Rollup merge of #61698 - davidtwco:ice-const-generic-length, r=varkor

[rust.git] / src / librustc_typeck / astconv.rs

diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 349c4e608c2446c5c577601f0516edb8d8bbf64c..5a46c9d440b5d82bb1378d636ed8fc8201409b93 100644 (file)
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -49,19 +49,17 @@ fn get_type_parameter_bounds(&self, span: Span, def_id: DefId)
                                  -> &'tcx ty::GenericPredicates<'tcx>;
 
     /// Returns the lifetime to use when a lifetime is omitted (and not elided).
-    fn re_infer(&self, span: Span, _def: Option<&ty::GenericParamDef>)
+    fn re_infer(
+        &self,
+        param: Option<&ty::GenericParamDef>,
+        span: Span,
+    )
                 -> Option<ty::Region<'tcx>>;
 
     /// Returns the type to use when a type is omitted.
-    fn ty_infer(&self, span: Span) -> Ty<'tcx>;
+    fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx>;
 
-    /// Same as `ty_infer`, but with a known type parameter definition.
-    fn ty_infer_for_def(&self,
-                        _def: &ty::GenericParamDef,
-                        span: Span) -> Ty<'tcx> {
-        self.ty_infer(span)
-    }
-    /// What const should we use when a const is omitted?
+    /// Returns the const to use when a const is omitted.
     fn ct_infer(
         &self,
         ty: Ty<'tcx>,
@@ -163,7 +161,7 @@ pub fn ast_region_to_region(&self,
             }
 
             None => {
-                self.re_infer(lifetime.span, def)
+                self.re_infer(def, lifetime.span)
                     .unwrap_or_else(|| {
                         // This indicates an illegal lifetime
                         // elision. `resolve_lifetime` should have
@@ -701,11 +699,12 @@ fn create_substs_for_ast_path<'a>(&self,
                             }
                         } else if infer_args {
                             // No type parameters were provided, we can infer all.
-                            if !default_needs_object_self(param) {
-                                self.ty_infer_for_def(param, span).into()
+                            let param = if !default_needs_object_self(param) {
+                                Some(param)
                             } else {
-                                self.ty_infer(span).into()
-                            }
+                                None
+                            };
+                            self.ty_infer(param, span).into()
                         } else {
                             // We've already errored above about the mismatch.
                             tcx.types.err.into()
@@ -1440,7 +1439,7 @@ fn conv_object_ty_poly_trait_ref(&self,
                 if tcx.named_region(lifetime.hir_id).is_some() {
                     self.ast_region_to_region(lifetime, None)
                 } else {
-                    self.re_infer(span, None).unwrap_or_else(|| {
+                    self.re_infer(None, span).unwrap_or_else(|| {
                         span_err!(tcx.sess, span, E0228,
                             "the lifetime bound for this object type cannot be deduced \
                              from context; please supply an explicit bound");
@@ -2134,7 +2133,7 @@ pub fn ast_ty_to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
                 // values in a ExprKind::Closure, or as
                 // the type of local variables. Both of these cases are
                 // handled specially and will not descend into this routine.
-                self.ty_infer(ast_ty.span)
+                self.ty_infer(None, ast_ty.span)
             }
             hir::TyKind::CVarArgs(lt) => {
                 let va_list_did = match tcx.lang_items().va_list() {
@@ -2156,6 +2155,17 @@ pub fn ast_ty_to_ty(&self, ast_ty: &hir::Ty) -> Ty<'tcx> {
         result_ty
     }
 
+    /// Returns the `DefId` of the constant parameter that the provided expression is a path to.
+    pub fn const_param_def_id(&self, expr: &hir::Expr) -> Option<DefId> {
+        match &expr.node {
+            ExprKind::Path(hir::QPath::Resolved(_, path)) => match path.res {
+                Res::Def(DefKind::ConstParam, did) => Some(did),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+
     pub fn ast_const_to_const(
         &self,
         ast_const: &hir::AnonConst,
@@ -2186,19 +2196,17 @@ pub fn ast_const_to_const(
             }
         }
 
-        if let ExprKind::Path(ref qpath) = expr.node {
-            if let hir::QPath::Resolved(_, ref path) = qpath {
-                if let Res::Def(DefKind::ConstParam, def_id) = path.res {
-                    let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
-                    let item_id = tcx.hir().get_parent_node(node_id);
-                    let item_def_id = tcx.hir().local_def_id(item_id);
-                    let generics = tcx.generics_of(item_def_id);
-                    let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
-                    let name = tcx.hir().name(node_id).as_interned_str();
-                    const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
-                }
-            }
-        };
+        if let Some(def_id) = self.const_param_def_id(expr) {
+            // Find the name and index of the const parameter by indexing the generics of the
+            // parent item and construct a `ParamConst`.
+            let node_id = tcx.hir().as_local_node_id(def_id).unwrap();
+            let item_id = tcx.hir().get_parent_node(node_id);
+            let item_def_id = tcx.hir().local_def_id(item_id);
+            let generics = tcx.generics_of(item_def_id);
+            let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(node_id)];
+            let name = tcx.hir().name(node_id).as_interned_str();
+            const_.val = ConstValue::Param(ty::ParamConst::new(index, name));
+        }
 
         tcx.mk_const(const_)
     }