None)),
             BuiltinDerivedObligation(derived)
-            | DerivedObligation(derived)
+            | WellFormedDerivedObligation(derived)
             | ImplDerivedObligation(box ImplDerivedObligationCause { derived, .. }) => {
                 Some((&derived.parent_code, Some(derived.parent_trait_pred)))
             }

compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs

@@ -128,7 +128,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         match obligation.cause.code() {
             ObligationCauseCode::BuiltinDerivedObligation(..)
             | ObligationCauseCode::ImplDerivedObligation(..)
-            | ObligationCauseCode::DerivedObligation(..) => {}
+            | ObligationCauseCode::WellFormedDerivedObligation(..) => {}
             _ => {
                 // this is a "direct", user-specified, rather than derived,
                 // obligation.

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -2294,7 +2294,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
                     next_code = Some(&cause.derived.parent_code);
                 }
-                ObligationCauseCode::DerivedObligation(derived_obligation)
+                ObligationCauseCode::WellFormedDerivedObligation(derived_obligation)
                 | ObligationCauseCode::BuiltinDerivedObligation(derived_obligation) => {
                     let ty = derived_obligation.parent_trait_pred.skip_binder().self_ty();
                     debug!(
@@ -3423,7 +3423,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     )
                 });
             }
-            ObligationCauseCode::DerivedObligation(ref data) => {
+            ObligationCauseCode::WellFormedDerivedObligation(ref data) => {
                 let parent_trait_ref = self.resolve_vars_if_possible(data.parent_trait_pred);
                 let parent_predicate = parent_trait_ref;
                 // #74711: avoid a stack overflow

compiler/rustc_trait_selection/src/traits/wf.rs

@@ -381,7 +381,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
             if let Some(parent_trait_pred) = predicate.to_opt_poly_trait_pred() {
                 cause = cause.derived_cause(
                     parent_trait_pred,
-                    traits::ObligationCauseCode::DerivedObligation,
+                    traits::ObligationCauseCode::WellFormedDerivedObligation,
                 );
             }
             extend_cause_with_original_assoc_item_obligation(tcx, item, &mut cause, predicate);