Move IntercrateAmbiguityCause back to rustc::traits::select.

Author: cjgillot

src/librustc/traits/select.rs

@@ -288,3 +288,44 @@ impl<T: Clone> WithDepNode<T> {
         self.cached_value.clone()
     }
 }
+
+#[derive(Clone, Debug)]
+pub enum IntercrateAmbiguityCause {
+    DownstreamCrate { trait_desc: String, self_desc: Option<String> },
+    UpstreamCrateUpdate { trait_desc: String, self_desc: Option<String> },
+    ReservationImpl { message: String },
+}
+
+impl IntercrateAmbiguityCause {
+    /// Emits notes when the overlap is caused by complex intercrate ambiguities.
+    /// See #23980 for details.
+    pub fn add_intercrate_ambiguity_hint(&self, err: &mut rustc_errors::DiagnosticBuilder<'_>) {
+        err.note(&self.intercrate_ambiguity_hint());
+    }
+
+    pub fn intercrate_ambiguity_hint(&self) -> String {
+        match self {
+            &IntercrateAmbiguityCause::DownstreamCrate { ref trait_desc, ref self_desc } => {
+                let self_desc = if let &Some(ref ty) = self_desc {
+                    format!(" for type `{}`", ty)
+                } else {
+                    String::new()
+                };
+                format!("downstream crates may implement trait `{}`{}", trait_desc, self_desc)
+            }
+            &IntercrateAmbiguityCause::UpstreamCrateUpdate { ref trait_desc, ref self_desc } => {
+                let self_desc = if let &Some(ref ty) = self_desc {
+                    format!(" for type `{}`", ty)
+                } else {
+                    String::new()
+                };
+                format!(
+                    "upstream crates may add a new impl of trait `{}`{} \
+                     in future versions",
+                    trait_desc, self_desc
+                )
+            }
+            &IntercrateAmbiguityCause::ReservationImpl { ref message } => message.clone(),
+        }
+    }
+}

src/librustc_infer/traits/select.rs

@@ -95,47 +95,6 @@ pub struct SelectionContext<'cx, 'tcx> {
     query_mode: TraitQueryMode,
 }
 
-#[derive(Clone, Debug)]
-pub enum IntercrateAmbiguityCause {
-    DownstreamCrate { trait_desc: String, self_desc: Option<String> },
-    UpstreamCrateUpdate { trait_desc: String, self_desc: Option<String> },
-    ReservationImpl { message: String },
-}
-
-impl IntercrateAmbiguityCause {
-    /// Emits notes when the overlap is caused by complex intercrate ambiguities.
-    /// See #23980 for details.
-    pub fn add_intercrate_ambiguity_hint(&self, err: &mut rustc_errors::DiagnosticBuilder<'_>) {
-        err.note(&self.intercrate_ambiguity_hint());
-    }
-
-    pub fn intercrate_ambiguity_hint(&self) -> String {
-        match self {
-            &IntercrateAmbiguityCause::DownstreamCrate { ref trait_desc, ref self_desc } => {
-                let self_desc = if let &Some(ref ty) = self_desc {
-                    format!(" for type `{}`", ty)
-                } else {
-                    String::new()
-                };
-                format!("downstream crates may implement trait `{}`{}", trait_desc, self_desc)
-            }
-            &IntercrateAmbiguityCause::UpstreamCrateUpdate { ref trait_desc, ref self_desc } => {
-                let self_desc = if let &Some(ref ty) = self_desc {
-                    format!(" for type `{}`", ty)
-                } else {
-                    String::new()
-                };
-                format!(
-                    "upstream crates may add a new impl of trait `{}`{} \
-                     in future versions",
-                    trait_desc, self_desc
-                )
-            }
-            &IntercrateAmbiguityCause::ReservationImpl { ref message } => message.clone(),
-        }
-    }
-}
-
 // A stack that walks back up the stack frame.
 struct TraitObligationStack<'prev, 'tcx> {
     obligation: &'prev TraitObligation<'tcx>,