Auto merge of #74662 - Manishearth:rollup-jdt7t71, r=Manishearth

[rust.git] / src / librustc_middle / ty / mod.rs

diff --git a/src/librustc_middle/ty/mod.rs b/src/librustc_middle/ty/mod.rs
index 9007bd99d7e4b6e8df08b1dbc00477781a0a4d79..a5ddcdfdb0408b8767ef0c75c4534ab44a55b85a 100644 (file)
--- a/src/librustc_middle/ty/mod.rs
+++ b/src/librustc_middle/ty/mod.rs
@@ -1617,12 +1617,33 @@ pub struct WithOptConstParam<T> {
 
 impl<T> WithOptConstParam<T> {
     /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
+    #[inline(always)]
     pub fn unknown(did: T) -> WithOptConstParam<T> {
         WithOptConstParam { did, const_param_did: None }
     }
 }
 
 impl WithOptConstParam<LocalDefId> {
+    /// Returns `Some((did, param_did))` if `def_id` is a const argument,
+    /// `None` otherwise.
+    #[inline(always)]
+    pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
+        tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
+    }
+
+    /// In case `self` is unknown but `self.did` is a const argument, this returns
+    /// a `WithOptConstParam` with the correct `const_param_did`.
+    #[inline(always)]
+    pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
+        if self.const_param_did.is_none() {
+            if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
+                return Some(WithOptConstParam { did: self.did, const_param_did });
+            }
+        }
+
+        None
+    }
+
     pub fn to_global(self) -> WithOptConstParam<DefId> {
         WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
     }