[rustdoc] Improve "in parameters" search and search more generally

src/librustc_typeck/collect.rs

@@ -1130,20 +1130,43 @@ fn report_assoc_ty_on_inherent_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, span:
 }
 
 fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
+    checked_type_of(tcx, def_id, true).unwrap()
+}
+
+/// Same as [`type_of`] but returns [`Option`] instead of failing.
+///
+/// If you want to fail anyway, you can set the `fail` parameter to true, but in this case,
+/// you'd better just call [`type_of`] directly.
+pub fn checked_type_of<'a, 'tcx>(
+    tcx: TyCtxt<'a, 'tcx, 'tcx>,
+    def_id: DefId,
+    fail: bool,
+) -> Option<Ty<'tcx>> {
     use rustc::hir::*;
 
-    let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
+    let hir_id = match tcx.hir().as_local_hir_id(def_id) {
+        Some(hir_id) => hir_id,
+        None => {
+            if !fail {
+                return None;
+            }
+            bug!("invalid node");
+        }
+    };
 
     let icx = ItemCtxt::new(tcx, def_id);
 
-    match tcx.hir().get_by_hir_id(hir_id) {
+    Some(match tcx.hir().get_by_hir_id(hir_id) {
         Node::TraitItem(item) => match item.node {
             TraitItemKind::Method(..) => {
                 let substs = InternalSubsts::identity_for_item(tcx, def_id);
                 tcx.mk_fn_def(def_id, substs)
             }
             TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => icx.to_ty(ty),
             TraitItemKind::Type(_, None) => {
+                if !fail {
+                    return None;
+                }
                 span_bug!(item.span, "associated type missing default");
             }
         },
@@ -1225,6 +1248,9 @@ fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
                 | ItemKind::GlobalAsm(..)
                 | ItemKind::ExternCrate(..)
                 | ItemKind::Use(..) => {
+                    if !fail {
+                        return None;
+                    }
                     span_bug!(
                         item.span,
                         "compute_type_of_item: unexpected item type: {:?}",
@@ -1264,7 +1290,7 @@ fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
             ..
         }) => {
             if gen.is_some() {
-                return tcx.typeck_tables_of(def_id).node_type(hir_id);
+                return Some(tcx.typeck_tables_of(def_id).node_type(hir_id));
             }
 
             let substs = ty::ClosureSubsts {
@@ -1342,6 +1368,9 @@ fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
                             }
                             // Sanity check to make sure everything is as expected.
                             if !found_const {
+                                if !fail {
+                                    return None;
+                                }
                                 bug!("no arg matching AnonConst in path")
                             }
                             match path.def {
@@ -1357,24 +1386,37 @@ fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
                                     for param in &generics.params {
                                         if let ty::GenericParamDefKind::Const = param.kind {
                                             if param_index == arg_index {
-                                                return tcx.type_of(param.def_id);
+                                                return Some(tcx.type_of(param.def_id));
                                             }
                                             param_index += 1;
                                         }
                                     }
                                     // This is no generic parameter associated with the arg. This is
                                     // probably from an extra arg where one is not needed.
-                                    return tcx.types.err;
+                                    return Some(tcx.types.err);
                                 }
                                 Def::Err => tcx.types.err,
-                                x => bug!("unexpected const parent path def {:?}", x),
+                                x => {
+                                    if !fail {
+                                        return None;
+                                    }
+                                    bug!("unexpected const parent path def {:?}", x);
+                                }
+                            }
+                        }
+                        x => {
+                            if !fail {
+                                return None;
                             }
+                            bug!("unexpected const parent path {:?}", x);
                         }
-                        x => bug!("unexpected const parent path {:?}", x),
                     }
                 }
 
                 x => {
+                    if !fail {
+                        return None;
+                    }
                     bug!("unexpected const parent in type_of_def_id(): {:?}", x);
                 }
             }
@@ -1385,13 +1427,21 @@ fn type_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Ty<'tcx> {
             hir::GenericParamKind::Const { ref ty, .. } => {
                 icx.to_ty(ty)
             }
-            x => bug!("unexpected non-type Node::GenericParam: {:?}", x),
+            x => {
+                if !fail {
+                    return None;
+                }
+                bug!("unexpected non-type Node::GenericParam: {:?}", x)
+            },
         },
 
         x => {
+            if !fail {
+                return None;
+            }
             bug!("unexpected sort of node in type_of_def_id(): {:?}", x);
         }
-    }
+    })
 }
 
 fn find_existential_constraints<'a, 'tcx>(

src/librustc_typeck/lib.rs

@@ -115,6 +115,8 @@ use util::common::time;
 
 use std::iter;
 
+pub use collect::checked_type_of;
+
 pub struct TypeAndSubsts<'tcx> {
     substs: SubstsRef<'tcx>,
     ty: Ty<'tcx>,

src/librustdoc/clean/inline.rs

@@ -212,15 +212,20 @@ fn build_external_function(cx: &DocContext<'_>, did: DefId) -> clean::Function {
     };
 
     let predicates = cx.tcx.predicates_of(did);
+    let generics = (cx.tcx.generics_of(did), &predicates).clean(cx);
+    let decl = (did, sig).clean(cx);
+    let (all_types, ret_types) = clean::get_all_types(&generics, &decl, cx);
     clean::Function {
-        decl: (did, sig).clean(cx),
-        generics: (cx.tcx.generics_of(did), &predicates).clean(cx),
+        decl,
+        generics,
         header: hir::FnHeader {
             unsafety: sig.unsafety(),
             abi: sig.abi(),
             constness,
             asyncness: hir::IsAsync::NotAsync,
-        }
+        },
+        all_types,
+        ret_types,
     }
 }